[Federal Register: February 14, 2007 (Volume 72, Number 30)]
[Rules and Regulations]
[Page 7135-7221]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr14fe07-14]
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Part II
Department of Labor
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Occupational Safety and Health Administration
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29 CFR Part 1910
Electrical Standard; Final Rule
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DEPARTMENT OF LABOR
Occupational Safety and Health Administration
29 CFR Part 1910
[Docket No. S-108C]
RIN 1218-AB95
Electrical Standard
AGENCY: Occupational Safety and Health Administration, Labor.
ACTION: Final rule.
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SUMMARY: The Occupational Safety and Health Administration (OSHA) is
revising the general industry electrical installation standard found in
Subpart S of 29 CFR Part 1910. The Agency has determined that
electrical hazards in the workplace pose a significant risk of injury
or death to employees, and that the requirements in the revised
standard, which draw heavily from the 2000 edition of the National Fire
Protection Association's (NFPA) Electrical Safety Requirements for
Employee Workplaces (NFPA 70E), and the 2002 edition of the National
Electrical Code (NEC), are reasonably necessary to provide protection
from these hazards. This final rule focuses on safety in the design and
installation of electric equipment in the workplace. This revision will
provide the first update of the installation requirements in the
general industry electrical installation standard since 1981.
OSHA is also replacing the reference to the 1971 NEC in the
mandatory appendix to the general industry powered platform standard
found in Subpart F of 29 CFR Part 1910 with a reference to OSHA's
electrical installation standard.
DATES: This final rule becomes effective on August 13, 2007.
ADDRESSES: In accordance with 28 U.S.C. 2112(a), the Agency designates
the Associate Solicitor of Labor for Occupational Safety and Health,
Office of the Solicitor of Labor, Room S4004, U.S. Department of Labor,
200 Constitution Avenue, NW., Washington, DC 20210, to receive
petitions for review of the final rule.
FOR FURTHER INFORMATION CONTACT: For general information and press
inquiries, contact Mr. Kevin Ropp, Director, Office of Communications,
Room N-3647, OSHA, U.S. Department of Labor, 200 Constitution Avenue,
NW., Washington, DC 20210; telephone (202) 693-1999. For technical
inquiries, contact Mr. David Wallis, Directorate of Standards and
Guidance, Room N-3609, OSHA, U.S. Department of Labor, 200 Constitution
Avenue, NW., Washington, DC 20210; telephone (202) 693-2222.
For additional copies of this Federal Register notice, contact
OSHA, Office of Publications, Room N-3101, U.S. Department of Labor,
200 Constitution Avenue, NW., Washington, DC 20210; telephone (202)
693-1888. Electronic copies of this Federal Register notice, as well as
news releases and other relevant documents, are available at OSHA's Web
page on the Internet at http://www.osha.gov.
SUPPLEMENTARY INFORMATION:
I. Introduction
This final rule revises OSHA's existing standard for electrical
installations, which is contained in Sec. Sec. 1910.302 through
1910.308 of Subpart S, with relevant definitions in Sec. 1910.399. It
applies, as the existing standard does, to employers in general
industry and in shipyard employment, longshoring, and marine terminals.
OSHA undertook the project to revise Subpart S for two major
reasons. First, the Agency wanted the standard to reflect the most
current practice and technology in the industry. The existing standard
is based on a national consensus standard, the 1979 edition of Part I
of NFPA 70E, entitled Standard for Electrical Safety Requirements for
Employee Workplaces. That consensus standard has been updated several
times since OSHA last revised its electrical installation requirements
in 1981. The final rule being published today is based on Part I of the
2000 edition of NFPA 70E. Second, in implementing this rule, OSHA is
responding to requests from stakeholders that the Agency revise Subpart
S so that it reflects the most recent editions of NFPA 70E and the
NEC.\1\ These stakeholders argued that interested members of the public
have had substantial input into the content of NFPA 70E and that
industry is complying with that consensus standard in its present form.
The revised standard will be more flexible and efficient for
stakeholders, including small businesses, while improving safety for
employees.
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\1\ See, for example, letters from: Judith Gorman, Managing
Director of the Institute of Electrical and Electronic Engineers;
George D. Miller, President and Chief Executive Officer of the
National Fire Protection Association; Frank K. Kitzantides, Vice
President of Engineering at the National Electrical Manufacturers
Association; and Kari P. Barrett, Director of Regulatory and
Technical Affairs, Plant Operations, at the American Chemistry
Council (Exhibit 2-62, 2-63, 2-64, 2-65).
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OSHA's existing electrical standard in Sec. Sec. 1910.302 through
1910.308 is based on the 1979 edition of NFPA 70E, which is a national
consensus standard developed by a cross section of industry, labor, and
other allied interests. Consensus standards like the NEC and NFPA 70E
provide nationally recognized safe electrical installation
requirements. Additionally, the consensus process used in developing
the 2000 edition of NFPA 70E, Part 1 of which is based on the NEC,
ensures that requirements contained in that standard are current and at
the forefront of electrical safety technology. Because the primary
objective of this revision of Subpart S is to update the standard to
recognize, and in some cases require, the more current electrical
safety technology, OSHA believes that the more recent editions of NFPA
70E should be the foundation of the final standard.\2\ Lastly, the
Agency has determined that electrical hazards in general industry
workplaces pose a significant risk and that the final standard will
substantially reduce that risk.
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\2\ A newer edition of NFPA 70E was published shortly after OSHA
issued the proposed rule. Whether the final rule should be based on
this edition, NFPA 70E-2004, is one of the issues raised by comments
on the proposal. See the discussion of this issue in section V,
Summary and Explanation of the Final Standard.
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The remainder of the preamble discusses the background of the final
rule, the history of the standard, and the legal authority for the
standard; provides a summary and explanation of the final standard;
includes the final economic and regulatory flexibility analysis and the
information collections associated with the rule; and covers other
miscellaneous topics. The outline of the preamble is as follows:
I. Introduction
II. Background
III. History of the Standard
IV. Legal Authority
V. Summary and Explanation of the Final Standard
VI. Final Economic and Regulatory Screening Analysis
VII. State Plan Standards
VIII. Environmental Impact Analysis
IX. Unfunded Mandates
X. Federalism
XI. OMB Review under the Paperwork Reduction Act of 1995
XII. Effective Date and Date of Application
II. Background
A. Hazards Associated With Electricity
Electricity is widely recognized as a serious workplace hazard,
exposing employees to electric shock, burns, fires, and explosions.
According to the Bureau of Labor Statistics, 289 employees were killed
by contact with electric current in 2002 (Ex. 2-8). Other employees
have been killed or injured in fires and explosions caused by electricity.
It is well known that the human body will conduct electricity. If
direct body contact is made with an electrically energized part while a
similar contact is made simultaneously with another conductive surface
that is maintained at a different electrical potential, a current will
flow, entering the body at one contact point, traversing the body, and
then exiting at the other contact point, usually the ground. Each year
many employees suffer pain, injuries, and death from such electric
shocks.
Current through the body, even at levels as low as 3 milliamperes,
can also cause injuries of an indirect or secondary nature in which
involuntary muscular reaction from the electric shock can cause
bruises, bone fractures and even death resulting from collisions or
falls.
Burns suffered in electrical accidents can be very serious. These
burns may be of three basic types: electrical burns, arc burns, and
thermal contact burns. Electrical burns are the result of the electric
current flowing in the tissues, and may be either skin deep or may
affect deeper layers (such as muscles and bones) or both. Tissue damage
is caused by the heat generated from the current flow; if the energy
delivered by the electric shock is high, the body cannot dissipate the
heat, and the tissue is burned. Typically, such electrical burns are
slow to heal. Arc burns are the result of high temperatures produced by
electric arcs or by explosions close to the body. Finally, thermal
contact burns are those normally experienced from the skin contacting
hot surfaces of overheated electric conductors, conduits, or other
energized equipment. In some circumstances, all three types of burns
may be produced simultaneously.
If the current involved is great enough, electric arcs can start a
fire. Fires can also be created by overheating equipment or by
conductors carrying too much current. Extremely high-energy arcs can
damage equipment, causing fragmented metal to fly in all directions. In
atmospheres that contain explosive gases or vapors or combustible
dusts, even low-energy arcs can cause violent explosions.
B. Nature of Electrical Accidents
Electrical accidents, when initially studied, often appear to be
caused by circumstances that are varied and peculiar to the particular
incidents involved. However, further consideration usually reveals the
underlying cause to be a combination of three possible factors: work
involving unsafe equipment and installations; workplaces made unsafe by
the environment; and unsafe work performance (unsafe acts). The first
two factors are sometimes considered together and simply referred to as
unsafe conditions. Thus, electrical accidents can be generally
considered as being caused by unsafe conditions, unsafe acts, or, in
what is usually the case, combinations of the two. It should also be
noted that inadequate maintenance can cause equipment or installations
that were originally considered safe to deteriorate, resulting in an
unsafe condition.
Some unsafe electric equipment and installations can be identified,
for example, by the presence of faulty insulation, improper grounding,
loose connections, defective parts, ground faults in equipment,
unguarded live parts, and underrated equipment. The environment can
also be a contributory factor to electrical accidents in a number of
ways. Environments containing flammable vapors, liquids, or gases;
areas containing corrosive atmospheres; and wet and damp locations are
some unsafe environments affecting electrical safety. Finally, unsafe
acts include the failure to deenergize electric equipment when it is
being repaired or inspected or the use of tools or equipment too close
to energized parts.
C. Protective Measures
There are various ways of protecting employees from the hazards of
electric shock, including insulation and guarding of live parts.
Insulation provides a barrier to the flow of current. To be effective,
the insulation must be appropriate for the voltage, and the insulating
material must be undamaged, clean, and dry. Guarding prevents the
employee from coming too close to energized parts. It can be in the
form of a physical barricade, or it can be provided by installing the
live parts out of employees' reach. (This technique is known as
"guarding by location.")
Grounding is another method of protecting employees from electric
shock; however, it is normally a secondary protective measure. To keep
guards or enclosures at a common potential with earth, they are
connected, by means of a grounding conductor, to ground. In addition,
grounding provides a path of low impedance and of ample capacity back
to the source to pass enough current to activate the overcurrent
devices in the circuit. If a live part accidentally contacts a grounded
enclosure, current flow is directed back to earth, and the circuit
protective devices (for example, fuses and circuit breakers) can
interrupt the circuit.
If it draws too much current, electric equipment can overheat,
which can result in fires. Overheating can also lead to electric shock
hazards if the insulation protecting a conductor melts. Protecting
electric equipment from overcurrent helps prevent this from happening.
Designing and installing equipment to protect against dangerous
arcing and overheating is also important in preventing unsafe
conditions that can lead to fires, high energy electric arcs, and
explosions. Employers and employees cannot usually detect improperly
designed or rated equipment. Thus, OSHA relies on third-party testing
and certification of electric equipment to ensure proper electrical
design. This helps ensure, for example, that equipment will not
overheat during normal operation and that equipment designed for use in
a hazardous location will not cause a fire or explosion. It also helps
ensure that equipment is appropriately rated and marked, allowing
employees designing electrical installations and installing electric
equipment to select equipment and size conductors in accordance with
those ratings.\3\ Many of the requirements in OSHA's electrical
standards in turn depend on accurate ratings on equipment.
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\3\ Electric equipment is typically rated for use with certain
voltages and current. For example, an electric hair dryer might be
rated at 125 volts, 1875 watts. The voltage rating indicates the
maximum voltage for which the equipment is rated. The wattage rating
indicates how much power the equipment will draw when connected to a
circuit at the maximum voltage. The current drawn by the equipment
is the wattage rating divided by the voltage rating. Thus, the
circuit voltage (120 volts, nominal) is less than the maximum rated
voltage of the hair dryer (125 volts), and the circuit is rated for
the current the equipment will draw (1875 watts/125 volts = 15
amperes). Thus, the hair dryer would be suitable for use on a 120-
volt circuit capable of safely carrying 15 amperes.
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These protective measures help ensure the safe installation of
electric equipment and are prescribed by the requirements presently
contained in 29 CFR Part 1910, Subpart S. Addressing common unsafe
conditions, these rules cover such safety considerations as guarding
and insulation of live parts, grounding of equipment enclosures, and
protection of circuits from overcurrent. This rulemaking updates those
requirements to make them consistent with the latest editions of NFPA
70E. This revision will better protect employees by recognizing the
latest techniques in electrical safety and by requiring installations
to incorporate those techniques whenever necessary.
D. Significant Risk and Reduction in Risk
As stated earlier, electricity has long been recognized as a
serious workplace hazard exposing employees to dangers such as electric
shock, electrocution, fires, and explosions. The 100-year-long history
of the National Electrical Code, originally formulated and periodically
updated by industry consensus, attests to this fact. The NEC has
represented the continuing efforts of experts in electrical safety to
address these hazards and provide standards for limiting exposure in
all electrical installations, including workplaces. OSHA has determined
that electrical hazards in the workplace pose a significant risk of
injury or death to employees and that this final rule, which draws
heavily on the experience of the NEC, will substantially reduce this
risk.
According to the U.S. Bureau of Labor Statistics, between 1992 and
2002, an average of 295 employees died per year from contact with
electric current, and between 1992 and 2001 an average of 4,309
employees lost time away from work because of electrical injuries.\4\
Overall, there has been a downward trend in injuries and illnesses, but
the percentage has varied from year to year. From 1992 to 2001, the
number of injuries involving days away from work decreased by 29
percent. From 1992 to 2002, the number of deaths decreased by 9
percent. This downward trend is due, in major part, to 30 years of
highly protective OSHA regulation in the area of electrical
installation, based on the NEC and NFPA 70E standards. The final
standard carries forward most of the existing requirements for
electrical installations, with the new and revised requirements
intended as fine tuning, introducing new technology along with other
improvements in safety. By complying with the final standard, employers
will prevent unsafe electrical conditions from occurring.
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\4\ The Survey of Occupational Injuries and Illnesses and the
Census of Fatal Occupational Injuries, http://www.bls.gov/iif/home.htm#tables.
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While the number of deaths and injuries associated with electrical
hazards has declined, contact with electric current still poses a
significant risk to employees in the workplace, as evidenced by the
numbers of deaths and serious injuries still occurring due to contact
with electric current. This final rule will help further reduce the
number of deaths and injuries associated with electrical hazards by
providing additional requirements for installation safety and by
recognizing alternative means of compliance.
III. History of the Standard
On February 16, 1972, OSHA incorporated the 1971 edition of the
National Fire Protection Association's (NFPA) National Electrical Code
(NEC), NFPA 70-1971, by reference as its electrical standard for
general industry (37 FR 3431). The Agency followed the procedures
outlined in Section 6(a) of the Occupational Safety and Health Act of
1970 (OSH Act; 29 U.S.C. 655), which directed the Secretary to adopt
existing national consensus standards as OSHA standards within 2 years
of the effective date of the OSH Act. In incorporating the 1971 NEC by
reference, OSHA made the entire 1971 NEC applicable to all covered
electrical installations made after March 15, 1972. For covered
installations made before that date, OSHA listed about 16 provisions
from the 1971 NEC that applied. No other provisions of the 1971 NEC
applied to these older installations. Thus, older installations were
"grandfathered" so that they did not need to meet most of the
requirements in the consensus standard.
On January 16, 1981, OSHA revised its electrical installation
standard for general industry (46 FR 4034). This revision replaced the
incorporation by reference of the 1971 NEC with relevant requirements
from Part I of the 1979 edition of NFPA 70E. The revision simplified
and clarified the electrical standard and updated its provisions to
match the 1978 NEC (the latest edition available at the time). The
standard was written to reduce the need for frequent revision and to
avoid technological obsolescence. These goals were achieved--NFPA 70E
had only minor changes over its initial 15 years of existence. The
first substantial changes were introduced in the 1995 edition of NFPA
70E.
The 2000 edition of NFPA 70E contains a number of significant
revisions, including a new, alternative method for classifying and
installing equipment in Class I hazardous locations (see preamble
Section I. N. Zone Classification, below). NFPA has recommended that
OSHA revise its general industry electrical standards to reflect the
latest edition of NFPA 70E, arguing that such a revision would provide
a needed update to the OSHA standards and would better protect
employees. This final rule responds to NFPA's recommendations with
regard to installation safety. It also reflects the Agency's commitment
to update its electrical standards, keep them consistent with NFPA
standards, and ensure that they appropriately protect employees. The
Agency intends to extend this commitment by using NFPA 70E as a basis
for future revisions to its electrical safety-related work practice
requirements and new requirements for electrical maintenance and
special equipment.
The proposed rule was published in the Federal Register on April 5,
2004. The public had a 60-day comment period that ended on June 4,
2004. OSHA received 38 comments on the proposed revision of OSHA's
electrical installation standard for general industry. The Agency
received one hearing request on the proposal, which was subsequently
withdrawn.
The comments addressed specific provisions in the proposal and
raised several issues, including: (1) Whether OSHA should use the
latest edition of NFPA 70E or the NEC to revise Subpart S; (2) whether
OSHA should update the corresponding construction standard at the same
time; (3) whether OSHA should address work practices and other revised
provisions of NFPA 70E; and (4) what the effective date of the standard
should be. (See section V, "Summary and Explanation of the Final
Standard," later in the preamble, for a discussion of the comments.)
IV. Legal Authority
The purpose of the OSH Act, 29 U.S.C. 651 et seq., is "to assure
so far as possible every working man and woman in the Nation safe and
healthful working conditions and to preserve our human resources." 29
U.S.C. 651(b). To achieve this goal, Congress authorized the Secretary
of Labor to promulgate and enforce occupational safety and health
standards. 29 U.S.C. 655(b) & 658.
A safety or health standard "requires conditions, or the adoption
or use of one or more practices, means, methods, operations, or
processes, reasonably necessary or appropriate to provide safe or
healthful employment and places of employment." 29 U.S.C. 652(8). A
standard is reasonably necessary or appropriate within the meaning of
Section 652(8) if:
A significant risk of material harm exists in the
workplace and the proposed standard would substantially reduce or
eliminate that workplace risk;
It is technologically and economically feasible;
It employs the most cost effective protective measures;
It is consistent with prior Agency action or supported by
a reasoned justification for departing from prior Agency action;
It is supported by substantial evidence; and
In the event the standard is preceded by a consensus
standard, it is better able to effectuate the purposes of the OSH Act
than the standard it supersedes.
International Union, UAW v. OSHA (LOTO II), 37 F.3d 665, 668 (D.C.
Cir. 1994).
OSHA has generally considered an excess risk of 1 death per 1000
employees over a 45-year working lifetime as clearly representing a
significant risk (see Industrial Union Dept. v. American Petroleum
Institute (Benzene), 448 U.S. 607, 655 (1980); International Union v.
Pendergrass (Formaldehyde), 878 F.2d 389, 392-93 (D.C. Cir. 1989);
Building and Construction Trades Dept., AFL-CIO v. Brock (Asbestos),
838 F.2d 1258, 1264-65 (D.C. Cir. 1988)).
A standard is considered technologically feasible if the protective
measures it requires already exist, can be brought into existence with
available technology, or can be created with technology that can
reasonably be expected to be developed (see American Iron and Steel
Institute v. OSHA (Lead II), 939 F.2d 975, 980 (D.C. Cir. 1991)). A
standard is economically feasible when industry can absorb or pass on
the costs of compliance without threatening the industry's long-term
profitability or competitive structure (see American Textile Mfrs.
Institute v. OSHA (Cotton Dust), 452 U.S. 490, 530 n. 55 (1981); Lead
II, 939 F.2d at 980). A standard is cost effective if the protective
measures it requires are the least costly of the available alternatives
that achieve the same level of protection (see LOTO II, 37 F.3d at
668).
All OSHA standards must be highly protective (LOTO II, 37 F.3d at
669) and, where practical, "expressed in terms of objective criteria
and of the performance desired." 29 U.S.C. 655(b)(5). Finally, the OSH
Act requires that when promulgating a rule that differs substantially
from a national consensus standard, OSHA must explain why the
promulgated rule is a better method for effectuating the purpose of the
OSH Act. 29 U.S.C. 655(b)(8). As discussed earlier, OSHA is using NFPA
70E as the basis for its final rule, with some modifications as
necessary, as explained in detail in the next section of the preamble.
V. Summary and Explanation of the Final Standard
This section discusses the important elements of the final
standard, explains the purpose of the individual requirements, and
explains any differences between the final standard and the existing
standard. This section also discusses and resolves issues raised during
the comment period, significant comments received as part of the
rulemaking record, and any substantive changes that were made from the
language of the proposed rule. References in parentheses are to
exhibits in the rulemaking record. Except as noted, OSHA is carrying
forward the language from the proposal into the final rule without
substantive differences.
A. Issues
1. Comments supporting the revision of Subpart S. The vast majority
of the comments supported OSHA's efforts to update the general industry
electrical standards (Exs. 3-3, 3-4, 3-6, 3-7, 3-8, 3-9, 4-10, 4-24).
For example, the National Petrochemical & Refiners Association
expressed support for updating Subpart S so that it is consistent with
the current editions of the NFPA 70E and the NEC, because, they stated,
its members place a high priority on safety and understand the
necessity for electrical installation standards (Ex. 3-4). The American
Society of Safety Engineers (ASSE) also supported the proposal,
stating: "It is appropriate to move forward with this revision, given
the seriousness of electrical hazards and the fact that nearly 300
workers are killed each year from contact with electrical current or as
the result of injuries caused by fires and explosions related to
electrical accidents [Ex. 3-5]."
The National Institute for Occupational Safety and Health (NIOSH)
and the North Carolina Department of Labor also supported OSHA's
proposed revision (Exs. 3-9, 5-2). NIOSH stated: "The proposed revised
standard will provide workers in general industry and maritime
employment with improved protection against injuries and death from
electrical hazards [Ex. 3-9]." The North Carolina Department of Labor
expressed a similar view, stating: "The revisions proposed to the
existing standard should provide a greater measure of protection to
employees working on and around electrical equipment and installations
[Ex. 5-2]."
OSHA appreciates the support of these commenters. The Agency
believes that the final standard will better protect employees than the
existing standard. The record overwhelmingly supports this view.
2. OSHA should use the latest version of NFPA 70E or the NEC. OSHA
received several comments recommending that the standard be based on
the latest version of NFPA 70E or the NEC (Exs. 3-8, 4-3, 4-6, 4-8, 4-
11). Some of the commenters argued that, by using the 2000 edition of
the NFPA 70E rather than the more recent 2004 edition, OSHA was not
reflecting the most current practices and technology. For example,
David Soffrin of the American Petroleum Institute stated:
We applaud the reasons for the proposal, as stated by OSHA: (a)
To reflect the most current practice and technology in the industry;
and (b) to respond to requests from stakeholders that the electrical
standards conform with the most recent editions of the National Fire
Protection Association (NFPA) 70E, Standard for Electrical Safety
Requirements for Employee Workplaces, and the National Electrical
Code (NEC). However, the proposal follows the NFPA standard 70E-
2000, while the NFPA Standards Council issued an updated version
January 14, 2004, which supercedes NFPA 70E-2000. We believe that if
the intent is to reflect the most current practice and technology,
using a four-year-old standard, which will be even more dated by the
time OSHA finalizes this standard, is inappropriate. We therefore
recommend that OSHA revise the proposal using NFPA 70E-2004,
Standard for Electrical Safety in the Workplace, or the 2002 NEC,
which would require numerous modifications [Ex. 4-11].
John Paschal of the Bechtel Corporation wrote: "Since NFPA 70E-
2004 is now published and issued to the public, and since it contains
significantly enhanced technical data that the NFPA 70E-2000 did not
contain, I recommend that OSHA adopt NFPA 70E-2004 instead of NFPA 70E-
2000 [Ex. 4-3]."
James Kendrick of ASSE noted that the major differences between the
current versions of the OSHA electrical installation standards and the
proposed rule fall into the following categories:
Changes in the hardware specifications that are consistent
with NEC requirements,
Changes in installation practices that are consistent with
the current, accepted installation practices followed by licensed
electricians and other qualified persons,
Clarification of existing requirements that add minimal
new obligations or otherwise permit flexibility in compliance, and
Requirements that do significantly modify electrical
system and equipment installation practices or impose new documentation
requirements (Ex. 3-5).
He was concerned that the OSHA final rule would be functionally
obsolete when it is published and, thus, have diminished utility in the
future since most electricians are currently learning the NEC 2002
coding system. He argued that it would be beneficial for OSHA to use
the same standard as those involved in electrical work.
OSHA has decided not to base the final rule as a whole on NFPA 70E-
2004, which was published on April 9, 2004, shortly after OSHA's
proposal was published. The 2004 version of the national consensus
standard was not placed in the rulemaking record; therefore, the Agency
does not believe that the public would have had adequate notice of the
many changes in the latest NFPA standard, to the extent that the Agency
would have incorporated these changes in the final rule. Basing Subpart
S on the latest edition of NFPA 70E would thus necessitate reproposing
the rule. Given the time involved in reproposing and finalizing an OSHA
standard, it is likely that NFPA 70E will be revised yet again within
that timeframe. In addition, because NFPA 70E and OSHA's electrical
installation standard were developed specifically to minimize the need
for revision with every new version of the NEC, a final rule based on
the 2000 edition of NFPA 70E will not be obsolete. Furthermore, several
provisions in the final rule are based on corresponding requirements in
the 2002 NEC, on which NFPA 70E-2004 is based. (See the distribution
table later in this section of the preamble.) In proposing and
finalizing this revision of Subpart S, OSHA carefully chose which NEC
changes would have the greatest impact on employee safety. The Agency
does not believe that delaying the substantial increase in employee
safety that would result from the standard published in the final rule
is warranted.
On the other hand, where the rulemaking record supports specific
requirements that are consistent with the 2004 edition of NFPA 70E,
OSHA has adopted those requirements in the final rule. For example,
final Sec. 1910.304(b)(3)(ii)(A) is based, in part, on Section
410.4(B)(1) of the 2004 edition of NFPA 70E rather than Part I, Chapter
2, Section 2.4 of the 2000 edition of NFPA 70E. (See the detailed
explanation, later in the preamble, discussing the rationale for this
provision, which requires a written assured equipment grounding
conductor program where ground-fault circuit-interrupters are not
available.) In these specific cases, the rulemaking record supports
OSHA's using the language from the relevant provision in NFPA 70E-2004
and from the 2002 NEC, on which the new NFPA 70E requirement is based.
This avoids the notice problem discussed earlier. In addition, OSHA
will consider using later versions of NFPA 70E to update the electrical
installation requirements adopted in this final rule when the Agency
develops future proposals to revise Subpart S to update the existing
electrical safety-related work practice requirements and to adopt new
provisions on safety-related maintenance and special equipment.
3. OSHA should update the Electrical Standard for construction at
the same time this rule is being promulgated. The Agency received one
comment asking OSHA to consider revising the Electrical Standard for
construction at the same time as the revision to the Electrical
Standard for general industry (Ex. 4-2). Reliable Safety Solutions,
LLC, stated that installing equipment in general industry and
installing equipment in the construction industry is much the same (Ex.
4-2). They argued that the hazards encountered are the same and the
safe work practices when working with electricity are the same. Thus,
they said that to update one standard and not the other would allow for
one standard to be out of date and certain hazards to exist.
The Agency is aware that the general industry and the construction
industry both address similar electrical hazards and have similar safe
work practices. OSHA is also aware that its electrical standards for
construction in 29 CFR 1926, Subpart K also need updating. Like Subpart
S, Subpart K is based on the 1979 edition of NFPA 70E. In addition, the
electrical safety-related work practices in Subpart K are even older
than their general industry counterparts. However, OSHA must consult
with the Advisory Committee on Construction Safety and Health before
publishing a proposal. In addition, OSHA would have to include the
construction industry in its regulatory analysis and repropose the
standard to address construction as part of this rulemaking. Although
OSHA will consider updating Subpart K to make it consistent with
Subpart S in the future, it is not possible to do so as part of this
final rule.
4. OSHA should update the safety-related work practice requirements
in Subpart S at the same time this rule is being promulgated. One
commenter recommended that OSHA revise its electrical safety-related
work practice standard in Subpart S based on the corresponding
requirements in NFPA 70E (Ex. 4-5). He argued that electricians
encounter exposed energized parts of electric circuits, which
demonstrates the need for the protective clothing and safe work
practices contained in NFPA 70E.
OSHA agrees that the latest editions of NFPA 70E provide improved
protection to employees through better electrical safety-related work
practices. In particular, the heightened focus on the hazards posed by
electric arcs may substantially reduce injuries and fatalities
associated with those hazards. However, revising the safety-related
work practice requirements in Subpart S is beyond the scope of this
rulemaking. The Agency is planning to update these requirements as the
next phase of the project to update OSHA's electrical standards.
Although OSHA expects this phase of the project to yield significant
benefits, the Agency also expects it to take longer to promulgate a
final rule on safety-related work practices owing to the more complex
regulatory analysis required and the greater controversy that is likely
to be encountered.
B. Scope
Existing Sec. Sec. 1910.302 through 1910.308 of Subpart S apply to
electrical installations and utilization equipment used and installed
in workplaces in general industry and in shipyard employment,
longshoring, and marine terminals. These sections do not apply to the
following types of installations:
(1) Installations in ships, watercraft, railway rolling stock,
aircraft, or automotive vehicles other than mobile homes and
recreational vehicles;
(2) Installations underground in mines; \5\
---------------------------------------------------------------------------
\5\ This exception was incorporated into the current OSHA
standard to be consistent with language used in the NEC and NFPA
70E. However, it should be noted that OSHA does not have
jurisdiction over mines in general, regardless of whether the mining
activity takes place above ground or underground. Under the Mine
Safety and Health Act (MSH Act) (30 U.S.C. 801 et seq.), the Mine
Safety and Health Administration (MSHA) regulates safety and health
in mines. For further information, see the Interagency Agreement
between MSHA and OSHA (http://www.osha.gov/pls/oshaweb/owadisp.show_document?
p_table=MOU&p_id=222).
---------------------------------------------------------------------------
(3) Installations of railways for generation, transformation,
transmission, or distribution of power used exclusively for operation
of rolling stock or installations used exclusively for signaling and
communication purposes;
(4) Installations of communication equipment under the exclusive
control of communication utilities and located outdoors or in building
spaces used exclusively for such installations; and
(5) Installations under the exclusive control of electric utilities
for the purpose of communication or metering; or for the generation,
control, transformation, transmission, and distribution of electric
energy. These exempted installations must be located in buildings used
exclusively by utilities for such purposes or located outdoors on
property owned or leased by the utility or on public highways, streets,
roads, etc., or outdoors by established rights on private property.
These exempted installations present special design considerations
that are not adequately addressed in Subpart S. For example, electric
power transmission and distribution installations are typically
installed where unqualified persons will not have access to them, and
the only employees working on them are highly trained and skilled.
Additionally, public safety considerations demand that these
installations be capable of quick repair when weather or equipment
failure disrupts electrical service. The National Electrical Safety
Code (ANSI/IEEE C2), which is developed by experts in electric power
generation, transmission, and distribution, contains design and
installation requirements applicable to electric power generation,
transmission, and distribution systems. Section 1910.269 contains
OSHA's standard for the maintenance of electric power generation,
transmission, and distribution installations. While it consists mostly
of work-practice requirements, it does contain several installation
requirements. For example, Sec. 1910.269(u)(4) and (v)(4) cover
guarding of rooms containing electric supply equipment in electric
power generating stations and substations, respectively.
Installations in ships, watercraft, railway rolling stock,
aircraft, or automotive vehicles (other than mobile homes and
recreational vehicles) are designed to be transportable.\6\ These
transportability considerations make many of the design requirements in
Subpart S irrelevant or infeasible. For example, attaching the grounded
circuit conductor and the equipment grounding conductor to a permanent
grounding electrode on a transportable wiring system is generally not
feasible. Thus, some of the provisions in final Sec. 1910.304(g),
which contains requirements for grounding electrical systems, are
inappropriate for the wiring of ships, watercraft, railway rolling
stock, aircraft, or automotive vehicles. By contrast, however, wiring
that is not a part of the wiring of the ship, watercraft, railway
rolling stock, aircraft, or automotive vehicle would be covered by
Subpart S, as appropriate. For example, a portable electric drill
carried into the cargo area of a truck would be covered by Subpart S if
it is plugged into the wiring of a service station.
---------------------------------------------------------------------------
\6\ Although the wiring of recreational vehicles and mobile
homes is transportable, it is also designed to be attached to
specially designed, permanently installed power distribution
outlets. This type of hybrid system must be designed for both
permanent and transportable uses.
---------------------------------------------------------------------------
In regard to ships, there has been some confusion about whether the
"exemption" applies to all wiring or electrical installations brought
on board a vessel during construction, repair, or ship scrapping even
when the wiring is supplied by shore-based electric power--or whether
it only applies to the ship's own wiring. OSHA is hereby clarifying the
application of the exemptions.
The "exempted" types of installations in both the existing and
final standards are identical to those "exempted" by the NEC and NFPA
70E, which form the basis of both standards. Installations covered
under the existing standard continue to be covered under the final
standard. For example, in longshoring operations and related
employments, this final rule applies to electrical installations aboard
vessels only if they are shore-based as stated in Sec. 1918.1(b)(3).
Electrical installations in marine terminals are also covered under
Subpart S, as noted in Sec. 1917.1(a)(2)(iv). (The marine terminals
standard in Part 1917 applies to the loading, unloading, movement or
other handling of cargo, ship's stores or gear within the terminal or
into or out of any land carrier, holding or consolidation area, and any
other activity within and associated with the overall operation and
function of the terminal. This includes the use and routine maintenance
of facilities and equipment and cargo transfer accomplished with the
use of shore-based material handling devices. See Sec. 1917.1(a).)
Section 1910.5 governs how the general industry standards apply to
shipyard employment. According to Sec. 1910.5(c), the general
standards in Part 1910 apply to shipyard employment to the extent that
no industry-specific standard applies to the "same condition,
practice, means, method, operation, or process." Part 1915 contains
few requirements related to electrical safety. Paragraph (b) of Sec.
1915.93 contains four such requirements, for grounding of vessels, the
safety of the vessel's wiring, overcurrent protection, and guarding of
infrared heat lamps. Section 1915.92 contains provisions on temporary
electric lighting, and Sec. 1915.132 contains requirements on portable
electric tools. Section 1915.181 contains electrical safety-related
work practices for deenergizing electric circuits and protecting
employees against contact with live parts during electrical work. In
addition, Part 1915 contains several other miscellaneous electrical
safety-related work practices and electrical design requirements. These
provisions continue to apply in lieu of any corresponding requirements
in Subpart S of Part 1910. Conversely, where there is no specific
electrical installation requirement for shipyard employment in Part
1915, Subpart S of Part 1910 applies.
As noted earlier, Subpart S does not cover installations in ships,
but it does cover installations used on ships if the installation is
shore-based (that is, not part of the vessel's original, internal
electrical system). Thus, final Sec. 1910.303(g)(2) (guarding live
parts) applies to the shore-based wiring of the shipyard and to any
wiring taken onto the ship when it is supplied by shore-based wiring.
It does not apply to the ship's permanent wiring. The final rule does
not change this coverage.
C. Grandfather Clause
The final rule, as does the current standard, exempts older
electrical installations from meeting some of the provisions of the
Design Safety Standards for Electrical Systems (that is, Sec. Sec.
1910.302 through 1910.308). The extent to which OSHA's electrical
installation standard applies depends on the date the installation was
made. Older installations must meet fewer requirements than newer ones.
The grandfathering of older installations, contained in paragraph (b)
of final Sec. 1910.302, is patterned after the current standard's
grandfather provisions in existing Sec. 1910.302(b). Most of the new
provisions contained in the final rule only apply prospectively, to
installations made after the effective date of the final rule.
The following paragraphs explain final Sec. 1910.302(b) in the
following order: Paragraph (b)(1), requirements applicable to all
installations; paragraph (b)(4), requirements applicable only to
installations made after the effective date of the revised standard;
paragraph (b)(3), requirements applicable only to installations made
after April 16, 1981; and paragraph (b)(2), requirements applicable
only to installations made after March 15, 1972.
Requirements applicable to all installations. Paragraph (b)(1) of
final Sec. 1910.302 contains a list of provisions that would apply to
all installations, regardless of when they were designed or installed.
The few requirements in this short list are so essential to employee
safety that even the oldest electrical installations must be modified,
if necessary, to meet them. The list is unchanged from the current
standard, except for the addition of: a prohibition on using grounding
terminals and devices for purposes other than grounding (in final
Sec. 1910.304(a)(3)); a documentation requirement for hazardous
locations made under the zone classification system (in final Sec.
1910.307(b)); and requirements covering the zone classification system
(in final Sec. 1910.307(g)).
New provisions applicable to all installations. Paragraph (a)(3) of
Sec. 1910.304 prohibits the use of a grounding terminal or grounding-
type device on a receptacle, cord connector, or attachment plug for
purposes other than grounding. OSHA's reasons for adding this
requirement to the list of provisions applicable to all installations
is discussed later in this section of the preamble.
Paragraph (b) of final Sec. 1910.307 contains a new requirement
that employers document areas designated as hazardous (classified)
locations. This requirement would ensure that the employer has records
of the extent and classification of each such area. The documentation
will help employers to determine what type of equipment is needed in
these locations and will inform employees of the need for special care
in the maintenance of the electric equipment installed there. OSHA has
carefully considered the need to document these areas and has tried to
balance that need with the extensive burden that would be placed on
employers who would have to survey and document their existing
hazardous locations.
The current standard's division classification system has been in
place for many years, and most employers and inspection authorities are
familiar with the boundaries for Class I, II, and III, Division 1 and 2
locations. An employee servicing equipment in one of these locations
can obtain this information relatively easily even if the employer has
not documented the boundaries. Accordingly, OSHA believes that the
benefit of documenting existing hazardous locations installed using the
division classification system would be minimal. Therefore, for
employers using the division system, OSHA is requiring documentation of
boundaries only for new installations made after the effective date of
the final standard. Employers would not need to document existing
division-classified systems.
On the other hand, the zone classification system is relatively
new. Most employers are not familiar with this system and have little
experience determining how to draw the boundaries between the three
zones. Relatively few NFPA or industry standards provide specifications
for placing those boundaries. Furthermore, the existing OSHA electrical
standard recognizes only installations made in accordance with the
division classification system, not the zone classification system. Any
existing installation made under the zone system is technically out of
compliance with OSHA's existing standard. However, because the NEC
represents standard industry practice, existing zone system
installations will almost certainly have been installed in accordance
with an edition of the NEC that recognizes the zone classification
system (the 1999 and 2002 editions). These editions of the NEC
explicitly require documentation of hazardous locations. Thus, an
employer with an existing installation made under the zone
classification system should already have the documentation required by
final Sec. 1910.307(b). For these reasons, OSHA is applying the
documentation requirement to all hazardous location installations made
under the zone classification system. This will provide employers,
employees, and OSHA with information critical for determining which
equipment is suitable in a given hazardous location.
The new requirements pertaining to zone classification in final
Sec. 1910.307(g) provide employers with an alternative installation
method that the current standard does not permit.\7\ Thus, applying
these provisions to older installations would give employers greater
flexibility without imposing any new costs. Furthermore, to the extent
that employers are already using the zone classification system, those
employers are likely already meeting final Sec. 1910.307(g), which is
based on provisions in the 1999 and 2002 editions of the NEC.
---------------------------------------------------------------------------
\7\ See the discussion under the heading "Zone Classification"
for an explanation of the zone classification system and its
differences from the current standard's division classification
system.
---------------------------------------------------------------------------
Requirements applicable only to installations made after the
effective date of the final rule. Paragraph (b)(4) of final Sec.
1910.302 makes the following provisions applicable only to
installations made or overhauled \8\ after the effective date of the
final rule:
---------------------------------------------------------------------------
\8\ See the discussion of the term "overhaul" later in this
section of the preamble.
------------------------------------------------------------------------
------------------------------------------------------------------------
Sec. 1910.303(f)(4).................. Disconnecting means and
circuits--Capable of accepting
a lock.
Sec. 1910.303(f)(5).................. Disconnecting means and
circuits--Marking for series
combination ratings.
Sec. 1910.303(g)(1)(iv) and 600 Volts, nominal, or less--
(g)(1)(vii). Space about electric
equipment.
Sec. 1910.303(h)(5)(vi).............. Over 600 volts, nominal--
Working space and guarding.
Sec. 1910.304(b)(1).................. Branch circuits--Identification
of multiwire branch circuits.
Sec. 1910.304(b)(3)(i)............... Branch circuits--Ground-fault
circuit interrupter protection
for personnel.
Sec. 1910.304(f)(2)(i)(A), Overcurrent protection--Feeders
(f)(2)(i)(B) (but not the introductory and branch circuits for over
text to Sec. 1910.304(f)(2)(i)), and 600 volts, nominal.
(f)(2)(iv)(A).
Sec. 1910.305(c)(3)(ii).............. Switches--Connection of
switches.
Sec. 1910.305(c)(5).................. Switches--Grounding.
Sec. 1910.306(a)(1)(ii).............. Electric signs and outline
lighting--Disconnecting means.
Sec. 1910.306(c)(4).................. Elevators, dumbwaiters,
escalators, moving walks,
wheelchair lifts, and stairway
chair lifts--Operation.
Sec. 1910.306(c)(5).................. Elevators, dumbwaiters,
escalators, moving walks,
wheelchair lifts, and stairway
chair lifts--Location.
Sec. 1910.306(c)(6).................. Elevators, dumbwaiters,
escalators, moving walks,
wheelchair lifts, and stairway
chair lifts--Identification
and signs.
Sec. 1910.306(c)(7).................. Elevators, dumbwaiters,
escalators, moving walks,
wheelchair lifts, and stairway
chair lifts--Single-car and
multicar installations.
Sec. 1910.306(j)(1)(iii)............. Swimming pools, fountains, and
similar installations--
Receptacles.
Sec. 1910.306(k)..................... Carnivals, circuses, fairs, and
similar events.
Sec. 1910.308(a)(5)(v) and Systems over 600 volts,
(a)(5)(vi)(B). nominal--Interrupting and
isolating devices.
Sec. 1910.308(a)(7)(vi).............. Systems over 600 volts,
nominal--Tunnel installations.
Sec. 1910.308(b)(3).................. Emergency power systems--Signs.
Sec. 1910.308(c)(3).................. Class 1, Class 2, and Class 3
remote control, signaling, and
power-limited circuits--
Separation from conductors of
other circuits.
Sec. 1910.308(f)..................... Solar photovoltaic systems.
------------------------------------------------------------------------
These provisions are based on requirements that have been added to
the NEC since the 1978 edition. OSHA has never required employers to
comply with these requirements, and the Agency believes that an
increase in employee protection will result from compliance with them
in new installations. At the same time, employers would incur minimal
costs to achieve this increase in new installations. In local
jurisdictions requiring compliance with the NEC, there should be no
additional costs involved, because the installations would already
conform to the new OSHA requirements. The Agency believes that even in
other jurisdictions, the vast majority of installations already comply
with the latest edition of the NEC, because compliance with the latest
Code is standard industry practice. OSHA, however, does not believe
that it is reasonably necessary and appropriate to require existing
installations to conform to these provisions, particularly given the
cost and difficulty associated with retrofitting older installations.
There are many provisions in the final rule that are not contained
in the existing standard but cannot be considered totally "new"
provisions. Most of these "new" requirements were actually contained
in the 1971 NEC. Table 1 lists these "new" provisions and denotes
their counterparts in the 1971 NEC. From March 15, 1972, until April
16, 1981, Subpart S incorporated the 1971 NEC by reference in its
entirety. Accordingly, OSHA required employers to comply with every
requirement in the 1971 NEC for any new installation made between those
dates and for any replacement, modification, repair, or rehabilitation
made during that period. The current standard, which became effective
on April 16, 1981, omitted many of the detailed provisions of the NEC
because they were already addressed by the more general requirements
that were contained in the OSHA standard. For example, OSHA did not
carry forward 1971 NEC Section 110-11, which required equipment to be
suitable for the environment if it is installed where the environment
could cause deterioration. However, the requirement for equipment to be
suitable for the location in which it was installed is implicit in the
more general requirements in existing Sec. 1910.303(a) that equipment
be approved and in existing Sec. 1910.303(b)(2) that equipment be
installed in accordance with any instructions included in its listing
or labeling. (Equipment that is not suitable for installation in
deteriorating environments, such as wet or damp locations, will include
instructions warning against such installation. These instructions are
required by the nationally recognized testing laboratory listing or
labeling the product.)
Even though OSHA no longer specifically incorporates the 1971 NEC
into Subpart S, the Agency believes that employers' installations
actually do comply with those requirements. The vast majority of
employers are following the entire NEC applicable to their
installations, as noted in the Economic Analysis section of this
preamble.\9\ For these reasons, OSHA is not exempting installations
made after March 15, 1972, from meeting any provision listed in Table 1
and is not including any of these provisions in final Sec.
1910.302(b)(4) (the list of provisions that apply only to new
installations).
---------------------------------------------------------------------------
\9\ All of the requirements in question appear in some form in
every edition of the NEC since 1972.
\10\ These provisions have no direct counterpart in existing
Subpart S, but were in the 1971 National Electrical Code.
Table 1.--"New" Provisions That Were Contained in 1971 NEC \10\
------------------------------------------------------------------------
Provision in the final Equivalent 1971
standard NEC section Subject
------------------------------------------------------------------------
Sec. 1910.303(b)(3)......... 110-20........... Insulation integrity.
(b)(4).................... 110-9............ Interrupting rating.
(b)(5).................... 10-10............ Circuit impedance and
other
characteristics.
(b)(6).................... 110-11........... Deteriorating agents.
(b)(7).................... 110-12........... Mechanical execution
of work.
(b)(8).................... 110-4(a) and (d). Mounting and cooling
110-12........... of equipment.
110-13...........
(c)(1).................... 110-14........... Electrical
connections,
general.
Sec. 1910.304(b)(2)......... 210-21(b)........ Branch circuits,
receptacles and cord
connectors.
(b)(4).................... 210-21........... Branch circuits,
outlet devices.
(b)(5).................... 210-22........... Branch circuits, cord
connections.
(e)(1)(iii)............... 230-70(c)........ Services,
disconnecting means.
(f)(1)(ix)................ 110-9............ Overcurrent
240-11........... protection, 600
volts, nominal, or
less, circuit
breaker ratings.
(f)(2), except for 240-5............ Overcurrent
(f)(2)(i)(A), 240-11........... protection, feeders
(f)(2)(i)(B), and 240-15........... and branch circuits
(f)(2)(iv)(A). over 600 volts,
nominal.
Sec. 190.305(a)(4)(ii)...... 320-5............ Open wiring on
insulators, support.
(b)(1)(iii)............... 370-7............ Conductors entering
373-5............ cabinets, boxes, and
fittings, securing
conductors.
(b)(2)(ii)................ 370-15(b)........ Fixture canopy or pan
installed in a
combustible wall or
ceiling.
(e)(1).................... 373-2............ Airspace for
384-5............ enclosures installed
in wet or damp
locations.
(h)(3).................... 710-6............ Portable cables,
grounding
conductors.
(j)(2)(i)................. 410-52(d)........ Receptacles, cord
connectors, and
attachment plugs; no
exposed energized
parts.
(j)(2)(iv) through 410-54........... Receptacles installed
(j)(2)(vii). in wet or damp
locations.
(j)(3)(ii)................ 422-20........... Appliances,
disconnecting means.
(j)(3)(iii)............... 422-30(a)........ Appliances,
nameplates.
(j)(3)(iv)................ 422-30(b)........ Appliances, marking
to be visible after
installation.
(j)(6)(ii)(A)............. 110-9............ Capacitor switches.
110-10...........
460-8(c)(4)......
(j)(6)(ii)(B)............. 460-8(c)(1)...... Capacitor
disconnecting means.
Sec. 1910.306(c)(3)......... 620-51(a)........ Elevators,
dumbwaiters,
escalators, moving
walks, wheelchair
lifts, and stairway
chair lifts; type of
disconnecting means.
(c)(10)................... 620-72........... Elevators,
dumbwaiters,
escalators, moving
walks, wheelchair
lifts, and stairway
chair lifts; motor
controllers.
(d)(1).................... 630-13........... Arc welders,
630-23........... disconnecting means.
(g)(1)(iii)............... 665-34........... Induction and
dielectric heating
equipment,
detachable panels
used for access to
live parts.
(g)(1)(vi)................ 665-8............ Induction and
dielectric heating
equipment, ampere
rating of
disconnecting means.
(j)(4)(iii)............... 680-20(a)(4)..... Swimming pools,
fountains, and
similar
installations,
underwater fixtures
facing upwards.
Sec. 1910.308(a)(2)......... 710-4............ Systems over 600
volts, nominal; open
installations of
braid-covered
insulated
conductors.
(a)(3)(i)................. 710-6............ Systems over 600
volts, nominal;
insulation shielding
terminations.
(a)(4).................... 710-8............ Systems over 600
volts, nominal;
moisture or
mechanical
protection for metal-
sheathed cables.
(a)(5)(i)................. 710-21(a)........ Systems over 600
volts, nominal;
interrupting and
isolating devices;
guarding and
indicating.
(a)(5)(ii)................ 240-11(a)........ Systems over 600
710-21(b)........ volts, nominal;
interrupting and
isolating devices;
fuses.
(a)(5)(iii) and (a)(5)(iv) 710-21(b)........ Systems over 600
volts, nominal;
interrupting and
isolating devices;
fused cutouts.
(a)(5)(vi), but not 710-21(c)........ Systems over 600
(a)(5)(vi)(B). volts, nominal;
interrupting and
isolating devices;
load interrupter
switches.
(a)(5)(vii)............... 710-22........... Systems over 600
volts, nominal;
interrupting and
isolating devices;
means for isolating
equipment.
(b)(2).................... 700-14........... Emergency systems,
emergency
illumination.
------------------------------------------------------------------------
In addition, OSHA is not including in the list of new provisions in
final Sec. 1910.302(b)(4) any provision that merely provides an
alternative means of compliance for an existing requirement. For
example, as noted earlier, final Sec. 1910.307(g) provides alternative
requirements for installations in hazardous (classified) locations
based on the zone classification system rather than the division
classification system that is required under the existing standard.
Such requirements accept alternative installation techniques recognized
as being equally protective by the NEC and NFPA 70E, and there is no
need to limit them to new installations.
OSHA also believes that there is no need to grandfather
requirements that apply only to temporarily installed equipment and
wiring.\11\ The few new requirements applying to temporarily installed
equipment and wiring have been in the NEC since at least 1999 and, in
most cases, since before that. Employers should already be in
compliance with such requirements since any existing temporary
installations almost certainly were put into place well after 1999.\12\
For example, final Sec. 1910.304(b)(3)(ii) contains requirements for
providing ground-fault circuit interrupter protection for temporary
wiring installations that are used during maintenance, remodeling, or
repair of buildings, structures, or equipment or during similar
activities. Temporary wiring installations used for any of these
purposes were likely to have been installed well after 1999. An
employer who is complying with the 1999 or later edition of the NEC
will already be complying with this provision of the rule. Even
employers who are not complying with recent versions of the NEC for
temporary wiring installations will face, in this example, only the
minimal cost of providing ground-fault circuit interrupters; no changes
would need to be made to any existing permanent wiring, which might
involve considerably more costs.
---------------------------------------------------------------------------
\11\ For the purposes of this discussion, "temporarily
installed equipment or wiring" is wiring and equipment installed on
a short-term rather than a long-term or permanent basis. It includes
temporary wiring covered by proposed Sec. 1910.305(a)(2) and other
equipment and wiring similarly installed on a short-term basis.
\12\ The limit for temporary wiring used for Christmas
decorative lighting, carnivals, and similar purposes is 90 days
(Sec. 1910.305(a)(2)(i)(B)). For other purposes, such as remodeling
and repair, the limit is the duration of the activity. However, OSHA
believes that it is highly unlikely that any particular temporary
activity covered by Subpart S has been on-going since 1999.
---------------------------------------------------------------------------
Requirements applicable only to installations made after April 16,
1981. Paragraph (b)(3) of final Sec. 1910.302 lists requirements that
apply only to installations made after April 16, 1981.
This paragraph carries forward essentially the same list as is
currently in Sec. 1910.302(b)(3). No provisions have been added to or
removed from the list.
Requirements applicable only to installations made after March 15,
1972. Paragraph (b)(2) of existing Sec. 1910.302 requires all
installations made after March 15, 1972, and every major replacement,
modification, repair, or rehabilitation made after that date to meet
all the installation requirements in Subpart S except for those listed
in existing Sec. 1910.302(b)(3). A note following existing Sec.
1910.302(b)(2) indicates that " `[m]ajor replacements, modifications,
repairs, or rehabilitations' include work similar to that involved when
a new building or facility is built, a new wing is added, or an entire
floor is renovated."
Paragraph (b)(2) of final Sec. 1910.302 will require all
installations built or overhauled after March 15, 1972, to comply with
all of the requirements of final Sec. Sec. 1910.302 through 1910.308,
except as provided in final Sec. 1910.302(b)(3) and (b)(4). As
discussed earlier, these latter two paragraphs limit the application of
newer provisions of Subpart S to installations made during later
periods.
In Sec. 1910.302(b)(2) in the final rule, OSHA is introducing the
term "overhaul" to include the types of activities that would trigger
compliance with the otherwise grandfathered provisions of Subpart S for
older installations. In Sec. 1910.399 of the final rule, "overhaul"
is defined as follows:
Overhaul means to perform a major replacement, modification,
repair, or rehabilitation similar to that involved when a new
building or facility is built, a new wing is added, or an entire
floor is renovated.
This new term incorporates all the elements of "major replacement,
modification, or rehabilitation" in the text of existing Sec.
1910.302(b)(2) and in the note following that provision. OSHA believes
that using and defining the term "overhaul" in the final rule will
simplify the standard without making any substantive change to the way
in which Subpart S applies to older installations.
Comments on the grandfather clause. OSHA received several comments
on the grandfather clause proposed in Sec. 1910.302(b) (Exs. 3-7, 4-
25). One commenter was concerned about the level of cross-referring an
employer would need to do to determine what standards are applicable to
a given installation (Ex. 3-7). He recommended that a simpler approach
be adopted or that OSHA develop guidance materials to help employers
determine which requirements apply to installations made during each of
the periods addressed by the grandfather clause. Neither commenter
proposed language that might accomplish this.
While OSHA acknowledges that some commenters believe that this
clause is too complex, the Agency believes that the approach taken in
the final standard is as simple as the Agency can make it. However,
OSHA will provide compliance assistance tools that will help employers
understand which requirements are applicable to their particular
electrical installations. For example, the Agency is considering
providing on the OSHA Website a color-coded version depicting
requirements with different applicability dates with different colors
or a version that lets the reader input the date of the installation
and that hides inapplicable provisions. Such tools should enable
employers to determine their compliance obligations quickly and easily.
In addition, for questions about compliance with the standard,
employers can contact OSHA through its toll-free telephone help line at
1-800-321-6742. Alternatively, employers can contact the OSHA Area
Office or State Plan office nearest them.
Paragraph (b)(4) of final Sec. 1910.302 lists Sec.
1910.304(b)(3)(i) (proposed Sec. 1910.304(b)(4)(i)), which requires
ground-fault circuit interrupter protection for certain permanently
installed receptacle outlets, as a provision that only applies to new
installations. One commenter recommended that all of proposed Sec.
1910.304(b)(4), which as noted previously contains requirements for
ground-fault circuit interrupters on temporary receptacle outlets,
apply only to new installations (Ex. 3-7). The commenter noted that
this provision is new and should only be applied to new installations.
As noted earlier, OSHA believes that most employers are already
complying with this provision. The National Electrical Code has
required ground-fault circuit interrupters in a manner similar to that
in the final rule since the 1996 edition of the NEC. In addition, the
final rule sets an effective date 180 days after publication of the
final rule in the Federal Register. OSHA believes that very few
temporary installations that were in place before publication of the
final rule will still be in place 6 months later. There may be some
projects using temporary wiring that last more than 6 months,
particularly in shipyards. However, even there, OSHA believes that
temporary receptacle outlets will be moved around, installed,
uninstalled, and reinstalled many times over the life of the project.
Even if the Agency were to apply final Sec. 1910.304(b)(3)(ii) only to
installations made after the effective date, it would apply as soon as
a receptacle outlet was installed (or reinstalled). OSHA does not
believe that there is a compelling reason to exempt the very few
remaining temporary receptacle outlets that may still be in place after
the effective date. Therefore, OSHA has not adopted the commenter's
recommendation.
Mr. Pat Kimmet of CHS Inc. and Mr. Rick Leicht of NCRA were
concerned that provisions listed in proposed Sec. 1910.302(b)(1),
which were to apply to all installations regardless of age, would
require employers to examine existing installations for compliance and
possibly replace noncompliant equipment even when no significant hazard
exists (Ex. 4-25). They specifically objected to the inclusion of wire
bending space (proposed Sec. 1910.303(b)(1)(iii)) on the list. They
argued that this provision is a relatively recent addition to the NEC
and that the NEC has revised the wire bending space requirements
periodically. They believed that the proposal would have required
employers to meet the wire bending space requirements in the 2000
edition of the NFPA 70E and the 2002 edition of the NEC.
OSHA believes that an installation that does not comply with the
provisions listed in final Sec. 1910.302(b)(1) poses a significant
hazard to employees. Furthermore, as noted earlier, almost all of the
provisions listed in that paragraph applied to all installations
regardless of age since March 15, 1972. Thus, employers should already
be in compliance with nearly all of the listed provisions.
The new provisions related to the zone classification system
(including the documentation requirement) provide for an alternative
compliance method to that required by the existing standard. The other
new provision, the prohibition on using grounding terminals and devices
for purposes other than grounding, as noted earlier, has been a long-
standing NEC requirement. Thus, OSHA does not believe that very many
existing installations are in violation of this new provision.
Consequently, Mr. Kimmet's and Mr. Leicht's general concerns about
widespread noncompliance are unfounded.
With respect to their specific concern with the inclusion of
proposed Sec. 1910.303(b)(1)(iii) in the list of provisions applicable
to all installations, OSHA notes that wire bending space, as mentioned
in this provision, is simply one of several factors to be considered in
judging electrical equipment for safety. Paragraph (b)(1) of final
Sec. 1910.303 reads, in part, as follows:
(b) Examination, installation, and use of equipment. (1)
Examination. Electric equipment shall be free from recognized
hazards that are likely to cause death or serious physical harm to
employees. Safety of equipment shall be determined using the
following considerations:
* * * * *
(iii) Wire-bending and connection space;
* * * * *
(viii) Other factors that contribute to the practical
safeguarding of persons using or likely to come in contact with the
equipment.
Paragraph (b)(1)(iii) of final Sec. 1910.303 does not require
compliance with the minimum wire bending space requirements in the NEC.
Rather, wire bending space will be one of the relevant factors in
judging the electrical safety of equipment in accordance with the
introductory text of final Sec. 1910.303(b)(1). OSHA does not consider
this a new requirement. The current standard contains the catchall
"other factors" language in existing Sec. 1910.303(b)(1)(vii). The
Agency construes wire bending space to be one of those "other
factors" judged under the existing standard. Thus, OSHA is simply
making explicit in the final rule a factor employers were required to
consider under Sec. 1910.303(b)(1)(vii) of the existing standard. If
conductors are installed so tightly into enclosures that they overheat
or that the insulation is damaged, a serious safety hazard would exist.
Such an installation would violate the existing standard as well as the
new one. For these reasons, OSHA has not adopted Mr. Kimmet's and Mr.
Leicht's recommendation to remove Sec. 1910.303(b)(1)(iii) from the
list of provisions in final Sec. 1910.302(b)(1) that apply to all
installations.
Several commenters suggested that proposed Sec. 1910.304(a)(3) be
added to the list of requirements in Sec. 1910.302(b)(1) applicable to
all installations (Exs. 4-13, 4-17, 4-18, 4-21). Proposed Sec.
1910.304(a)(3) read as follows:
A grounding terminal or grounding-type device on a receptacle,
cord connector, or attachment plug may not be used for purposes
other than grounding.
Mr. Bernie Ruffenach typified these commenters, reasoning as
follows:
The use of the grounding terminal(s) of any device has never
been permitted in any electrical standards, codes or other
recognized practices at any time. Typically, the use of the
grounding terminal for other than grounding purposes is due to
improper wiring and occurs when an ungrounded (hot) conductor is
applied. The result is an imminent danger electrocution hazard. [Ex.
4-17]
OSHA agrees that using a grounding terminal or device for purposes
other than grounding can present a hazard threatening imminent death or
serious injury. For example, using a grounding terminal as the
attachment point for a circuit conductor can energize the frame of
equipment used by employees. If an employee was to touch such miswired
equipment and a grounded surface at the same time, he or she would
receive an electric shock and possibly die of electrocution. As the
commenters noted, compliance with this provision has been a long-
standing common industry practice. Therefore, OSHA has adopted the
suggestion of these commenters and has added Sec. 1910.304(a)(3) to
the list of provisions in final Sec. 1910.302(b)(1) that are
applicable to all installations.
D. Applicability of Requirements for Disconnecting Means
Several provisions in the final standard require electrical
disconnecting means to be capable of being locked in the open position
under certain conditions. For example, final Sec. 1910.306(a)(2)(i)
requires the disconnecting means for sign and outline lighting systems
to be capable of being locked in the open position if they are out of
the line of sight from any section that may be energized. These
provisions ensure that employees servicing or maintaining the electric
circuits supplied by the disconnecting means are protected against
electric shock.
Sometimes, these disconnecting means also serve as energy isolating
devices as defined in paragraph (b) of Sec. 1910.147, OSHA's existing
standard for the control of hazardous energy sources (lockout-tagout).
Energy isolating devices physically prevent the transmission or release
of energy. In the case of electric equipment, disconnecting means that
meet the definition of energy isolating devices prevent the
transmission of electric energy so that the equipment cannot start up
and injure employees.
Paragraph (c)(2)(iii) of the lockout-tagout standard reads as
follows:
After January 2, 1990, whenever replacement or major repair,
renovation or modification of a machine or equipment is performed,
and whenever new machines or equipment are installed, energy
isolating devices for such machine or equipment shall be designed to
accept a lockout device.
Paragraph (c) of final Sec. 1910.302 clarifies that the provision
in the lockout-tagout standard is in addition to any requirements in
Subpart S for disconnecting means to be capable of being locked open.
The requirements in Subpart S are intended for the protection of
servicing and maintenance employees from electric shock, which is not
covered by Sec. 1910.147. The lockout-tagout standard on the other
hand addresses nonelectric-shock hazards related to servicing and
maintaining equipment. Thus, the requirements of both standards are
necessary to protect employees from all servicing- and maintenance-
related hazards.
OSHA received no comments on this provision in the proposal, and it
is being carried into the final rule without change.
E. Summary of Changes in Sec. Sec. 1910.303 Through 1910.308
The Distribution Table for Subpart S lists all the provisions and
sections from Sec. Sec. 1910.303 through 1910.308. This table
summarizes changes being made to the standard that involve grammatical
edits, additions, removals, and paragraph numbers. There are places in
the standard where no substantial change is made. Most of the changes
are editorial in nature. Substantive changes made to the existing
standard are discussed in further detail following the Distribution
Table.
Distribution Table
------------------------------------------------------------------------
Description of
OLD--section NEW--section changes and rationale
------------------------------------------------------------------------
See the note at the end of the table.
------------------------------------------------------------------------
Sec. 1910.303 General....... Sec. 1910.303
General.
1910.303(a)................... 1910.303(a)...... No substantive
change. A reference
to the Sec.
1910.399 definition
of "approved" is
added for
clarification.
1910.303(b)(1), introductory 1910.303(b)(1), No substantive
text. introductory change.
text.
1910.303(b)(1)(i)............. 1910.303(b)(1)(i) No substantive
change.
1910.303(b)(1)(ii)............ 1910.303(b)(1)(ii No substantive
). change.
1910.303(b)(1)(ii **Adds wire-bending
i). and connection space
to the explicit list
of things to
consider when
judging equipment.
1910.303(b)(1)(iii)........... 1910.303(b)(1)(iv No substantive
). change.
1910.303(b)(1)(iv)............ 1910.303(b)(1)(v) No substantive
change.
1910.303(b)(1)(v)............. 1910.303(b)(1)(vi No substantive
). change.
1910.303(b)(1)(vi)............ 1910.303(b)(1)(vi No substantive
i). change.
1910.303(b)(1)(vii)........... 1910.303(b)(1)(vi No substantive
ii). change.
1910.303(b)(2)................ 1910.303(b)(2)... No substantive
change.
1910.303(b)(3)... **Adds a requirement
for completed wiring
to be free from
short circuits and
grounds other than
those required in
the standard.
1910.303(b)(4)... **Adds requirements
for equipment
intended to
interrupt current to
have adequate
interrupting
ratings.
1910.303(b)(5)... **Adds requirements
for the coordination
of overcurrent
protection for
circuits and
equipment.
1910.303(b)(6)... **Adds a requirement
for conductors and
equipment to be
identified for the
purpose when
installed in an
environment
containing
deteriorating
agents.
1910.303(b)(7)... **Adds requirements
for installing
electric equipment
in a neat and
workmanlike manner.
1910.303(b)(8)... **Adds requirements
for equipment to be
mounted securely and
to allow for proper
cooling.
1910.303(c)(1)... **Adds requirements
to ensure that
electrical
connections are
secure and
electrically safe.
1910.303(c)(2)... **Adds requirements
for connections at
terminals and for
the identification
of terminals
intended for
connection to more
than one conductor
or to aluminum.
1910.303(c)................... 1910.303(c)(3)(i) No substantive
change.
1910.303(c)(3)(ii **Adds a requirement
). that wire connectors
or splicing means
installed on
directly buried
conductors be listed
for such use.
1910.303(d)................... 1910.303(d)...... No substantive
change.
1910.303(e)................... 1910.303(e)...... No substantive
change. (Individual
requirements are
placed in separate
paragraphs).
1910.303(f)................... 1910.303(f)(1), No substantive
(f)(2), and change. (Individual
(f)(3). requirements are
placed in separate
paragraphs).
1910.303(f)(4)... Adds a requirement
for disconnecting
means required by
Subpart S to be
capable of accepting
a lock. This
provision is added
to make the Subpart
S requirements on
disconnecting means
consistent with Sec.
1910.147(c)(2)(iii),
which requires
energy isolating
devices (a generic
term, which includes
electrical
disconnecting means)
to be designed to
accept a lockout
device.
1910.303(f)(5)... **Adds marking
requirements for
series combination
ratings of circuit
breakers or fuses.
1910.303(g)(1), introductory 1910.303(g)(1), No substantive
text. introductory change.
text.
1910.303(g)(1)(i)............. 1910.303(g)(1)(i) **The final rule
Table S-1, Note revises the language
3. to clarify how wide
and high the clear
space must be. (See
detailed explanation
later in the
preamble).
1910.303(g)(1)(ii)............ 1910.303(g)(1)(ii No substantive
). change.
1910.303(g)(1)(iii)........... 1910.303(g)(1)(ii No substantive
i). change.
1910.303(g)(1)(iv **Adds a requirement
). for a second
entrance on
equipment rated 1200
amperes under
certain conditions.
1910.303(g)(1)(iv)............ 1910.303(g)(1)(i) **Reduces the minimum
(B). width of the clear
space to 762 mm.
1910.303(g)(1)(v)............. 1910.303(g)(1)(v) **Adds a prohibition
against controlling
illumination for
working spaces by
automatic means
only.
1910.303(g)(1)(vi)............ 1910.303(g)(1)(vi **Increased the
). minimum height of
the working space
from 1.91m to 1.98m
for new
installations.
1910.303(g)(1)(vi ** Adds requirements
i). for switchboards,
panelboards, and
distribution boards
installed for the
control of light and
power circuits, and
motor control
centers to be
installed in
dedicated space and
to be protected
against damage.
1910.303(g)(2)................ 1910.303(g)(2)... No substantive
change.
1910.303(h)(1)................ 1910.303(h)(1)... No substantive
change.
1910.303(h)(2), introductory 1910.303(h)(2)(i) **The minimum height
text. and (h)(2)(ii). of fences
restricting access
to electrical
installations over
600 V is reduced
from 2.44 m to 2.13
m.
1910.303(h)(2)(i) and 1910.303(h)(2)(ii **1. The final rule
(h)(2)(ii). i), (h)(2)(iv), organizes these
(h)(2)(v), and requirements based
(h)(5)(iii). on whether the
installations are
indoors or outdoors.
(The existing
standard organizes
them based on
whether or not the
installations are
accessible to
unqualified
employees).
2. Adds requirements
intended to prevent
tampering by the
general public.
3. Removes
requirement to lock
underground box
covers weighing more
than 45.4 kg.
1910.303(h)(3), introductory 1910.303(h)(3)... No substantive
text. change.
1910.303(h)(3)(i)............. 1910.303(h)(5)(i) **The distances in
Table S-2, Note Table S-2 for the
3. depth of working
space in front of
electric equipment
are increased for
new installations to
match the distances
in NFPA 70E-2000.
1910.303(h)(3)(ii)............ 1910.303(h)(5)(iv No substantive
). change.
1910.303(h)(3)(iii)........... 1910.303(h)(5)(v) **The distances in
Table S-3 for the
elevations of
unguarded live parts
are increased for
new installations to
match the distances
in NFPA 70E-2000.
1910.303(h)(4)(i)............. 1910.303(h)(4)(i) **The existing
standard requires a
second entrance to
give access to the
working space about
switchboards and
control panels over
600 V if the
equipment exceeds
1.22 m in width if
it is practical to
install a second
entrance. The final
rule requires an
entrance on each end
of switchboards and
panelboards
exceeding 1.83 m
unless the working
space permits a
continuous and
unobstructed way of
travel or the
working space is
doubled. In
addition, the final
rule requires the
lone entrance
permitted under
either of these
exceptions to be at
least the distance
specified in Table S-
2 from exposed live
parts.
1910.303(h)(4)(ii)............ 1910.303(h)(4)(ii No substantive
). change.
1910.303(h)(5)(ii **Adds requirements
). for equipment
operating at 600 V
or less installed in
rooms or enclosures
containing exposed
live parts or
exposed wiring
operating at more
than 600 V.
1910.303(h)(5)(vi **Adds requirements
). limiting the
installation of
pipes or ducts that
are foreign to
electrical
installation
operating at more
than 600 V.
Sec. 1910.304 Wiring design Sec. 1910.304
and protection. Wiring design
and protection.
1910.304(a)(1)................ 1910.304(a)(1)... No substantive
change. (Individual
requirements are
placed in separate
paragraphs).
1910.304(a)(2)................ 1910.304(a)(2)... No substantive
change.
1910.304(a)(3)................ 1910.304(a)(3)... No substantive
change.
1910.304(b)(1)... **Adds requirements
for the
identification of
multiwire branch
circuits.
1910.304(b)(2)(i) **Adds requirements
that receptacles
installed on 15- and
20-ampere circuits
be of the grounding
type and that
grounding-type
receptacles be
installed in
circuits within
their rating.
1910.304(b)(2)(ii **Adds a requirement
). for grounding
contacts on
receptacles to be
effectively
grounded.
1910.304(b)(2)(ii **Adds requirements
i). on the methods used
to ground
receptacles and cord
connectors.
1910.304(b)(2)(iv **Adds requirements
). on the replacement
of receptacles.
1910.304(b)(2)(v) **Adds a requirement
that receptacles
installed on branch
circuits having
different voltages,
frequencies, or
types of current be
noninterchangeable.
1910.304(b)(3)... **Adds requirements
for ground fault
circuit interrupter
protection. (See the
discussion of these
requirements later
in this section of
the preamble).
1910.304(b)(2)................ 1910.304(b)(4), No significant
introductory change.
text.
1910.304(b)(4)(i) **Adds requirements
for ratings of
lampholders.
1910.304(b)(4)(ii **Adds requirements
). for ratings of
receptacles.
1910.304(b)(5)... **Adds requirements
for receptacles to
be installed
wherever cords with
attachment plugs are
used.
1910.304(c), introductory text 1910.304(c), No significant
introductory change. (The
text. requirements in
existing paragraph
(c)(5) are placed in
a separate paragraph
(d)).
1910.304(c)(1)................ 1910.304(c)(1)... **Adds a requirement
for the separation
of conductors on
poles.
1910.304(c)(2)................ 1910.304(c)(2)... Increases the minimum
clearances for new
installations of
open conductors and
service drops to
match those in NFPA
70E-2000.
1910.304(c)(3)................ 1910.304(c)(3)(i) No substantive
change. (The final
rule clarifies that
paragraph (c)(2)
applies to
platforms,
projections, or
surfaces from which
runs of open
conductors can be
reached).
1910.304(c)(3)(ii **Adds restrictions
). for installing
overhead service
conductors near
building openings
through which
materials may be
moved.
1910.304(c)(4)................ 1910.304(c)(4)... **Adds an exception
to the minimum
clearance
requirement for
conductors attached
to the side of a
building. (The final
rule also clarifies
that paragraph
(c)(2) applies to
roof surfaces that
are subject to
pedestrian or
vehicular traffic).
1910.304(c)(5)................ 1910.304(d)...... No substantive
change.
1910.304(d)(1)(i)............. 1910.304(e)(1)(i) No substantive
change.
1910.304(d)(1)(ii)............ 1910.304(e)(1)(ii No substantive
). change.
1910.304(e)(1)(ii **Adds a requirement
i). for service
disconnecting means
to be suitable for
the prevailing
conditions.
1910.304(d)(2)................ 1910.304(e)(2)... No substantive
change.
1910.304(e)(1), introductory 1910.304(f)(1), No substantive
text. introductory change.
text.
1910.304(e)(1)(i)............. 1910.304(f)(1)(i) No substantive
change.
[[Page 7149]]
1910.304(e)(1)(ii)............ 1910.304(f)(1)(ii No substantive
). change.
1910.304(e)(1)(iii)........... 1910.304(f)(1)(ii **The types of
i). circuits that are
allowed to have a
single switch
disconnect for
multiple fuses are
now specified in the
standard.
1910.304(e)(1)(iv)............ 1910.304(f)(1)(iv No substantive
). change.
1910.304(e)(1)(v)............. 1910.304(f)(1)(v) **Adds a requirement
to clarify that
handles of circuit
breakers and similar
moving parts also
need to be guarded
so that they do not
injure employees.
1910.304(e)(1)(vi)(A)......... 1910.304(f)(1)(vi No substantive
). change.
1910.304(e)(1)(vi)(B)......... 1910.304(f)(1)(vi No substantive
i). change.
1910.304(e)(1)(vi)(C)......... 1910.304(f)(1)(vi **Adds circuit
ii). breakers used on 277-
volt fluorescent
lighting circuits to
the types of
breakers required to
be marked "SWD."
1910.304(f)(1)(ix **Adds a requirement
). to clarify ratings
of circuit breakers.
1910.304(e)(2)................ 1910.304(f)(2)... **Adds specific
requirements on how
to protect feeders
and branch circuits
energized at more
than 600 volts.
1910.304(f), introductory text 1910.304(g), No substantive
introductory change.
text.
1910.304(f)(1), introductory 1910.304(g)(1), No substantive
text. introductory change.
text.
1910.304(f)(1)(i)............. 1910.304(g)(1)(i) No substantive
change.
1910.304(f)(1)(ii)............ 1910.304(g)(1)(ii No substantive
). change.
1910.304(f)(1)(iii)........... 1910.304(g)(1)(ii No substantive
i). change.
1910.304(f)(1)(iv)............ 1910.304(g)(1)(iv No substantive
). change. (The
specific voltage
ratings in existing
paragraphs
(g)(1)(iv)(B) and
(g)(1)(iv)(C) are
being removed.
However, this is not
a substantive change
as those are the
voltages used in the
described systems).
1910.304(f)(1)(v)............. 1910.304(g)(1)(v) **Adds an exception
to the requirement
to ground systems
for high-impedance
grounded systems of
480 V to 1000 V
under certain
conditions.
1910.304(f)(2)................ 1910.304(g)(2)... **No substantive
change. (The
standard adds
descriptions of
which conductor is
to be grounded for
the different
systems).
1910.304(g)(3)... **Changes
requirements for
grounding portable
and vehicle mounted
generators so that
the requirements are
equivalent to those
in OSHA's
Construction
Standards (Sec.
1926.404(f)(3)). The
sentence in the
construction
standard reading:
"No other
[nonneutral]
conductor need be
bonded to the
generator frame"
has been dropped
from the general
industry version.
This sentence is not
regulatory in
nature, and its
omission has no
effect on the
requirement.
1910.304(f)(3)................ 1910.304(g)(4)... **No longer allows
employers to use a
cold water pipe as a
source of ground for
installations made
or modified after
the effective date.
1910.304(f)(4)................ 1910.304(g)(5)... **Adds a requirement
that the path to
ground be effective.
1910.304(f)(5)(i)............. 1910.304(g)(6)(i) No substantive
change.
1910.304(f)(5)(ii)............ 1910.304(g)(6)(ii No substantive
). change.
1910.304(f)(5)(iii)........... 1910.304(g)(6)(ii No substantive
i). change.
1910.304(f)(5)(iv)............ 1910.304(g)(6)(iv **The exceptions for
) and (g)(6)(v). grounding fixed
equipment operating
at more than 150 V
are extended to all
fixed electric
equipment regardless
of voltage. Also,
the final rule
includes a new
exception for double-
insulated equipment.
1910.304(f)(5)(v)............. 1910.304(g)(6)(vi **Adds the following
) and equipment to the
(g)(6)(vii). list of cord- and
plug-connected
equipment required
to be grounded:
stationary and fixed
motor-operated tools
and light industrial
motor-operated
tools.
1910.304(f)(5)(vi)............ 1910.304(g)(7)... **Adds frames and
tracks of
electrically
operated hoists to
the list of
nonelectrical
equipment required
to be grounded.
1910.304(f)(6)................ 1910.304(g)(8)... No substantive
change.
1910.304(f)(7)(i)............. 1910.304(g)(9), No substantive
introductory change.
text.
1910.304(f)(7)(ii)............ 1910.304(g)(9)(i) No substantive
change.
1910.304(f)(7)(iii)........... 1910.304(g)(9)(ii No substantive
). change.
Sec. 1910.305 Wiring Sec. 1910.305
methods, components, and Wiring methods,
equipment for general use. components, and
equipment for
general use.
1910.305(a), introductory text 1910.305(a), No substantive
introductory change.
text.
1910.305(a)(1)(i)............. 1910.305(a)(1)(i) **Adds a requirement
that equipment be
bonded so as to
provide adequate
fault-current-
carrying capability.
Also, clarifies that
nonconductive
coatings need to be
removed unless the
fittings make this
unnecessary.
1910.305(a)(1)(ii **Adds an exception
). to the bonding
requirement for the
reduction of
electrical noise.
1910.305(a)(1)(ii)............ 1910.305(a)(1)(ii No substantive
i). change.
[[Page 7150]]
1910.305(a)(2), introductory 1910.305(a)(2), No substantive
text. introductory change. Removes the
text. provision allowing
temporary wiring to
be of a class less
than permanent
wiring per the 2002
NEC. The change has
no substantive
effect because: (1)
The term "a class
less than" is not
defined, and (2)
temporary wiring is
required to meet the
same requirements
regardless of the
deleted language.
(Both the final rule
and the existing
standard contain the
following
requirement:
"Except as
specifically
modified in this
paragraph, all other
requirements of this
subpart for
permanent wiring
shall apply to
temporary wiring
installations.").
1910.305(a)(2)(i), 1910.305(a)(2)(i) No substantive
introductory text. , introductory change.
text.
1910.305(a)(2)(i)(A).......... 1910.305(a)(2)(i) Removes demolition
(A). from the list of
activities for which
temporary wiring is
permitted.
Demolition is a form
of construction
work, which is not
covered by the
Subpart S
installation
requirements.
1910.305(a)(2)(i)(B).......... 1910.305(a)(2)(i) **Adds emergencies to
(C). the list of
activities for which
temporary wiring is
permitted.
1910.305(a)(2)(i)(C).......... 1910.305(a)(2)(i) No substantive
(B). change.
1910.305(a)(2)(ii **Clarifies that
). temporary wiring
must be removed when
the project or
purpose for which it
was used has been
completed.
1910.305(a)(2)(ii)............ 1910.305(a)(2)(ii **Adds "construction-
i). like activities" to
the list of
permitted uses for
temporary electrical
installations over
600 volts.
1910.305(a)(2)(iii)(A)........ 1910.305(a)(2)(iv **Feeders may now
). only be run as
single insulated
conductors when
accessible to
qualified employees
only and used for
experiments,
development work, or
emergencies.
(Individual
requirements are
placed in separate
paragraphs).
1910.305(a)(2)(iii)(B)........ 1910.305(a)(2)(v) No substantive
change. (Individual
requirements are
placed in separate
paragraphs).
1910.305(a)(2)(iii)(C)........ 1910.305(a)(2)(vi No substantive
). change.
1910.305(a)(2)(iii)(D)........ 1910.305(a)(2)(vi No substantive
i). change.
1910.305(a)(2)(iii)(E)........ 1910.305(a)(2)(vi **Adds a requirement
ii). that disconnecting
means for a
multiwire circuit
simultaneously
disconnect all
ungrounded
conductors of the
circuit.
1910.305(a)(2)(iii)(F)........ 1910.305(a)(2)(ix **This provision no
). longer allows
installing fixtures
or lampholders more
than 2.1 meters
above the working
surface as a means
of guarding. Also,
the final rule adds
a requirement for
grounding metal-case
sockets.
1910.305(a)(2)(iii)(G)........ 1910.305(a)(2)(x) No substantive
change.
1910.305(a)(2)(xi **Adds requirements
). for cable assemblies
and flexible cords
and cables to be
adequately
supported.
1910.305(a)(3)(i)(a).......... 1910.305(a)(3)(i) No substantive
change. (Some
raceway and cable
types that were
included in generic
terms have been
explicitly added to
the list of wiring
methods acceptable
in cable trays).
1910.305(a)(3)(i)(b).......... 1910.305(a)(3)(ii **Adds several types
). of cables and single
insulated conductors
to the list of types
permitted in
industrial
establishments.
1910.305(a)(3)(ii **Adds a requirement
i). limiting the use of
metallic cable trays
as an equipment
grounding conductor.
1910.305(a)(3)(i)(c).......... 1910.305(a)(3)(iv No substantive
). change.
1910.305(a)(3)(ii)............ 1910.305(a)(3)(v) No substantive
change.
1910.305(a)(4)(i)............. 1910.305(a)(4)(i) No substantive
change.
1910.305(a)(4)(ii)............ 1910.305(a)(4)(ii **Adds specific
). support requirements
and limits the
application of these
requirements to
conductors smaller
than No. 8.
1910.305(a)(4)(iii)........... 1910.305(a)(4)(ii No substantive
i). change.
1910.305(a)(4)(iv)............ 1910.305(a)(4)(iv No substantive
). change.
1910.305(a)(4)(v)............. 1910.305(a)(4)(v) No substantive
change.
1910.305(b)(1)................ 1910.305(b)(1)(i) No substantive
and (b)(1)(ii). change. (Individual
requirements are
placed in separate
paragraphs).
1910.305(b)(1)(ii **Adds requirements
i). for supporting
cables entering
cabinets, cutout
boxes, and meter
sockets.
1910.305(b)(2)................ 1910.305(b)(2)(i) No substantive
change.
1910.305(b)(2)(ii **Adds a requirement
). for any exposed edge
of a combustible
ceiling finish at a
fixture canopy or
pan to be covered
with noncombustible
material.
1910.305(b)(3)................ 1910.305(b)(3)... No substantive
change. (Individual
requirements are
placed in separate
paragraphs).
1910.305(c)(1)................ 1910.305(c)(1), No substantive
(c)(2), and change. (Individual
(c)(3)(i). requirements are
placed in separate
paragraphs).
1910.305(c)(3)(ii **Adds a requirement
). for load terminals
on switches to be
deenergized when the
switches are open
except under limited
circumstances.
1910.305(c)(4)... **Adds a specific
requirement for
flush-mounted
switches to have
faceplates that
completely cover the
opening and that
seat against the
finished surface.
1910.305(c)(2)................ 1910.305(c)(5)... **Adds a requirement
to ground faceplates
for snap switches.
1910.305(d)................... 1910.305(d)...... No substantive
change. (Individual
requirements are
placed in separate
paragraphs).
1910.305(e)(1)................ 1910.305(e)(1)... **Adds a requirement
for metallic
cabinets, cutout
boxes, fittings,
boxes, and
panelboard
enclosures installed
in damp or wet
locations to have an
air space between
the enclosure and
the mounting
surface.
1910.305(e)(2)................ 1910.305)(e)(2).. No substantive
change.
1910.305(f)................... 1910.305(f)...... No substantive
change. (Individual
requirements are
placed in separate
paragraphs).
1910.305(g)(1)(i)............. 1910.305(g)(1)(i) **Adds the following
and (g)(1)(ii). to the types of
connections
permitted for
flexible cords and
cables: Portable and
mobile signs and
connection of moving
parts. The final
rule also clarifies
that flexible cords
and cables may be
used for temporary
wiring as permitted
in final Sec.
1910.305(a)(2).
1910.305(g)(1)(ii)............ 1910.305(g)(1)(ii No substantive
i). change.
1910.305(g)(1)(iii)........... 1910.305(g)(1)(iv No substantive
). change. (Clarifies
that flexible cords
and cables may not
be installed inside
raceways).
1910.305(g)(1)(iv)............ 1910.305(g)(1)(v) **Permits additional
cord types to be
used in show windows
and show cases.
1910.305(g)(2)(i)............. 1910.305(g)(2)(i) **Adds new types of
cords to the list of
those that must be
marked with their
type designation.
1910.305(g)(2)(ii)............ 1910.305(g)(2)(ii **Changes the minimum
). size of hard service
and junior hard
service cords that
may be spliced from
No. 12 to 14.
1910.305(g)(2)(iii)........... 1910.305(g)(2)(ii No substantive
i). change.
1910.305(h)................... 1910.305(h), **Permits the minimum
introductory size of the
text, (h)(1), insulated ground-
(h)(2), (h)(3), check conductor of
(h)(6), (h)(7), Type G-GC cables to
and (h)(8). be No. 10 rather
than No. 8.
(Individual
requirements are
placed in separate
paragraphs).
1910.305(h)(4)... **Adds a requirement
for shields to be
grounded.
1910.305(h)(5)... **Adds minimum
bending radii
requirements for
portable cables.
1910.305(i)(1)................ 1910.305(i)(1)... No substantive
change.
1910.305(i)(2)................ 1910.305(i)(2)... No substantive
change.
1910.305(i)(3)................ 1910.305(i)(3)... **Also permits
fixture wire to be
used in fire alarm
circuits.
1910.305(j)(1)(i)............. 1910.305(j)(1)(i) No substantive
change.
1910.305(j)(1)(ii)............ 1910.305(j)(1)(ii No substantive
). change. (Clarifies
that metal-shell
paper-lined
lampholders may not
be used for
handlamps).
1910.305(j)(1)(iii)........... 1910.305(j)(1)(ii **Adds a requirement
i). that the grounded
circuit conductor,
where present, be
connected to the
screw shell.
1910.305(j)(1)(iv)............ 1910.305(j)(1)(iv No substantive
). change.
1910.305(j)(2)(i) **Adds requirements
to ensure that
attachment plugs and
connectors have no
exposed live parts.
1910.305(j)(2)(i)............. 1910.305(j)(2)(ii No substantive
). change.
1910.305(j)(2)(ii **Clarifies that
i). nongrounding-type
receptacles may not
be used with
grounding-type
attachment plugs.
1910.305(j)(2)(ii)............ 1910.305(j)(2)(iv No substantive
). change.
1910.305(j)(2)(v) **Adds requirements
, (j)(2)(vi), for receptacles
and (j)(2)(vii). outdoors to be
installed in
weatherproof
enclosures
appropriate for the
use of the
receptacle and for
the location.
1910.305(j)(3)(i)............. 1910.305(j)(3)(i) No substantive
change.
1910.305(j)(3)(ii)............ 1910.305(j)(3)(ii **Adds a requirement
). to group and
identify
disconnecting means
for appliances
supplied by more
than one source.
1910.305(j)(3)(iii)........... 1910.305(j)(3)(ii **Adds requirements
i). for marking
frequency and
required external
overload protection
for appliances.
1910.305(j)(3)(iv **Clarifies that
). markings must be
visible or easily
accessible after
installation.
1910.305(j)(4), introductory 1910.305(j)(4), No substantive
text. introductory change.
text.
1910.305(j)(4)(i)............. 1910.305(j)(4)(i) No substantive
change.
1910.305(j)(4)(ii)(A)......... 1910.305(j)(4)(ii No substantive
). change.
1910.305(j)(4)(ii)(B)......... 1910.305(j)(4)(ii No substantive
i). change.
1910.305(j)(4)(ii)(C)......... ................. Removed. All
disconnecting means
must be capable of
being locked in the
open position by
Sec. Sec.
1910.302(c) and
1910.303(f)(4).
1910.305(j)(4)(ii)(D)......... 1910.305(j)(4)(iv No substantive
). change.
1910.305(j)(4)(ii)(E)......... 1910.305(j)(4)(v) No substantive
change.
1910.305(j)(4)(ii)(F)......... 1910.305(j)(4)(vi No substantive
). change.
1910.305(j)(4)(iii)........... 1910.305(j)(4)(vi No substantive
i). change.
1910.305(j)(4)(iv)(A)......... ................. Removed. Covered by
Sec.
1910.303(g)(2),
(h)(2), and
(h)(4)(iii).
1910.305(j)(4)(iv)(B)......... 1910.305(j)(4)(vi No substantive
ii). change.
1910.305(j)(5)(i)............. 1910.305(j)(5)(i) No substantive
change.
1910.305(j)(5)(ii)............ 1910.305(j)(5)(ii No substantive
). change.
1910.305(j)(5)(iii)........... 1910.305(j)(5)(ii No substantive
i). change.
1910.305(j)(5)(iv)............ 1910.305(j)(5)(iv No substantive
). change. (Oil-
insulated
transformers
installed indoors
are presumed to
present a hazard to
employees since a
transformer failure
will lead to a fire
within the building
unless the
transformer is
installed in a
vault).
1910.305(j)(5)(v)............. 1910.305(j)(5)(v) No substantive
change.
1910.305(j)(5)(vi)............ 1910.305(j)(5)(vi No substantive
). change.
1910.305(j)(5)(vii)........... 1910.305(j)(5)(vi No substantive
i). change.
1910.305(j)(5)(viii).......... 1910.305(j)(5)(vi No substantive
ii). change.
1910.305(j)(6)(i)............. 1910.305(j)(6)(i) No substantive
change.
1910.305(j)(6)(ii), 1910.305(j)(6)(ii No substantive
introductory text. ), introductory change.
text.
1910.305(j)(6)(ii **Adds requirements
)(A) and to provide
(j)(6)(ii)(B). disconnecting means
of adequate capacity
for capacitors
operating at more
than 600 V.
1910.305(j)(6)(ii)(A)......... 1910.305(j)(6)(ii No substantive
)(C). change.
1910.305(j)(6)(ii)(B)......... 1910.305(j)(6)(ii No substantive
)(D). change.
1910.305(j)(7)................ 1910.305(j)(7)... No substantive
change.
Sec. 1910.306 Specific Sec. 1910.306
purpose equipment and Specific purpose
installations. equipment and
installations.
1910.306(a)(1)................ 1910.306(a)(1)(i) **Reorganized and
, (a)(2)(i), and clarified the
(a)(2)(ii). requirements for
disconnecting means
for signs. The final
rule does not apply
these requirements
to exit signs.
1910.306(a)(1)(ii **Adds a requirement
). for the disconnects
for signs located
within fountains to
be at least 1.52 m
from the fountain
wall.
1910.306(a)(2)................ 1910.306(a)(2)(ii No substantive
i). change.
1910.306(b), introductory text 1910.306(b), No substantive
introductory change.
text.
1910.306(b)(1)(i)............. 1910.306(b)(1)... **Adds specific
requirements for the
type and location of
disconnecting means
for runway
conductors.
1910.306(b)(1)(ii)............ 1910.306(b)(2)... No substantive
change. (The final
rule reorganizes
these requirements).
1910.306(b)(2)................ 1910.306(b)(3)... No substantive
change.
1910.306(b)(3)................ 1910.306(b)(4)... No substantive
change.
1910.306(c)................... 1910.306(c), **This paragraph now
introductory covers wheelchair
text. lifts, and stairway
chair lifts.
1910.306(c)(1)................ 1910.306(c)(1)... No substantive
change.
1910.306(c)(2)................ 1910.306(c)(8)... No substantive
change.
1910.306(c)(3)................ 1910.306(c)(2)... No substantive
change.
1910.306(c)(3)... **Adds requirements
for the type of
disconnecting means.
1910.306(c)(4)... **Adds requirements
for the operation of
disconnecting means.
1910.306(c)(5)... **Adds requirements
for the location of
disconnecting means.
1910.306(c)(6)... **Adds requirements
for the
identification of
disconnecting means.
1910.306(c)(7)... **Adds requirements
for disconnecting
means for single car
and multicar
installations
supplied by more
than one source.
1910.306(c)(9)... **Adds requirements
for warning signs
for interconnected
multicar
controllers.
1910.306(c)(10).. **Adds exceptions
related to the
location of motor
controllers.
1910.306(d)(1)................ 1910.306(d)(1)... **Adds requirements
for the type and
rating of the
disconnecting means.
1910.306(d)(2)................ 1910.306(d)(2)... Clarifies that a
supply circuit
switch may be used
as a disconnecting
means if the circuit
supplies only one
welder.
1910.306(e)................... 1910.306(e)...... **Adds a requirement
to group the
disconnecting means
for the HVAC systems
serving information
technology rooms
with the
disconnecting means
for the information
technology
equipment. The final
rule exempts
integrated
electrical systems
covered by Sec.
1910.308(g). (The
existing standard
refers to this
equipment as data
processing
equipment).
1910.306(f), introductory text 1910.306(f), **Adds coverage of X-
introductory rays for dental or
text. medical use.
1910.306(f)(1)(i)............. 1910.306(f)(1)(i) No substantive
change.
1910.306(f)(1)(ii)............ 1910.306(f)(1)(ii No substantive
). change.
1910.306(f)(2)(i)............. 1910.306(f)(2)(i) No substantive
change.
1910.306(f)(2)(ii)............ 1910.306(f)(2)(ii No substantive
). change.
1910.306(g)(1)................ 1910.306(g), No substantive
introductory change.
text.
1910.306(g)(2)(i)............. 1910.306(g)(1)(i) No substantive
change.
1910.306(g)(2)(ii)............ 1910.306(g)(1)(ii No substantive
). change.
1910.306(g)(2)(iii)........... 1910.306(g)(1)(ii **Adds a requirement
i). for the installation
of doors or
detachable panels to
provide access to
internal parts. Adds
a requirement that
detachable panels
not be readily
removable.
1910.306(g)(2)(iv)............ 1910.306(g)(1)(iv No substantive
). change.
1910.306(g)(2)(v)............. 1910.306(g)(1)(v) No substantive
change. (Individual
requirements are
placed in separate
paragraphs).
1910.306(g)(2)(vi)............ 1910.306(g)(1)(vi **Adds a requirement
). to ensure adequate
rating of
disconnecting means.
The final rule also
clarifies when the
supply circuit
disconnecting means
may be used as the
disconnecting means
for induction and
dielectric heating
equipment.
1910.306(g)(3)................ 1910.306(g)(2)... No substantive
change. (Individual
requirements are
placed in separate
paragraphs).
1910.306(h)(1)................ 1910.306(h), No substantive
introductory change.
text.
1910.306(h)(2)................ 1910.399......... No substantive
change.
1910.306(h)(3)................ 1910.306(h)(1)... No substantive
change.
1910.306(h)(4)(i) and 1910.306(h)(2)... No substantive
(h)(4)(ii). change. (The two
provisions are
combined into one
paragraph).
1910.306(h)(5)(i)............. 1910.306(h)(3)(i) No substantive
change.
1910.306(h)(5)(ii)............ 1910.306(h)(3)(ii No substantive
). change.
1910.306(h)(6)(i)............. 1910.306(h)(4)(i) **Adds requirements
limiting primary and
secondary voltage on
isolating
transformers
supplying
receptacles for
ungrounded cord- and
plug-connected
equipment. Also,
adds requirement for
overcurrent
protection for
circuits supplied by
these transformers.
1910.306(h)(6)(ii)............ 1910.306(h)(4)(ii No substantive
). change.
1910.306(h)(6)(iii)........... 1910.306(h)(4)(ii No substantive
i). change. (Individual
requirements are
placed in separate
paragraphs).
1910.306(h)(7)(i) and 1910.306(h)(5)(i) No substantive
(h)(7)(ii). change.
1910.306(h)(7)(iii)........... 1910.306(h)(5)(ii No substantive
). change.
1910.306(h)(7)(iv)............ 1910.306(h)(5)(ii No substantive
i). change.
1910.306(h)(8)................ 1910.306(h)(6)... No substantive
change.
1910.306(h)(9)................ 1910.306(h)(7)... No substantive
change.
1910.306(i)(1)................ 1910.306(i)(1)... No substantive
change.
1910.306(i)(2)................ 1910.306(i)(2)... **Allows the
disconnecting means
for a center pivot
irrigation machine
to be located not
more than 15.2 m (50
ft) from the machine
if the disconnecting
means is visible
from the machine.
(Individual
requirements are
placed in separate
paragraphs).
1910.306(j)(1)................ 1910.306(j), **Clarifies that
introductory hydro-massage
text. bathtubs are covered
by this paragraph.
1910.306(j)(2)(i)............. 1910.306(j)(1)(i) No substantive
change.
1910.306(j)(1)(ii **Extends the
). boundary within
which receptacles
require ground-fault
circuit interrupter
protection from 4.57
m (15 ft) to 6.08 m
(20 ft) for new
installations.
1910.306(j)(1)(ii **Adds requirements
i). for the installation
of at least one
receptacle near
permanently
installed pools at
dwelling units.
1910.306(j)(2)(ii)(A)......... 1910.306(j)(2)(i) **Clarifies that
ceiling suspended
(paddle) fans are
covered by this
requirement.
1910.306(j)(2)(ii)(B)......... 1910.306(j)(2)(ii No substantive
). change.
1910.306(j)(3)................ 1910.306(j)(3)... No substantive
change.
1910.306(j)(4)(i)............. 1910.306(j)(4)(i) No substantive
change.
1910.306(j)(4)(ii)............ 1910.306(j)(4)(ii No substantive
). change.
1910.306(j)(4)(ii **Adds a requirement
i). to guard lighting
fixtures facing
upward.
1910.306(j)(5)................ 1910.306(j)(5)... No substantive
change.
1910.306(k)...... **Adds requirements
for carnivals,
circuses, fairs, and
similar events.
Sec. 1910.307 Hazardous Sec. 1910.307
(classified) locations. Hazardous
(classified)
locations.
1910.307(a)................... 1910.307(a)...... **Adds the Zone
classification
system for Class I
locations. (See
detailed discussion
later in this
section of the
preamble).
1910.307(b)...... **Adds documentation
requirements for
hazardous locations
classified using
either the division
or zone
classification
system. (See
detailed discussion
later in this
section of the
preamble).
1910.307(b), introductory text 1910.307(c), No substantive
introductory change.
text.
1910.307(b)(1)................ 1910.307(c)(1)... No substantive
change.
1910.307(b)(2)(i)............. 1910.307(c)(2)(i) No substantive
change.
1910.307(b)(2)(ii), 1910.307(c)(2)(ii No substantive
introductory text. ), introductory change.
text.
1910.307(b)(2)(ii)(A)......... 1910.307(c)(2)(ii No substantive
)(A). change.
1910.307(b)(2)(ii)(B)......... 1910.307(c)(2)(ii **Also permits
)(B). fixtures approved
for Class II,
Division 2 locations
to omit the group
marking.
1910.307(b)(2)(ii)(C)......... 1910.307(c)(2)(ii No substantive
)(C). change.
1910.307(b)(2)(ii)(D)......... 1910.307(c)(2)(ii No substantive
)(D). change.
1910.307(c)(2)(ii **Adds a requirement
)(E). that electric
equipment suitable
for an ambient
temperature
exceeding 40 [deg]C
(104 [deg]F) be
marked with the
maximum ambient
temperature.
1910.307(b)(3)................ 1910.307(c)(3)... No substantive
change.
1910.307(b)(3), Note.......... 1910.307(c)(3), The last sentence of
Note. the note is removed
to make it clear
that the OSHA
standard does not
incorporate the
National Electrical
Code by reference.
The NEC continues to
be a guideline that
employers may
reference in
determining the type
and design of
equipment and
installations that
will meet the OSHA
standard.
1910.307(c)................... 1910.307(d)...... No substantive
change.
1910.307(d)................... 1910.307(e)...... No substantive
change.
[[Page 7154]]
1910.307(f)...... **The final rule adds
a list of specific
protective
techniques for
electrical
installations in
hazardous locations
classified under the
division
classification
system.
1910.307(g)...... **Adds the zone
classification
system as an
alternative method
of installing
electric equipment
in hazardous
locations. This
paragraph sets the
protective
techniques and other
requirements
necessary for safe
installation of
electric equipment
in hazardous
locations classified
under the zone
classification
system. (See
detailed discussion
later in this
section of the
preamble).
Sec. 1910.308 Special Sec. 1910.308
systems. Special systems.
1910.308(a), introductory text 1910.308(a), No substantive
introductory change.
text.
1910.308(a)(1)(i)............. 1910.308(a)(1)(i) **Adds the following
and (a)(3)(ii). wiring methods to
those acceptable for
installations
operating at more
than 600 V:
Electrical metallic
tubing, rigid
nonmetallic conduit,
busways, and cable
bus. The proposal
also removes the
specific requirement
to support cables
having a bare lead
sheath or a braided
outer covering in a
manner to prevent
damage to the braid
or sheath. This
hazard is covered by
Sec.
1910.303(b)(1) and
(b)(8)(i) and new
Sec.
1910.308(a)(4).
1910.308(a)(1)(ii)............ 1910.308(a)(1)(ii No substantive
). change.
1910.308(a)(2) ** Adds requirements
and (a)(3)(i). to ensure that high-
voltage cables can
adequately handle
the voltage stresses
placed upon them and
to ensure that any
coverings are flame
retardant.
1910.308(a)(4)... **Adds requirements
for the protection
of high-voltage
cables against
moisture and
physical damage
where the cable
conductors emerge
from a metal sheath.
1910.308(a)(2)(i)............. 1910.308(a)(5)(i) No substantive
change.
1910.308(a)(5)(ii **Adds requirements
). for fuses to protect
each ungrounded
conductor, for
adequate ratings of
fuses installed in
parallel, and for
the protection of
employees from power
fuses of the vented
type.
1910.308(a)(2)(ii)............ 1910.308(a)(5)(ii **Clarifies that
i). distribution cutouts
are not suitable for
installation in
buildings or
transformer vaults.
1910.308(a)(5)(iv **Adds requirements
). for fused cutouts to
either be capable of
interrupting load
current or be
supplemented by a
means of
interrupting load
current. In
addition, a warning
sign would be
required for fused
cutouts that cannot
interrupt load
current.
1910.308(a)(5)(v) **Adds a requirement
for guarding
nonshielded cables
and energized parts
of oil-filled
cutouts.
1910.308(a)(5)(vi **Adds requirements
). to ensure that load
interrupting
switches will be
protected against
interrupting fault
current and to
provide for warning
signs for backfed
switches.
1910.308(a)(2)(iii)........... 1910.308(a)(5)(vi No substantive
i). change.
1910.308(a)(3)................ 1910.308(a)(6)... No substantive
change.
1910.308(a)(4)(i)............. 1910.308(a)(7), No substantive
introductory change.
text.
1910.308(a)(4)(ii)............ 1910.308(a)(7)(i) No substantive
and (a)(7)(iii). change. (Individual
requirements are
placed in separate
paragraphs).
1910.308(a)(7)(ii **Clarifies that
). multiconductor
portable cable may
supply mobile
equipment.
1910.308(a)(4)(iii)........... 1910.308(a)(7)(iv No substantive
) and (a)(7)(v). change. (Individual
requirements are
placed in separate
paragraphs).
1910.308(a)(7)(vi **Limits the
). conditions under
which switch or
contactor enclosures
may be used as
junction boxes or
raceways.
1910.308(a)(4)(iv)............ 1910.308(a)(7)(vi No substantive
i). change.
1910.308(a)(4)(v)............. 1910.308(a)(7)(vi No substantive
ii). change.
1910.308(b)(1)................ 1910.308(b), No substantive
introductory change.
text.
1910.308(b)(2)................ 1910.308(b)(1)... No substantive
change.
1910.308(b)(3)................ 1910.308(b)(2)... **Clarifies that
emergency
illumination
includes all
required means of
egress lighting,
illuminated exit
signs, and all other
lights necessary to
provide required
illumination.
1910.308(b)(3)... **Adds requirements
to provide signs
indicating the
presence and
location of on-site
emergency power
sources under
certain conditions.
1910.308(c)(1), introductory 1910.308(c)(1), No substantive
text. introductory change.
text.
1910.308(c)(1)(i), (c)(1)(ii), 1910.308(c)(1)(i) **Clarifies the power
and (c)(1)(iii). , (c)(1)(ii), limitations of Class
and (c)(1)(iii). 1, 2, and 3 remote
control, signaling,
and power-limited
circuits based on
equipment listing.
1910.308(c)(2)................ 1910.308(c)(2)... No substantive
change.
1910.308(c)(3)... **Adds requirements
for the separation
of cables and
conductors of Class
2 and Class 3
circuits from cables
and conductors of
other types of
circuits.
1910.308(d)(1)................ 1910.308(d)(1)... No substantive
change.
1910.308(d)(2), introductory 1910.308(d)(2), No substantive
text. introductory change.
text.
1910.308(d)(2)(i)............. 1910.308(d)(2)(i) No substantive
change.
1910.308(d)(2)(ii)............ 1910.308(d)(2)(ii **Adds a requirement
). for power-limited
fire alarm circuit
power sources to be
listed and marked as
such.
1910.308(d)(3)................ 1910.308(d)(3)(i) No substantive
change.
1910.308(d)(4)................ 1910.308(d)(3)(ii **Clarifies the
), (d)(3)(iii), requirements for
and (d)(3)(iv). installing power-
limited fire-
protective signaling
circuits with other
types of circuits.
(Individual
requirements are
placed in separate
paragraphs).
1910.308(d)(5)................ 1910.308(d)(4)... No substantive
change.
1910.308(e)(1)................ 1910.308(e), No substantive
introductory change.
text.
1910.308(e)(2)................ 1910.308(e)(1)... **Clarifies the
requirement for
listed primary
protectors to make
it clear that
circuits confined
within a block do
not need protectors.
1910.308(e)(3)(i)............. 1910.308(e)(2)(i) No substantive
and (e)(2)(ii). change.
1910.308(e)(3)(ii)............ 1910.308(e)(2)(ii No substantive
i). change.
1910.308(e)(3)(iii)........... 1910.308(e)(2)(iv No substantive
). change.
1910.308(e)(4)................ 1910.308(e)(3)... No substantive
change.
1910.308(e)(5)................ 1910.308(e)(4)... No substantive
change.
1910.308(f)...... **Adds requirements
to separate
conductors of solar
photovoltaic systems
from conductors of
other systems and to
provide a
disconnecting means
for solar
photovoltaic
systems.
1910.308(g)...... **Adds an exception
to the provisions on
the location of
overcurrent
protective devices
for integrated
electrical systems.
------------------------------------------------------------------------
Note to table:
**These new and revised provisions are included in the 2000 and 2004
editions of NFPA 70E standard. The NFPA 70E Committee believes that
these provisions, which were taken from the 1999 and 2002 NEC,
respectively, are essential to employee safety. OSHA agrees with the
consensus of NFPA's expert opinion that these requirements are
reasonably necessary to protect employees and has included them in the
final rule. On occasion, OSHA has rewritten the provision to lend
greater clarity to its requirements. However, these editorial changes
to the language of NFPA 70E do not represent substantive differences.
NFPA's handling of these provisions and the rationale underpinning
them is a matter of public record for the NEC and NFPA 70E and is part
of the record for this rulemaking (Exs. 2-9 through 2-18). OSHA agrees
with the rationale in this record as it pertains to the new and
revised provisions the Agency is adopting.
F. General Requirements (Sec. 1910.303)
Paragraph (b) of proposed Sec. 1910.303 contained a general
requirement for electric equipment to be free of recognized hazards
likely to cause death or serious physical harm to employees. This
provision also contained criteria for judging the safety of electric
equipment. One of the criteria was suitability for installation and use
in accordance with Subpart S, and a note following paragraph (b)(1)(i)
indicated that listing or labeling by a nationally recognized testing
laboratory could be evidence of suitability.
The National Multihousing Council recommended adding a second note
to this paragraph to indicate that nothing in this provision was to be
taken as a directive that limits a local jurisdiction's authority to
amend the adopted electrical code (Ex. 4-20).
Local electrical inspection authorities have jurisdiction over
public safety as well as employee safety and this jurisdiction is not
preempted by OSHA standards. OSHA does not believe that a note to the
standard is necessary to clarify this authority. Indeed, the
recommended note might serve to confuse employers and employees,
leading them to believe that OSHA might enforce those local
requirements. Therefore, Sec. 1910.303(b)(1)(i) in the final standard
does not include such a note.
In paragraph (g) of proposed Sec. 1910.303, OSHA would have
required the employer to maintain sufficient access and working space
about electric equipment to permit ready and safe operation and
maintenance of equipment. This paragraph would have required the access
and working space to meet certain minimum dimensions. One commenter
expressed concern regarding the physical space about electric equipment
on ships (Ex. 3-7). This commenter argued that, in shipbuilding and
repair, the limited space on a ship is a design concern for shore-based
equipment. He stated that some shore-based electric equipment is placed
in locations that ensure safe access to disconnect switches in the
event of an emergency or routine connection of other equipment and that
the working space in these locations can be limited. However, he stated
that his company deenergizes and removes shore-based equipment before
servicing or maintenance.
OSHA believes that this commenter's installation complies with
final Sec. 1910.303(g). The introductory text to paragraph (g)(1)
contains the general requirement that sufficient access and working
space shall be provided and maintained about all electric equipment to
permit ready and safe operation and maintenance of such equipment.
These provisions ensure that employees maintaining electric equipment
while it is energized have enough room to work without danger of
contacting energized parts and grounded parts or two circuit parts
energized at different potentials simultaneously. The specific
dimensions required by paragraph (g)(1)(i) apply only to equipment
likely to require examination, adjustment, servicing, or maintenance
while it is energized. As long as the employer implements,
communicates, and enforces a policy to ensure that the equipment is
deenergized before employees engage in any of these tasks that might
expose them to contact with energized parts, paragraph (g)(1)(i) does
not apply, and the equipment need not provide the specific amount of
working space required by that provision. In the commenter's case, the
employer not only deenergizes the equipment but removes it from the
space in question altogether, thus providing an additional measure of
safety. On the other hand, if the equipment were not deenergized, then
employees would not be able to work on the equipment safely.
Table S-3 and Sec. 1910.303(h)(5)(v) in the proposed rule would
have required a minimum elevation of 2.8 m (9.0 ft) for unguarded live
parts operating at 601 to 7500 V and located above working space. A
note following proposed Table S-3 permitted the minimum elevation to be
2.6 m (8.5 ft) for installations built before the effective date of the
final standard. However, Table S-3 in the existing standard provides
for a minimum elevation of 2.4 m (8.0 ft) for installations built before
April 16, 1981, if the voltage is in the range of 601 to 6600 V. OSHA
unintentionally omitted this exception for older installations from the
footnote to Table S-3 in the proposal. The Agency does not intend for
installations made before April 16, 1981, to be modified to provide an
additional 0.2 m (0.5 ft) of elevation. Therefore, the Agency is carrying
forward the language from the existing standard allowing for the reduced
minimum elevation for those older installations.
G. Branch Circuits--Identification of Multiwire Branch Circuits
Identification requirements. Paragraph (b)(1) of final Sec.
1910.304 adds requirements for identification of multiwire branch
circuits. The rule requires that all ungrounded conductors of multiwire
branch circuits in a building be identified, where accessible, by phase
and system where more than one nominal voltage system exists. It goes
on to add that the identification means shall be permanently posted at
each branch circuit panelboard. For example, the identification means
can be color coding, marking tape, or tagging.
For instance, a building served by both 208Y/120-volt and 480Y/277-
volt multiwire branch circuits must use a wiring identification means.
One method of meeting final Sec. 1910.304(b)(1) would be to use a
color-coded scheme with brown, orange, and yellow insulation for the
480-volt system's phase conductors and black, red, and blue insulation
for the 208-volt system's phase conductors. A legend, which may include
other information such as the panelboard identification, must be
permanently affixed at each branch circuit panelboard to identify the
respective phase and system color-coding scheme.
One commenter requested clarification of the term "where
accessible" used in Sec. 1910.304(b)(1) of the proposed rule (Ex. 4-
14). He questioned whether the identification means must be posted at
each pull and junction box. He suggested allowing a color-coding scheme
identified in the employer's written electrical safety program.
OSHA believes that the typical means of complying with this
provision, which was ultimately taken from 1999 NEC Section 210-
4(d),\13\ will be to use conductors with insulation of different colors
for each system and post a legend identifying which colors are used
with which systems at each panelboard. The color-coded conductors for
each circuit are visible at each pull and junction box, which are
locations where the conductors are accessible; thus, the employees can
determine the voltage on a circuit and at utilization equipment or
devices such as motors or receptacle outlets by referring to the legend
at the panelboard supplying the circuit. Final Sec. 1910.304(b)(1)
requires the legend to be posted at the panelboard for each branch
circuit, not at the pull and junction boxes.
---------------------------------------------------------------------------
\13\ Section 210-4(d) of the 1999 NEC reads as follows:
(d) Identification of Ungrounded Conductors. Where more than one
nominal voltage system exists in a building, each ungrounded
conductor of a multiwire branch circuit, where accessible, shall be
identified by phase and system. This means of identification shall
be permitted to be by separate color coding, marking tape, tagging,
or other approved means and shall be permanently posted at each
branch-circuit panelboard.
---------------------------------------------------------------------------
The requirements proposed in Sec. 1910.304(b)(1) and (b)(3) for
ungrounded conductors of systems of different voltages to be identified
were very similar. Proposed paragraph (b)(1) would have required
identification of multiwire branch circuits \14\ only, whereas
paragraph (b)(3) would have required identification regardless of
whether a circuit was a multiwire circuit. Paragraph (b)(1) was taken
from NFPA 70E-2000 Section 2-2.1, and paragraph (b)(3) was taken from
NFPA 70E-2000 Section 2-2.3 (Ex. 2-2). In addition, both NFPA sections
are taken from 1999 NEC Section 210-4(d). Proposed paragraph (b)(3)
inadvertently omitted language from the NFPA standard (Section 2-2.3)
restricting its application to multiwire circuits. Although no one
submitted comments on this problem, OSHA has decided to correct this
error by not carrying proposed Sec. 1910.304(b)(3) into the final
rule.
---------------------------------------------------------------------------
\14\ A multiwire branch circuit is a branch circuit that
consists of two or more ungrounded conductors that have a voltage
between them and a grounded conductor that has equal voltage between
it and each ungrounded conductor of the circuit and that is
connected to the neutral or grounded conductor of the system.
---------------------------------------------------------------------------
H. Branch Circuits--Ground-Fault Circuit-Interrupters for Employees
Introduction. Each year many employees suffer electric shocks while
using portable electric tools and equipment. The nature of the injuries
ranges from minor burns to electrocution. Electric shocks produced by
alternating currents (ac) at power line frequency passing through the
body of an average adult from hand to foot for 1 second can cause
various effects, starting from a condition of being barely perceptible
at 1 milliampere to loss of voluntary muscular control for currents
from 9 to 25 milliamperes. The passage of still higher currents, from
75 milliamperes to 4 amperes, can produce ventricular fibrillation of
the heart; and, finally, immediate cardiac arrest at over 4 amperes.
These injuries occur when employees contact electrically energized
parts. Typically, the frame of a tool becomes accidentally energized
because of an electrical fault (known as a ground fault) that provides
a conductive path to the tool casing. For instance, with a grounded
electric supply system, when the employee contacts the tool casing, the
fault current takes a path through the employee to an electrically
grounded object. The amount of current that flows through an employee
depends, primarily, upon the resistance of the fault path within the
tool, the resistance of the path through the employee's body, and the
resistance of the paths, both line side and ground side, from the
employee back to the electric power supply. Moisture in the atmosphere
can contribute to the electrical fault by enhancing both the conductive
path within the tool and the external ground path back to the electric
power supply. Dry skin can have a resistance range of anywhere from
about 500 to 500,000 ohms and wet skin can have a resistance range of
about 200 to 20,000, depending on several factors, such as the physical
characteristics and mass of the employee. More current will flow if the
employee is perspiring or becomes wet because of environmental
conditions. If the current is high enough, the employee will suffer a
ground-fault electrocution.
One method of protection against injuries from electric shock is
the ground-fault circuit-interrupter (GFCI). This device continually
monitors the current flow to and from electric equipment. If the
current going out to the protected equipment differs by approximately
0.005 amperes (5-milliamperes) from the current returning, then the
GFCI will deenergize the equipment within as little as 25 milliseconds,
quickly enough to prevent electrocution.
GFCI requirements. Paragraph (b)(3) of final Sec. 1910.304 sets
new requirements for ground-fault circuit-interrupter protection of
receptacles and cord connectors used in general industry. Paragraph
(b)(3)(i) requires ground-fault circuit protection for all 125-volt,
single-phase, 15- and 20-ampere receptacles installed in bathrooms and
on rooftops. As noted earlier, this provision only applies to
installations made after the effective date of the final rule. Cord
sets and cord- and plug-connected equipment in these locations can get
wet and expose employees to severe ground-fault hazards. The NFPA 70E
Technical Committee believes, and OSHA agrees, that using 125-volt,
15- and 20-ampere cord- and plug-connected equipment in these locations
exposes employees to great enough risk of ground-fault electrocution
(as noted earlier) to warrant the protection afforded by GFCIs.\15\
---------------------------------------------------------------------------
\15\ Part I 2-2.4.1 of NFPA 70E, 2000 edition, requires GFCI
protection for all 120-volt, single-phase, 15- and 20-ampere
receptacles installed in bathrooms and on rooftops for other than
dwelling units.
---------------------------------------------------------------------------
Paragraph (b)(3)(ii) of final Sec. 1910.304 requires GFCI
protection for all receptacle outlets on temporary wiring installations
that are used during maintenance, remodeling, or repair of buildings,
structures, or equipment, or during similar construction-like
activities.\16\ Such activities include cleanup, disaster remediation,
and restoration of large electrical installations.
---------------------------------------------------------------------------
\16\ See also the discussion of the term "construction-like
activities" under the summary and explanation of final Sec.
1910.305(a)(2), later in this section of the preamble. It should be
noted that the discussion of the term "construction-like
activities" is intended for application only to the use of this
term in Subpart S.
---------------------------------------------------------------------------
OSHA currently requires GFCI protection for 120-volt, single-phase,
15- and 20-ampere temporary receptacle outlets used on construction
sites (Sec. 1926.404(b)(1)). In the 28 years that this requirement has
been in effect, the Agency estimates that between about 650 and 1,100
lives have been saved because of it.\17\ Temporary wiring associated
with construction-like activities in general industry exposes employees
to the same ground-fault hazards as those associated with temporary
receptacle outlets on construction sites. In Sec. 1910.304(b)(3)(ii),
OSHA is extending the ground-fault protection requirement to temporary
receptacles used in construction-like activities performed in general
industry. At the same time, this final rule extends protection to
temporary wiring receptacles of higher voltage and current ratings
(such as 125-volt, single-phase, 30-ampere and 480-volt, three-phase
receptacles). It better protects employees from ground-fault hazards
than the construction rule because it covers other equipment that is
just as subject to damage as 120-volt, single-phase, 15- and 20-ampere
equipment and that is more prevalent today than when the construction
rule was promulgated over 28 years ago.
---------------------------------------------------------------------------
\17\ In the preamble to the final rule adopting a requirement
for GFCIs on construction sites, OSHA estimated that there were
between 30 and 45 deaths per year caused by 120-volt ground faults
on construction sites, and the Agency determined that nearly all of
those deaths could be prevented by the use of GFCI protection or an
assured grounding program (41 FR 55701, December 21, 1976). OSHA
fatality investigation data indicate that 46 deaths involving 120-
volt ground-faults in temporary wiring occurred over the years 1990
to 1996 (the latest year for which data are complete). This is a
death rate of only 6.6 per year. Thus, OSHA believes that the rule
has saved between 23 and 39 lives per year or, over the 28 years the
rule has been in effect, a total of between about 650 and 1,100
lives.
---------------------------------------------------------------------------
The Agency had proposed not to permit the NFPA 70E "Assured
Grounding Program" as an alternative to GFCIs in this rule. NFPA 70E's
Assured Grounding Program, differs in several important respects from
the assured equipment grounding conductor program in OSHA's
construction standards (Sec. 1926.404(b)(1)). For example, NFPA 70E
permits the Assured Grounding Program as an alternative to GFCI
protection for personnel (1) for 125-volt, single-phase, 15- and 20-
ampere receptacle outlets in industrial establishments only, with
conditions of maintenance and supervision that ensure that only
qualified personnel are involved, and (2) for receptacle outlets rated
other than 125 volts, single-phase, 15, 20, or 30 amperes. The OSHA
construction rule recognizes an assured equipment grounding conductor
program as an alternative to GFCIs without restriction. Additionally,
under its Assured Grounding Program, NFPA 70E requires electric
equipment to be tested only when there is evidence of damage. This is
in contrast to the assured equipment grounding conductor program
required by OSHA's construction standard, which requires electric
equipment to be tested after any incident that can reasonably be
suspected to have caused damage.
During the development of the proposal, OSHA had considered
including NFPA 70E's Assured Grounding Program or the construction
standard's assured equipment grounding conductor program requirements
as alternatives to GFCIs, but rejected them. In the preamble to the
proposal, OSHA gave the following reasons for rejecting NFPA's Assured
Grounding Program: (1) The differences between the general industry and
construction requirements would have been too confusing for employers
who are subject to both standards, and (2) the NFPA alternative would
offer less protection for employees than the assured equipment
grounding conductor program in OSHA's construction standard.
Additionally, OSHA reasoned in the proposal that requiring GFCIs alone,
without even the construction standard's assured equipment grounding
conductor program as an alternative, would provide better protection
for employees. The construction standard's assured equipment grounding
conductor program demands constant vigilance on the part of employees
to provide them with the same level of protection as GFCIs. Under that
program, employers must perform rigorous inspections and tests of cord
sets and cord- and plug-connected equipment generally at 3-month
intervals and employees must inspect them daily. In contrast, GFCIs
constantly monitor the circuit for ground faults and open the circuit
when ground-fault current becomes excessive without the need for either
the employer or the employee to take action. Because three fourths of
all electrical accidents are caused by poor work practices (55 FR
31986), OSHA believes that GFCIs are a more reliable method of
protecting employees.
OSHA received several comments generally supportive of the proposed
requirement for GFCIs for 125-volt, single-phase, 15- and 20-ampere
receptacles installed in bathrooms or on rooftops and for all 125-volt,
single-phase, 15-, 20-, and 30-ampere receptacle outlets that are not
part of the permanent wiring of the building or structure and that are
in use by personnel (Exs. 3-5, 3-6, 3-10, 4-9, 4-23, 4-24). For
example, the American Society of Safety Engineers (ASSE) supported the
new requirements for GFCI protection of receptacles and cord connectors
and for temporary wiring installations, stating that this is an
important aspect of the rule (Ex. 3-5). ASSE stated that this
requirement will greatly contribute to the rule's effectiveness in
saving lives and it is also consistent with OSHA's current requirements
in 29 CFR Part 1926 for construction sites. Another commenter supported
OSHA's statement in the proposal that GFCIs for temporary wiring
installations have been required in the NEC for many years and that the
requirement overall does not impose any hardships on employers (Ex. 5-
2). One of the commenters agreed that GFCIs provide continuous
protection for employees (Ex. 4-9). A comment (Ex. 4-24) from the
National Electrical Manufacturers Association (NEMA) stated that GFCIs
provide better protection for employees and a safer workplace than the
alternate assured equipment grounding conductor program included in
OSHA's construction standard. NEMA added that GFCIs provide continuous
protection whereas the assured equipment grounding conductor program
requires monthly inspection. NEMA recommended that the assured
equipment grounding program not be added as an alternative to GFCIs in
the general industry electrical installation standard.
Other commenters opposed OSHA's proposal not to include the assured
grounding program as an alternative to GFCIs (Exs. 3-3, 3-6, 3-10, 4-
11, 4-14, 4-19, 4-23). Some of them hinted that GFCI-type receptacles
and circuit breakers at voltages above 125 volts, 15, 20, and 30
amperes may require constant attention because of nuisance tripping
(Exs. 3-6, 3-10, 4-11, 4-19, 4-23). They added that it is possible and
likely that construction-type portable equipment used in industry will
trip GFCIs during normal operation. For example, Mike Johnson of
International Paper argued that portable welding units for the repair
of major pieces of equipment such as industrial boilers and other
massive pieces of equipment pose a real concern (Ex. 3-6). He noted
that the cord sets on such portable equipment are typically heavier and
less prone to damage than cords furnished with 125-volt equipment. He
further noted his experience with tripping of GFCIs during the normal
use of hermetic compressors, which are used for temporary cooling of
personnel. Some of those objecting to the omission of the assured
equipment grounding conductor program alternative argued that to avoid
nuisance tripping on circuits of more than 125 volts, they would be
forced to keep circuits very short beyond the location of the GFCI
protection (Exs. 4-11, 4-19). Another commenter, Alcoa, supported the
use of GFCI protection for all temporary 125-volt, single-phase wiring,
including the use of extension cord sets, but did not support the use
of GFCI protection on 480-volt, three-phase extension cord sets or 480-
volt temporary wiring (Ex. 4-14). Finally, some commenters argued that
the lack of commercially available GFCIs at voltages higher than 125
volts makes it impossible to comply with Sec. 1910.304(b)(4)(ii) as
proposed (Exs. 4-11, 4-19, 4-23).
These commenters gave three reasons why the Agency should permit an
assured equipment grounding conductor program as an alternative to
GFCIs, particularly at voltages higher than 125 volts: (1) Because,
they asserted, the assured equipment grounding conductor program is
equally effective; (2) because of tripping caused by (a) the inherently
high leakage current for some electric equipment or (b) the capacitive
leakage on long circuits of voltages over 125 volts; and (3) because
GFCIs are not available for all branch-circuit voltage and current
ratings.
Nothing in the record has convinced the Agency that its preliminary
conclusion that GFCIs are more effective protection than the assured
equipment grounding conductor program is incorrect. In fact, the 2002
NEC, which permits its assured equipment grounding conductor program as
an alternative to GFCIs only in very limited circumstances,\18\
indicates that NFPA has reached the same conclusion. OSHA disagrees
with the commenters' assertion that the assured equipment grounding
conductor program provides protection equivalent to GFCIs. Thus, the
Agency has determined based on the record that GFCIs are a more
effective means of protecting employees than the assured equipment
grounding conductor program.
---------------------------------------------------------------------------
\18\ NEC Section 527.6 requires electric shock or electrocution
protection for personnel using temporary wiring during activities
such as construction, remodeling, maintenance, repair, demolition,
and the like. GFCI protection or a written assured equipment
grounding conductor program must be used to provide this protection.
All 125-volt, single-phase 15-, 20-, and 30-ampere receptacle
outlets must have GFCI protection except that in industrial
establishments only, where only qualified personnel perform
maintenance, the assured equipment grounding conductor program is
permitted for specific situations. The limitations of the exception
in industrial establishments only are for situations in which: (1)
Qualified personnel are using equipment that is not compatible, by
design, with GFCI protection or (2) a greater hazard exists if power
was interrupted by GFCI protection.
For receptacle outlets other than those rated 125 volts, single
phase 15, 20, and 30 amperes, personnel protection must be provided
by either GFCI protection or a written assured equipment grounding
conductor program.
---------------------------------------------------------------------------
The Agency cannot determine whether the commenters concerns about
tripping caused by capacitive charging currents between the circuit
conductors and the equipment grounding conductor at voltages over 125
volts are valid. For multiphase circuits, capacitive currents should
balance out across the phases. Even on single-phase circuits, employers
should be able to control leakage and capacitive currents by limiting
the length of the conductors between the GFCI and the utilization
equipment.
However, OSHA recognizes the limited availability of GFCIs for
circuits operating at voltages above 125 volts to ground. Consequently,
it would be very difficult, if not impossible, for employers to comply
with a requirement for GFCI protection for all branch-circuit ratings.
For this reason, OSHA has decided to permit an assured equipment
grounding conductor program as an alternative to GFCIs when approved
GFCIs are unavailable for the voltage and current rating of the circuit
involved. However, the final rule does require employers to provide
GFCI protection whenever these devices are available at the branch-
circuit rating involved. The Agency anticipates that approved 1-, 2-,
and 3-pole GFCIs for branch-circuits with ratings above 125 volts and
30 amperes will become available in the future. Employers will need to
use those new devices for any temporary wiring installed after they do
become available. OSHA will continue to monitor developments in this
area and inform employers as appropriate of the availability of GFCIs.
Certain equipment designs cause tripping of GFCIs. For example,
some motors, due to design or application, have higher leakage current
to ground than a GFCI will allow. In other cases, GFCI tripping can
result in undesired consequences. For example, the NEC requires GFCI-
protected receptacles in garages at residences but allows for a non-
GFCI receptacle for large appliances such as a food freezer. If the
GFCI trips, the food in the freezer will spoil. An NEC exception to
GFCI protection for temporary installations recognizes the
incompatibility of these types of equipment on a GFCI-protected circuit
and allows the assured equipment grounding conductor program in place
of GFCIs under certain circumstances. Another NEC exception allows the
assured equipment grounding conductor program for temporary
installations where a greater hazard exists if power is interrupted by
a GFCI. For example, a motor for a ventilation fan used to exhaust
toxins in the atmosphere may not be compatible with GFCI protection.
Loss of the fan because of tripping by a GFCI can pose a risk to
employee health and safety. However, OSHA believes that even this type
of equipment should not be subject to the risks associated with
temporary cord- and plug-connected wiring. The Agency believes that
hard-wired methods, which avoid the use of a plug-receptacle
combination, afford better protection of employees relying on such
critical equipment. Because the GFCI requirement applies only to
receptacle outlets, employers can avoid having to install GFCIs by
wiring the equipment directly to the circuit conductors at an outlet or
panelboard.
Many of the commenters supporting the assured grounding alternative
recommended that the Agency include an assured equipment grounding
conductor program consistent with OSHA's existing requirements in 29
CFR 1926.404(b)(1)(iii) as an alternative to using GFCIs for protection
of personnel (Exs. 3-3, 3-5, 3-6). For example, ASSE recommended that
OSHA work at harmonizing this program with the assured equipment
grounding conductor program permitted under OSHA's construction
standards (Ex. 3-5). ASSE did concur that OSHA's testing program in the
construction standard, which requires testing after any incident that
can reasonably be suspected to have caused damage, is preferable to the
approach taken in NFPA 70E.
OSHA agrees with these commenters that any assured equipment
grounding conductor program in the general industry standards must be
consistent with the corresponding construction standard in Sec.
1926.404(b)(1)(iii). The Agency maintains that the assured equipment
grounding conductor program in the existing construction standards is
more protective than NFPA's assured grounding program. OSHA's
construction standard requires testing of all cord sets and receptacles
whenever it can reasonably be suspected that an incident may have
caused damage to the equipment, whereas the NFPA standard requires
testing only if an incident produces evidence of damage. The purpose of
the assured equipment grounding conductor program is designed to detect
and correct damage to the equipment grounding conductor particularly
when it is unseen. Demanding evidence of damage, as NFPA does,
partially thwarts that purpose. Therefore, the Agency has brought the
assured equipment grounding conductor program from Sec.
1926.404(b)(1)(iii) into this revision of the general industry
electrical installation standard. The final rule requires employers to
use the assured equipment grounding conductor program whenever approved
GFCIs are not available.
Although the assured equipment grounding conductor program in the
final rule is consistent with the one in the construction standard, the
final rule, unlike the construction standard, does not always permit it
to be used as an alternative to GFCIs. The determination that GFCIs are
a preferable form of protection and not to permit the assured equipment
grounding conductor in all circumstances is based on the public record
of this rulemaking. The final rule applies only to general industry and
not to construction. OSHA will not enforce this rule for construction
work; however, employers are encouraged to use GFCIs in accordance with
the general industry standard even when the construction standard
applies.
The assured equipment grounding conductor program in the
construction standard relies on the definition of "competent person"
in Sec. 1926.32(f).\19\ The assured equipment grounding conductor
program in this final rule also requires one or more competent persons
for implementation. Consequently, the Agency is bringing the definition
of "competent person" from OSHA's construction standards into final
Sec. 1910.399.
---------------------------------------------------------------------------
\19\ Paragraph (f) of Sec. 1926.32 reads as follows:
Competent person means one who is capable of identifying
existing and predictable hazards in the surroundings or working
conditions which are unsanitary, hazardous, or dangerous to
employees, and who has authorization to take prompt corrective
measures to eliminate them.
---------------------------------------------------------------------------
OSHA received numerous comments concerning proposed Sec.
1910.304(b)(4)(ii)(A). The pertinent part of this proposed provision
read, "receptacles on a 2-wire, single-phase portable or vehicle-
mounted generator rated not more than 5 kW, where the circuit
conductors of the generator are insulated from the generator frame and
all other grounded surfaces, are permitted without ground-fault
circuit-interrupter protection for personnel." This exemption from the
GFCI requirement was taken from NFPA 70E-2000.
Several commenters recommended removing this exemption (Exs. 4-13,
4-15, 4-17, 4-18, 4-21). These commenters stated that this exemption
has been removed from the most recent editions of the NEC and NFPA 70E.
They argued that there was never any technical justification for this
provision and, thus, its inclusion in the OSHA standard is unjustified.
OSHA agrees with these comments and has decided to remove this
exemption to better align the final rule with the consensus standards.
The proposed exemption from the GFCI requirement for portable and
vehicle-mounted generators was based on 1999 NEC Section 305-6(a),
Exception 1. The exemption in the 1999 NEC and the exemption in
proposed Sec. 1910.304(b)(4)(ii)(A) were the same as the exemption for
portable and vehicle-mounted generators in OSHA's construction
requirement for ground-fault circuit-interrupters (Sec.
1926.404(b)(1)(ii)). In promulgating the construction standard, OSHA
gave the following rationale for exempting these generators from the
requirement for GFCI protection:
On generators whose supply wires are not required to be
grounded, and are in fact not grounded, the return path for a
ground-fault current to flow is not completed and the hazard which a
GFCI would protect against is not present. Consequently, the rule as
promulgated in [Sec. 1926.404(b)(1)(ii)] does not require the use
of GFCI's on portable or vehicle-mounted generators of 5kW capacity
or less if its output is a two-wire, single-phase system and its
circuit conductors are insulated from the generator frame and all
other grounded surfaces. [41 FR 55702, December 21, 1976]
The NEC used to require only neutral conductors to be bonded to the
generator frame. (See, for example, 1981 NEC Section 250-6.) The NEC
now requires single-phase, two-wire circuits to have one circuit
conductor bonded to the generator frame. (See Sections 250-26 and 250-
34(c) of the 1999 NEC and Sections 250.26 and 250.34(C) of the 2002
NEC.) Thus, the NEC no longer permits generators to be wired so as to
meet the conditions in the proposed exemption. That is, because one of
the circuit conductors must be bonded to the generator frame, the
conductors cannot be "insulated from the generator frame" as required
by the exemption.
In addition, connecting one conductor on a single-phase, two-wire
generator to the generator frame facilitates the operation of a GFCI
when a ground fault occurs. Even though the generator frame is not
required to be grounded, it frequently is, through direct contact with
ground or through grounding-type equipment, which has its equipment
grounding conductor connected to the generator frame. Bonding one of
the circuit conductors to the generator frame provides a path outside
the circuit conductors for ground-fault current to flow. Such current
will be detected by a GFCI. If the circuit conductors are insulated
from the generator frame, it is more likely that any ground fault
current will return through the circuit conductors and go undetected by
a GFCI.\20\
---------------------------------------------------------------------------
\20\ For a ground fault to occur on an ungrounded circuit, two
faults must be present. If both faults are on the load side of the
GFCI, then any leakage current will go undetected.
---------------------------------------------------------------------------
For these reasons, OSHA has determined that the exemption from the
GFCI requirement for single-phase generators is not warranted and has
revised final Sec. 1910.304(b)(3)(ii)(A) (proposed Sec.
1910.304(b)(4)(ii)(A)) accordingly. In addition, the evidence in the
record indicates that it is also necessary to revise the generator
grounding requirements in final Sec. 1910.304(g)(2) and (g)(3)(iii) to
match Sections 250.26 and 250.34(C) of the 2002 NEC, respectively. (See
the summary and explanation of these provisions later in this section
of the preamble.) Removing the exception from final Sec.
1910.304(b)(3)(ii)(A) without revising the generator grounding
provisions would result in a requirement for GFCIs when they would not
work as intended to protect employees. Incorporating the NEC
provisions on generator grounding will work in concert with the GFCI
provisions to ensure that employees are adequately protected from
ground faults.
OSHA proposed Note 2 to Sec. 1910.304(b)(4)(ii)(A) to read as
follows:
Cord sets and devices incorporating listed ground-fault circuit-
interrupter protection for personnel are acceptable forms of
protection.
Several commenters suggested that the note be reworded to recognize
portable GFCI protection only when it is placed at the end closest to
the source of power (Exs. 4-13, 4-15, 4-17, 4-18, 4-21). They argued
that GFCI protection should be provided for the entire cord set and
that the only way to do so is to put the GFCI at the source of
power.\21\
---------------------------------------------------------------------------
\21\ The National Electrical Code Handbook for the 2002 NEC, in
its explanation of the NEC requirements for GFCI protection for
temporary installations, identifies a GFCI device as being designed
for insertion at the line, or source, end of a flexible cord set.
The short style of cord set shown in the Handbook lends itself to
in-series connection with single or multiple, series-connected, cord
sets.
---------------------------------------------------------------------------
OSHA agrees with these commenters and has revised the note to read:
Cord sets and devices incorporating the required ground-fault
circuit-interrupter that are connected to the receptacle closest to
the source of power are acceptable forms of protection.
This language, which was similar to that recommended by these
commenters, will provide the most effective protection for employees
using temporary wiring. Employers using portable GFCIs to comply with
final Sec. 1910.304(b)(3)(ii)(A) must install them at the first
receptacle on the circuit (the end closest to the source of power).
This will protect employees from faults in all downstream cord sets and
equipment.
I. Accessibility of Overcurrent Devices
Proposed Sec. 1910.304(f)(1)(iv) addressed the location of
overcurrent devices. The first sentence of this provision would have
required overcurrent devices to be accessible "to each employee or
authorized building management personnel."
OSHA received a request to insert the word "qualified" before
"employee" in that provision (Ex. 4-22). The commenter was concerned
that the provision would require every employee at the workplace to
have access to overcurrent devices.
This proposed provision is identical to existing Sec.
1910.304(e)(1)(iv) and is consistent with Sec. 240.24 of the 2002 NEC.
The wording of this provision permits employers to restrict access to
authorized building management personnel. Consequently, the proposed
rule does not require access by every employee, and there is no need to
revise the language of the rule.
J. Grounding
Proposed Sec. 1910.304(g)(1) listed systems that would have been
required to be grounded. Proposed paragraphs (g)(1)(iv) and (g)(1)(v)
governed grounded and ungrounded ac systems of 50 to 1000 volts. These
two paragraphs were substantively the same as paragraphs (f)(1)(iv) and
(f)(1)(v) of existing Sec. 1910.304, except that in the existing rule
ac circuits of 480 to 1000 volts are permitted to use a high-impedance
grounded neutral in lieu of a neutral with a direct connection to the
grounding electrode.
In a joint comment, CHS Inc., and the National Cooperative Refinery
Association (NCRA) expressed concern about these provisions (Ex. 4-25).
These two companies requested that the Agency consider permitting the
operation of three-phase ungrounded delta systems that have been
utilized for many years by the refining industry and others for
electrical systems. They argued that these systems became popular in
the early 20th century because of the need to operate loads without
interruption because of the operation of overcurrent protection devices
on a short circuit. The comment referenced Soares Book on Grounding
published by the International Association of Electrical Inspectors.
Quoting this book, the commenter stated that the reason to operate a
system in this manner is to "obtain an additional degree of service
continuity. Since the system is ungrounded, the occurrence of the first
ground fault (as distinguished from a short circuit) on the system will
not cause an overcurrent protective device to open." CHS and NCRA
further noted that these ungrounded systems are used with ground
detection equipment and that trained electrical maintenance personnel
investigate and repair problems without causing an abrupt outage.
Electrical systems are grounded primarily to:
(1) Limit overvoltages caused by lightning, line surges, or contact
with higher voltage systems;
(2) Stabilize voltage to earth during normal operation; and
(3) Facilitate the operation of overcurrent devices protecting the
circuit. (See 1999 NEC Section 250-2.) \22\
---------------------------------------------------------------------------
\22\ Soares Book on Grounding, a recognized reference on
grounding to which CHS and NCRA referred, offers a list of known
disadvantages of operating ungrounded three-phase ac systems as
follows:
Disadvantages of operating systems ungrounded include but are
not limited to the following:
1. Power system overvoltages are not controlled. In some cases,
these overvoltages are passed through transformers into the premises
wiring system. Some common sources of overvoltages include:
lightning, switching surges and contact with a high voltage system.
2. Transient overvoltages are not controlled, which, over time,
may result in insulation degradation and failure.
3. System voltages above ground are not necessarily balanced or
controlled.
4. Destructive arcing burnouts can result if a second fault
occurs before the first fault is cleared.
---------------------------------------------------------------------------
An ac system that is connected for ungrounded operation is a system
that is connected to ground via the capacitance of the insulating
medium, be it air, rubber or thermoplastic insulation. The capacitance-
to-ground varies resulting in system operating problems. The line-to-
ground voltage is not constant. Such erratic voltage makes ungrounded
systems difficult to troubleshoot.
OSHA views these conditions as hazardous to employees working near
the power system. A hazard of this type of installation is the
possibility for the frame of a piece of equipment to become energized
at some voltage above ground. A shock hazard exists if an employee
simultaneously touches the equipment and a grounded object such as a
handrail.
In general, the NEC and the IAEI Soares Book on Grounding cite very
similar if not the same recommendations for grounding of electrical
systems, and the final rule parallels these requirements. In fact,
contrary to the suggestions made by the commenters, the provisions in
question are entirely consistent with the IAEI Soares Book on
Grounding. Paragraph (g)(1)(iv) of final Sec. 1910.304 requires delta
systems of 50 to 1000 volts \23\ to be grounded only if:
---------------------------------------------------------------------------
\23\ Systems over 1000 volts are covered by final Sec.
1910.304(g)(9), to which CHS and NRCA did not object.
---------------------------------------------------------------------------
(1) They can be grounded so that the maximum voltage to ground on
the ungrounded conductors does not exceed 150 volts (that is, a delta
system with a phase-to-phase voltage of 150 volts or less),
(2) The system is a three-phase, four-wire delta circuit in which
the midpoint of one phase is used as a circuit conductor, or
(3) A service conductor is uninsulated.
OSHA believes that few delta systems meet any of these conditions,
in which case the final rule does not require them to be grounded. Even
if one of those conditions is met, the circuit may operate using a
high-impedance grounded neutral system as permitted by final
Sec. 1910.304(g)(1)(v)(E). Such systems provide higher system
reliability in a manner similar to ungrounded systems in that a single
ground fault triggers alarms on ground-detection equipment instead of
causing the circuit protective devices to deenergize the circuit.
However, these systems provide better protection against ground faults
and overvoltages than do ungrounded systems.
Finally, the provisions to which CHS and NCRA refer are not new
requirements. They are in the existing OSHA electrical standard and
have been enforced by the Agency since 1972.
For all of these reasons, OSHA believes that grounded systems are a
much more reliable method of protecting employees than ungrounded
systems and has retained Sec. 1910.304(g)(1)(iv) and (g)(1)(v) as
proposed.
For the reasons presented under the summary and explanation of
final Sec. 1910.304(b)(3)(ii)(A) (proposed Sec.
1910.304(b)(4)(ii)(A)), earlier in this section of the preamble, OSHA
is revising the grounding requirements in Subpart S for consistency
with 2002 NEC Sections 250.26 and 250.34(C). This revision is in two
parts: A new provision (final Sec. 1910.304(g)(2)) and a revised
provision (final Sec. 1910.304(g)(3)(iii), proposed Sec.
1910.304(g)(2)(iii)). Final Sec. 1910.304(g)(2), which had no
counterpart in the proposal, adopts requirements from 2002 NEC Section
250.26 specifying which conductor in an ac system must be grounded.
This new provision complements final Sec. 1910.303(g)(1), which
specifies which systems must be grounded. These two provisions ensure
that the voltage to ground on ungrounded conductors is minimized. It
should be noted that final Sec. 1910.304(g)(2) requires a system
conductor to be grounded only when that system is required to be
grounded by Sec. 1910.304(g)(1).
Paragraph (g)(3)(iii) of final Sec. 1910.304 is revised to match
2002 NEC Section 250.34(C). The revised provision requires that any
system conductor required to be grounded by final Sec. 1910.304(g)(2)
be bonded to the generator frame, which serves as the grounding
electrode for the system. This requirement ensures that systems fed by
portable and vehicle-mounted generators are wired consistently with
service-supplied systems and provide a level of safety equal to that of
service-supplied systems.
Proposed Sec. 1910.304(g)(3)(iii) (final Sec.
1910.304(g)(4)(iii)) stated, "On extensions of existing branch
circuits that do not have an equipment grounding conductor, grounding-
type receptacles may be grounded to a grounded cold water pipe near the
equipment."
OSHA received several comments on the use of cold water pipes for
equipment grounding connections (Exs. 4-4, 4-13, 4-15, 4-17, 4-18, 4-
21). For example, Mr. Brooke Stauffer of the National Electrical
Contractors Association (NECA) recommended deleting this requirement
from the standard, arguing that this method of grounding is not
permitted in the 2002 NEC (Ex. 3-2). He noted that Section 250.52 of
the NEC states that an interior metal water pipe more than 1.52 meters
(5 feet) from the point of entrance of the water pipe into the building
is no longer allowed to serve as part of the grounding electrode
system. Other comments stated that using an isolated equipment
grounding conductor such as a cold water pipe may increase the risk of
reactance along the equipment grounding conductor when an ac fault is
involved (Exs. 4-4, 4-13, 4-15, 4-17, 4-18, 4-21). For example, one
commenter stated that using a water pipe to ground equipment violates
2002 NEC Section 300.3(B), which requires all circuit conductors to be
grouped together so magnetic fields are offset and reluctance is
minimized (Exs. 4-13, 4-15). He further argued that plastic pipe makes
water pipes an unreliable ground and that using water pipes to ground
electric equipment can pose hazards to employees working on the piping
system, as follows:
Water pipes cannot be counted upon to serve the same function as
an equipment grounding conductor, which is to prevent electrocution
due to malfunctioning equipment on the branch circuit by allowing
large amounts of current to flow and trip the overcurrent device.
The use of water pipes as equipment grounding conductors is actually
more likely to cause an electrocution in the event that a plumber,
pipe-fitter or similar professional working on the water piping
system would break a pipe connection involved in a fault, thereby
exposing themselves to the full lethal circuit voltage and providing
a path for current to flow. Unlike electrical workers working on
branch circuits, there are no specific requirements for plumbers,
pipe-fitters or similar professionals to deenergize and lock out
electrical circuits in order to work on plumbing systems, nor should
there be one.
The advent of current technology and practice of using
nonmetallic pipe in all or part of a plumbing system would cause
metallic parts of equipment or sections of the water piping to
become energized if a tool or equipment were to malfunction and
expose anyone (plumber, pipe-fitter, general plant employee) to an
electrocution hazard from simple contact with the piping system.
[Ex. 4-13]
OSHA agrees with these comments. It is important for the equipment
grounding conductor to be reliable and of low impedance. Water pipes
are neither. In addition, as noted by this commenter, employees working
on water pipes used in this manner can be exposed to hazardous
differences in electrical potential across an open pipe. On the other
hand, OSHA has allowed grounded cold water pipes to be used for
grounding branch circuit extensions since 1972. (See, for example,
existing Sec. 1910.304(f)(3)(iii).\24\) Since there have been very few
reported accidents, the Agency does not believe that the risk to
employees, not to mention the substantial cost to employers, of
rerunning these branch circuit extensions is worth the reduction in
risk associated with the continued use of water pipes for grounding
purposes. To redo a branch circuit extension, an employee would need to
deenergize the existing circuit and run new conductors back to a point
where an acceptable connection to the ground is available. (Section
250.130(C) of the 2002 NEC lists acceptable grounding points.) The risk
of inadvertently contacting an energized part during the recircuiting
process is likely to be at least as high as the risk of electric shock
caused by using the water pipe as an equipment grounding conductor.
Also, it may not be known which branch circuit receptacles are grounded
to a water pipe; thus, employees may be introduced to hazards in the
process of tracing the existing wiring installation. Consequently, the
final rule allows using a grounded cold water pipe as the equipment
grounding conductor on branch circuit extensions only in existing
installations. The final rule would also require such equipment
grounding connections to be replaced any time work is performed on the
branch circuit. In such cases, the circuit would need to be deenergized
anyway, and there would be no increased risk during the installation of
a new equipment grounding conductor.
---------------------------------------------------------------------------
\24\ The existing standard permits the use of a grounded cold
water pipe as an equipment grounding only for extensions of branch
circuits that do not have an equipment grounding conductor.
---------------------------------------------------------------------------
Proposed Sec. 1910.304(g)(4) (final Sec. 1910.304(g)(5)) would
have required the path to ground from circuits, equipment, and
enclosures to be permanent and continuous. The language in this
proposed provision is identical to existing Sec. 1910.304(f)(4).
Several commenters recommended adding the word "effective" in the
requirement to ensure that the grounding path of the conductor is
successful in providing a permanent and continuous path to ground (Exs.
4-4, 4-13, 4-15, 4-17, 4-18, 4-21). These commenters noted that the NEC
has requirements on effective grounding and has had these requirements
in the code for many years and that the proposed rule was inconsistent
with the NEC, NFPA 70E, and other OSHA requirements. For example, Mr.
Douglas Baxter stated:
Equipment grounding is important enough for OSHA to require it
to be effective as stated in the proposal at these locations:
Page 17817-1910.304(b)(2)(ii) "Receptacles and cord connectors
having grounding contacts shall have those contacts effectively
grounded."
Page 17823-1910.305(c)(5) "Grounding. Snap switches, including
dimmer switches, shall be effectively grounded and shall provide a
means to ground metal faceplates."
It is unclear as to why OSHA believes that electrical circuits
and equipment (which would be referenced under 1910.304(g)(4))
somehow will not present an electrocution hazard if not effectively
grounded unlike receptacles or snap switches.
Particularly noteworthy to underscore is the fact that as
written in the proposal, 1910.304(g)(4) is not consistent with the
2004 (current) edition of NFPA 70E, nor is it consistent with any
edition since the original 1979 Edition. The proposal should read
the same as the 2000 edition of NFPA 70E, as shown above. [Ex. 4-17]
OSHA believes that the effectiveness of grounding is important and
will save lives when done properly. Therefore, the final rule, in Sec.
1910.304(g)(5), requires the equipment grounding conductor to be
permanent, continuous, and effective.
The 2002 edition of NEC defines "effectively grounded" in Article
100 as:
Intentionally connected to earth through a ground connection or
connections of sufficiently low impedance and having sufficient
current-carrying capacity to prevent the buildup of voltages that
may result in undue hazards to connected equipment or to persons.
This same definition appears in Part I of the 2000 edition of NFPA
70E. OSHA proposed a similar definition of "effectively grounded,"
which would have applied to voltages over 600 volts, nominal. To
clarify the final standard and to maintain consistency with the NEC and
NFPA 70E, OSHA is adopting the NEC definition of "effectively
grounded" in Sec. 1910.399 and is applying that definition in the
final rule to all voltages. The term "effectively grounded" (or the
equivalent) is used in final Sec. Sec. 1910.304(b)(2)(ii), (g)(5),
(g)(8)(ii), and (g)(8)(iii), 1910.305(c)(5), and 1910.308(a)(6)(ii),
(a)(7)(viii), (e)(4)(ii), and (e)(4)(iii). OSHA believes that the
definition adopted in the final rule accurately describes the intent of
that term for all of these requirements. The adopted definition merely
makes explicit what was implicit in the proposal.
Paragraph (g)(7)(ii) of proposed Sec. 1910.304 (final Sec.
1910.304(g)(8)(ii) and (g)(8)(iii)) would have recognized several
methods of grounding electric equipment by means other than direct
connection to an equipment grounding conductor. This provision would
have permitted, for installations made before April 16, 1981, only,
electric equipment to be considered effectively grounded if it was
secured to, and in metallic contact with, the grounded structural metal
frame of a building. This paragraph is the same as existing Sec.
1910.304(f)(6)(ii).
Several commenters requested that OSHA totally remove the
structural metal frame of a building as an acceptable grounding method
(Exs. 3-2, 4-13, 4-15, 4-18, 4-21). For example, NECA believed that
this grounding technique is obsolete and unsafe (Ex. 3-2). NECA noted
that 2002 NEC Section 250.136(A) states: "The structural metal frame
of a building shall not be used as the required equipment grounding
conductor for ac equipment." Other commenters argued that this
allowance is incongruent with the 2004 and prior editions of NFPA 70E
(Exs. 4-13, 4-15, 4-18, 4-21). For example, Mr. Michael Kovacic stated
that this has been prohibited for ac circuits since the 1978 edition of
the NEC. He presented the reason for this as follows:
This requirement [in proposed paragraph (g)(7)(i) for equipment
grounded by an equipment grounding conductor that is contained
within the same raceway, cable, or cord, or runs with or encloses
the circuit conductors] is to keep conductors grouped close together
so magnetic fields generated by the flow of ac electricity, which
reacts with the circuit conductors, will cancel each other out,
thereby minimizing the total circuit impedance for safety reasons
(preventing electrocution in the event of a breakdown or fault in
the equipment by rapid operation of the overcurrent device). In the
case of dc circuits, there are no pulsating magnetic fields and
consequently no circuit reactance, which increases the circuit
impedance to negatively affect the grounding path of equipment. [Ex.
4-18]
OSHA agrees with these comments. In fact, the Agency provided
similar rationale in prohibiting the use of the metal structure of a
building for grounding electric equipment when it adopted the existing
standard in 1981 (46 FR 4034, 4046, January 16, 1981). However, at that
time, the Agency also decided not to apply this prohibition
retroactively, reasoning as follows:
[F]rom the standpoint of employee safety, installations where
electric equipment is secured to, and in metallic contact with, the
grounded structural frame of a building are essentially free of
electrical shock hazards. This condition occurs because the electric
equipment enclosures and the metal building frame will be
approximately at the same potential if a ground fault occurs and
will provide a measure of employee safety. [46 FR 4046]
In that rulemaking, OSHA agreed with comments that it would be
impractical to require changes to installations that had been permitted
by the NEC for many years before 1978.
OSHA believes that this rationale continues to apply today. Nothing
in the record has convinced the Agency that the conclusion drawn in the
existing standard in 1981 is incorrect. Also, the Agency does not
believe that the substantial cost to employers of changing these
grounding connections is worth the slight possible reduction in risk
associated with moving from the use of the structural metal frame of a
building to a separate equipment grounding conductor. In addition, in
actual practice, such a change might not lead to an overall reduction
in risk at all. To reconfigure a branch circuit and run new conductors
back to a point where an acceptable connection to the ground is
available,\25\ an employee would need to deenergize the existing
circuits connected. An employee could inadvertently contact an
energized part during the recircuiting process.
---------------------------------------------------------------------------
\25\ Section 250.130(C) of the 2002 NEC lists acceptable
grounding methods.
---------------------------------------------------------------------------
Consequently, the final rule in Sec. 1910.304(g)(8)(iii) continues
to allow the use of the grounded structural metal frame of a building
as the equipment grounding conductor for equipment secured to, and in
metallic contact with, the metal frame only for installations made
before April 16, 1981. However, unlike the existing standard, the final
rule requires such grounds to be replaced any time work is performed on
the branch circuit. In such cases, the circuit needs to be deenergized
anyway, and there would be no increased risk during the installation of
a new equipment grounding conductor. Additionally, the costs of
installing an acceptable equipment grounding conductor in such cases
would be minimized.
K. Equipment for General Use (Sec. 1910.305)
Paragraph (a)(2) of proposed Sec. 1910.305 would have applied to
temporary wiring installations. According to proposed Sec.
1910.305(a)(2)(iii), temporary installations over 600 volts would only
be permitted for periods of tests, experiments, or emergencies.
Northrop Grumman-Newport News objected to this restriction on the
use of temporary wiring of more than 600 volts (Ex. 3-7). It noted that
employers performing shipbuilding and ship repair use temporary wiring
to provide power to the ships that arrive at the shipyard, stating:
During construction and major overhaul of a vessel, ship and
shore-based electrical installations may be interconnected. For
instance, permanent ship electrical systems will typically be
powered by temporary shore power whenever a ship is not at sea.
Ships are specifically designed in this manner. [Ex. 3-7-1]
It noted further that the ships must have their normal power source
shut down and use the power source from connection points within the
shipyards, which can be more than 600 volts. It stated that flexible
cords and cables are used to supply power to these ships for repair and
maintenance and that they are temporary wiring installations.
Paragraph (a)(2) of proposed Sec. 1910.305 was taken from Article
305 of the 1999 NEC and section 3-1.2 in Part I of NFPA 70E-2000. Both
of these standards permit temporary wiring of more than 600 volts to be
used for construction in addition to the uses permitted in the OSHA
proposal. The Agency did not include "construction" as a permitted
use in the proposal (or, for that matter, in the existing standard)
because construction work is covered by the construction standards in
29 CFR Part 1926. However, Northrop Grumman-Newport News's comments
show that certain types of construction-like activities occur in
general industry and maritime. The Agency believes that the NEC and
NFPA 70E intend to permit high-voltage temporary wiring installations
used for purposes like those described in the Northrop Grumman-Newport
News comments. Thus, to permit this type of temporary installation and
to improve consistency with the NEC and NFPA 70E, OSHA has added
"construction-like activities" to the list of permitted uses for
high-voltage temporary wiring in final Sec. 1910.305(a)(2)(iii). OSHA
intends this term to include such construction-like activities as ship
building and ship repair without regard to whether the activity falls
under OSHA's construction standards. As noted earlier, construction-
like activities also include cleanup, disaster remediation, and
restoration of large electrical installations.\26\
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\26\ It should be noted that the discussion of the term
"construction-like activities" applies only to the use of this
term in Subpart S.
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Proposed Sec. 1910.305(a)(3)(v) would have permitted nonmetallic
cable trays to be installed only in corrosive areas and in areas
requiring voltage isolation. Two commenters objected to this provision
(Exs. 3-8, 4-16, 4-22). Mr. Mark Spence, representing Dow Chemical
Company (Exs. 3-8, 4-16), noted that the corresponding provision in the
NEC, section 392.3(E), reads as follows:
In addition to the uses permitted elsewhere in Article 392,
nonmetallic cable tray shall be permitted in corrosive areas and in
areas requiring voltage isolation.
He pointed out that section 392.3 specifically permits cable tray
systems to be installed as support systems for services, feeders,
branch circuits, communications circuits, control circuits, and
signaling circuits. Thus, he concluded that the NEC does not restrict
the use of nonmetallic cable trays as OSHA's proposal did.
OSHA agrees with Mr. Spence's comments and has not carried proposed
Sec. 1910.305(a)(3)(v) into the final rule. This action removes the
proposed restriction on the use of nonmetallic cable trays. Under the
final rule, nonmetallic cable trays can be used wherever metallic cable
trays may be used.
Mr. Spence also objected to the application of proposed Sec.
1910.305(j)(2)(iii) to all installations made after March 15, 1972
(Exs. 3-8, 4-16). This provision would have prohibited nongrounding-
type receptacles from being used for grounding-type attachment plugs.
He stated that Dow Chemical was concerned that this provision could
pose problems with existing buildings with two-wire receptacles. He
reasoned as follows:
This [proposed provision] is adapted from NFPA 70E Sec.
420.10(C)(2), which states:
Non-grounding-type receptacles and connectors shall not accept
grounding-type attachment plugs.
* * * * *
OSHA apparently considers that this proposed requirement is
implicit in the existing Subpart S. The preamble to the proposed
rule refers to this provision as a "clarification" (69 Fed. Reg.
at 17788). However, the text of existing Subpart S does not address
this issue, and Dow could not identify any previous OSHA
interpretation of its existing requirements which reached the
conclusion articulated in proposed Sec. 1910.305(j)(2)(iii).
Accordingly, OSHA should include this requirement (and all
others that are new to Subpart S) in section 1910.302(b)(4),
requirements applicable only to installations made after the
effective date of the final rule. [Ex. 4-16]
The NEC has required receptacles to be of the grounding type for
decades. The 1972 NEC, which was adopted by reference in Subpart S from
March 15, 1972, until April 16, 1981, contained many requirements for
grounding-type receptacles. For example, Section 210-21(b) of the 1971
NEC required all receptacles on 15- and 20-ampere branch circuits to be
of the grounding type. That section also requires grounding-type
receptacles to be used as replacements for existing nongrounding-type
receptacles unless it was impractical to reach a source of ground.
Thus, the vast majority of receptacles installed since 1972 are of the
grounding type. In addition, equipment supplied with an equipment
grounding conductor is intended to have that conductor properly
connected to ground. Using an adapter with such equipment is prohibited
by existing Sec. 1910.334(a)(3)(iii) if the adapter interrupts the
equipment grounding conductor. Connecting or altering an attachment
plug in a manner that prevents proper connection of the equipment
grounding conductor is prohibited by existing Sec. 1910.334(a)(3)(ii).
Consequently, OSHA's current standards essentially prohibit connecting
grounding-type attachment plugs to nongrounding-type receptacles. For
these reasons, OSHA is carrying proposed Sec. 1910.305(j)(2)(iii)
forward unchanged into the final rule.
Proposed Sec. 1910.305(j)(2)(v) would have required a receptacle
installed outdoors in a location protected from the weather to have an
enclosure that is weatherproof when the receptacle is covered. A note
following that provision indicated that a receptacle is considered to
be in a location protected from the weather where it is located under
roofed open porches, canopies, marquees, or the like and where it will
not be subjected to a beating rain or water runoff. OSHA received
several comments on the language in the note (Exs. 3-2, 4-13, 4-17, 4-
18, 4-21). These commenters argued that the word "beating" is not
defined making this provision difficult to enforce. They recommended
that OSHA remove this word from the note.
The Agency is retaining the term "beating rain" in the final
rule. The language in the note to final Sec. 1910.305(j)(2)(v) mirrors
that in section 406.8(A) of the 2002 NEC, which uses the same term in
describing "locations protected from the weather." More importantly,
OSHA has determined that the word "beating" as used in the note is
critical to the meaning of the note itself. Paragraph (j)(2)(v) in
final Sec. 1910.305 is intended to require weatherproof enclosures to
ensure that water does not enter or accumulate within the
enclosure.\27\ If rain can strike the receptacle face directly, water
will almost certainly enter and accumulate within the enclosure. Thus,
the term "beating rain" as used in the note means a rain that
directly contacts the receptacle face. This interpretation is
consistent with the definition of "damp location" in the final
rule.\28\
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\27\ See final Sec. 1910.305(j)(1)(iv) for fixtures, which
contains a corresponding requirement for fixtures installed in wet
or damp locations.
\28\ The definition of "damp location" reads as follows:
Partially protected locations under canopies, marquees, roofed
open porches, and like locations, and interior locations subject to
moderate degrees of moisture, such as some basements, some barns,
and some cold-storage warehouses.
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Proposed Sec. 1910.305(j)(3)(iii) would have required each
electric appliance to be provided with a nameplate with the identifying
name and the rating in volts and amperes, or in volts and watts. This
provision also would have required the marking to include frequency
ratings if the appliance is to be used on specific frequencies.
Finally, if motor overload protection external to the appliance is
necessary, this paragraph would have required the appliance to be so
marked.
Dow Chemical Company argued that the requirements to mark
appliances when external overload protection is needed and when the
appliance must be used on specific frequencies were new requirements
that should be made applicable only to new installations built after
the publication of the final rule (Exs. 3-8, 4-16). Dow noted that the
counterpart in the existing standard, Sec. 1910.305(j)(3)(iii),
requires the marking to include only the rating in volts and amperes or
volts and watts. They recommended that proposed Sec.
1910.305(j)(3)(iii) be included in the list of requirements applicable
only to installations made after the effective date of the final
standard.
The requirement for appliances to be marked with any necessary
frequency ratings was contained in section 422-30(a) of the 1971 NEC.
The requirement for marking of the need for external overload
protection was also contained in section 422-30(a) of the 1971 NEC. In
addition, the existing OSHA standard in Sec. 1910.303(e) requires
electric equipment to be marked with voltage, current, wattage, or
other ratings as necessary. The ratings required by the NEC are
necessary for the safety of any employee installing or using affected
appliances. Thus, the marking provisions proposed in Sec.
1910.305(j)(3)(iii) are not new. The existing rule requires the
markings implicitly. The final rule simply makes the requirement
explicit. Therefore, OSHA has not added that paragraph to the list of
requirements applicable only to new installations given in final Sec.
1910.302(b)(4).
Proposed Sec. 1910.305(j)(4)(ii) would have required that each
motor controller be provided with an individual disconnecting means
within sight of the controller. However, this provision would have
permitted a single disconnecting means to be located adjacent to a
group of coordinated controllers mounted adjacent to each other on a
multi-motor continuous process machine. In addition, the proposed rule
would have permitted the controller disconnecting means for motor
branch circuits over 600 volts, nominal, to be out of sight of the
controller, if the controller was marked with a warning label giving
the location and identification of the disconnecting means to be locked
in the open position.
Mr. Mark Spence of Dow Chemical requested that the standard allow
disconnecting means for motor controllers of 600 volts, nominal, or
less to be out of sight of the controller location if the disconnecting
means is capable of being locked out (Exs. 3-8, 4-16). He pointed to an
exception to section 430.102(B) of the 2002 NEC, which, under certain
conditions, permits disconnecting means to be located out of sight of
the motor when the disconnecting means is capable of being locked in
the open position.
OSHA has not adopted Dow's recommendation. The proposed rule
requires disconnecting means to be located within sight of the motor
controller location whereas the NEC exception permits the disconnecting
means to be out of sight of the motor, not the controller. The
requirement in 2002 NEC section 430.102(A) for the disconnecting means
to be within sight of the controller location still exists. Thus,
proposed Sec. 1910.305(j)(4)(ii) is consistent with the 2002 NEC, and
OSHA is carrying it forward, unchanged, into the final rule.
L. Specific Purpose Equipment and Installations--Sec. 1910.306
Proposed Sec. 1910.306(e) read as follows:
A means shall be provided to disconnect power to all electronic
equipment in an information technology equipment room. There shall
also be a similar means to disconnect the power to all dedicated
heating, ventilating, and air-conditioning (HVAC) systems serving
the room and to cause all required fire/smoke dampers to close. The
control for these disconnecting means shall be grouped and
identified and shall be readily accessible at the principal exit
doors. A single means to control both the electronic equipment and
HVAC system is permitted.
This proposed provision is equivalent to existing Sec.
1910.306(e), which requires data processing systems to have
disconnecting means for electronic equipment in data processing or
computer rooms and for the air conditioning system serving the area.
Several commenters noted that the 2002 edition of the NEC provided
an exception to this requirement for integrated systems (Exs. 3-8, 4-
11, 4-16, 4-19). Typifying these comments, the Dow Chemical Company
argued as follows:
Using disconnects for information technology systems that are
part of integrated electrical systems may be an unsafe practice,
since an orderly shutdown of such systems may be necessary for
safety. Accordingly, OSHA should amend its proposal to include the
NEC exception for integrated electrical systems. [Ex. 4-16]
OSHA agrees with these commenters that providing ready
disconnecting means for integrated electrical systems can pose greater
hazards for employees than having the data processing and air
conditioning systems shut down as part of an orderly process.
Integrated electrical systems, which are covered by final Sec.
1910.308(g) provide for deenergizing of electric equipment in an
orderly fashion to prevent hazards to people and damage to equipment.
For example, in certain chemical processes, a cooling system is needed
to maintain control over the chemical process. Deenergizing the cooling
system for this process while the chemical reaction continues can lead
to catastrophic failure of containment vessels, which lead to extensive
property damage and employee injuries. Consequently, OSHA is including
an exception to final Sec. 1910.306(e) for integrated electrical
systems covered by Sec. 1910.308(g).
M. Carnivals, Circuses, Fairs, and Similar Events
Proposed Sec. 1910.306(k) contained new requirements for
carnivals, circuses, exhibitions, fairs, traveling attractions, and similar
events. No comments were received concerning these provisions, and OSHA
is carrying them forward into the final rule unchanged. The
requirements in final Sec. 1910.306(k), which are based on
corresponding requirements in NFPA 70E, cover the installation of
portable wiring and equipment for these temporary attractions. From
1991 to 2002, OSHA received reports of 46 serious accidents \29\
associated with carnivals, circuses, exhibitions, fairs, and similar
events (Ex. 2-7). Eleven of these accidents, resulting in 10 fatalities
and 5 injuries, involved electric shock. Eight of those 11 cases (8
fatalities and 1 injury) involved electric wiring and equipment covered
by the installation requirements in Subpart S. OSHA believes that the
new electrical requirements for these events will prevent similar
accidents in the future.
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\29\ These accidents were investigated by OSHA generally in
response to employer reports of a fatality or three or more
hospitalized injuries.
---------------------------------------------------------------------------
In paragraph (k) of final Sec. 1910.306, OSHA is requiring
mechanical protection of electric equipment (paragraph (k)(1)) and of
wiring methods in and around rides, concessions, or other units subject
to physical damage (paragraph (k)(2)). Inside tents and concession
stands, the electrical wiring for temporary lighting must be secured
and protected from physical damage (paragraph (k)(3)). In paragraph
(k)(4), the final rule sets requirements for portable distribution and
termination boxes. These new provisions will provide more electrical
safety for employees working in and around this equipment.
Under final Sec. 1910.306(k)(5), the disconnecting means must be
readily accessible to the operator; that is, the fused disconnect
switch or circuit breaker must be located within sight and within 1.83
meters (6 feet) of the operator for concession stands and rides. This
provision provides protection by enabling the operator to stop the
equipment in an emergency. The disconnecting means must also be
lockable if it is exposed to unqualified persons, to prevent such
persons from operating it.
N. Zone Classification
Introduction. Existing Sec. 1910.307 contains OSHA's electrical
safety requirements for locations that can be hazardous because of the
presence of flammable or combustible substances. Hazardous locations
are classified according to the properties of flammable vapors, liquids
or gases, or combustible dusts or fibers that may be present. These
locations are designated in the NEC and existing Sec. 1910.307 as one
of six types: Class I, Division 1; Class I, Division 2; Class II,
Division 1; Class II, Division 2; Class III, Division 1; and Class III,
Division 2. This system is called the "division classification
system," or the "division system." The NEC first addressed this
system in 1920. The OSHA website has a short but informative paper on
this topic, which is available at http://www.osha.gov/doc/
outreachtraining/htmlfiles/hazloc.html.
The 2000 edition of NFPA 70E incorporates an alternative system (in
addition to the division classification system) for installing electric
equipment in Class I locations. (Class II locations continue under the
division system.) This system is called the "zone classification
system," or the "zone system." The zone system designates three
classifications: Class I, Zone 0; Class I, Zone 1; and Class I, Zone 2.
The zone system is based on various European standards that were
developed by the International Electrotechnical Commission (IEC).\30\ A
modified version of this system was first adopted into the NEC in the
1996 edition. Although the zone and division classification systems
differ in concept, individual equipment can be approved for use under
both systems when the equipment incorporates protective techniques for
both systems (as determined by the nationally recognized testing
laboratory that lists or labels the equipment). Based on the successful
use of the zone system in European countries for many years and the
acceptance of the zone system by the NEC and international standards,
OSHA believes that an installation conforming to requirements for this
system is as safe as one conforming to requirements for the division
system.
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\30\ The IEC prepares and publishes international standards for
all electrical, electronic and related technologies. This global
organization is made up of members from more than 60 participating
countries, including the U.S.
---------------------------------------------------------------------------
The zone system incorporated in the final rule is an alternative
method to the division system; employers may use either system for
installations of electric equipment in Class I hazardous locations.
OSHA will recognize the use of the zone system under Sec. 1910.307 and
any other OSHA standard that references Sec. 1910.307.\31\
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\31\ Several OSHA general industry standards outside Subpart S
require electric equipment to meet the Subpart S requirements for
Class I, Division 1 or 2 locations. For example, Sec.
1910.103(b)(3)(ii)(e) requires electric equipment installed in
separate buildings housing gaseous hydrogen systems to meet the
Subpart S provisions for Class I, Division 2 locations. Although the
Agency is not revising any of these other general industry standards
to specifically accept installations meeting the Subpart S zone
system requirements, OSHA will consider any nonconformance by an
installation that the employer can demonstrate is properly
classified and installed under the Subpart S zone system
requirements as a de minimis violation.
---------------------------------------------------------------------------
As noted earlier, OSHA is requiring employers to document the
designation of hazardous locations within their facilities in final
Sec. 1910.307(b). The documentation must denote the boundaries of each
division or zone so that employees who install, inspect, maintain, or
operate equipment in these areas will be able to determine whether the
equipment is safe for the location. As noted earlier, OSHA is requiring
documentation for the division system only for new installations that
use that system. The document requirement does apply, however, to all
installations made under the zone system.
Several commenters supported the proposed requirement for
documenting installations (Exs. 3-5, 3-9, 5-2). For example, NIOSH
stated:
An important addition to the proposed standard is the new
requirement for employers to document the designation of hazardous
locations within their facilities, thus allowing workers who
install, inspect, maintain, or operate equipment in these areas to
identify the correct equipment or system components to be used to
ensure worker safety. This requirement would also ensure that the
employer maintain a record of the boundaries of each hazardous
location and its classification either under the current division
system or the proposed zone system. [Ex. 3-9-1]
One commenter objected to the documentation requirement to the
extent that it would apply to shipbuilding and ship repair (Ex. 3-7).
The commenter argued as follows:
[Proposed Sec. 1910.307] requires documentation of each
hazardous location, followed by design and installation of equipment
meeting certain requirements. The standard does not appear to
consider mobile operations and the difficulty in maintaining
documentation for an interim operation. For instance, in
shipbuilding and repair, ship modules and compartments must be spray
painted. Therefore, at the time the compartment is being painted, it
may meet the definition of a Class I, Division 2 area.
There are over 3,000 compartments on an aircraft carrier that
will be spraypainted at least twice during the course of
construction. It is not feasible or realistic to expect shipyards to
maintain a list of precisely which compartments are being
spraypainted on any particular day. Furthermore, it provides no
added protection since controls are already established as required
by 29 CFR 1915, Subpart B. Subpart B--Confined and Enclosed Spaces
and Other Dangerous Atmospheres, including 1915.13 (Cleaning and
Other Cold Work), specifies the required controls for spraypainting
and other cold work, including when explosion proof, self-contained
lamps or other electric equipment must be approved and used. Based on
our evaluation that current shipyard standards in Subpart B, 1915 provide
equal or greater protection and the infeasibility of documenting mobile
operations, we request that OSHA clarify in the applicability section or
in the preamble to the final rule that Subpart B is applicable to the
shipbuilding and repair industry in lieu of 1910.307. [Ex. 3-7-1]
OSHA does not agree that areas being spraypainted on a temporary
basis are Class I locations. The areas described by the commenter are
normally nonhazardous locations that are made hazardous through the
temporary introduction of flammable gases and vapors; thus, they would
not be considered a hazardous location. (See 55 FR 32008.) In most
general industry applications, Sec. 1910.334(d) applies to the
temporary or occasional use of flammable materials. In the commenter's
specific case, the shipyard employment standards in Subpart B of 29 CFR
Part 1915 apply, as the commenter noted (Ex. 3-7-1).\32\ Consequently,
the employer is not required to document these locations unless the
painting is done in a location that is hazardous when the spray
painting operation is not being performed.
---------------------------------------------------------------------------
\32\ Other provisions that may be applicable in shipyard
employment include Sec. Sec. 1915.35 and 1915.36.
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ORC Worldwide recommended that OSHA clarify what employers must
include in their documentation of hazardous locations in a nonmandatory
appendix. As noted earlier, final Sec. 1910.307(b) requires
documentation that denotes the boundaries of each division or zone. The
documentation may be in the form of drawings that visually depict the
boundaries or in text that precisely describes the extent of each
hazardous location. Examples of acceptable documentation are contained
in the NEC (see, for example, Figure 514.3, showing the extent of Class
I, Division 1 and 2 locations surrounding motor fuel dispensers,
commonly known as gasoline pumps) and in several national consensus
standards included in Appendix A to Subpart S (see, for example, ANSI/
API RP 505-1997, Recommended Practice for Classification of Locations
for Electrical Installations at Petroleum Facilities Classified as
Class I, Zone 0, Zone 1, or Zone 2). Because these standards are
already listed in Appendix A, OSHA does not believe it is necessary to
include a separate appendix on the documentation requirements in final
Sec. 1910.307.
Changes to OSHA's existing requirements for the division
classification system. The term "hazardous concentrations" is
currently used in various definitions of specific hazardous locations
in Sec. 1910.399. For example, Sec. 1910.399 defines "Class I,
Division 1," in part, as follows:
A Class I, Division 1 location is a location: (a) in which
hazardous concentrations of flammable gases or vapors may exist
under normal operating conditions * * *
The final standard replaces the term "hazardous concentrations"
with "ignitable concentrations" in each of the definitions of Class I
locations in Sec. 1910.399. This change reflects changes already
incorporated into the NEC (both the 1999 and 2002 editions) and the
2000 edition of NFPA 70E to make the definitions more specific about
the hazard being addressed. The changes, which OSHA does not consider
to be substantive, make these definitions clearer in addition to making
the OSHA standard consistent with the latest editions of NEC and NFPA
70E.
OSHA is also adding a new paragraph (f) to final Sec. 1910.307
that lists specific protection techniques under the division system.
Neither the current Subpart S nor NFPA 70E explicitly list particular
protection techniques that can be used in the division classification
system; however, the NEC does provide specific protection techniques
for installations made under the division classification system in
various requirements throughout the Articles covering hazardous
locations. OSHA has listed these techniques in one paragraph in the
final rule to make the standard easier to use and to provide parallel
requirements for both the division classification system and the zone
classification system, which is addressed in final Sec. 1910.307(g).
Protective techniques other than those listed in final paragraph (f)
are acceptable if the equipment is: (1) Intrinsically safe as specified
in Sec. 1910.307(c)(1); (2) approved for the specific hazardous
location as specified in Sec. 1910.307(c)(2); or (3) of a type and
design that the employer demonstrates is safe for the specific
hazardous location as specified in Sec. 1910.307(c)(3). New paragraph
(f) is intended to clarify the existing OSHA requirements for hazardous
locations by explicitly listing the types of protective techniques that
can be used under the division classification system. (The protection
techniques are required implicitly under the existing standard through
the requirements for approval and listing or labeling by a nationally
recognized testing laboratory and through the reference to the NEC in
the note following existing Sec. 1910.307(c)(3).)
OSHA received one comment recommending the adoption of additional
protection techniques for the division system (Ex. 4-22). This
commenter recommended including protection techniques listed in Section
500.7 of the 2002 NEC, including nonincendive, hermetically sealed, and
combustible gas detection protection techniques.
Paragraph (f)(5) of proposed Sec. 1910.307 (final Sec.
1910.307(f)(10)) recognized protection techniques not specifically
listed in the preceding four paragraphs as long as the technique in
question met proposed Sec. 1910.307(c). Because the techniques
mentioned by the commenter meet the 2002 NEC requirements for Class I
hazardous locations, those techniques would have been recognized under
proposed Sec. 1910.307(f)(5). However, to clarify the standard, OSHA
has included all the protective techniques listed in Section 500.7 of
the 2002 NEC in final Sec. 1910.307(f).
Brief background and description of the zone system. The zone
system stemmed from the independent efforts of countries in Europe and
elsewhere to develop an area classification system to address safety in
locations containing hazardous substances. The IEC formalized these
efforts into the zone system, which is now used to classify the
majority of the world's hazardous location systems.\33\
---------------------------------------------------------------------------
\33\ Brenon, M., Kelly, P., McManama, K., Klausmeyer, U., Shao,
W., Smith, P., "The Impact of the IECEx Scheme on the Global
Availability of Explosion Protected Apparatus," Record of
Conference Papers of the 1999 Petroleum and Chemical Industry
Technical Conference, September 13-15, 1999, Paper No. PCIC-99-07,
pp. 99-109.
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Article 505 of the 1996 NEC included requirements for the U.S.
version of the zone system for the first time. The 2000 edition of NFPA
70E includes requirements for the zone system based on the 1999 version
of the NEC. OSHA is adopting zone system rules that are based on these
NFPA 70E provisions. This will permit electric equipment approved for
use in hazardous locations to be used in U.S. workplaces, under either
the division or zone system.
Major differences between the division classification system and
the zone classification system. The zone system can best be described
by comparing it with the division system. Both systems characterize
locations by the likelihood and circumstances under which flammable
gases or vapors exist.
The systems both define the types of gases or vapors that may exist and
categorize them under a number of groups. Each system specifies an
allowable range of operating temperature, and corresponding
requirements, for electric equipment used in a particular division or
zone.
In contrast to the division system, however, the zone system is
only used to classify areas that are hazardous because of the presence
of flammable gases or vapors (Class I locations). The division system
must be used to classify areas that may contain combustible dusts or
easily ignitable fibers or flyings (Class II and III locations,
respectively).
The zone system defines three types of Class I locations (Zones 0,
1, and 2) rather than two locations under the division system
(Divisions 1 and 2). Zones 0 and 1 equate to Division 1, whereas Zone 2
equates to Division 2. In a Class I, Division 1 location, flammable
gases or vapors are or may be present in the air in ignitable
concentrations. In a Class I, Zone 1 location, ignitable concentrations
of flammable gases or vapors are not always present, but such
concentrations may exist periodically even under normal conditions. By
contrast, in a Class I, Zone 0 location, such gases or vapors are
present either continuously or for long periods. (See Table 2.) Thus, a
Class I, Zone 0 location is, in essence, a worst-case Class I, Division
1 location.
Each system classifies flammable gases and vapors into a number of
groups. The division system has four such groups, designated A, B, C,
and D, with group A containing the most volatile substances, and groups
B, C, and D containing gases or vapors that are progressively less
volatile. The zone system has three such groups, designated IIA, IIB,
and IIC, with group IIC containing the most volatile gases, and groups
IIA and II B containing gases or vapors that are progressively less
volatile. Substances classified under groups A and B in the division
system generally fall under group IIC of the zone system. However, some
differences exist between the groups in the two systems. Thus,
regardless of the classification system being used, equipment intended
for use in a Class I hazardous location must indicate the groups for
which it is approved, as required by final Sec. 1910.307(c)(2)(ii) and
(g)(5)(ii). Table 2 summarizes the similarities and differences between
the two systems.
The other major differences concern the allowable protection
schemes and the maximum allowable surface temperature of equipment
under each system. The protection schemes acceptable for each division
and zone are listed in Table 3, and the remainder of this paragraph
discusses the differences in maximum allowable temperature. According
to the NEC, equipment is acceptable for a hazardous location only if
its surface temperatures will not approach the ignition temperature, or
more specifically the autoignition temperature, of the particular gases
and vapors that might be present in that location. There are 14
temperature limits, and corresponding identification codes, under the
division system. Each limit specifies the maximum surface temperature
for equipment labeled with the matching code. There are six such
temperature limits and corresponding identification codes under the
zone system. The six zone system limits correspond directly to 6 of the
14 division system temperature limits. However, as shown in Table 2,
the remaining eight division temperature limits have values
intermediate to the six zone system temperature limits. For example,
the division system has 4 intermediate temperature limits, 215 [deg]C,
230 [deg]C, 260 [deg]C, and 280 [deg]C (T2D, T2C, T2B, and T2A,
respectively), between the zone system's temperature limits of 200
[deg]C (T3) and 300 [deg]C (T2). Equipment approved for one of these
intermediate values may be used under the zone system only for the
higher (in temperature) of the two closest zone system values. For
example, equipment marked T2A under the division system, which has a
maximum surface temperature of 280 [deg]C, could only be used in
locations where the ignition temperature of the substance is greater
than or equal to the T2 value, which is 300 [deg]C. In essence, T2A
equipment becomes derated to T2 equipment when it is installed using
the zone classification system. It could not be used in zone-classified
locations where the ignition temperature of the substance is less than
or equal to the T3 value, which is 200 [deg]C, because the equipment
could become hot enough to cause ignition.
More details on the differences in gas groups. In the 1999 NEC, the
definitions for each of the division system gas and vapor groups,
except Group A,\34\ were changed to make them comparable to the
definitions of the zone system groups. A gas or vapor is classified in
the division system's Group B, C, or D or the zone systems Group IIC,
IIB, or IIA based on the gas's or vapor's maximum experimental safe gap
(MESG) \35\ or its minimum igniting current ratio (MIC ratio).\36\
These values are established under standard experimental conditions for
each gas and vapor.
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\34\ Acetylene is the only Group A gas under the division
system.
\35\ The MESG is the maximum clearance between two parallel
metal surfaces that has been found, under specified test conditions,
to prevent an explosion in a test chamber from being propagated to a
secondary chamber containing the same gas or vapor at the same
concentration.
\36\ The MIC ratio is the ratio of the minimum current required
from an inductive spark discharge to ignite the most easily
ignitable mixture of a gas or vapor, divided by the minimum current
required from an inductive spark discharge to ignite methane under
the same test conditions.
---------------------------------------------------------------------------
The 1999 NEC indicates two factors that may affect MESG and MIC
values: (1) Lower ambient temperatures (lower than minus 25 [deg]C or
minus 13 [deg]F), and (2) oxygen enriched atmospheres. The 1999 NEC
Handbook states that the latter factor can drastically change the
explosion characteristics of materials. Such an atmosphere lowers the
minimum ignition energy, increases the explosion pressure, and can
reduce the maximum experimental safe gap. These factors would make it
unsafe to use otherwise approved "intrinsically safe" and
"explosion-proof" equipment, unless the equipment has been tested for
the specific conditions involved. Employers must ensure that the
equipment approval is valid for the actual conditions present where the
equipment is installed. This is required generally for all electric
equipment. However, it is essential in hazardous locations because of
the dire consequences that may result.
Rationale for adopting the zone system requirements. As stated
earlier, the zone system has been accepted in many countries. Such
international acceptance has meant that U.S. manufacturers of electric
equipment suitable for installation in hazardous locations have had to
ensure that their equipment met the zone system requirements if they
wished to sell such equipment in zone-system countries in addition to
meeting the U.S. division system requirements. Also, U.S. employers
that had hazardous locations in their workplaces have sought to use
equipment approved for use only in zone-classified locations in this
country. This, in turn, led NFPA to incorporate the zone system in the
NEC starting in the 1996 edition.
OSHA has determined that employees can be protected from the
hazards of explosion in Class I hazardous locations by the installation
of electric equipment following the latest NEC requirements for the
zone classification system (Article 505 of the 2002 NEC). Therefore,
the Agency is incorporating the zone system in this revision of the
electrical installation requirements in Subpart S. Under the final
standard, employers are able to comply with either the zone classification
system or the division system for Class 1 hazardous locations.
New Sec. 1910.307(g) and related definitions. In the final rule,
OSHA is adding a new paragraph (g) to final Sec. 1910.307 that covers
the zone classification system. This new paragraph addresses the
following topics related to the zone classification system: scope;
location and general requirements; protection techniques; special
precaution; and listing and marking. A brief description of the
contents of each paragraph follows.
Paragraph (g)(1) permits employers to use the zone classification
system as an alternative to the division classification system. As
explained in paragraph (a)(4), the requirements in final Sec. 1910.307
that are specific to installations built under the division
classification do not apply to installations built under the zone
classification system. Thus, paragraph (c), electrical installations;
paragraph (d), conduits; paragraph (e), equipment in Division 2
locations; and paragraph (f), protection techniques do not apply to
installations built under the zone system. Paragraph (g) contains
counterparts to each of these requirements.
Paragraphs (g)(2)(i) and (g)(2)(ii) describe how hazardous
locations are classified under the zone system. The employer must
consider each individual room, section, or area separately and must
designate locations according to the specific properties of the
flammable gases, liquids, or vapors that might be present. The same
requirements apply to the division system. (See final Sec.
1910.307(a).)
Paragraphs (g)(2)(iii) and (g)(2)(iv) require that conduit threads
be of certain types and that connections be made wrench tight. These
provisions ensure that there is no arcing across conduit connections in
the event that they have to carry fault current. Paragraph (d) contains
similar requirements for division system installations.
Paragraph (g)(3) of final Sec. 1910.307 presents the protection
techniques that are acceptable in zone-classified hazardous locations.
Electric equipment in these locations must incorporate at least one of
these protection techniques, and the equipment must be approved for the
specific hazardous location. The protection techniques listed in final
Sec. 1910.307(g)(3) have been taken directly from NFPA 70E-2000.
OSHA received two comments on this proposed provision (Exs. 4-11,
4-19). These comments recommended that OSHA modify proposed paragraph
(g)(3) to include Exception 4 to Section 505.20(C) of the 2002 NEC,
which states: "In Class I, Zone 2 locations, the installation of open
or nonexplosion-proof or nonflame-proof enclosed motors, such as
squirrel-cage induction motors without brushes, switching mechanisms,
or similar arc-producing devices that are not identified for use in a
Class I, Zone 2 location shall be permitted." They argued that the
2002 NEC does not require these types of motors to use one of the
listed protection types.
OSHA disagrees with these comments. The exception to which these
commenters pointed is to a requirement that equipment in Class I, Zone
2 locations be specifically listed and marked as suitable for the
location. (See 2002 NEC Section 505.20(C).) Final Sec. 1910.307(g)(3),
however, is based on 1999 NEC Section 505-4, which corresponds to 2002
NEC Section 505.8. The types of motors mentioned by the commenters fall
under protection technique "n" (known as "type of protection").
This protection technique is defined in Section 505.2 of the 2002 NEC
as "Type of protection where electrical equipment, in normal
operation, is not capable of igniting a surrounding explosive gas
atmosphere and a fault capable of causing ignition is not likely to
occur." A nonexplosion-proof motor without arc producing devices must
also have a surface temperature under normal operating conditions that
will be lower than the ignition temperature of the gas or vapor
involved to be safe in a Class I, Zone 2 location. By definition, these
are locations that are subject, albeit infrequently, to the
introduction of hazardous quantities of flammable gases or vapors. If
the surface temperature of the motor is too high, an explosion could
result in those unusual but foreseeable situations involving hazardous
accumulations of flammable gases or vapors. Thus, OSHA concludes that
motors addressed by the NEC exception must still meet the criteria
imposed by protection technique "n."
On the other hand, it appears that such motors are acceptable under
the 2002 NEC even though they are not marked with any protection
technique.\37\ Proposed Sec. 1910.307(g)(5) would have required all
equipment installed under the zone classification system to be marked
either with an acceptable class and division marking or with relevant
class and zone markings. Based on the 2002 NEC requirements for
installing and marking electric equipment in installations made under
the zone classification system, OSHA has determined that it is
unnecessary for certain types of equipment to be marked as required by
final Sec. 1910.307(g)(5). Therefore, in paragraph (g)(5)(ii)(C), the
Agency has added an exception to final paragraph (g)(5) for electric
equipment that the employer demonstrates will provide protection from
the hazards arising from the flammability for the gas or vapor and zone
of location involved and will be recognized by employees as providing
such protection. Employers may point to the NEC as evidence that the
equipment is safe.
---------------------------------------------------------------------------
\37\ The marking requirement is contained in Section 505.9(C) of
the 2002 NEC.
---------------------------------------------------------------------------
Paragraph (g)(4) of final Sec. 1910.307 sets special precautions
that must be taken with respect to hazardous locations classified under
the zone system. First, the classification of areas and the selection
of equipment and wiring must be under the supervision of a qualified
registered professional engineer. This provision is contained in NFPA
70E-2000 and in the 1999 NEC. Because the zone system has been
permitted in the U.S. only since 1997,\38\ employers and installers in
this country have had relatively little experience with installations
made using the zone classification system. The technical committees
that developed NFPA 70E and the NEC have determined that, for the zone
system, it is essential for competent persons to classify the hazardous
locations and select equipment for those locations. OSHA agrees with
the consensus determination by these committees, which are composed of
members (such as NRTLs, electric equipment manufacturers, electrical
contractors, and affected employee organizations) with expertise in
electrical safety in hazardous locations.
---------------------------------------------------------------------------
\38\ As noted earlier, the zone system was first incorporated
into the NEC in the 1996 edition. This edition was adopted by
various governmental jurisdictions beginning in 1997. Installations
made using the zone system were not permitted by these jurisdictions
before then. In addition, the existing OSHA standard does not permit
classifying hazardous locations under the zone system, and employers
have not been certain that installations made using the zone
classification systems would be acceptable to OSHA.
---------------------------------------------------------------------------
Some commenters objected to the requirement that the classification
of areas and selection of equipment and wiring methods be under the
supervision of a qualified registered professional engineer (Exs. 3-5,
3-8, 4-16). ASSE argued that qualified electricians and safety
professionals should be permitted to classify areas and select equipment
and wiring methods for installations made under the zone classification system
(Ex. 3-5). They further stated that not all professional engineers possess the
electrical background to qualify for these tasks. Dow Chemical Company urged the
Agency to permit any qualified person to classify areas and select equipment for
zone-classified locations. They pointed to the action the NFPA took in
adopting new Article 506 for the next edition of the NEC (the 2005
NEC). Dow stated that this new article contains Sec. 506.6, which
reads as follows:
Classification of areas, engineering and design, selection of
equipment and wiring methods, installation, and inspection shall be
performed by qualified persons [Ex. 3-8].
Thus, Dow argues that NFPA has endorsed using qualified persons not
just qualified registered professional engineers to make these
determinations.
OSHA does not agree with the rationale put forth by ASSE and Dow.
The NEC design requirements for installations made under the zone
classification system are general, performance-oriented provisions that
demand sound engineering judgment on the part of persons responsible
for designing the installation. Paragraph (g)(4) of final Sec.
1910.307 requires the services of a qualified registered professional
engineer to ensure that the person primarily responsible for the design
of the installation is particularly suited to the task. A registered
professional engineer who does not have an understanding of the
construction and operation of the equipment and the hazards involved in
zone-classified locations would not meet the criteria spelled out in
final Sec. 1910.307(g)(4) and in the definition of "qualified
person." \39\ The NEC requirements for installations made under the
division classification system, on the other hand, are far more
detailed and are more specification oriented. Because the division
system has been in existence in this country for so long, because
electricians and safety professionals have had decades to become
familiar with it, and because (as noted earlier) many consensus
standards specifically delineate the boundaries of locations classified
under the division system, it is much easier for an electrician or a
safety professional with a strong electrical background to properly
classify a hazardous location under the division classification system.
Furthermore, because the NEC division-system requirements are so
detailed, it is easy for an electrician or a safety professional to
select equipment appropriate for such a location. It is considerably
more difficult to perform those same duties under the zone
classification system. It should be noted that the 2005 edition of the
NEC was not available while the rulemaking record was open. However,
the new article in the 2005 NEC cited by Dow does not apply to Class I
locations, which are locations made hazardous because of the presence
of flammable gases or vapors, but to Class II and III locations,\40\
which are locations made hazardous because of the presence of
combustible dust, fibers, and flyings. Class II and III locations are
not as hazardous as Class I locations and do not warrant the same
degree of caution. For these reasons, OSHA is carrying Sec.
1910.307(g)(4) into the final rule unchanged.
---------------------------------------------------------------------------
\39\ The definition of "qualified person" in final Sec.
1910.399 reads as follows: "One who has received training in and
has demonstrated skills and knowledge in the construction and
operation of the electric equipment and installations and the
hazards involved."
\40\ Under the zone classification system, these locations are
categorized simply as Zone 20, 21, and 22 locations, with no
reference to the class of the location.
---------------------------------------------------------------------------
Paragraph (g)(4) also indicates when it is safe to have locations
classified using the division system on the same premises as locations
classified under the zone system and vice versa. These provisions are
also taken from NFPA 70E-2000.
Several commenters pointed out an error in a metric conversion in
the note to proposed Sec. 1910.307(g)(4) (Exs. 4-13, 4-15, 4-18, 4-
21). The proposed note listed -13 [deg]F as the English unit equivalent
to -20 [deg]C. The correct English value is -4 [deg]F. The Agency has
made this correction in the final rule.
Paragraph (g)(5) of final Sec. 1910.307 contains requirements for
marking equipment that is approved for hazardous locations classified
under the zone system. These provisions are comparable to the
corresponding marking requirements under the division system, but
reflect the need to provide information necessary for safely installing
equipment in a zone-classified location. As noted earlier, paragraph
(g)(5)(ii)(C) contains an exception for equipment that the employer
demonstrates will provide protection from the hazards arising from the
flammability of the vapors, liquids, or gasses involved and that will
be recognized as such by employees.
Equivalence of systems and permitted protection techniques. Table 2
shows the general equivalence between the two classification systems.
It should be noted, however, that a given area classified under one
system is not permitted to overlap an area classified under the other
system. For example, although Division 2 and Zone 2 are basically
equivalent classifications, under the final standard a Zone 2 location
is permitted to touch a Division 2 location, but the two locations are
not permitted to overlap. This ensures that equipment installed and
maintenance performed in these locations are appropriate for the
conditions in each location.\41\
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\41\ Division 2 and Zone 2 are basically equivalent
classifications, but there are some differences in what types of
equipment are acceptable in each of those locations. See, for
example, the earlier discussion on maximum allowable surface
temperatures.
Table 2.--Equivalence of Hazardous (Classified) Location Systems, Class
I Locations Only \1\ \2\
------------------------------------------------------------------------
Category Division system Zone system
------------------------------------------------------------------------
Locations....................... Division 1........ Zone 0, Zone 1.
Division 2........ Zone 2.
Gas Groups (see Table 3 since A, B.............. IIC (not fully
systems are not fully equivalent to
equivalent). Groups A and B).
C................. IIB (not fully
equivalent to
Group C).
D................. IIA (not fully
equivalent to
Group D).
Temperature Codes............... T1 (< =450 [deg]C). T1 (< =450 [deg]C).
T2 (< =300 [deg]C). T2 (< =300 [deg]C).
T2A, T2B, T2C, T2D T2
(< =280, < =260, (effectively).\3\
< =230, < =215
[deg]C).
T3 (< =200 [deg]C). T3 (< =200 [deg]C).
T3A, T3B, T3C T3
(< =180, < =165, (effectively).\3\
< =160 [deg]C).
T4 (< =135 [deg]C). T4 (< =135 [deg]C).
T4A (< =120 [deg]C) T4
(effectively).\3\
T5 (< =100 [deg]C). T5 (< =100 [deg]C).
T6 (< =85 [deg]C).. T6 (< =85 [deg]C).
------------------------------------------------------------------------
Notes to Table 2:
\1\ Use of the equivalence shown in the table above must be done only as
permitted by Sec. 1910.307.
\2\ The zone classification system described in this preamble does not
cover Class II or Class III locations.
\3\ See the discussion of maximum allowable surface temperatures earlier
in the preamble.
Table 3 describes which protection techniques may be used in which
classified locations.
Table 3.--Permitted Protection Techniques (Design Criteria) in Class I
Locations
------------------------------------------------------------------------
------------------------------------------------------------------------
Zone 0:
--intrinsically safe "ia".
--Class I, Division 1
intrinsically safe.
Division 1: Zone 1:
--explosion-proof. --flameproof "d".
--purged and pressurized (Type X or Y). --purged and pressurized.
--intrinsically safe. --intrinsically safe "ib".
--oil immersion "o".
--increased safety "e".
--encapsulation "m".
--powder filling "q".
--any Class I, Division 1
method.
--any Class I, Zone 0
method.
------------------------------------------------------------------------
Division 2: Zone 2:
--purged and pressurized (Type Z). --non-sparking "nA".
--intrinsically safe. --protected sparking "nC".
--nonincendive. --restricted breathing
--oil immersion. "nR".
--hermetically sealed. --any Class I, Division 1 or
--any Class I, Zone 0 or 1 method. 2 method.
--any Class I, Zone 0, Zone 1, or Zone 2 --any Class I, Zone 0 or 1
method. method.
------------------------------------------------------------------------
Listing and labeling by NRTLs. Paragraph (a) of final Sec.
1910.303 continues the existing requirement that all electric equipment
be approved. While OSHA believes that approval is necessary for all
electric equipment, the need for third-party approval of electric
equipment in hazardous locations is particularly crucial. The
techniques for ensuring safety in hazardous locations require careful
manufacturing and testing of products because tolerances are tight and
the margin for error is slim. Thus, OSHA's general industry electrical
installation standard has always called for equipment approval, which
generally requires listing or labeling by a nationally recognized
testing laboratory (NRTL) of equipment installed in hazardous
locations.\42\ Under 29 CFR 1910.7, OSHA recognizes testing
organizations that are capable of performing third-party testing for
safety and designates them as NRTLs. Employers may use products listed
by NRTLs to meet OSHA standards that require testing and certification.
NRTLs test and certify equipment to demonstrate conformance to
appropriate test standards. Many of these test standards cover
equipment used in hazardous locations.
---------------------------------------------------------------------------
\42\ Equipment that is of a type that no nationally recognized
testing laboratory accepts as being safe can achieve approval
through acceptance by a Federal, State, or local authority having
jurisdiction over the safety of electrical installations. Custom-
made equipment can gain approval through testing by the equipment
manufacturer. However, these two modes of approval are rare for
equipment installed in hazardous locations. Federal, State, and
local authorities generally look to NRTLs for equipment approval,
and this is even more true for equipment installed in hazardous
locations. This type of equipment must be tested to ensure that it
is safe, and these authorities generally do not have the capability
to do electrical testing. Custom-made equipment, by its nature, is
very rare.
Existing Sec. 1910.307(b) also recognizes equipment that is
"safe for the hazardous (classified) location." This provision
permits equipment that is approved for installation in nonhazardous
locations if the employer demonstrates that the equipment will
provide protection from the hazards arising from the combustibility
and flammability of vapors, liquids, gases, dusts, or fibers. This
condition exists only in limited circumstances as demonstrated by
the 2002 NEC, which permits only certain types of general-purpose
equipment in hazardous locations and then only under limited
conditions. For example, Section 501.8(B) of the 2002 NEC permits
nonexplosionproof enclosed motors in Class I, Division 2 locations
if they have no brushes, switching mechanisms, or similar arc-
producing devices and if exposed motor surfaces do not exceed 80
percent of the ignition temperature of the gas or vapor involved.
---------------------------------------------------------------------------
OSHA's existing requirements for hazardous locations in Subpart S
only address locations classified under the division system, and NRTLs
perform testing based on that system. However, test standards currently
used by NRTLs to test equipment in hazardous locations classified by
division are not automatically appropriate for testing such equipment
for use under the zone system. These current test standards are based
on protective techniques used for equipment designed for use under the
division system and do not contain criteria for protective techniques
used in the zone system. Electric equipment that has been approved by
an NRTL for use in division-classified hazardous locations may be capable
of igniting flammable gases or vapors when used inappropriately in
zone-classified locations. Such hazardous equipment can cause a catastrophic
explosion and the deaths of and injuries to many employees. In recognizing
laboratories under Sec. 1910.7 to test products designed for installation
in zone-classified locations, OSHA will ensure that the proper test standards
are used and look closely at the capability of the laboratory to
perform testing under those standards.
Effects and changes to other Part 1910 standards (Sec. Sec.
1910.103, 1910.106, 1910.107, 1910.110, 1910.178, and 1910.253). A
number of other OSHA standards under 29 CFR Part 1910 contain
references to or requirements related to Sec. 1910.307. Some of these
standards refer only to hazardous locations classified under the
division system. The standards particularly affected are as follows:
Sec. 1910.103(b)(3)(ii)(e) and (b)(3)(iii)(e), (c)(1)(ix)(a), and
(c)(1)(ix)(b);
Sec. 1910.106(d)(4)(iii), (e)(7)(i)(b), (e)(7)(i)(c),
(e)(7)(i)(d), (g)(1)(i)(g), (g)(4)(iii)(a), (h)(7)(iii)(b), and
(h)(7)(iii)(c);
Sec. 1910.107(c)(6), (c)(8), (j)(4)(iv);
Sec. 1910.110(b)(17)(v);
Sec. 1910.178(c)(2)(iv) and (q)(2); and
Sec. 1910.253(f)(4)(iv)(B) and (f)(6)(v).
OSHA is not modifying any of these standards in this rulemaking.
Several of these requirements call for designating particular locations
as Class I, Division 1 or Division 2 locations, and OSHA believes that
revising them would not be straightforward and would be too complicated
to do in this rulemaking. For example, Sec. 1910.103(c)(1)(ix)(a)
requires electric wiring and equipment "located within 3 feet of a
point where connections are regularly made and disconnected, shall be
in accordance with Subpart S of this Part, for Class I, Group B,
Division 1 locations." Under the zone system, this location would
likely be partly a Zone 0 location and partly a Zone 1 location. Thus,
this requirement cannot be revised by a straightforward substitution of
"Zone" for "Division." Similar problems exist in revising the other
requirements. OSHA will make a case-by-case determination of whether a
particular installation under the zone classification system meets the
criteria for a de minimis violation based on: (1) Evidence the employer
provides to show that the installation is as safe as it would be if it
complied with Subpart S requirements for installations made under the
division system and (2) the extent to which the employer's designation
of Class I, Zone 0, 1, and 2 locations is consistent with sound
engineering practices, as evidenced by national consensus and industry
standards.
O. Remote Control, Signaling, Power-Limited, and Fire Alarm Circuits
Proposed Sec. 1910.308(c) addressed Class 1, 2, and 3 remote
control, signaling, and power-limited circuits. The American Petroleum
Institute (API) and Dow Chemical Company noted that Section 725.55 of
the 2002 NEC specifically permits many types of installations that are
not listed in OSHA's proposal (Exs. 3-8, 4-11). They recommended that
the OSHA standard also list permitted uses for these types of circuits
for consistency with the NEC.
The provision in the 2002 NEC to which API and Dow referred
(Section 725.55) does not actually list permitted uses. Rather, this
provision contains requirements for separating different classes of
circuits, with the method of separation differing in some respect for
the various types of installations.\43\ For example, Section 725.55(B)
states, "Class 2 and Class 3 circuits shall be permitted to be
installed together with Class 1, non-power-limited fire alarm and
medium power network-powered broadband communications circuits where
they are separated by a barrier [emphasis added]."
---------------------------------------------------------------------------
\43\ The title of Sec. 725.55 of the 2002 NEC is "Separation
from Electric Light, Power, Class 1, Non-Power-Limited Fire Alarm
Circuit Conductors, and Medium Power Network-Powered Broadband
Communications Cables."
---------------------------------------------------------------------------
Proposed Sec. 1910.308(c), which was nearly identical to Section
6.3.1.3.1.1 of NFPA 70E-2000, read as follows:
Cables and conductors of Class 2 and Class 3 circuits may not be
placed in any cable, cable tray, compartment, enclosure, manhole,
outlet box, device box, raceway, or similar fitting with conductors
of electric light, power, Class 1, nonpowerlimited fire alarm
circuits, and medium power network-powered broadband communications
cables.
This provision in the proposal and the corresponding one in NFPA
70E were taken from 1999 NEC Section 725-54(a)(1), which contains the
same basic requirement, but which also contains six exceptions to this
general rule. All the exceptions permit cables and conductors of Class
2 and Class 3 circuits to be placed in one of the listed enclosures
with a higher powered circuit as long as an extra barrier of one form
or another is installed to separate the two different classes of
circuits. Consequently, OSHA agrees with the commenters that the
proposal could have unnecessarily restricted the installation of Class
2 and Class 3 circuits. On the other hand, adopting the specific
language in the NEC (either the 1999 edition or the 2002 edition, which
converted the exception into separate rules) would make the OSHA
standard too detailed and specification oriented. To address API's and
Dow's concerns, OSHA has decided to incorporate the exceptions in 1999
NEC Section 725-54(a)(1) in performance terms. Final Sec.
1910.308(c)(3) thus reads as follows:
Cables and conductors of Class 2 and Class 3 circuits may not be
placed in any cable, cable tray, compartment, enclosure, manhole,
outlet box, device box, raceway, or similar fitting with conductors
of electric light, power, Class 1, nonpower-limited fire alarm
circuits, and medium power network-powered broadband communications
cables unless a barrier or other equivalent form of protection
against contact is employed. [Emphasis added.]
Employers can look to the NEC to help determine acceptable methods
of separating Class 2 and Class 3 circuits from electric light, power,
Class 1, and nonpower-limited fire alarm circuit conductors and from
medium power network-powered broadband communications cables.
OSHA received a similar comment on proposed Sec. 1910.308(d)(3)
recommending that the provision mention all the permitted uses for fire
alarm circuits listed in 2002 NEC Section 760.55 (Ex. 4-22). The Agency
has rejected this recommendation for the same reasons it rejected the
recommendation concerning remote control, signaling, and power-limited
circuits.
Dow Chemical Company objected to proposed Sec. 1910.308(d)(3)(iii)
(Exs. 3-8, 4-16). They stated their objections as follows:
The current provision, section 1910.308(d)(4), has a 2-inch
requirement for separation of power-limited conductor locations with
an option for alternative protections (emphasis added):
Power-limited conductor location. Where open conductors are
installed, power-limited fire protective signaling circuits shall be
separated at least 2 inches from conductors of any light, power,
Class 1, and non-power-limited fire protective signaling circuits
unless a special and equally protective method of conductor
separation is employed.
The proposed revision of that 2-inch requirement does not have that
option:
Power-limited fire alarm circuit conductors shall be separated
at least 50.8 mm (2 in.) from conductors of any electric light,
power, Class 1, nonpower-limited fire alarm, or medium power
network-powered broadband communications circuits.
The preamble characterizes this change as a clarification of
existing requirements (69 FR at 17792). This is not a clarification,
however, but a limitation.
As a significant change, at a minimum this provision should be
applicable only to installations after the effective date of the final
rule under Sec. 1910.302(b)(4). The proposed rule lists all of Sec.
1910.308(d) as being triggered in installations made after April 16,
1981, per proposed Sec. 1910.302(b)(3).
Further, this deletion of the option for using equally protective
methods is not justified and should not be adopted. NEC Sec.
800.52(A)(2) provides that option today with two exceptions. That
provision reads:
Other Applications. Communications wires and cables shall be
separated at least 50 mm (2 in.) from conductors of any electric
light, power, Class 1, non-power-limited fire alarm, or medium power
network-powered broadband communications circuits.
Exception No. 1: Where either (1) all of the conductors of the
electric light, power, Class 1, non-power-limited fire alarm, and
medium power network-powered broadband communications circuits are
in a raceway or in metal-sheathed, metal-clad, nonmetallic-sheathed,
Type AC, or Type UF cables, or (2) all of the conductors of
communications circuits are encased in raceway.
Exception No. 2. Where the communications wires and cables are
permanently separated from the conductors of electric light, power,
Class 1, non-power-limited fire alarm, and medium power network-
powered broadband communications circuits by a continuous and firmly
fixed nonconductor, such as porcelain tubes or flexible tubing, in
addition to the insulation on the wire. [Ex. 3-8]
Dow further noted that NFPA provides similar exceptions to the
corresponding provision in that standard. They concluded their comments
as follows:
The availability of such options is important because computer
rooms, control rooms, and communications closets may have mixed
wiring under the floor that relies on the availability of those
exceptions.
OSHA should not take away the options present in the existing
rule, particularly since they are supported by both the NEC and NFPA
70E. [Ex. 3-8]
OSHA agrees with Dow's rationale. The 2002 NEC and the 2000 and
2004 editions of NFPA 70E recognize that it is safe to install power-
limited fire protective signaling circuits within 50.8 millimeters (2
inches) of power conductors when there is an additional barrier between
the two sets of conductors. Consequently, the Agency is adding the
phrase "unless a special and equally protective method of conductor
separation is employed," from existing Sec. 1910.308(d)(4) as
highlighted in Dow's comments, to final Sec. 1910.308(d)(3)(iii) to
permit additional means of protecting fire protective signaling circuit
conductors from contact with conductors of other circuits. The final
rule, with the revision emphasized, reads as follows:
Power-limited fire alarm circuit conductors shall be separated
at least 50.8 mm (2 in.) from conductors of any electric light,
power, Class 1, nonpower-limited fire alarm, or medium power
network-powered broadband communications circuits unless a special
and equally protective method of conductor separation is employed.
P. Definitions
The definitions for Subpart S are located in Sec. 1910.399. The
changes to these definitions from the existing standard reflect the
provisions of the 2002 NEC and NFPA 70E-2000. Table 4 (located at the
end of section I. P. of the preamble) summarizes the changes to the
definitions.
OSHA is removing several definitions from the standard. "Special
permission," "permanently installed swimming pools, wading and
therapeutic pools," and "storable swimming and wading pools" are
removed because these terms are not used in final Subpart S. Lastly,
the definitions of "electric sign" and "may" are removed. The
existing Subpart S definitions of these terms are not substantially
different from the commonly accepted dictionary definitions. The
definition of "electric sign" may appear different from the
dictionary definition; however, the information in the existing
definition adds nothing substantive within the context of the standard.
Thus, their removal does not change the meaning of the standard.
The final rule redefines the term "identified." The existing
definition of "identified" applies to the use of this term in
reference to a conductor or its terminal. The final rule discontinues
the current standard's use of the word "identified" in this manner.
The final rule does, however, define "identified" to refer to
equipment suitable for a specific purpose, function, use, environment,
or application.
OSHA is also removing the definition of "utilization
systems.\44\" This term is only used in existing Sec. 1910.301(a),
which describes the content of Sec. Sec. 1910.302 through 1910.308,
and in the title and introductory text of existing Sec. 1910.302.
Existing Sec. 1910.301(a) reads as follows:
---------------------------------------------------------------------------
\44\ In the proposed rule, OSHA listed the removal of this
definition in the preamble in a table listing the summary of changes
to the definitions. However, OSHA neglected to include the removal
of this definition in the proposed regulatory text.
Design safety standards for electrical systems. These
regulations are contained in Sec. Sec. 1910.302 through 1910.330.
Sections 1910.302 through 1910.308 contain design safety standards
for electric utilization systems. Included in this category are all
electric equipment and installations used to provide electric power
and light for employee workplaces. Sections 1910.309 through
1910.330 are reserved for possible future design safety standards
---------------------------------------------------------------------------
for other electrical systems.
The introductory text of Sec. 1910.302 reads as follows:
Sections 1910.302 through 1910.308 contain design safety
standards for electric utilization systems.
These two provisions are intended as introductory text providing a
general discussion of the contents of the standard. The precise scope
of Sec. Sec. 1910.302 through 1910.308 is presented in final Sec.
1910.302(a). However, OSHA is concerned that some employers and
employees could incorrectly interpret the use of the term "utilization
systems" and its definition as narrowing the scope of Sec. Sec.
1910.303 through 1910.308. The term "utilization system" in the
introduction to Subpart S is intended as a shorthand way of referring
to the systems covered by Subpart S generally and Sec. Sec. 1910.303
through 1910.308 specifically. Removing the definition from the
standard should clarify that the language used in the introduction to
Subpart S is not intended to alter the scope of Sec. Sec. 1910.302
through 1910.308, as given in Sec. 1910.302(a).
OSHA is adding 13 definitions to Sec. 1910.399. (See Table 4.)
These definitions, all but one of which are based on NFPA 70E-2000 and
the 2002 NEC, will help clarify the requirements in Subpart S. Other
modifications made to the definitions are grammatical in nature, and no
substantive change is being made in the meaning of the terms.
A few terms warrant additional explanation: "Identified,"
"labeled," and "listed." The existing standard requires certain
electric equipment to be "approved for the purpose," and current
Sec. 1910.399 defines this term as follows:
Approved for a specific purpose, environment, or application
described in a particular standard requirement.
Suitability of equipment or materials for a specific purpose,
environment or application may be determined by a nationally
recognized testing laboratory, inspection agency or other
organization concerned with product evaluation as part of its
listing and labeling program. (See "Labeled" or "Listed.")
In the final rule, OSHA is replacing the word "approved" in the
phrase "approved for the purpose," with "identified." The final
rule's definition of "identified," which is based on the definition
of this term in NFPA 70E-2000,\45\ reads as follows:
---------------------------------------------------------------------------
\45\ Except for the note to the definition, the exact language
was taken from the 2002 NEC. This version is clearer than the
definition in NFPA 70E, but the intent is the same. OSHA has
clarified the note to indicate that acceptability of testing and
inspection agencies is given in the definition of "acceptable."
Identified (as applied to equipment). Approved as suitable for
the specific purpose, function, use, environment, application, and
so forth, where described in a particular requirement.
Note to the definition of "identified:" Some examples of ways
to determine suitability of equipment for a specific purpose,
environment, or application include investigations by a nationally
recognized testing laboratory (through listing and labeling),
inspection agency, or other organization recognized under the
definition of "acceptable."
The definition of "identified" as it applies to equipment is
intended to be equivalent to the existing definition of "approved for
the purpose." \46\
---------------------------------------------------------------------------
\46\ NFPA 70E-2000 uses the word "recognizable" in lieu of
"approved" in the definition of "identified." It also contains a
fine print note following the definition indicating that suitability
of equipment for a specific purpose, environment, or application may
be determined by a qualified testing laboratory, inspection agency,
or other organization concerned with product evaluation. The revised
and existing OSHA standards both require all electric equipment to
be approved, and this approval is the only mechanism for recognizing
equipment as suitable. The Agency believes that the proposed
definition of "identified" as applied to equipment clarifies the
intent of the standard and is consistent with the existing
standard's provisions that require electric equipment to be
"approved for the purpose."
---------------------------------------------------------------------------
In the final rule, OSHA uses the terms "listed" and "labeled"
to refer to electric equipment determined to be safe by a nationally
recognized testing laboratory (NRTL). When equipment has been listed
and labeled, this means that the equipment has been tested and found
safe for use by a nationally recognized testing laboratory. The
laboratory marks the equipment with a symbol identifying its trademark.
The equipment is then considered by OSHA to be safe for its intended
use. If the equipment is altered or used for other purposes, then the
equipment is not acceptable under Subpart S. The laboratories typically
require the equipment to be marked with such information as: The
standards under which the equipment has been tested; the current rating
in amperes; and the frequency. OSHA evaluates and recognizes
"nationally recognized testing laboratories" under Sec. 1910.7 to
test equipment for safety and label or list it. It should be noted that
the final rule would continue the existing Sec. 1910.399 definitions
of "labeled" and "listed" without substantive change.
The Dow Chemical Company recommended that OSHA supplement the
proposed definition of "identified" with language from Section
500.8(A)(1) of the 2002 NEC so that the definition would read as
follows:
Suitability of identified equipment for the purpose shall be
determined by any of the following:
(1) Equipment listing or labeling;
(2) Evidence of equipment evaluation from a qualified testing
laboratory or inspection agency concerned with product evaluation; or
(3) Evidence acceptable to the authority having jurisdiction, such
as a manufacturer's self-evaluation or an owner's engineering judgment.
[Ex. 3-8]
Dow Chemical believes that this language would provide flexibility
to the employer when the equipment is not approved by a nationally
recognized testing laboratory.
As noted earlier, Sec. 1910.303(a) requires electric equipment to
be approved, and the definitions of "approved" and "acceptable" set
out what types of equipment OSHA will accept in enforcing Subpart
S.\47\ Dow's suggestion does not clarify these definitions. Instead, it
seems to imply equivalence between the three listed options. In
comparison, OSHA's existing definition of "acceptable" clearly
indicates a preference for listing, labeling, or other approval by a
nationally recognized testing laboratory. At the same time, OSHA's
existing definitions provide flexibility for employers when equipment
is of a type that no nationally recognized testing laboratory
evaluates. OSHA believes that the proposed definitions of
"identified," "approved," and "acceptable" are clear and provide
sufficient flexibility to employers. Therefore, the Agency is carrying
them forward into the final rule without change.
---------------------------------------------------------------------------
\47\ OSHA proposed no substantive changes to the definitions of
"approved" or "acceptable" or to the requirement in existing
Sec. 1910.303(a) that electric equipment be approved.
---------------------------------------------------------------------------
The proposed definition of "acceptable" reads as follows:
An installation or equipment is acceptable to the Assistant
Secretary of Labor, and approved within the meaning of this Subpart
S:
(1) If it is accepted, or certified, or listed, or labeled, or
otherwise determined to be safe by a nationally recognized testing
laboratory recognized pursuant to Sec. 1910.7; or
(2) With respect to an installation or equipment of a kind that
no nationally recognized testing laboratory accepts, certifies,
lists, labels, or determines to be safe, if it is inspected or
tested by another Federal agency, or by a State, municipal, or other
local authority responsible for enforcing occupational safety
provisions of the National Electrical Code, and found in compliance
with the provisions of the National Electrical Code as applied in
this subpart; or
(3) With respect to custom-made equipment or related
installations that are designed, fabricated for, and intended for
use by a particular customer, if it is determined to be safe for its
intended use by its manufacturer on the basis of test data which the
employer keeps and makes available for inspection to the Assistant
Secretary and his authorized representatives.
Mr. Ron Nickson, representing the National Multi Housing Council
and the National Apartment Association, recommended that OSHA add the
International Code Council Electrical Code (ICCEC), which is published
by the International Code Council (ICC), to the second alternative in
the definition of "acceptable" (Ex. 4-20). They believe that OSHA
should accept evaluations made by local authorities enforcing the ICCEC
as being equivalent to those made by authorities enforcing the NEC. In
support of their position, they stated:
The provisions in the ICCEC were developed during the ICC code
development process to address and/or expand on issues not covered
in the NEC. The ICC codes, including the ICCEC, are the result of
more than 90 years of code enforcement by local building and fire
officials. The ICCEC responds to issues that have come up during the
inspection and approval process or have been brought to the
attention of the ICC by participants in the ICC code development
process. They have been reviewed by ICC Code development committees
and voted into the code by the building and fire official members of
ICC. They form an important part of the electrical installation and
inspection process to insure that electrical work is installed in a
safe manner to limit the possibility of injury to workers and others
involved in the construction process. [Ex. 4-20]
The commenter acknowledged that there are differences between the
NEC and the ICCEC. However, there is little information in Mr.
Nickson's submission or elsewhere in the rulemaking record that would
enable OSHA to judge whether an evaluation of an electrical
installation made under the ICCEC would be equivalent to one made under
the NEC. In addition, Mr. Nickson does not present any evidence of how
many jurisdictions, if any at all, enforce the ICCEC. Consequently, the
Agency has decided against adding the International Code Council
Electrical Code to the definition of "acceptable."
However, if in enforcing Subpart S the Agency determines that the
underlying electrical standard, such as the ICCEC, being used by a
particular local authority is based on the NEC, then OSHA will consider
accepting that authority's determinations of electrical installation
safety under the second alternative given in the definition of
"acceptable."
OSHA received several comments suggesting the addition of a
definition of "fountain" to clarify the use of this word in proposed
Sec. 1910.306(j)(5) (Exs. 4-13, 4-15, 4-18, 4-21). Typifying these
comments, Mr. Michael Kovacic argued that the term "fountains" has
been the source of considerable confusion and misinterpretation for
many years. He stated that, although some apply the requirements on
fountains in existing Sec. 1910.306(j)(5) to drinking fountains and
water coolers, the NEC does not intend to apply the requirements on
fountains to drinking fountains. To support his assertion, he pointed
to 2002 NEC Section 680.2, which states that the definition of
"fountains" does not include drinking fountains. The commenters
recommend that OSHA either add the NEC definition of "fountains" to
Sec. 1910.399 or otherwise clarify the application of Sec.
1910.306(j)(5).
OSHA agrees with these commenters and has included the 2002 NEC
definition of "fountains" in final Sec. 1910.399.
The Agency has also retained the proposed definitions of
"permanently installed swimming pools, wading and therapeutic pools"
and "storable swimming or wading pool." The preamble indicated that
the definitions of these terms were to be removed because the terms
were not used in the proposed standard. However, the proposal did
include definitions of these terms in the regulatory text. The
introductory text to final Sec. 1910.306(j) reads, in part, as
follows:
This paragraph applies to electric wiring for and equipment in
or adjacent to all swimming, wading, therapeutic, and decorative
pools and fountains; hydro-massage bathtubs, whether permanently
installed or storable; and metallic auxiliary equipment, such as
pumps, filters, and similar equipment. [Emphasis added.]
OSHA believes that defining the terms "permanently installed
swimming pools, wading and therapeutic pools" and "storable swimming
or wading pool" will clarify the intent of final Sec. 1910.306(j).
Even though the terms are not used precisely in the form used in the
definitions, it is clear from the regulatory text that those two terms
are what OSHA intends by the language in final Sec. 1910.306(j).
Proposed Sec. 1910.308(c)(1) contained requirements governing the
marking and limitations on power of Class 1, 2, and 3 remote control,
signaling, and power-limited circuits. Some commenters recommended
clarifying the standard by moving those provisions to Sec. 1910.399 or
by including a cross-reference to Sec. 1910.308(c)(1) within the
definition section.
Paragraph (c)(1) of final Sec. 1910.308 sets mandatory limits on
the power output for remote control, signaling, and power-limited
circuits and sets requirements for marking the source of power for
these circuits. These provisions are requirements, not definitions.
Consequently, the Agency does not believe that it is appropriate to
move them to or refer to them in the definition section.
Some commenters identified definitions in the proposed rule that
were inconsistent with the definitions in the NFPA 70E-2004 (Exs. 4-11,
4-19). They identified as examples: "Armored cable" and "live
parts." \48\ The commenters recommended that the definitions in Sec.
1910.399 be consistent with NFPA 70E and the NEC.
---------------------------------------------------------------------------
\48\ These commenters also identified the definition of
"qualified person" as being inconsistent with the NEC definition.
This comment is addressed later in this section of the preamble.
---------------------------------------------------------------------------
In comparing the proposed definition of "live parts" with the one
in the 2002 NEC (on which NFPA 70E-2004 is based), OSHA has found that
the definition in its proposal is only slightly different from that of
NFPA.\49\ The intent of OSHA's definition and the NEC definition is
identical. To promote consistency with the NEC and NFPA 70E, the Agency
has decided to adopt the 2002 NEC language for this definition in the
final OSHA rule.
---------------------------------------------------------------------------
\49\ The NEC definition of "live parts" is "energized
conductive componenets." OSHA's proposed definition was
"[E]lectric conductors, buses, terminals, or components that are
energized." Since the word "components" includes conductors,
buses, and terminals, there is no substantive difference between the
two definitions.
---------------------------------------------------------------------------
The definition of "armored (Type AC) cable" in the proposal is
identical to the one in the 2002 NEC, though OSHA's proposed definition
is worded as a complete sentence. The Agency has reworded the
definition in the final rule (along with similarly worded definitions
\50\) so that the format matches the other definitions in the final
rule and the NEC.
---------------------------------------------------------------------------
\50\ The following definitions were similarly worded in the
proposed rule: "Medium voltage cable," "metal-clad cable,"
"mineral-insulated metal-sheathed cable," "nonmetallic-sheathed
cable," "power and control tray cable," "power-limited tray
cable," "service-entrance cable," "shielded nonmetallic-sheathed
cable," and "wireways."
---------------------------------------------------------------------------
In addition, the Agency has identified two additional definitions
that could be clarified with the use of the corresponding 2002 NEC
definitions: "Health care facilities" and "mineral-insulated, metal
sheathed cable."
The existing and proposed definitions of "health care facilities"
read as follows:
Buildings or portions of buildings and mobile homes that
contain, but are not limited to, hospitals, nursing homes, extended
care facilities, clinics, and medical and dental offices, whether
fixed or mobile.
This is not a true definition. Rather, it provides examples of
health care facilities. The 2002 NEC definition of this term, in Sec.
517.2, reads as follows:
Buildings or portions of buildings in which medical, dental,
psychiatric, nursing, obstetrical, or surgical care are provided.
Health care facilities include, but are not limited to, hospitals,
nursing homes, limited care facilities, clinics, medical and dental
offices, and ambulatory care centers, whether permanent or moveable.
OSHA believes that this language will clarify how that term is used
and has adopted the NEC definition in the final rule.
The proposed definition of "mineral-insulated, metal sheathed
cable" stated that this was a type of cable with a "continuous copper
sheath." The 2002 NEC states that the sheath may be of alloy steel in
addition to copper. For consistency with the 2002 NEC, OSHA has revised
the term "continuous copper sheath" from the definition in the
proposal to "continuous copper or alloy steel sheath" in the final
rule. This will ensure that the OSHA standard recognizes all the
different types of approved mineral-insulated, metal sheathed cables
currently available.
The proposed definition of "qualified person" read as follows:
A person who is familiar with the construction and operation of
the equipment and the hazards involved. [Notes omitted.]
OSHA received several comments on this definition (Exs. 4-11, 4-13,
4-15, 4-18, 4-19, 4-21). These commenters recommended that OSHA use the
corresponding definition from the 2002 NEC, which reads:
One who has the skills and knowledge related to the construction
and operation of the electrical equipment and installations and has
received safety training on the hazards involved.
Some of these commenters asserted that there is confusion in the
electrical safety industry over the use of this term (Exs. 4-13, 4-15,
4-18, 4-21). They also recommended including a note regarding the type
of training needed before an employee could meet the definition.
Paragraph (b)(3) of existing Sec. 1910.332 set specific training
requirements that an employee must have to be considered a "qualified
person." In fact, the first note to the proposed definition of
"qualified person" pointed to that training requirement. Although the
suggested definition is consistent with the training provisions, it
does not demand that the person have the knowledge and skills related
to the hazards posed by electrical installations that are to be
imparted by the training. To capture the commenters' intent and retain
the proposed definition's emphasis on acquired knowledge, the Agency is
adopting the following definition of "qualified person:"
One who has received training in and has demonstrated skills and
knowledge in the construction and operation of electric equipment
and installations and the hazards involved.
The final rule also carries forward, unchanged, the two notes to
the proposed definition.
Table 4.--Summary of Changes to the Definitions
------------------------------------------------------------------------
Old definition New definition Rationale
------------------------------------------------------------------------
Barrier.......... OSHA is adding this
definition to Sec.
1910.399 from NFPA
70E-2000.
Bathroom......... OSHA is adding this
definition to Sec.
1910.399 from NFPA
70E-2000.
Class I, Zone 0.. OSHA is adding this
definition to Sec.
1910.399 from NFPA
70E-2000 to support
the new section on
Zone Classification
in Sec. 1910.307.
Class I, Zone 1.. OSHA is adding this
definition to Sec.
1910.399 from NFPA
70E-2000 to support
the new section on
Zone Classification
in Sec. 1910.307.
Class I, Zone 2.. OSHA is adding this
definition to Sec.
1910.399 from NFPA
70E-2000 to support
the new section on
Zone Classification
in Sec. 1910.307.
Competent person. OSHA is adding this
definition to Sec.
1910.399 from Sec.
1926.32. See
discussion earlier
in the preamble.
Electric sign................. [Removed]........ No substantive
change. See the
detailed explanation
earlier in this
section of the
preamble.
Energized........ OSHA is adding this
definition to Sec.
1910.399 from NFPA
70E-2000.
Fountain......... OSHA is adding this
definition to Sec.
1910.399 from NEC-
2002. See the
detailed explanation
earlier in this
section of the
preamble.
Health care facilities........ Health care OSHA is removing the
facilities. old definition and
adding the new
definition to Sec.
1910.399 from NEC-
2002. See the
detailed explanation
earlier in this
section of the
preamble.
Identified.................... Identified....... This term is used in
a different manner
in the proposed
revision. The new
use and definition
are taken from NFPA
70E-2000. See the
detailed explanation
earlier in this
section of the
preamble.
Insulated........ OSHA is adding this
definition to Sec.
1910.399 from NFPA
70E-2000.
Live parts....... OSHA is adding this
definition to Sec.
1910.399 from NEC-
2002.
May........................... [Removed]........ No substantive
change. The
definition adds
nothing to the
dictionary
definition of this
term.
Motor Control OSHA is adding this
Center. definition to Sec.
1910.399 from NFPA
70E-2000.
Nonmetallic-sheathed cable.... Nonmetallic- OSHA is removing the
sheathed cable. old definition and
adding the new
definition to Sec.
1910.399 from NEC-
2002. See the
detailed explanation
earlier in this
section of the
preamble.
Overhaul......... OSHA is using this
term in the standard
in place of "major
replacement,
modification,
repair, or
rehabilitation,"
which is used in the
existing standard to
delineate when an
electrical
installation must
meet new
requirements in the
standard. See the
explanation of the
definition and
related changes
under the summary
and explanation of
the grandfather
clause earlier in
this preamble.
Qualified person.............. Qualified person. OSHA is revising this
definition. (See the
summary and
explanation of the
definition of
"qualified
person," earlier in
this section of the
preamble.)
Service point.... OSHA is adding this
definition to Sec.
1910.399 from NFPA
70E-2000.
Special permission............ [Removed]........ This term is not used
in Subpart S.
Utilization system............ [Removed]........ This definition is
being removed. See
the detailed
explanation earlier
in this section of
the preamble.
------------------------------------------------------------------------
Q. Appendices
Appendices B and C of the current Subpart S contain no material;
they are reserved for future use. OSHA is removing these two "empty"
appendices because the Agency has no material to include there.
The existing Appendix A contains a list of references. OSHA is
revising and updating the references in this appendix to reflect the
most recent editions of various national consensus standards.\51\ These
nonmandatory references can be used to assist employers who desire
additional information that will help them to comply with the
performance standard in Subpart S. In addition, OSHA is removing
various reference standards from the appendix because the documents are
no longer in print and because the information can be found in other
listed sources. The following references are removed:
---------------------------------------------------------------------------
\51\ The references in Appendix A in the final rule are to the
latest revisions of the relevant documents, except for references to
the NEC and NFPA 70E. For these two NFPA standards, OSHA has listed
both the current versions (NFPA 70-2005 and 70E-2004) and the
versions on which the final rule is based (NFPA 70-2002 and 70E-
2000). The Agency has reviewed these documents and found them to
provide suitable guidance to assist employers in complying with the
OSHA standards.
ANSI B9.1-71 Safety Code for Mechanical Refrigeration;
ANSI B30.15-73 Safety Code for Mobile Hydraulic Cranes;
ANSI C33.27-74 Safety Standard for Outlet Boxes Fittings for Use in
Hazardous Locations, Class I, Groups A, B, C, and D, and Class II,
Groups E, F, and G;
ASTM D2155-66 Test Method for Autoignition Temperature of Liquid
Petroleum Products;
IEEE 463-77 Standard for Electrical Safety Practices in Electrolytic
Cell Line Working Zones;
NFPA 56A-73 Standard for the Use of Inhalation Anesthetics (Flammable,
Nonflammable);
NFPA 56F-74 Standard for Nonflammable Medical Gas Systems;
NFPA 70C-74 Hazardous Locations Classification;
NFPA 71-77 Standard for the Installation, Maintenance, and Use of
Central Station Signaling Systems;
NFPA 72A-75 Standard for the Installation, Maintenance, and Use of
Local Protective Signaling Systems for Watchman, Fire Alarm, and
Supervisory Service;
NFPA 72B-75 Standard for the Installation, Maintenance, and Use of
Auxiliary Protective Signaling Systems for Fire Alarms Service;
NFPA 72C-75 Standards for Installation, Maintenance, and Use of Remote
Station Protective Signaling Systems;
NFPA 72D-75 Standard for the Installation, Maintenance and Use of
Proprietary Protective Signaling Systems for Watchman, Fire Alarm, and
Supervisory Service;
NFPA 72E-74 Standard for Automatic Fire Detectors;
NFPA 74-75 Standard for Installation, Maintenance, and Use of Household
Fire Warning Equipment;
NFPA 76A-73 Standard for Essential Electrical Systems for Health Care
Facilities;
NFPA 86A-73 Standard for Ovens and Furnaces; Design, Location and
Equipment;
NFPA 88B-73 Standard for Repair Garages;
NFPA 325M-69 Fire-Hazard Properties of Flammable Liquids, Gases, and
Volatile Solids; and
NFPA 493-75 Standard for Intrinsically Safe Apparatus for Use in Class
I Hazardous Locations and Its Associated Apparatus.
OSHA is adding five national consensus standards to the list.\52\
All but one of these documents refers to hazardous (classified)
locations. The other document addresses articulating boom cranes. ANSI/
ASME B30.22-2005 Articulating Boom Cranes was not included in the
proposal. However, the Agency has reviewed this standard and has found
useful information comparable to the other ANSI/ASME standards for
other types of cranes (for example, ANSI/ASME B30.5-2004 Mobile And
Locomotive Cranes). Consequently, the following references are added:
\52\ OSHA had proposed to add an additional national consensus
standard to the list, ANSI/UL 2279-1997, Electrical Equipment for
Use in Class I, Zone 0, 1 and 2 Hazardous (Classified) Locations.
This standard is no longer active, because UL has added zone-related
provisions to other of its standards on equipment for hazardous
locations. Therefore, OSHA has not included this standard in
Appendix A in the final rule.
ANSI/UL 913-2002 Intrinsically Safe Apparatus and Associated Apparatus
for Use in Class I, II, and III, Division 1, Hazardous (Classified)
Locations;
ANSI/API RP 500-1998 (2002) Recommended Practice for Classification of
Locations for Electrical Installations at Petroleum Facilities
Classified as Class I Division 1 and Division 2;
ANSI/API RP 505-1997 (2002) Recommended Practice for Classification of
Locations for Electrical Installations at Petroleum Facilities
Classified as Class I, Zone 0, Zone 1 and Zone 2;
ANSI/ASME B30.22-2005 Articulating Boom Cranes; and
NFPA 820-2003 Standard for Fire Protection in Wastewater Treatment and
Collection Facilities.
Comments to the appendices. OSHA received a comment to reference
other national consensus standards in Appendix A, like ANSI Z490.1 and
ANSI Z244.1, to help employers with new training requirements in
electrical installations (Ex. 3-5). These voluntary consensus standards
offer benefits in guiding employers on establishing appropriate
training procedures for their employees. The national consensus
standards listed in Appendix A are there to be used as a guideline to
help employers with implementing the requirements for electrical
installation and safe work practices and procedures in Subpart S. OSHA
has reviewed both standards and has added them to the list of voluntary
standards in the appendices.
R. Powered Platforms for Building Maintenance
Mandatory Appendix D to Sec. 1910.66, powered platforms for
building maintenance, applies to powered platforms installed between
August 28, 1971, and July 23, 1990. Paragraphs (c)(22)(i) and
(c)(22)(vii) in that appendix incorporate the 1971 NEC by reference.
OSHA is referencing Subpart S instead. The final rule, which would
replace the highly specification-oriented NEC with the performance-
oriented Subpart S, will make the standard more flexible for employers
maintaining these platforms but will retain the protection currently
afforded employees.\53\ In addition, employers will no longer need to
refer to the NEC to determine how to comply with OSHA's standard for
powered platforms. This change is deregulatory in nature and should not
result in significant costs to employers.
---------------------------------------------------------------------------
\53\ Employers who make minor modifications to these platforms
would thus be required to follow Subpart S rather than the 1971 NEC.
Newer installations and major modifications of older platforms are
already required to meet Subpart S with respect to the platform's
electrical wiring and equipment.
---------------------------------------------------------------------------
OSHA received no comments in response to this proposed change.
Consequently, it is being carried without change into the final rule.
VI. Final Economic and Regulatory Screening Analysis
A. Existing Versus Final Rule
The final rule revises and updates the provisions contained in
Sections 1910.302-1910.308 and 1910.399 of the existing Subpart S
electrical installation standard. The original version of Subpart S,
adopted under Sec. 6(a) of the OSH Act, incorporated the 1971 National
Electrical Code (NEC) by reference. In 1981, OSHA replaced the
incorporation by reference with updated provisions based on the 1979
National Fire Protection Association (NFPA) 70E committee
recommendations. The 1981 version relied on the 1978 NEC. The
rulemaking will revise and update the OSHA electrical installation
standard to be consistent with most of the NFPA 70E recommendations
developed in 2000, which are based on the 1999 NEC, and to update
requirements for new electrical installations.
OSHA has conducted a detailed comparison of the existing and final
rules in order to determine the extent to which the provisions of the
final rule will increase compliance costs. Table 7 summarizes the
changes associated with the provisions of the final rule that have cost
implications. OSHA's comparative analysis indicates that the changes in
the final rule fall into four categories: (1) Changes in hardware
specifications that are consistent with NEC requirements; (2) changes
in installation practices that are consistent with current, normal and
customary installation practices routinely followed by licensed
electricians; (3) clarifications of existing requirements that do not
add additional obligations and/or allow greater flexibility for
achieving compliance; and (4) requirements that may require
significant changes in electrical system and equipment installation
practices.
The first three categories of changes introduced by the final rule
are not expected to result in any additional costs. Category 1 changes
are not expected to increase costs because virtually all equipment
manufacturers routinely follow current NEC requirements regarding
hardware specifications. Category 2 changes are not expected to result
in any increase in compliance costs since virtually all licensed
electricians routinely follow NEC requirements for installing
electrical systems and equipment. Category 3 changes do not add any new
installation or work practice requirements, but simply restate or
eliminate existing requirements.
Regarding Category 4, a number of changes indicated by the final
rule correspond to revisions to the NEC made prior to 1999. Because
these changes have been in the NEC since the previous edition (1996),
they are believed to represent widespread current industry practice.
Therefore, these changes are not expected to result in increased
compliance costs. Moreover, construction requirements usually imposed
by mortgage lenders and insurance carriers, as well as installation
practices routinely followed by licensed electricians (given their
formal training), are generally consistent with the NEC requirements.
In sum, there is a subset of Category 4 changes that can be assumed to
be equivalent to the Category 2 changes described above. Only those
Category 4 changes that represent additions or revisions in the 1999
NEC (to the 1996 NEC) are expected to potentially result in any
increase in compliance costs.
As noted, many Category 4 changes are not expected to increase
compliance costs. In order to avoid having employers incur the costs of
retrofitting the existing electrical systems and equipment in their
buildings and facilities, OSHA has identified (in Sec. 1910.302(b)(4))
the substantive new provisions in the final rule, and then excluded
(grandfathered) all existing electrical systems and equipment
installations from having to comply with these new requirements. These
provisions will only apply to new installations (that is, electrical
systems and equipment installed for the first time, as well as
installations that represent a major replacement, modification, repair,
or rehabilitation of an existing electrical system) made after the
effective date of the standard. Of the new provisions identified in
Sec. 1910.302(b)(4), there are 14 provisions (or sets of related
provisions) in Category 4 that were added or last revised in the 1999
NEC. A number of these provisions represent changes in design and/or
operating practices. OSHA believes that with the appropriate lead time
(that is, sufficient delay in the effective date of the final rule),
these provisions should not result in any incremental costs because
these requirements can be reviewed and considered, and the electrical
installation practices altered as necessary, prior to any work being
performed. For instance, the requirement in Sec. 1910.303(f)(4) for
disconnecting means to be capable of being locked in the open position
can be met through selecting appropriate equipment in the installation
design phase of a project. The feature required by this provision is
already available in new equipment. OSHA sees no appreciable difference
in cost between a disconnecting means that is capable of being locked
in the open position and one that is not. Other provisions, such as
Sec. 1910.303(g)(1)(vii), which requires certain electric equipment to
be installed in dedicated space, involve facility layout that can be
met with no appreciable cost impact as long as the requirement is taken
into consideration during the installation design phase of a
project.\54\ The final rule provides employers with a 6-month delay in
effective date, in part, so that they can incorporate such
considerations during the design of new electrical installations. (See
section XII, Effective Date and Date of Application, later in this
preamble.)
---------------------------------------------------------------------------
\54\ For example, a lighting fixture installed over a panelboard
must be more than 1.83 m above the floor. It should not cost
significantly more to install the fixture at such a height than it
would to install it at a lower one.
---------------------------------------------------------------------------
In addition to the provisions identified in Sec. 1910.302(b)(4),
there are also new provisions identified in Sec. 1910.302(b)(2) and
(b)(3) of the final rule that apply to: (1) Electrical system and
equipment installations (either first time or major replacement,
modification, repair, or rehabilitation) made after March 15, 1972; and
(2) electrical system and equipment installations (either first time or
major replacement, modification, repair, or rehabilitation) made after
April 16, 1981, respectively. Reviewing the provisions identified in
Sec. 1910.302(b)(2) and (b)(3) of the final rule, there are 13 new
provisions (or sets of related provisions) in Category 4 that were
added or last revised in the 1999 NEC. Table 7 also lists those
provisions with cost implications. Again, a number of these 13 new
provisions represent changes in design or operating practice rather
than new equipment requirements, and as discussed earlier, are not
expected to result in any incremental costs as long as there is
sufficient delay in the effective date of the final rule.
OSHA has examined other new provisions for possible cost impacts.
First, Sec. 1910.302(b)(1) of the existing and final rule identifies
those provisions (that is, specific sections in the standards) that all
new and existing electrical system and equipment installations must
meet regardless of the installation date. For these provisions in the
existing and final rule, there is no grandfathering of older, existing
electrical system and equipment installations. However, OSHA has
concluded that Sec. 1910.302(b)(1) imposes no new, substantive
Category 4 requirements for existing electrical systems and equipment
installations. Further, while Sec. 1910.302(b)(1) does add new
coverage from Sec. 1910.307, only documentation of hazardous locations
is a totally new requirement, and the documentation for the division
system only applies to installations made or overhauled after the
effective date. The rest of the new provisions in Sec. 1910.307 allow
employers to continue using the division system or to implement an
alternative zone system for classifying hazardous locations containing
flammable gases or vapors. They should not result in any additional
costs unless employers voluntarily choose to abandon their present
division system in favor of the alternative zone system. Finally, there
are new provisions not contained in the existing OSHA electrical
installation standard that were originally in the 1971 NEC and were
enforced by OSHA between March 15, 1972, and April 16, 1981. The latest
version of NFPA 70E reincorporated these provisions. (For a full
explanation, see the discussion of final Sec. 1910.302(b)(2), in
section V, Summary and Explanation of the Final Standard, earlier in
the preamble.) OSHA believes that these provisions represent widespread
current industry practices, because they have been part of every
version of the NEC since 1971, including the 1999 and 2002 editions,
and will not impose any additional cost.
B. Potentially Affected Establishments
The electrical safety standard is based primarily upon the 2000
NFPA 70E recommendations, which, in turn, are based on the 1999 NEC.
Consequently, companies that are installing electrical systems and
equipment in their facilities in locations where the 1999 (or 2002) NEC
is currently being followed will not be further impacted by OSHA's
rulemaking with respect to new installations. Further, given that there
are no new, substantive Category 4 provisions in the rule that are
mandatory for all existing electrical system and equipment installations
(see above discussion), these provisions will not result in any economic
impact for existing installations, until they are replaced, repaired,
and/or renovated.
In order to estimate the number of employers potentially impacted
by the rulemaking, OSHA has identified the States and municipalities
that currently mandate the 1999 (or 2002) National Electrical Code
(NEC), that currently mandate using an earlier NEC, or that have no
mandated statewide electrical code pertaining to new installations.\55\
These states were identified using information contained in the
Directory of Building Codes and Regulations, by City and State
(National Conference of States on Building Codes and Standards, NCSBCS,
2002). In sum, 38 of the 50 States have already passed mandatory
minimum building or fire codes specifying that new construction
(including new electrical installations) must meet or exceed the
requirements of the 1999 (or 2002) National Electrical Code (NEC).\56\
Thus, OSHA assumes that employers in the covered industries in all
locations in these 38 States (except for Baltimore, MD) will be
unaffected by OSHA's rulemaking with respect to new installations.
These States (with the particular NEC indicated) are listed in Table 5:
---------------------------------------------------------------------------
\55\ In States with no mandated electrical code pertaining to
new installations, OSHA's existing standards, which are primarily
based on the 1971 and 1978 NECs, are the governing rules. (In State
Plan States, each State has adopted a standard that Federal OSHA has
found to be at least as effective as the Federal standard. For all
practical purposes, this means that OSHA's existing standard is the
governing standard unless the State has adopted a more stringent
standard.)
\56\ Maryland has adopted the 1999 NEC as a Mandatory Minimum
Code, exempting Baltimore from compliance. Generally when a state
updates these mandatory minimum requirements, the new requirements
apply only to new facilities or installations.
Table 5.--States With Building or Fire Codes That Meet or Exceed the
1999 National Electrical Code
------------------------------------------------------------------------
-----------------------------------------------------------------------------
Alaska
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Idaho
Indiana
Kentucky
Maine
Maryland
Massachusetts
Michigan
Minnesota
Montana
Nebraska
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Utah
Vermont
Washington
West Virginia
Wisconsin
Wyoming
------------------------------------------------------------------------
Moreover, 16 large cities in other States have also adopted the
1999 NEC. Therefore, employers in the covered industries in these
municipalities are also expected to be unaffected by OSHA's rulemaking
with respect to new installations. These cities are listed in Table 6:
Table 6.--Cities That Have Adopted the 1999 National Electrical Code
------------------------------------------------------------------------
---------------------------------------------------------------------------
Austin, Texas
Chicago, Illinois
Dallas, Texas
Des Moines, Iowa
El Paso, Texas
Forth Worth, Texas
Honolulu, Hawaii
Houston, Texas
Jackson, Mississippi
Kansas City, Missouri
Las Vegas, Nevada
Phoenix, Arizona
San Antonio, Texas
St. Louis, Missouri
Tucson, Arizona
Wichita, Kansas
------------------------------------------------------------------------
Further, the State of Alabama has adopted a limited mandatory
minimum code, which, in effect, requires that hotels, schools, and
movie theaters follow the 2002 NEC. Therefore, in this analysis,
hotels, schools, and movie theaters in Alabama have been included with
the group of 38 States and 16 large cities (described above) that
currently follow the 1999 (or 2002) NEC.
The remaining 12 States (or portions of these States) that would
likely be affected by OSHA's rulemaking can be separated into two
subgroups: (1) States or municipal jurisdictions that have adopted the
1996 version of the NEC; and (2) States that have not adopted any
statewide electrical code covering all non-government-owned buildings
or facilities (that is, private sector installations). For group 1, to
the extent that any of these jurisdictions adopt a later version of the
NEC before this final rule goes into effect, annual compliance costs
will likely be lower than estimated below.
Five States and three cities fall into the first of the two
subgroups described above. These include all locations in Louisiana and
Virginia, as well as portions of Arizona, Iowa, and Nevada (that is,
all locations in these three States excluding the four large cities in
these States that have adopted the 1999 NEC, as indicated in the list
above). The three large cities in the first subgroup include Baltimore,
MD, Birmingham, AL (excluding hotels, schools, and movie theaters), and
Washington, DC. Employers in these locations may be affected to the
extent that the 1999 NEC, which is the basis for the rulemaking,
differs from the 1996 NEC.
Many of the new provisions in the final rule, including those in
Category 4 that have potential cost implications for new electrical
systems and equipment installations, date back to the 1996 NEC or to an
NEC prior to 1996. Thus, for these provisions, employers in locations
now requiring that the 1996 NEC be followed will not be affected by
OSHA's rulemaking with respect to new installations.
Seven States have not yet adopted any statewide electrical code
that applies to all private sector employers. These States include:
Alabama (excluding hotels, schools, and movie theaters), Hawaii,
Illinois, Kansas, Mississippi, Missouri, and Texas. Employers in these
States are expected to be the most affected (of the three subgroups) by
OSHA's rulemaking, since no Statewide electrical code is currently
required. For these seven States, OSHA's existing electrical
installation standard, which is primarily based on the 1971 and 1978
NECs, governs.\57\ Below the Statewide level, it is not clear to what
extent local jurisdictions have passed local electrical ordinances that
exceed the 1971 and 1978 NECs and are consistent with the 1999 NEC.
While it is likely that some local jurisdictions within these
states enforce the 1999 (or 2002) NEC, OSHA's analysis treats these
States as though they are not in compliance with either the 1999 or
2002 NEC for purposes of analysis. As a consequence, the estimated
compliance costs are likely to be overstated.
---------------------------------------------------------------------------
\57\ Note that of these seven States, Hawaii is the only State
Plan State. Hawaii has adopted the Federal standard.
---------------------------------------------------------------------------
Using data from the U.S. Department of Commerce's 1997 County
Business Patterns database, OSHA has estimated the total number of
affected establishments and employment in those establishments for the
58 two-digit SICs covered by the general industry electrical safety
installation standard.\58\ In addition, the number of establishments
and employment that are already subject to the 1999 NEC, the 1996 NEC,
the 1990 NEC, and no statewide electrical code, are also estimated. For
those cities (identified above) that are currently following a
particular electrical code, OSHA has estimated the number of
establishments and employment in these cities using, as a surrogate,
the data for the county in which the cities are located.
---------------------------------------------------------------------------
\58\ These 58 SICs include employers in shipyard employment,
longshoring, and marine terminals. Consistent with the preliminary
analysis, OSHA in this final analysis has grouped affected
industries according to the 1987 Standard Industrial Classification
System. For industry coding under the North American Industry
Classification System (NAICS), see NAICS, Executive Office of the
President, Office of Management and Budget, 1997 and 2002, or http://www.census.gov/epcd/www/naics.html.
---------------------------------------------------------------------------
The data indicate that there are an estimated 5.6 million
establishments with 89.8 million employees in the industries covered by
the general industry electrical safety installation standard. About
84.7 percent of the establishments, employing about 85.3 percent of the
employees, are in States or cities that have adopted the 1999 (or 2002)
NEC. Approximately 6.3 percent of both the establishments and employees
are in States or cities that have adopted the 1996 NEC. The remaining
approximately 9.0 percent of the establishments, employing about 8.4
percent of the employees, are in States (excluding certain cities in
these States) that have not adopted a statewide electrical code
applicable to private sector employers. Table 8 summarizes these
findings.
C. Benefits
Occupational fatalities associated with electrical accidents remain
a significant and ongoing problem. The final rule would benefit
employees by reducing their exposure to electrical hazards thereby
reducing both fatal and nonfatal injuries.
Table 9 presents data from the Survey of Occupational Injuries and
Illnesses and the Census of Fatal Occupational Injuries on the number
of work-related injuries and deaths in private industry attributed to
contact with electrical current for 1992-2004. While the numbers of
injuries and deaths appear to have declined, this decline has not been
consistent throughout the time for which data are available.
Electrical-related injuries increased between 1992 and 1994, then
declined for 1995 to 1997. For 1998 and 1999, injuries again increased.
Note that the percentage of occupational injuries associated with
electrical hazards has remained essentially constant throughout 1992 to
2004. The number of deaths associated with contact with electrical
current declined in 1993, but rose during 1994 and 1995. Deaths dropped
in 1996, but rose again in 1997 and 1998. As a percentage of total
occupational fatalities, death due to electrocution appears to have
remained constant or declined slightly. However, contact with
electrical current remains a significant source of occupational
fatality, accounting for 4.4 percent of total occupational fatalities
in 2004.
For more than 30 years, electrical hazards have been a target of
OSHA rules. This rule will help to further reduce the number of deaths
and injuries associated with electrical accidents, and ensure that a
downward trend in these incidents is sustained.
To determine the extent to which the standard may reduce the number
of deaths attributable to electrical accidents, OSHA examined its
accident investigation reports for the States without any statewide
electrical code.\59\ The most recent and complete reports cover 1990-
1996, and provide detailed information on the cause of fatal electrical
accidents. The accident cause can be used to ascertain whether the
death would have been prevented by compliance with the final rule. As
an initial screen, OSHA reviewed the reports for accidents that could
have been prevented through the use of a GFCI. While OSHA expects that
other provisions of the revised standard potentially will reduce deaths
due to electrical accidents, this initial screen focused on GFCI-
related accidents since they are relatively easy to isolate using a key
word search through all reports. Thus, the accident report analysis is
conservative in the sense that it likely understates the number of
deaths preventable under the revision to Subpart S.
---------------------------------------------------------------------------
\59\ Some cities within these States have adopted the 1999 (or
later) NEC, and these cities were excluded when examining the
accident report data.
---------------------------------------------------------------------------
OSHA found that there were at least nine deaths in the seven States
that lacked a statewide electrical code during 1990-1996, or an average
of 1.3 deaths per year that could have been prevented with the use of a
GFCI. Based on EPA's estimate of a value of $6.1 million for a
statistical life, the estimated 1.3 lives saved per year (that is,
between 1 and 2 lives saved per year) under the final rule would
translate to an annual benefit of $7.9 million (ranging from $6.1
million to $12.2 million).\60\ As noted above, the monetized benefits
understate total benefits since they do not cover all potentially
preventable deaths. Moreover, they do not account for any preventable
nonfatal injuries.
---------------------------------------------------------------------------
\60\ See EPA's Guidelines for Preparing Economic Analyses, EPA
240-R-00-003, September 2000. Note that the $6.1 million is in 1999
dollars. If this figure is updated for inflation using the CPI as
EPA indicates is appropriate, the estimated 1.3 lives saved per year
(between 1 and 2 lives saved per year) would translate to an annual
benefit of $9.4 million (between $7.2 million and $14.4 million) in
2005 dollars.
---------------------------------------------------------------------------
In addition to quantifiable potential benefits, this update to
OSHA's electrical standards yields important unquantified benefits. The
revised standard potentially reduces industry confusion and
inefficiency associated with the current standard, which is out of date
with today's technology. While OSHA has a long-standing policy of
permitting employers to comply with more current versions of national
consensus standards to the extent the more current version is as
protective as the older version, this does not address all the concerns
with the outdated standard. The older electrical standards may not
address the hazards associated with newer equipment and machinery,
leaving employers unsure which requirements presently apply. For
example, the final standard contains requirements for electric
equipment installed in hazardous locations classified under the zone
classification system, which is not addressed in the existing standard.
(See the summary and explanation of zone classification in section N.
earlier in the preamble.) The update to Subpart S will reduce or
eliminate these problems.
D. Estimation of Compliance Costs
OSHA adopted a conservative approach to estimating compliance
costs, and consequently, the estimates reported below are likely to
overstate actual compliance costs. In summary, OSHA did not estimate
any cost savings associated with the final rule, even though many new,
potentially less costly alternative compliance methods are incorporated
in the final rule. For example, as noted above, the rule will permit
electric equipment in Class I hazardous locations to be installed under
the zone classification system, which is not addressed in the existing
standard. Because the hazardous locations provision potentially reduces
industry confusion and inefficiency associated with the current standard,
costs savings are likely.
For all provisions with the exception of Sec. 1910.304(b)(3)(ii)
(GFCI protection for temporary wiring installations), cost estimates
were developed on a project-level basis. This involved obtaining data
on the number of construction and other major renovation, addition, and
alteration projects performed annually in States and local
jurisdictions that do not now mandate the 1999 NEC (or equivalent).\61\
Table 10 summarizes the data on the number of projects potentially
impacted by the final rule. In States and local jurisdictions that do
not now mandate the 1999 NEC (or equivalent), the data indicate that
there were a total of 29,306 project starts in 2001, consisting
primarily (91 percent) of small projects under $3 million. Less than
0.5 percent of the projects were large projects over $25 million.
---------------------------------------------------------------------------
\61\ Data on new and other (major renovation, addition, and
alteration) construction projects started annually between 1998 and
2001 are compiled by F.W. Dodge (Schriver, 2002). While construction
projects serve as the basis for estimating costs, construction is
not covered by the final standard. Rather, it is the particular
product or output of the construction project that is covered.
---------------------------------------------------------------------------
For Sec. 1910.304(b)(3)(ii), compliance costs were estimated on an
establishment-level rather than project-level basis. OSHA estimates
that approximately 861,400 establishments are in locations that either
are currently following the 1996 NEC or have not adopted a statewide
electrical code applicable to private sector employers. These employers
potentially are impacted by the final rule. Costs per provision were
computed according to establishment size: establishments with fewer
than 100 employees, establishments with 100-499 employees, and
establishments with 500 or more employees.
All potentially impacted projects/establishments would not
necessarily be affected by each and every provision, and some would not
be affected at all in any given year. Thus, it was necessary to
estimate the percentage of projects/establishments affected by each
provision annually. This percentage, when multiplied by the number of
potentially impacted projects/establishments yields the number of
projects/establishments subject to each provision annually without
considering baseline levels of compliance. Table 11 presents the
estimated percentage of projects/establishments that actually would be
affected by each provision annually. These estimates were based on
experience and technical knowledge of electrical practices.
Baseline levels of compliance associated with each of the new
provisions also were considered. Baseline levels of compliance were
estimated for each provision by considering construction requirements
imposed by mortgage lenders and insurance carriers and installation
practices routinely followed by licensed electricians (given their
formal training). (See the earlier discussion of categories of changes
in the final rule.) These requirements and installation practices are
generally consistent with the current NEC requirements. Moreover, it is
expected that these requirements and practices generally become more
prevalent as the size of the establishment or project increases. Table
12 presents the estimated percentages for baseline compliance rates.
These estimates were based on experience and technical knowledge of
electrical practices.
For each provision, estimates of labor and material costs were
developed on a project level basis. Labor costs are based on an hourly
wage rate of $20.44 for an electrician in the construction sector (SICs
15-17 (NAICS 236-238)) to perform the work (plus fringe benefits at 37
percent).\62\ Costs for materials, which consist of labels, GFCIs,
conduits, connectors, and outlets, are based on data in the Maintenance
Direct Catalog of Lab Supply, Inc. (2001). Equipment costs were
annualized assuming the useful life of the equipment is two years and
an interest rate of 7 percent. Table 13 summarizes the key data and
bases for the cost estimates.
---------------------------------------------------------------------------
\62\ The wage rate data are for 2000, taken from the BLS (2001)
2000 National Occupational Employment Statistics (OES) Survey.
Fringe benefit rate data are from BLS (2000) Employer Costs for
Employee Compensation, March. USDL: 00-186.
---------------------------------------------------------------------------
OSHA received very few comments on the preliminary economic and
regulatory flexibility screening analysis.
The National Petrochemical and Refiners Association (NPRA) stated
in Ex. 3-2 that "the cost merely to read and comprehend the ruling,
and to train personnel, will be at least in the tens of thousands of
dollars per facility." However, NPRA provided no material to
substantiate this claim. OSHA believes that the final rule imposes no
cost to comprehend or to train personnel, particularly given the
widespread use of the 1999 and 2000 NEC.
CHS, Inc. stated, "the proposed rule could result in several unit
start-ups/shutdowns at farmer-owned petroleum refineries" (Ex. 4-25).
However, CHS did not explain how the new provisions in this standard
would require additional outages to deenergize beyond those which could
develop from compliance with the existing standard.
Although OSHA received no new data in response to the preliminary
analysis, OSHA has slightly revised its economic model in order to make
it more realistic and to reflect changes between the proposed and final
regulatory text. For example, in assigning compliance costs to Sec.
1910.304(b)(3), Ground-fault circuit interrupter protection for
personnel, OSHA's final model predicts that a small percentage of
projects will establish and implement an assured grounding conductor
program where ground-fault circuit interrupter protection is not
available. An example of a revision to the preliminary analysis that
reflects real-world considerations is the addition in the final
analysis of an explicit cost for legible marking of equipment to
indicate that the equipment has been applied with a series combination
rating, as required by Sec. 1910.303(f)(5), Marking for series
combination ratings.
In addition, the final rule contains some new provisions that were
not in the proposed rule or that were revised from what was in the
proposal. Three of those provisions potentially require modification of
existing installations: (1) Final Sec. 1910.304(a)(3), which prohibits
a grounding terminal or grounding-type device on a receptacle, cord
connector, or attachment plug from being used for purposes other than
grounding, (2) final Sec. 1910.304(g)(4)(iii), which no longer permits
extensions of branch circuits to be grounded by connection to a
grounded cold water pipe, and (3) final Sec. 1910.304(g)(8)(iii),
which no longer permits electric equipment to be grounded only by
connection to the grounded structural metal frame of a building when
any element of the equipment's branch circuit is replaced.
A prohibition against using grounding terminals and grounding-type
devices for purposes other than grounding is already contained in
existing Sec. 1910.304(a)(3). Under the current standard, this
provision applies to all electrical installations including major
replacements, modifications, repairs, or rehabilitations made after
March 15, 1972. In the final rule, OSHA is extending the application of
this prohibition to installations made before that date. Wiring a
receptacle, cord connector, or attachment plug so that the grounding
terminal or other grounding-type device is used for purposes other than
grounding (for example, by connecting a circuit conductor to the grounding
terminal) makes the electric equipment extremely unsafe, posing an immediate
threat of electrocution. In addition, such an incorrect wiring
connection renders the equipment unusable, and it would likely have
already been changed. Consequently, it is extremely unlikely that
violations of this rule exist in significant numbers, and OSHA has
concluded that applying this provision to all existing installations
will have little if any economic impact.
Existing Sec. 1910.304(f)(3)(iii) permits connecting the equipment
grounding terminal of grounding-type receptacles to a nearby grounded
cold water pipe for extensions of existing branch circuits that do not
have an equipment grounding conductor. In the final rule, OSHA is
requiring that, when any element of this branch circuit is replaced,
the entire circuit include an equipment grounding conductor that
complies with all other provisions of paragraph (g) of Sec.
1910.304.\63\ This change only affects a small percentage of branch
circuits extended after March 15, 1972, the date the provision went
into effect. The existing requirement makes the equipment grounding
path dependent upon the metallic continuity of the cold water piping
and upon the earth for the electric current's return path back to the
electric source. If a ground fault occurs at electric utilization
equipment (for example, a portable cord-connected electric drill with a
grounding-type attachment plug) plugged into a grounding-type
receptacle and if the continuity of the water pipe is interrupted by a
section plastic pipe or by another means, the electric equipment
becomes extremely lethal, posing an immediate threat of electrocution.
Additionally, the practice of using metallic water pipes as an
equipment grounding conductor poses an electrocution hazard to
plumbers, pipe fitters, and other employees working on the system who
might unknowingly interrupt a path of fault current flowing through the
piping. The return current path in both instances is through the
employee instead of through a reliable equipment grounding conductor.
Employers have become aware that using cold water plumbing for
grounding is a poor practice and most have already corrected this
condition, which is a violation of recent editions of the NEC \64\.
According to Karl M. Cunningham of Alcoa (Ex. 4-4), the permission to
use a cold water pipe near the equipment was clearly removed from the
NEC for many Code cycles, including the 2002, 1999, 1996, and 1993
editions.
---------------------------------------------------------------------------
\63\ For example, 1910.304(g)(4)(iii) requires that when any
element of a branch circuit extension is replaced, the entire branch
circuit shall include an equipment grounding conductor.
\64\ For example, a metallic cold water pipe is not listed in
Section 250.118 of the 2002 NEC as a type of equipment grounding
conductor.
---------------------------------------------------------------------------
Because the NEC has not allowed this practice for over 10 years,
few employers use this provision in the existing rule due to the known
hazards. Therefore, it is unlikely that violations of this rule exist
in significant numbers. Even then, employers who are still using cold
water piping to ground branch-circuit extensions are only required to
upgrade them when they are replacing one of the branch circuit
extension's elements. The installation of the equipment grounding
conductors would be coincidental with the modification work; and, thus
the cost of compliance would be incidental. Hence, OSHA has concluded
that requiring this provision for all modifications made to existing
installations will impose no appreciable costs on employers.
A prohibition against maintaining the grounded structural metal
framing of a building for purposes of grounding electric equipment is
contained in existing Sec. 1910.304(f)(6)(ii). This provision
currently applies only to installations made after April 16, 1981. In
the final rule, Sec. 1910.304(g)(8)(iii), OSHA is also applying this
prohibition to installations made or designed before April 16, 1981,
when any element of the equipment's branch circuit is replaced.
Metal frames of buildings provide a poor substitute for an
equipment grounding conductor. Installations that might have initially
provided a permanent, continuous, and effective equipment grounding
path fail to function adequately as time passes. If a fault occurs in
the electric equipment an extremely lethal condition exists, posing an
immediate threat of electrocution, since the return current path is
through the employee instead of the intended equipment grounding path.
As brought forth by one commenter (Ex. 4-18) and stated in the preamble
discussion for proposed Sec. 1910.304(g)(7)(ii) (final Sec.
1910.304(g)(8)(ii) and (g)(8)(iii)), this practice has been prohibited
for ac circuits since the 1978 edition of the NEC. Thus, this change
only affects a small percentage of branch circuits extended after March
15, 1972, the date the provision went into effect and until 1979 when
the NEC prohibition applied.
Many employers recognized the safety hazards and the operating
anomalies of grounding utilization equipment to the structural metal
framing of buildings. Consequently, they have already abandoned the
practice. Therefore, it is extremely unlikely that violations of this
rule exist in significant numbers. After all, this practice has been
banned for over a quarter of a century by the NEC. OSHA has concluded
that requiring the installation of an equipment grounding conductor
instead of allowing the structural metal frame of a building to serve
as the equipment grounding conductor for all modifications to existing
installations will have no appreciable cost impacts.
The final rule also includes a new provision, final Sec.
1910.304(b)(3)(ii)(C), that allows implementation of an assured
equipment grounding conductor program during maintenance, remodeling,
or repair of buildings, structures, or equipment or during similar
construction-like activities when GFCIs are not available. OSHA has
added costs for this provision in the analysis, as explained below.
Final Sec. 1910.304(b)(3)(ii)(B) requires receptacles other than
125-volt, single-phase, 15-, 20-, and 30-ampere receptacles that are
not part of the permanent wiring of the building or structure and that
are in use by personnel to have ground-fault circuit-interrupter
protection for personnel. OSHA recognizes that it may be impossible for
employers to comply with this requirement for GFCI protection for
circuits operating at voltages above 125 volts to ground. For instance,
portable electric welding units for the repair of major pieces of
equipment such as industrial boilers and other massive units of
industrial equipment generally require a 480-volt power connection
rated 30 amperes or more. At these ratings, GFCI protection for
personnel may not be feasible since it is not presently available for
all branch-circuit voltage and current ratings. Therefore, the final
rule permits an assured equipment grounding conductor (AEGC) program as
an alternative.\65\
---------------------------------------------------------------------------
\65\ Final Sec. 1910.304(b)(3)(ii)(C) requires the employer to
establish and implement an assured equipment grounding conductor
program covering cord sets, receptacles that are not a part of the
building or structure, and equipment connected by cord and plug that
are available for use or used by employees on those receptacles.
---------------------------------------------------------------------------
Although OSHA believes that the AEGC program costs more to
implement than GFCI protection for personnel (equivalent to a unit cost
of $110 instead of $55) it could reduce compliance costs for employers
when compared to hard-wired methods.\66\ OSHA believes that about five percent
(one in twenty) of all temporary electric circuits may not be serviceable with
GFCI protection for personnel at the higher current and voltage ratings
and would require the AEGC program. The need to connect electric
equipment with ratings other than 125 volts, single phase, 15, 20, and
30 amperes, or 250 volts, single phase, 15 and 20 amperes \67\
increases as the size of the project increases. Nearly all temporary
power requirements for smaller-sized projects, those with contract
values under $3 million, would be serviceable with GFCI-protected
receptacles or from nearby receptacles that are a part of the existing
building structure. Smaller projects tend to take up minimal plant real
estate. The work area is sandwiched among other facility equipment and
is contained within the confines of the existing plant. Few, if any, of
these projects would have need for the higher-power or higher-voltage
equipment. Even if a project does need such equipment, these facilities
typically have existing, permanently wired electric power receptacles
that are capable of supporting loads at higher voltage and current
ratings. Such receptacles are typically located throughout the plant on
30-meter, maximum, intervals allowing for easy connection of portable
electric equipment with 15-meter flexible cords. Consequently, OSHA
estimates that the number of smaller-sized projects that require the
AEGC program is negligible.
---------------------------------------------------------------------------
\66\ Employers have two alternatives when GFCI protection for
personnel is required for receptacles that are not part of the
permanent wiring of a building or structure: (1) Implement an
assured equipment grounding conductor program or (2) provide a hard-
wired installation, in which the equipment is wired directly to the
circuit conductors, obviating the need for a receptacle outlet.
\67\ GFCI protective devices for personnel protection may not
readily available above 30 amperes at 125 volts, above 20 amperes at
250 volts, or at higher voltages.
---------------------------------------------------------------------------
As many as half of all medium-sized projects, those ranging from $3
million to $25 million, would potentially require the AEGC program.
These projects can include a sizable block of real estate such that the
cords on portable equipment will not reach existing, permanently wired
receptacles.
Nearly all major projects, those larger than $25 million and
encompassing significant plant real estate, are likely to use an AEGC
program to comply with the standard.
OSHA estimates that, at projects that would be required to use the
AEGC program, they would be needed for only about five percent of
temporary electric circuits. The remaining 95 percent of all temporary
electric circuits can be protected by GFCIs. Over the entire universe
of employers affected by the final rule, the estimated total cost of
using an AEGC program instead of GFCIs is approximately $5,300.
Table 14 presents the cost estimates for the final rule. The total
annual incremental compliance costs associated with the new provisions
in the final rule, for new electrical system and equipment
installations, are estimated to be $9.6 million. The overwhelming
majority of costs, 84.4 percent, are associated with Sec.
1910.304(b)(3)(ii), Ground-fault circuit interrupter protection for
personnel during temporary wiring installations. The total cost for
this requirement is based upon the following unit estimates and
assumptions:
(1) GFCI power station or cord, initial cost = $55 (annualized cost
= $30.42);
(2) the number of required units ranges from two for establishments
with less than 100 employees, to 10 for establishments with 100 to 499
employees, to 50 for establishments with more than 500 employees;
(3) the percentage of affected establishments ranges from 30
percent for the smallest establishments to 100 percent for the largest
establishments (Table 11); and
(4) baseline industry compliance of 50 percent for the smallest
establishments to 95 percent for the largest establishments (Table 12).
Some of the costs and exposures to temporary wiring could
potentially be incurred by employers performing construction work
rather than general industry work. Temporary wiring for construction
work is already covered under Subpart K of Part 1926; and,
consequently, this analysis likely overestimates the incremental costs
associated with the revisions to Subpart S.
E. Technological and Economic Feasibility
As noted previously, the final rule incorporates the NFPA 70E
recommendations developed in 2000, which are based on the 1999 NEC. The
NFPA 70E Committee has updated the document in accordance with
revisions to the NEC, which periodically recodifies acceptable
electrical practices as a national consensus standard. More than 80
percent of establishments covered by the final rule are located in
areas that currently mandate adherence to these recommendations or the
1999 or more stringent version of the NEC. Moreover, the vast majority
of employers comply with the NEC in the absence of any legal
obligation.\68\ Thus, most potentially affected parties already are in
compliance with the final rule, which clearly demonstrates that it is
technologically feasible. The costs of the rule are also extremely low,
as discussed earlier in this section of the preamble. These costs do
not threaten the long-term profitability or competitive structure of
affected industries. Therefore, the final rule is also economically
feasible.
---------------------------------------------------------------------------
\68\ As noted previously, construction requirements imposed by
mortgage lenders and insurance carriers and installation practices
followed by licensed electricians (given their formal training) are
reasons to expect that some employers comply with the NEC in the
absence of any legal obligation.
---------------------------------------------------------------------------
F. Regulatory Flexibility Screening Analysis and Regulatory
Flexibility Certification
In order to determine whether a regulatory flexibility analysis is
required under the Regulatory Flexibility Act, OSHA has evaluated the
potential economic impacts of this action on small entities. Table 15
presents the data used in this analysis to determine whether this rule
would have a significant impact on a substantial number of small
entities.
First, compliance costs were computed on a per establishment basis,
which required consideration of the number of establishments
potentially impacted. The analysis of County Business Patterns data
discussed above indicated that approximately 861,400 establishments are
in local jurisdictions in the 12 States that are either currently
requiring compliance with the 1996 NEC or have not adopted a statewide
electrical code applicable to private sector employers. Regarding the
documentation provisions for new installations in hazardous locations
(Sec. 1910.307(b) in Table 14), only industries that handle flammable
and/or combustible liquids, vapors, gases, dusts, and/or fibers will be
impacted. OSHA identified these industries by reviewing data on Sec.
1910.307 citations issued between October 2000 and September 2001
(available on the OSHA website at http://www.osha.gov/oshstats/) and
IMIS accident data from 1994 to 2001 indicating Sec. 1910.307
citations (OSHA, 2001). OSHA estimated that approximately 441,400
establishments with hazardous locations are in local jurisdictions in
the 12 States that either are currently following the 1996 NEC or have
not adopted a statewide electrical code applicable to private sector
employers. These are the establishments potentially impacted by the
hazardous locations provision. The remaining provisions potentially
affect all 861,400 establishments in the 12 States as noted above.\69\
---------------------------------------------------------------------------
\69\ For Sec. 1910.307(b), OSHA's calculation of per-
establishment costs and impacts is based on an estimated 441,400
affected establishments. For all other provisions of the final
standard, OSHA's calculation of per-establishment costs and impacts
is based on an estimated 861,400 affected establishments.
---------------------------------------------------------------------------
OSHA assumed for purposes of conducting the regulatory flexibility
screening analysis, that small firms, on average, will conduct the same
type and size of projects as larger establishments. This is a
conservative assumption, since it is more likely that smaller
establishments will tend to perform small sized, less costly projects.
Consequently, OSHA applied an average cost per establishment in
analyzing the effect on small entities. The average cost per
establishment was computed by dividing the total costs reported in
Table 14 by the number of affected establishments reported in Table 8.
For Provisions 1 to 5 and 7, the cost per establishment is $10.10 and
for Provision 6, the cost per establishment is $1.92. Thus, for
industries that handle flammable and/or combustible liquids, vapors,
gases, dusts, and/or fibers, the total cost per establishment is
estimated to be $12.02.
OSHA guidelines for determining the need for regulatory flexibility
analysis require determining the regulatory costs as a percentage of
the revenues and profits of small entities. OSHA derived estimates of
the profits and revenues using data from U.S. Census and Dun and
Bradstreet. In defining a small business, OSHA followed Small Business
Administration (SBA) criteria for each sector. For many of the affected
industries, the SBA small business criteria are determined directly by
the number of employees. But for those industries where the SBA small
business criteria are not determined by the number of employees (but
rather by annual sales), the sales-based criteria were converted to
employment-based criteria. Specifically, an employment-based firm size
standard was determined by first calculating an employment level, based
on the industry average annual receipts per employee, which would be
sufficient to produce a total sales amount per firm consistent with the
SBA sales-based firm size standard.
As shown in Table 15, at worst, compliance costs represent 0.005
percent of the revenues (for SIC 72, Personal Services) and 0.15
percent of profits (for SIC 56, Apparel and Accessory Stores). On
average (computed by weighting by number of establishments), compliance
costs constitute 0.002 percent of revenues and 0.048 percent of
profits. Based on this evaluation, OSHA certifies that this rule will
not have a significant economic impact on a substantial number of small
entities.\70\
---------------------------------------------------------------------------
\70\ OSHA also examined the situation where all compliance costs
accrue to the construction sector (in SIC 1731, Electrical
Services). In this case, costs constitute 0.04 percent of revenues
1.3 percent of profits. Thus, even if all costs are assigned to
construction, the proposed regulation will not have a significant
impact on small entities.
Table 7.--Changes to the Existing Standard With Cost Implications
--------------------------------------------------------------------------------------------------------------------------------------------------------
Provisions
Comments on cost Basis for estimating identified in the
Final rule \1\ impact Types of establishments/projects affected costs final rule Sec.
1910.302(b)(4) \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
1910.303(f)(5)...................... Requires the purchase All Establishments........................ Projects................ X
and installation of All Projects..............................
labels.
1910.303(h)(5)(iii)(B).............. Requires the purchase All Establishments........................ Projects................ .....................
and installation of All Projects..............................
signs.
1910.304(b)(1)...................... Requires the purchase All Establishments........................ Projects................ X
and installation of All Projects..............................
labels and
identification of
branch circuits.
1910.304(b)(3)(i)................... Requires the purchase All Establishments........................ Projects................ .....................
and installation of All Projects..............................
GFCI for bathrooms
and rooftops.
1910.304(b)(3)(ii)(A) and Requires that each All Establishments........................ Establishments.......... .....................
(b)(3)(ii)(B). affected facility All Projects..............................
purchase GFCI
equipment (power
stations or
extension.
1910.304(b)(3)(ii)(C)............... Requires that the All Establishments........................ Establishments.......... .....................
facility establish All Projects..............................
and implement an
assured equipment
grounding conductor
program.
1910.306(c)(6)...................... Requires the purchase All Establishments........................ Projects................ X
and installation of All Projects..............................
signs.
1910.306(j)(1)(iii)................. Change in design Real Estate Development and Dwelling Projects................ X
impacts construction Projects.
cost (near universal
compliance assumed).
1910.306(k)(4)(iv).................. Requires the purchase Carnivals, Circuses, Fairs, and Similar Projects................ X
and installation of Events.
labels.
1910.307(b)......................... Facility owner must Industrial Establishments................. Projects................ X
develop All Projects..............................
documentation.
1910.308(b)(3)...................... Requires the purchase All Establishments........................ Projects................ X
and installation of All Projects..............................
signs.
1910.308(e)(1)...................... Change in facility All Establishments........................ Projects................ .....................
design and Large Projects............................
additional materials
and installation
cost.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Note: In the proposal, Sec. Sec. 1910.303(e)(2)(ii) and 1910.308(a)(5)(vi)(B) and (d)(2)(ii) were mistakenly identified as paperwork requirements
imposing a cost burden on employers. The costs for the labeling required by these provisions is borne by the manufacturers as usual and customary. In
addition, proposed Sec. 1910.304(b)(3) has not been carried forward into the final rule. Consequently, this Final Economic Analysis does not include
costs for these four requirements. However, OSHA has determined that final Sec. Sec. 1910.303(f)(5), 1910.306(c)(6) and (k)(4)(iv), and
1910.308(b)(3) do impose paperwork-associated costs on employers, but they were not included in the Preliminary Economic Analysis. Therefore, this
Final Economic Analysis does include costs for these four provisions.
\2\ Note: Provisions listed in Sec. 1910.302(b)(4) only apply to new installations.
Table 8.--Establishments and Employment Affected by the Final Standard, by Version of NEC Adopted
----------------------------------------------------------------------------------------------------------------
Establishments Employment
-----------------------------------------------------
Applicable version of NEC Percent of Percent of
Number total Number total
----------------------------------------------------------------------------------------------------------------
1996...................................................... \1\ 0.4 6.3 \1\ 5.6 6.3
1999 or 2002.............................................. \1\ 4.8 84.7 \1\ 76.6 85.3
None...................................................... \1\ 0.5 9.0 \1\ 7.6 8.4
-----------------------------------------------------
Total................................................. \1\ 5.6 100 \1\ 89.8 100
----------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on 1997 County Business Patterns (U.S.
Census Bureau) database.
\1\ In millions.
Table 9.--Fatal and Nonfatal Occupational Injuries Attributable To Contact With Electric Current (Private
Industry)
----------------------------------------------------------------------------------------------------------------
Number of Percent of Percent of
injuries Total nonfatal Number of total fatal
Year involving days occupational deaths occupational
away from work injuries injuries
----------------------------------------------------------------------------------------------------------------
1992.................................... 4,806 0.2 317 5.8
1993.................................... 4,995 0.2 303 5.4
1994.................................... 6,018 0.3 332 5.6
1995.................................... 4,744 0.2 327 6.0
1996.................................... 4,126 0.2 268 4.8
1997.................................... 3,170 0.2 282 5.0
1998.................................... 3,910 0.2 324 5.9
1999.................................... 4,224 0.2 259 4.7
2000.................................... 3,704 0.2 256 4.8
2001.................................... 3,394 0.2 285 4.8
2002.................................... 2,967 0.2 289 5.2
2003.................................... 2,390 0.2 246 4.4
2004.................................... 2,650 0.2 254 4.4
----------------------------------------------------------------------------------------------------------------
Source: U.S. Bureau of Labor Statistics, Survey of Occupational Injuries and Illnesses and the Census of Fatal
Occupational Injuries (http://www.bls.gov/iif/home.htm).
Table 10.--Construction Project Starts in 2001 for States That Have Adopted the 1996 NEC or Do Not Have a
Statewide Electrical Code
----------------------------------------------------------------------------------------------------------------
Size of project (contract value)
---------------------------------------------------
Building type Less than $3 Total
million $3-25 million More than $25
(small) (medium) million (large)
----------------------------------------------------------------------------------------------------------------
Commercial and Public Buildings............. 15,219 1,490 45 16,754
Warehouses.................................. 1,659 204 8 1,871
Health Facilities and Laboratories.......... 1,691 245 33 1,969
Funeral and Interment Facilities............ 45 ............... ............... 45
Athletic and Entertainment Facilities....... 54 9 2 65
Auto, Bus, and Truck Service................ 797 47 ............... 844
Residential Housing......................... 1,491 169 6 1,666
Apartments, Hotels and Dormitories.......... 2,505 269 24 2,798
Tanks....................................... 309 8 ............... 317
Hydroelectric Power Plants.................. 3 ............... ............... 3
Natural Gas Plants.......................... 2 2 1 5
Gas, Water, and Sewer Lines................. 2,340 91 1 2,432
Manufacturing Facilities.................... 447 84 6 537
-------------------------------------------------------------------
Total................................... 26,562 2,618 126 29,306
----------------------------------------------------------------------------------------------------------------
Source: William R. Schriver (2002), The University of Tennessee, Knoxville, Construction Industry Research and
Policy Center, based on F.W. Dodge data on construction project starts for 2001.
Table 11.--Estimated Percentages of Projects/Establishments Affected by the Final Standard
[By provision and project/establishment size]
----------------------------------------------------------------------------------------------------------------
Project/establishment size
-----------------------------------
Provision No. Final rule Description of requirement Small Medium Large
(percent) (percent) (percent)
----------------------------------------------------------------------------------------------------------------
1.................... 1910.303(f)(5)......... Marking for series 50 50 50
combination ratings.
2.................... 1910.303(h)(5)(iii)(B). Working Space and Guarding-- 50 100 100
Posting of Warning Signs.
1a................... 1910.304(b)(1)......... Branch Circuits-- 50 50 50
Identification of Multiwire
Branch Circuits.
3.................... 1910.304(b)(3)(i)...... Ground-fault circuit 100 100 100
interrupter protection for
bathrooms and rooftops.
4.................... 1910.304(b)(3)(ii)(A) Ground-fault circuit 30 80 100
and (b)(3)(ii)(B). interrupter protection for
temporary wiring
installations.
4a................... 1910.304(b)(3)(ii)(C).. Assured equipment grounding 0 50 100
conductor program for
temporary wiring
installations.
1b................... 1910.306(c)(6)......... Identification and signs for 50 50 50
elevators, dumbwaiters,
escalators, moving walks,
wheelchair lifts, and
stairway chair lifts.
5.................... 1910.306(j)(1)(iii).... Swimming Pools, Fountains, 20 80 100
and Similar Installations--
Receptacles.
1c................... 1910.306(k)(4)(iv)..... Marking for single-pole 50 50 50
portable cable connectors
for parallel sets of
conductors used in
installations for
carnivals, circuses, fairs,
and similar events.
6.................... 1910.307(b)............ Hazardous (Classified) 60 80 100
Locations--Documentation.
1d................... 1910.308(b)(3)......... Signs for emergency power 50 50 50
systems.
7.................... 1910.308(e)(1)......... Communication Systems-- 5 60 100
Protective Devices.
----------------------------------------------------------------------------------------------------------------
Source: OSHA estimates, based on experience and knowledge of electrical practices.
Table 12.--Estimated Percentages for Baseline Compliance, by Provision and Project/Establishment Size
----------------------------------------------------------------------------------------------------------------
Project/establishment size
-----------------------------------
Provision No. Final rule Description of requirement Small Medium Large
(percent) (percent) (percent)
----------------------------------------------------------------------------------------------------------------
1.................... 1910.303(f)(5)......... Marking for series 25 25 50
combination ratings.
2.................... 1910.303(h)(5)(iii)(B). Working Space and Guarding-- 25 25 50
Posting of Warning Signs.
1a................... 1910.304(b)(1)......... Branch Circuits-- 25 25 50
Identification of Multiwire
Branch Circuits.
3.................... 1910.304(b)(3)(i)...... Ground-fault circuit 50 95 95
interrupter protection for
bathrooms and rooftops.
4.................... 1910.304(b)(3)(ii)(A) Ground-fault circuit 50 95 95
and (b)(3)(ii)(B). interrupter protection for
temporary wiring
installations.
4a................... 1910.304(b)(3)(ii)(C).. Assured equipment grounding 0 5 5
conductor program for
temporary wiring
installations.
1b................... 1910.306(c)(6)......... Identification and signs for 25 25 50
elevators, dumbwaiters,
escalators, moving walks,
wheelchair lifts, and
stairway chair lifts.
5.................... 1910.306(j)(1)(iii).... Swimming Pools, Fountains, 60 90 90
and Similar Installations--
Receptacles.
1c................... 1910.306(k)(4)(iv)..... Marking for single-pole 25 25 50
portable cable connectors
for parallel sets of
conductors used in
installations for
carnivals, circuses, fairs,
and similar events.
6.................... 1910.307(b)............ Hazardous (Classified) 50 80 80
Locations--Documentation.
1d................... 1910.308(b)(3)......... Signs for emergency power 25 25 50
systems.
7.................... 1910.308(e)(1)......... Communication Systems-- 10 30 40
Protective Devices.
----------------------------------------------------------------------------------------------------------------
Source: OSHA estimates, based on experience and knowledge of electrical practices.
Table 13.--Data and Bases for Unit Costs Applied in OSHA's Final Cost
Analysis
------------------------------------------------------------------------
Provision No. Final rule Labor costs \1\ Material costs
------------------------------------------------------------------------
1.............. 1910.303(f)(5), Average of 2 Average cost of
1910.304(b)(1), minutes of labor label or sign:
1910.306(c)(6), for each $2.
1910.306(k)(4)(i provision to
v) and install label at
1910.308(b)(3). $28/hour ($20.44
x 1.37).
2.............. 1910.303(h)(5)(ii 1 minute of labor Cost of label:
i)(B). to install label $1.
at $28/hour
($20.44 x 1.37).
3.............. 1910.304(b)(3)(i) None............. GFCI: $5.
4.............. 1910.304(b)(3)(ii None............. GFCI power
)(A) and station or cord:
(b)(3)(ii)(B). $55 each,
annualized over
2-year useful
life.
4a............. (b)(3)(ii)(C) \2\ None............. AEGC $110
(equivalent
cost).
5.............. 1910.306(j)(1)(ii 3 hours at $28/ Various conduit,
i). hour ($20.44 x connectors,
1.37). outlets: $75.
6.............. 1910.307(b)...... 4 hours at $28/ None.
hour ($20.44 x
1.37).
7.............. 1910.308(e)(1)... 1 minute of labor Cost of label:
to install label $1.
at $28/hour
($20.44 x 1.37).
------------------------------------------------------------------------
\1\ Note: The wage rate data are for 2000, taken from the BLS (2001)
2000 National Occupational Employment Statistics (OES) Survey. Fringe
benefit rate data are from BLS (2000) Employer Costs for Employee
Compensation, March. USDL: 00-186.
\2\ Note: See the discussion of the methodology for estimating costs
associated with the assured equipment grounding conductor program
earlier in this section of the preamble.
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, 2006.
Table 14.--Annual Incremental Compliance Costs for Changes to Subpart S Electrical Standard
----------------------------------------------------------------------------------------------------------------
Annual costs for projects/establishments \1\
Provision No. Final rule Description of -----------------------------------------------
requirement Total Small Medium Large
----------------------------------------------------------------------------------------------------------------
1................ 1910.303(f)(5)..... Marking for series $346,208 $221,365 $109,091 $15,751
combination ratings.
2................ 1910.303(h)(5)(ii)( Working Space and 66,839 49,141 16,145 1,554
B). Guarding--Posting of
Warning Signs.
-----------------------------------------------
1a............... 1910.304(b)(1)..... Branch Circuits-- Included in Provision 1.
Identification of
Multiwire Branch
Circuits.
-----------------------------------------------
3................ 1910.304(b)(3)(i).. Ground-fault circuit 141,336 132,810 6,872 1,654
interrupter protection
for bathrooms and
rooftops.
4................ 1910.304(b)(3)(ii)( Ground-fault circuit 8,057,529 7,686,276 206,832 164,420
A) and interrupter protection
(b)(3)(ii)(B). for temporary wiring
installations.
4a............... 1910.304(b)(3)(ii)( Assured equipment 5,332 0 3,600 1,733
C). grounding conductor
program for temporary
wiring installations.
-----------------------------------------------
1b............... 1910.306(c)(6)..... Identification and signs Included in Provision 1.
for elevators,
dumbwaiters,
escalators, moving
walks, wheelchair
lifts, and stairway
chair lifts.
-----------------------------------------------
5................ 1910.306(j)(1)(iii) Swimming Pools, 36,050 31,865 3,422 763
Fountains, and Similar
Installations--Receptac
les.
-----------------------------------------------
1c............... 1910.306(k)(4)(iv). Marking for single-pole Included in Provision 1.
portable cable
connectors for parallel
sets of conductors used
in installations for
carnivals, circuses,
fairs, and similar
events.
-----------------------------------------------
6................ 1910.307(b)........ Hazardous (Classified) 846,930 756,479 77,816 12,635
Locations--Documentatio
n.
-----------------------------------------------
1d............... 1910.308(b)(3)..... Signs for emergency Included in Provision 1.
power systems.
-----------------------------------------------
7................ 1910.308(e)(1)..... Communication Systems-- 51,044 8,172 37,593 5,280
Protective Devices.
-----------------------------------------------
Total........ ................... ........................ 9,550,457 8,886,108 460,716 203,633
----------------------------------------------------------------------------------------------------------------
\1\ The total cost per establishment is estimated to be $12.36 for industries that handle flammable and/or
combustible liquids, vapors, gases, dusts, and/or fibers and $10.44 for all other industries.
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, 2006.
Note: Compliance costs for all provisions except 4 are based on projects. Compliance costs for provision 4 are
based on establishments (small establishments have 1-99 employees medium establishments have 100-499
employees, and large establishments have 500+ employees).
Table 15.--Impacts on Small Businesses
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cost as a
Number of Small business Revenue per Profit Profit per percent Cost as a
SIC \1\ Industry description small business revenues establishment rate (%) establishment of percent
establishments ($1000) revenue of profit
--------------------------------------------------------------------------------------------------------------------------------------------------------
700............................ Agricultural services.. 109,663 $38,501,047 $351,085 6.02 $21,130 0.0029 0.0478
800............................ Forestry............... 2,400 1,496,747 623,645 10.30 64,235 0.0016 0.0157
900............................ Fishing, hunting, and NA NA NA 5.80 NA NA NA
trapping.
1300........................... Oil And Gas Extraction. 14,787 29,931,841 2,024,200 8.65 175,093 0.0006 0.0069
1500........................... General building 195,315 234,203,450 1,199,106 4.00 47,964 0.0008 0.0211
contractors.
1600........................... Heavy construction, 35,618 68,664,092 1,927,792 4.00 77,112 0.0005 0.0131
except building.
1700........................... Special trade 426,477 270,401,924 634,036 4.00 25,361 0.0016 0.0398
contractors.
2000........................... Food And Kindred 15,992 104,629,113 6,542,591 3.46 226,600 0.0002 0.0053
Products.
2100........................... Tobacco Products....... 91 1,255,255 13,794,011 4.02 554,130 0.0001 0.0022
2200........................... Textile Mill Products.. 4,845 20,377,246 4,205,830 2.77 116,423 0.0003 0.0103
2300........................... Apparel And Other 22,383 38,507,048 1,720,370 2.56 44,010 0.0007 0.0273
Textile Products.
2400........................... Lumber And Wood 35,076 58,343,756 1,663,353 3.90 64,854 0.0007 0.0185
Products.
2500........................... Furniture And Fixtures. 11,217 26,295,821 2,344,283 3.51 82,285 0.0005 0.0146
2600........................... Paper And Allied 4,057 31,334,277 7,723,509 4.50 347,629 0.0002 0.0035
Products.
2700........................... Printing And Publishing 57,018 85,620,541 1,501,641 3.80 57,055 0.0008 0.0211
2800........................... Chemicals And Allied 8,227 59,010,014 7,172,726 4.49 321,776 0.0002 0.0037
Products.
2900........................... Petroleum And Coal 1,047 13,950,653 13,324,406 2.99 398,317 0.0001 0.0030
Products.
3000........................... Rubber And Misc. 13,043 58,709,872 4,501,255 4.02 181,167 0.0003 0.0066
Plastics Products.
3100........................... Leather And Leather 1,675 4,003,751 2,390,299 2.20 52,509 0.0005 0.0229
Products.
3200........................... Stone, Clay, And Glass 11,791 34,254,470 2,905,137 4.93 143,127 0.0004 0.0084
Products.
3300........................... Primary Metal 4,806 36,511,582 7,597,083 4.52 343,213 0.0002 0.0035
Industries.
3400........................... Fabricated Metal 34,250 113,752,781 3,321,249 4.55 150,988 0.0004 0.0080
Products.
3500........................... Industrial Machinery 52,548 127,178,710 2,420,239 4.05 97,917 0.0005 0.0123
And Equipment.
3600........................... Electronic & Other 14,355 69,499,940 4,841,514 5.59 270,705 0.0002 0.0044
Electric Equipment.
3700........................... Transportation 10,653 41,544,504 3,899,794 3.74 145,974 0.0003 0.0082
Equipment.
3800........................... Instruments And Related 10,190 33,908,725 3,327,647 5.06 168,410 0.0004 0.0071
Products.
3900........................... Miscellaneous 17,837 30,627,905 1,717,100 3.80 65,322 0.0007 0.0184
Manufacturing
Industries.
4000........................... Railroad transportation NA NA NA 11.08 NA NA NA
4100........................... Local and interurban 16,537 7,690,615 465,055 4.51 20,964 0.0022 0.0482
passenger transit.
4200........................... Trucking And 114,623 79,888,400 696,967 3.91 27,278 0.0017 0.0441
Warehousing.
4400........................... Water Transportation... 8,051 14,075,608 1,748,306 7.48 130,855 0.0007 0.0092
4500........................... Transportation by air.. 6,386 15,156,218 2,373,351 3.62 85,925 0.0004 0.0118
4600........................... Pipelines, Except 39 986,979 25,307,154 6.55 1,657,050 0.0000 0.0007
Natural Gas.
4700........................... Transportation Services 40,529 19,513,397 481,468 3.39 16,327 0.0025 0.0736
4800........................... Communications......... 17,482 41,125,079 2,352,424 5.58 131,244 0.0004 0.0077
4900........................... Electric, Gas, And 8,938 10,824,146 1,211,026 10.37 125,641 0.0010 0.0096
Sanitary Services.
5000........................... Wholesale Trade-- 258,492 837,107,306 3,238,426 2.54 82,401 0.0004 0.0146
Durable Goods.
5100........................... Wholesale Trade-- 143,751 637,454,650 4,434,436 4.46 197,917 0.0003 0.0061
Nondurable Goods.
5200........................... Building Materials & 46,450 37,776,200 813,266 2.37 19,289 0.0015 0.0623
Garden Supplies.
5300........................... General Merchandise 8,796 3,346,901 380,503 2.70 10,283 0.0027 0.0982
Stores.
5400........................... Food Stores............ 123,572 101,566,550 821,922 1.41 11,595 0.0012 0.0871
5500........................... Automotive Dealers & 116,015 149,337,410 1,287,225 1.45 18,609 0.0009 0.0646
Service Stations.
5600........................... Apparel And Accessory 50,308 18,706,435 371,838 1.85 6,867 0.0027 0.1471
Stores.
5700........................... Home Furniture And 78,842 45,392,798 575,744 2.28 13,142 0.0018 0.0768
Furnishings Stores.
5800........................... Eating And Drinking 355,297 128,561,814 361,843 3.00 10,850 0.0033 0.1108
Places.
5900........................... Miscellaneous Retail... 258,538 119,265,615 461,308 2.49 11,479 0.0026 0.1047
6000........................... Depository Institutions 14,378 15,538,559 1,080,718 10.80 116,718 0.0009 0.0087
6100........................... Nondepository 21,262 13,454,697 632,805 15.05 95,230 0.0016 0.0106
Institutions.
6200........................... Security And Commodity 27,262 19,644,662 720,588 13.32 95,949 0.0014 0.0105
Brokers.
6300........................... Insurance Carriers..... 4,967 5,850,805 1,177,935 6.82 80,375 0.0009 0.0126
6400........................... Insurance Agents, 119,907 47,083,678 392,668 6.83 26,800 0.0026 0.0377
Brokers, & Service.
6500........................... Real Estate............ 230,304 142,479,284 618,657 13.31 82,340 0.0016 0.0123
6700........................... Holding And Other 21,022 35,174,755 1,673,235 24.01 401,733 0.0006 0.0025
Investment Offices.
7000........................... Hotels And Other 47,698 24,876,889 521,550 6.96 36,302 0.0019 0.0278
Lodging Places.
7200........................... Personal Services...... 176,477 36,957,629 209,419 5.86 12,262 0.0048 0.0824
7300........................... Business Services...... 337,126 188,061,601 557,838 4.79 26,703 0.0022 0.0450
7500........................... Auto Repair, Services, 167,057 66,003,052 395,093 4.39 17,356 0.0030 0.0692
And Parking.
7600........................... Miscellaneous Repair 63,328 25,861,556 408,375 5.44 22,198 0.0029 0.0541
Services.
7800........................... Motion Pictures........ 29,959 13,026,870 434,823 5.14 22,341 0.0023 0.0452
7900........................... Amusement & Recreation 90,742 47,922,810 528,122 4.28 22,604 0.0023 0.0532
Services.
8000........................... Health Services........ 413,561 243,370,668 588,476 6.17 36,312 0.0020 0.0331
8100........................... Legal Services......... 156,877 54,265,197 345,909 17.50 60,534 0.0029 0.0167
8200........................... Educational Services... 40,592 25,677,552 632,577 8.14 51,502 0.0016 0.0196
8300........................... Social Services........ 117,544 50,553,841 430,084 4.44 19,088 0.0023 0.0529
8400........................... Museums, Botanical, 4,912 2,928,264 596,145 21.45 127,873 0.0017 0.0079
Zoological Gardens.
8600........................... Membership 242,081 78,452,141 324,074 7.21 23,371 0.0031 0.0432
Organizations.
8700........................... Engineering and 271,169 151,671,072 559,323 6.39 35,745 0.0018 0.0283
management services.
8900........................... Services, n.e.c........ 16,395 8,169,059 498,265 6.80 33,882 0.0020 0.0298
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Consistent with the preliminary analysis, OSHA in this final analysis has grouped affected industries according to the 1987 Standard Industrial
Classification System. For industry coding under the North American Industry Classification System (NAICS), see NAICS, Executive Office of the
President, Office of Management and Budget, 1997 and 2002.
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, 2006, based on U.S. Census Bureau, 2001, and Dun & Bradstreet, 2001.
VII. State Plan Standards
The 26 States or territories with OSHA-approved occupational safety
and health plans must adopt an equivalent amendment or one that is at
least as protective to employees within 6 months of the publication
date of the final standard. These are: Alaska, Arizona, California,
Connecticut (for State and local government employees only), Hawaii,
Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Nevada, New
Mexico, New Jersey (for State and local government employees only), New
York (for State and local government employees only), North Carolina,
Oregon, Puerto Rico, South Carolina, Tennessee, Utah, Vermont,
Virginia, Virgin Islands, Washington, and Wyoming.
VIII. Environmental Impact Analysis
The final rule's provisions have been reviewed in accordance with
the requirements of the National Environmental Policy Act (NEPA) of
1969 (42 U.S.C. 4321, et seq.), the regulations of the Council on
Environmental Quality (40 CFR Part 1502), and the Department of Labor's
NEPA procedures (29 CFR Part 11). As a result of this review, OSHA has
determined that these provisions will have no significant effect on
air, water or soil quality, plant or animal life, on the use of land,
or other aspects of the environment.
IX. Unfunded Mandates
This final rule has been reviewed in accordance with the Unfunded
Mandates Reform Act of 1995 (UMRA) (2 U.S.C. 1501 et seq.). For the
purposes of the UMRA, the Agency certifies that this final rule does
not impose any Federal mandate that may result in increased
expenditures by State, local, or tribal governments, or increased
expenditures by the private sector, of more than $100 million in any
year.
X. Federalism
OSHA has reviewed this rule in accordance with the Executive Order
on Federalism (Executive Order 13132, 64 FR 43255, August 10, 1999),
which requires that agencies, to the extent possible, refrain from
limiting State policy options, consult with States prior to taking any
actions that would restrict State policy options, and take such actions
only when there is clear constitutional authority and the presence of a
problem of national scope. The Order provides for preemption of State
law only if there is a clear Congressional intent for the Agency to do
so. Any such preemption is to be limited to the extent possible.
Section 18 of the OSH Act expresses Congress's intent to preempt
State laws where OSHA has promulgated occupational safety and health
standards. A State can avoid preemption on issues covered by Federal
standards only if it submits, and obtains Federal approval of, a plan
for the development of such standards and their enforcement. 29 U.S.C.
667, Gade v. National Solid Wastes Management Association, 505 U.S. 88
(1992). Occupational safety and health standards developed by such Plan
States must, among other things, be at least as effective in providing
safe and healthful employment and places of employment as the Federal
standards. Subject to the statutory limitations of the OSH Act, State-
Plan States are free to develop and enforce their own requirements for
occupational safety and health protections.
Although OSHA has a clear statutory mandate to preempt State
occupational safety and health laws, States may enforce standards, such
as State and local fire and building codes, which are designed to
protect a wider class of persons than employees. As discussed earlier,
the final rule introduces few new requirements that are not already
mandated by applicable State and local law. In fact, most States and
municipalities require compliance with the NEC, which is consistent
with the final rule.
XI. OMB Review Under the Paperwork Reduction Act of 1995
The final rule Electrical Standard contains several collection-of-
information (paperwork) requirements that are subject to review by the
Office of Management and Budget (OMB) under the Paperwork Reduction Act
of 1995 (PRA-95), 44 U.S.C. 3501 et seq., and OMB's regulations at 5
CFR part 1320. PRA-95 defines "collection of information" as "the
obtaining, causing to be obtained, soliciting, or requiring the
disclosure to third parties or the public of facts or opinions by or
for an agency regardless of form or format * * *" (44 U.S.C.
3502(3)(A)). The collection-of-information requirements contained in
the proposed Design Safety Standards for Electrical Systems was
submitted to OMB on April 2, 2004. On December 7, 2004, OMB provided
the following comment regarding its review of the paperwork
requirements contained in the proposed rule:
The information collection provisions associated with the Design
Safety Standards for Electrical Systems proposed rule are not
approved at this time. OSHA will examine public comment in response
to the [Notice of Proposed Rulemaking] and will describe in the
preamble of the final rule how the [A]gency has maximized the
practical utility of the collection and minimized its burden.
In the preamble to the proposed rule, OSHA asked for comments on
each of the paperwork requirements in the Electrical Standard for
general industry, Subpart S. OSHA received no comments on the paperwork
burdens or OSHA's estimation of those burdens. However, OSHA added a
provision to the standard based on comments received on the proposed
GFCI requirements. In response to those comments, the Agency added a
requirement for the assured equipment grounding conductor program under
limited conditions. This new provision will add 203 hours to the
paperwork burden.
The collection-of-information requirements contained in the final
rule also include requirements in Sec. 1910.303 for marking series
combination ratings, Sec. 1910.304--Wiring design and protection,
Sec. 1910.306--Specific purpose equipment and installations, Sec.
1910.307--Hazardous (classified) locations, and Sec. 1910.308--Special
systems. The final Information-Collection Request estimates the total
burden hours associated with the collection-of-information requirements
to be approximately 9,353 hours and estimates the cost for maintenance
and operation to be approximately $3,750. OMB is currently reviewing
OSHA's request for approval of the collection-of-information
requirements in the final rule.
These collection-of-information requirements are needed to provide
electrical safety to employees against the electric shock hazards that
might be present in the workplace. The marking of electric equipment
with proper ratings, identifying the phase and system of each
ungrounded conductor, labeling certain disconnecting means with
indentification signs, using the assured equipment grounding conductor
program whenever approved GFCIs are not available, and documenting
hazardous classified areas are all ways of reducing the electrical
hazards posed on employees. OSHA will use the records developed in
response to this standard to determine compliance. The employer's
failure to generate and disclose the information required in this
standard will affect significantly OSHA's effort to control and reduce
injuries and fatalities related to electrical hazards in the workplace.
OSHA minimized the burden hours imposed by collections of
information contained in the standard by relying heavily on the
National Electrical Code and NFPA 70E, Standard for Electrical Safety
Requirements for Employee Workplaces. The collections of information in
the standard mirror current industry practice and, therefore, impose
minimal burden on employers and eliminate any confusion between current
industry practice and the standard. The Agency believes that the
information-collection frequencies required by the standard are the
minimum frequencies necessary to effectively regulate the electrical
hazards posed by the workforce.
Potential respondents are not required to respond to the
information collection requirements until they have been approved and a
currently valid OMB control number is displayed. OMB is currently
reviewing OSHA's request for approval of the 29 CFR Part 1910 Subpart S
information collections. OSHA will publish a subsequent Federal
Register document when OMB takes further action on the information
collection requirements in the Electrical Standards rule.
XII. Effective Date and Date of Application
The scope and application of Subpart S is set forth in Sec.
1910.302 in paragraphs (b)(1) through (b)(4). The paragraphs are as
follows: (b)(1) all installations regardless of when the installation
was built; (b)(2) all installations built after March 15, 1972; (b)(3)
all installations built after April 16, 1981; and (b)(4) all
installations built after the final rule is published.
In the preamble to the Proposal, OSHA proposed to make some new
requirements effective 90 days after the final rule is published. We
invited comments on whether this time is sufficient to implement the
changes required by the revised standard.
International Paper stated that companies will need at least 90
days to effectively communicate and implement the provisions in the
standard, even within a large organization (Ex. 3-6). They further
stated that this period would allow companies to develop and update
site specific electrical safety programs and would allow large
companies to develop policies supplemental to the OSHA standards as
well as adequately address site issues and concerns. In addition, they
noted that the current electrical design and installation would need to
be reviewed for compliance. They stated that the proposed changes to
the depth of working space in front of electrical equipment, and
proposed changes to elevation requirements to unguarded live parts of
electrical equipment, for example, may necessitate design or
construction changes.
Two commenters did not believe that 90 days after the final rule is
published would be enough time for employers to effectively implement
the new requirements proposed in the electrical standard, especially in
states not mandating the latest codes (Exs. 3-3, 3-10). These
commenters recommended that the effective date be 180 days after the
final rule is published. One of these commenters, Duke Energy
Corporation, argued that additional time would be needed for employers
to determine compliance and then retrofit installations if necessary.
The other commenter, ORC World Wide, said that employers need to
determine how the new requirements apply to their installations and
plan accordingly. They argued that the standard is complex and may take
companies time to understand and assimilate the standard into their
operations.
OSHA agrees with the public comments on the effective date and
recognizes that companies may need additional time to implement the
standard. For the reasons given by these commenters, the Agency will
grant the request to extend the effective date to 180 days after the
final rule is published.
Accordingly, the effective date of this final rule is 180 days
after publication. The 180-day period between the issuance of the
standard and their effective date is intended to provide sufficient
time for employers and employees to become informed of and comply with
the requirements of the standard.
The standards currently found in the existing Subpart S (Sec. Sec.
1910.302 through 1910.308) remain in effect until the standards
contained in this rule actually go into effect. Should the new
standards be stayed, judicially or administratively, or should the
standards not sustain legal challenge under section 6(f) of the OSH
Act, the existing standards in Subpart S will remain in effect.
Any petitions for administrative reconsiderations of these
standards or for an administrative stay pending judicial review must be
filed with the Assistant Secretary of Labor for Occupational Safety and
Health on or before April 16, 2007. Any petitions filed after this day
will be considered to be filed untimely.
As discussed fully in the summary and explanation of final Sec.
1910.302(b), in section V. earlier in this preamble, OSHA is making the
new requirements in revised Subpart S effective 180 days after the
final rule is published in the Federal Register. It should be noted
that applying new provisions only to new installations is the same
approach that OSHA took in promulgating the current version of Subpart
S in 1981. The Agency found that this approach was successful and has
no indication that it was unduly burdensome or insufficiently
protective.
List of Subjects in 29 CFR Part 1910
Electric power, Fire prevention, Hazardous substances, Occupational
safety and health, Safety.
Authority and Signature
This document was prepared under the direction of Edwin G. Foulke,
Jr., Assistant Secretary of Labor for Occupational Safety and Health,
200 Constitution Avenue, NW., Washington, DC 20210.
This action is taken pursuant to sections 4, 6, and 8 of the
Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655, 657),
Secretary of Labor's Order No. 5-2002 (67 F.R. 65008), and 29 CFR Part
1911.
Signed at Washington, DC, this 24th day of January, 2007.
Edwin G. Foulke, Jr.,
Assistant Secretary of Labor.
PART 1910--[AMENDED]
0
Part 1910 of Title 29 of the Code of Federal Regulations is amended as
follows:
Subpart A--General
0
1. The authority citation for Subpart A is revised to read as follows:
Authority: Sections 4, 6, and 8 of the Occupational Safety and
Health Act of 1970 (29 U.S.C. 653, 655, and 657); Secretary of
Labor's Order No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48
FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 111), 3-2000 (65 FR
50017), or 5-2002 (67 FR 65008), as applicable.
Sections 1910.6, 1910.7, and 1910.8 also issued under 29 CFR
part 1911. Section 1910.7(f) also issued under 31 U.S.C. 9701, 29
U.S.C. 9 a, 5 U.S.C. 553; Public Law 106-113 (113 Stat. 1501A-222);
and OMB Circular A-25 (dated July 8, 1993) (58 FR 38142, July 15,
1993).
0
2. Section 1910.6 is amended by revising the introductory text to
paragraph (e), removing and reserving paragraph (e)(33), revising the
introductory text to paragraph (q), and removing and reserving
paragraph (q)(16). The revised text reads as follows:
Sec. 1910.6 Incorporation by reference.
* * * * *
(e) The following material is available for purchase from the
American National Standards Institute (ANSI), 25 West 43rd Street,
Fourth Floor, New York, NY 10036:
* * * * *
(q) The following material is available for purchase from the
National Fire Protection Association (NFPA), 1 Batterymarch Park,
Quincy, MA 02269:
* * * * *
Subpart F--Powered Platforms, Manlifts, and Vehicle-Mounted Work
Platforms
0
3. The authority citation for Subpart F is revised to read as follows:
Authority: Secs. 4, 6, and 8 of the Occupational Safety and
Health Act of 1970 (29 U.S.C. 653, 655, and 657); Secretary of
Labor's Order No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48
FR 35736), 1-90 (55 FR 9033), or 5-2002 (67 FR 65008), as
applicable; and 29 CFR part 1911.
0
4. Appendix D to Sec. 1910.66 is amended as follows:
0
a. Paragraph (c)(22)(i) is revised as set forth below.
0
b. In the second sentence of paragraph (c)(22)(vii), the words
"Article 610 of the National Electrical Code, NFPA 70-1971; ANSI C1-
1971 (Rev. of C1-1968)" are revised to read "Subpart S of this
Part."
Sec. 1910.66 Powered platforms for building maintenance.
* * * * *
Appendix D to Sec. 1910.66--Existing Installations (Mandatory)
* * * * *
(c) * * *
(22) * * * (i) All electrical equipment and wiring shall conform
to the requirements of Subpart S of this Part, except as modified by
ANSI A120.1--1970 "American National Standard Safety Requirements
for Powered Platforms for Exterior Building Maintenance" (see Sec.
1910.6). For detail design specifications for electrical equipment,
see Part 2, ANSI A120.1-1970.
* * * * *
Subpart S--Electrical
0
5. The authority citation for Subpart S is revised to read as follows:
Authority: Secs. 4, 6, 8, Occupational Safety and Health Act of
1970 (29 U.S.C. 653, 655, 657); Secretary of Labor's Order No. 8-76
(41 FR 25059), 1-90 (55 FR 9033), or 5-2002 (67 F.R. 65008), as
applicable; 29 CFR Part 1911.
0
6. Sections 1910.302 through 1910.308 are revised to read as follows:
Design Safety Standards for Electrical Systems
Sec. 1910.302 Electric utilization systems.
Sections 1910.302 through 1910.308 contain design safety standards
for electric utilization systems.
(a) Scope--(1) Covered. The provisions of Sec. Sec. 1910.302
through 1910.308 cover electrical installations and utilization
equipment installed or used within or on buildings, structures, and
other premises, including:
(i) Yards;
(ii) Carnivals;
(iii) Parking and other lots;
(iv) Mobile homes;
(v) Recreational vehicles;
(vi) Industrial substations;
(vii) Conductors that connect the installations to a supply of
electricity; and
(viii) Other outside conductors on the premises.
(2) Not covered. The provisions of Sec. Sec. 1910.302 through
1910.308 do not cover:
(i) Installations in ships, watercraft, railway rolling stock,
aircraft, or automotive vehicles other than mobile homes and
recreational vehicles;
(ii) Installations underground in mines;
(iii) Installations of railways for generation, transformation,
transmission, or distribution of power used exclusively for operation
of rolling stock or installations used exclusively for signaling and
communication purposes;
(iv) Installations of communication equipment under the exclusive
control of communication utilities, located outdoors or in building
spaces used exclusively for such installations; or
(v) Installations under the exclusive control of electric utilities
for the purpose of communication or metering; or for the generation,
control, transformation, transmission, and distribution of electric
energy located in buildings used exclusively by utilities for such
purposes or located outdoors on property owned or leased by the utility
or on public highways, streets, roads, etc., or outdoors by established
rights on private property.
(b) Extent of application--(1) Requirements applicable to all
installations. The following requirements apply to all electrical
installations and utilization equipment, regardless of when they were
designed or installed:
Sec. 1910.303(b)--Examination, installation, and use of equipment
Sec. 1910.303(c)(3)--Electrical connections--Splices
Sec. 1910.303(d)--Arcing parts
Sec. 1910.303(e)--Marking
Sec. 1910.303(f), except (f)(4) and (f)(5)--Disconnecting means and
circuits
Sec. 1910.303(g)(2)--600 volts or less--Guarding of live parts
Sec. 1910.304(a)(3)--Use of grounding terminals and devices
Sec. 1910.304(f)(1)(i), (f)(1)(iv), and (f)(1)(v)--Overcurrent
protection--600 volts, nominal, or less
Sec. 1910.304(g)(1)(ii), (g)(1)(iii), (g)(1)(iv), and (g)(1)(v)--
Grounding--Systems to be grounded
Sec. 1910.304(g)(4)--Grounding--Grounding connections
Sec. 1910.304(g)(5)--Grounding--Grounding path
Sec. 1910.304(g)(6)(iv)(A) through (g)(6)(iv)(D), and (g)(6)(vi)--
Grounding--Supports, enclosures, and equipment to be grounded
Sec. 1910.304(g)(7)--Grounding--Nonelectrical equipment
Sec. 1910.304(g)(8)(i)--Grounding--Methods of grounding fixed
equipment
Sec. 1910.305(g)(1)--Flexible cords and cables--Use of flexible cords
and cables
Sec. 1910.305(g)(2)(ii) and (g)(2)(iii)--Flexible cords and cables--
Identification, splices, and terminations
Sec. 1910.307, except as specified in Sec. 1910.307(b)--Hazardous
(classified) locations
(2) Requirements applicable to installations made after March 15,
1972. Every electrical installation and all utilization equipment
installed or overhauled after March 15, 1972, shall comply with the
provisions of Sec. Sec. 1910.302 through 1910.308, except as noted in
paragraphs (b)(3) and (b)(4) of this section.
(3) Requirements applicable only to installations made after April
16, 1981. The following requirements apply only to electrical
installations and utilization equipment installed after April 16, 1981:
Sec. 1910.303(h)(4)--Over 600 volts, nominal--Entrance and access to
work space
Sec. 1910.304(f)(1)(vii) and (f)(1)(viii)--Overcurrent protection--600
volts, nominal, or less
Sec. 1910.304(g)(9)(i)--Grounding--Grounding of systems and circuits
of 1000 volts and over (high voltage)
Sec. 1910.305(j)(6)(ii)(D)--Equipment for general use--Capacitors
Sec. 1910.306(c)(9)--Elevators, dumbwaiters, escalators, moving walks,
wheelchair lifts, and stairway chair lifts--Interconnection between
multicar controllers
Sec. 1910.306(i)--Electrically driven or controlled irrigation
machines
Sec. 1910.306(j)(5)--Swimming pools, fountains, and similar
installations--Fountains
Sec. 1910.308(a)(1)(ii)--Systems over 600 volts, nominal--Aboveground
wiring methods
Sec. 1910.308(c)(2)--Class 1, Class 2, and Class 3 remote control,
signaling, and power-limited circuits--Marking
Sec. 1910.308(d)--Fire alarm systems
(4) Requirements applicable only to installations made after August
13, 2007. The following requirements apply only to electrical
installations and utilization equipment installed after August 13,
2007:
Sec. 1910.303(f)(4)--Disconnecting means and circuits--Capable of
accepting a lock
Sec. 1910.303(f)(5)--Disconnecting means and circuits--Marking for
series combination ratings
Sec. 1910.303(g)(1)(iv) and (g)(1)(vii)--600 Volts, nominal, or less--
Space about electric equipment
Sec. 1910.303(h)(5)(vi)--Over 600 volts, nominal--Working space and
guarding
Sec. 1910.304(b)(1)--Branch circuits--Identification of multiwire
branch circuits
Sec. 1910.304(b)(3)(i)--Branch circuits--Ground-fault circuit
interrupter protection for personnel
Sec. 1910.304(f)(2)(i)(A), (f)(2)(i)(B) (but not the introductory text
to Sec. 1910.304(f)(2)(i)), and (f)(2)(iv)(A)--Overcurrent
protection--Feeders and branch circuits over 600 volts, nominal
Sec. 1910.305(c)(3)(ii)--Switches--Connection of switches
Sec. 1910.305(c)(5)--Switches--Grounding
Sec. 1910.306(a)(1)(ii)--Electric signs and outline lighting--
Disconnecting means
Sec. 1910.306(c)(4)--Elevators, dumbwaiters, escalators, moving walks,
wheelchair lifts, and stairway chair lifts--Operation
Sec. 1910.306(c)(5)--Elevators, dumbwaiters, escalators, moving walks,
wheelchair lifts, and stairway chair lifts--Location
Sec. 1910.306(c)(6)--Elevators, dumbwaiters, escalators, moving walks,
wheelchair lifts, and stairway chair lifts--Identification and signs
Sec. 1910.306(c)(7)--Elevators, dumbwaiters, escalators, moving walks,
wheelchair lifts, and stairway chair lifts--Single-car and multicar
installations
Sec. 1910.306(j)(1)(iii)--Swimming pools, fountains, and similar
installations--Receptacles
Sec. 1910.306(k)--Carnivals, circuses, fairs, and similar events
Sec. 1910.308(a)(5)(v) and (a)(5)(vi)(B)--Systems over 600 volts,
nominal--Interrupting and isolating devices
Sec. 1910.308(a)(7)(vi)--Systems over 600 volts, nominal--Tunnel
installations
Sec. 1910.308(b)(3)--Emergency power systems--Signs
Sec. 1910.308(c)(3)--Class 1, Class 2, and Class 3 remote control,
signaling, and power-limited circuits--Separation from conductors of
other circuits
Sec. 1910.308(f)--Solar photovoltaic systems
(c) Applicability of requirements for disconnecting means. The
requirement in Sec. 1910.147(c)(2)(iii) that energy isolating devices
be capable of accepting a lockout device whenever replacement or major
repair, renovation or modification of a machine or equipment is
performed, and whenever new machines or equipment are installed after
January 2, 1990, applies in addition to any requirements in Sec.
1910.303 through Sec. 1910.308 that disconnecting means be capable of
being locked in the open position under certain conditions.
Sec. 1910.303 General.
(a) Approval. The conductors and equipment required or permitted by
this subpart shall be acceptable only if approved, as defined in Sec.
1910.399.
(b) Examination, installation, and use of equipment--(1)
Examination. Electric equipment shall be free from recognized hazards
that are likely to cause death or serious physical harm to employees.
Safety of equipment shall be determined using the following
considerations:
(i) Suitability for installation and use in conformity with the
provisions of this subpart;
Note to paragraph (b)(1)(i) of this section: Suitability of
equipment for an identified purpose may be evidenced by listing or
labeling for that identified purpose.
(ii) Mechanical strength and durability, including, for parts
designed to enclose and protect other equipment, the adequacy of the
protection thus provided;
(iii) Wire-bending and connection space;
(iv) Electrical insulation;
(v) Heating effects under all conditions of use;
(vi) Arcing effects;
(vii) Classification by type, size, voltage, current capacity, and
specific use; and
(viii) Other factors that contribute to the practical safeguarding
of persons using or likely to come in contact with the equipment.
(2) Installation and use. Listed or labeled equipment shall be
installed and used in accordance with any instructions included in the
listing or labeling.
(3) Insulation integrity. Completed wiring installations shall be
free from short circuits and from grounds other than those required or
permitted by this subpart.
(4) Interrupting rating. Equipment intended to interrupt current at
fault levels shall have an interrupting rating sufficient for the
nominal circuit voltage and the current that is available at the line
terminals of the equipment. Equipment intended to interrupt current at
other than fault levels shall have an interrupting rating at nominal
circuit voltage sufficient for the current that must be interrupted.
(5) Circuit impedance and other characteristics. The overcurrent
protective devices, the total impedance, the component short-circuit
current ratings, and other characteristics of the circuit to be protected
shall be selected and coordinated to permit the circuit protective devices
used to clear a fault to do so without the occurrence of extensive damage
to the electrical components of the circuit. This fault shall be assumed
to be either between two or more of the circuit conductors, or between
any circuit conductor and the grounding conductor or enclosing metal raceway.
(6) Deteriorating agents. Unless identified for use in the
operating environment, no conductors or equipment shall be located in
damp or wet locations; where exposed to gases, fumes, vapors, liquids,
or other agents that have a deteriorating effect on the conductors or
equipment; or where exposed to excessive temperatures.
(7) Mechanical execution of work. Electric equipment shall be
installed in a neat and workmanlike manner.
(i) Unused openings in boxes, raceways, auxiliary gutters,
cabinets, equipment cases, or housings shall be effectively closed to
afford protection substantially equivalent to the wall of the
equipment.
(ii) Conductors shall be racked to provide ready and safe access in
underground and subsurface enclosures that persons enter for
installation and maintenance.
(iii) Internal parts of electrical equipment, including busbars,
wiring terminals, insulators, and other surfaces, may not be damaged or
contaminated by foreign materials such as paint, plaster, cleaners,
abrasives, or corrosive residues.
(iv) There shall be no damaged parts that may adversely affect safe
operation or mechanical strength of the equipment, such as parts that
are broken, bent, cut, or deteriorated by corrosion, chemical action,
or overheating.
(8) Mounting and cooling of equipment. (i) Electric equipment shall
be firmly secured to the surface on which it is mounted.
Note to paragraph (b)(8)(i) of this section: Wooden plugs driven
into holes in masonry, concrete, plaster, or similar materials are
not considered secure means of fastening electric equipment.
(ii) Electric equipment that depends on the natural circulation of
air and convection principles for cooling of exposed surfaces shall be
installed so that room airflow over such surfaces is not prevented by
walls or by adjacent installed equipment. For equipment designed for
floor mounting, clearance between top surfaces and adjacent surfaces
shall be provided to dissipate rising warm air.
(iii) Electric equipment provided with ventilating openings shall
be installed so that walls or other obstructions do not prevent the
free circulation of air through the equipment.
(c) Electrical connections--(1) General. Because of different
characteristics of dissimilar metals:
(i) Devices such as pressure terminal or pressure splicing
connectors and soldering lugs shall be identified for the material of
the conductor and shall be properly installed and used;
(ii) Conductors of dissimilar metals may not be intermixed in a
terminal or splicing connector where physical contact occurs between
dissimilar conductors (such as copper and aluminum, copper and copper-
clad aluminum, or aluminum and copper-clad aluminum) unless the device
is identified for the purpose and conditions of use; and
(iii) Materials such as solder, fluxes, inhibitors, and compounds,
where employed, shall be suitable for the use and shall be of a type
that will not adversely affect the conductors, installation, or
equipment.
(2) Terminals. (i) Connection of conductors to terminal parts shall
ensure a good connection without damaging the conductors and shall be
made by means of pressure connectors (including set-screw type), solder
lugs, or splices to flexible leads. However, No. 10 or smaller
conductors may be connected by means of wire binding screws or studs
and nuts having upturned lugs or equivalent.
(ii) Terminals for more than one conductor and terminals used to
connect aluminum shall be so identified.
(3) Splices. (i) Conductors shall be spliced or joined with
splicing devices identified for the use or by brazing, welding, or
soldering with a fusible metal or alloy. Soldered splices shall first
be spliced or joined to be mechanically and electrically secure without
solder and then soldered. All splices and joints and the free ends of
conductors shall be covered with an insulation equivalent to that of
the conductors or with an insulating device identified for the purpose.
(ii) Wire connectors or splicing means installed on conductors for
direct burial shall be listed for such use.
(d) Arcing parts. Parts of electric equipment that in ordinary
operation produce arcs, sparks, flames, or molten metal shall be
enclosed or separated and isolated from all combustible material.
(e) Marking--(1) Identification of manufacturer and ratings.
Electric equipment may not be used unless the following markings have
been placed on the equipment:
(i) The manufacturer's name, trademark, or other descriptive
marking by which the organization responsible for the product may be
identified; and
(ii) Other markings giving voltage, current, wattage, or other
ratings as necessary.
(2) Durability. The marking shall be of sufficient durability to
withstand the environment involved.
(f) Disconnecting means and circuits--(1) Motors and appliances.
Each disconnecting means required by this subpart for motors and
appliances shall be legibly marked to indicate its purpose, unless
located and arranged so the purpose is evident.
(2) Services, feeders, and branch circuits. Each service, feeder,
and branch circuit, at its disconnecting means or overcurrent device,
shall be legibly marked to indicate its purpose, unless located and
arranged so the purpose is evident.
(3) Durability of markings. The markings required by paragraphs
(f)(1) and (f)(2) of this section shall be of sufficient durability to
withstand the environment involved.
(4) Capable of accepting a lock. Disconnecting means required by
this subpart shall be capable of being locked in the open position.
(5) Marking for series combination ratings. (i) Where circuit
breakers or fuses are applied in compliance with the series combination
ratings marked on the equipment by the manufacturer, the equipment
enclosures shall be legibly marked in the field to indicate that the
equipment has been applied with a series combination rating.
(ii) The marking required by paragraph (f)(5)(i) of this section
shall be readily visible and shall state "Caution--Series Combination
System Rated ---- Amperes. Identified Replacement Component Required."
(g) 600 Volts, nominal, or less. This paragraph applies to electric
equipment operating at 600 volts, nominal, or less to ground.
(1) Space about electric equipment. Sufficient access and working
space shall be provided and maintained about all electric equipment to
permit ready and safe operation and maintenance of such equipment.
(i) Working space for equipment likely to require examination,
adjustment, servicing, or maintenance while energized shall comply with
the following dimensions, except as required or permitted elsewhere in
this subpart:
(A) The depth of the working space in the direction of access to
live parts may not be less than indicated in Table S-1. Distances shall
be measured from the live parts if they are exposed or from the
enclosure front or opening if they are enclosed;
(B) The width of working space in front of the electric equipment
shall be the width of the equipment or 762 mm (30 in.), whichever is
greater. In all cases, the working space shall permit at least a 90-
degree opening of equipment doors or hinged panels; and
(C) The work space shall be clear and extend from the grade, floor,
or platform to the height required by paragraph (g)(1)(vi) of this
section. However, other equipment associated with the electrical
installation and located above or below the electric equipment may
extend not more than 153 mm (6 in.) beyond the front of the electric
equipment.
(ii) Working space required by this standard may not be used for
storage. When normally enclosed live parts are exposed for inspection
or servicing, the working space, if in a passageway or general open
space, shall be suitably guarded.
(iii) At least one entrance of sufficient area shall be provided to
give access to the working space about electric equipment.
(iv) For equipment rated 1200 amperes or more and over 1.83 m (6.0
ft) wide, containing overcurrent devices, switching devices, or control
devices, there shall be one entrance not less than 610 mm (24 in.) wide
and 1.98 m (6.5 ft) high at each end of the working space, except that:
(A) Where the location permits a continuous and unobstructed way of
exit travel, one means of exit is permitted; or
(B) Where the working space required by paragraph (g)(1)(i) of this
section is doubled, only one entrance to the working space is required;
however, the entrance shall be located so that the edge of the entrance
nearest the equipment is the minimum clear distance given in Table S-1
away from such equipment.
(v) Illumination shall be provided for all working spaces about
service equipment, switchboards, panelboards, and motor control centers
installed indoors. Additional lighting fixtures are not required where
the working space is illuminated by an adjacent light source. In
electric equipment rooms, the illumination may not be controlled by
automatic means only.
(vi) The minimum headroom of working spaces about service
equipment, switchboards, panelboards, or motor control centers shall be
as follows:
(A) For installations built before August 13, 2007, 1.91 m (6.25
ft); and
(B) For installations built on or after August 13, 2007, 1.98 m
(6.5 ft), except that where the electrical equipment exceeds 1.98 m
(6.5 ft) in height, the minimum headroom may not be less than the
height of the equipment.
Table S-1.--Minimum Depth of Clear Working Space at Electric Equipment, 600 V or Less
----------------------------------------------------------------------------------------------------------------
Minimum clear distance for condition \2\ \3\
-----------------------------------------------------------------
Nominal voltage to ground Condition A Condition B Condition C
-----------------------------------------------------------------
m ft m ft m ft
----------------------------------------------------------------------------------------------------------------
0-150......................................... \1\0.9 \1\3.0 \1\0.9 \1\3.0 0.9 3.0
151-600....................................... \1\0.9 \1\3.0 1.0 3.5 1.2 4.0
----------------------------------------------------------------------------------------------------------------
Notes to Table S-1:
1. Minimum clear distances may be 0.7 m (2.5 ft) for installations built before April 16, 1981.
2. Conditions A, B, and C are as follows:
Condition A--Exposed live parts on one side and no live or grounded parts on the other side of the working
space, or exposed live parts on both sides effectively guarded by suitable wood or other insulating material.
Insulated wire or insulated busbars operating at not over 300 volts are not considered live parts.
Condition B--Exposed live parts on one side and grounded parts on the other side.
Condition C--Exposed live parts on both sides of the work space (not guarded as provided in Condition A) with
the operator between.
3. Working space is not required in back of assemblies such as dead-front switchboards or motor control centers
where there are no renewable or adjustable parts (such as fuses or switches) on the back and where all
connections are accessible from locations other than the back. Where rear access is required to work on
deenergized parts on the back of enclosed equipment, a minimum working space of 762 mm (30 in.) horizontally
shall be provided.
(vii) Switchboards, panelboards, and distribution boards installed
for the control of light and power circuits, and motor control centers
shall be located in dedicated spaces and protected from damage.
(A) For indoor installation, the dedicated space shall comply with
the following:
(1) The space equal to the width and depth of the equipment and
extending from the floor to a height of 1.83 m (6.0 ft) above the
equipment or to the structural ceiling, whichever is lower, shall be
dedicated to the electrical installation. Unless isolated from
equipment by height or physical enclosures or covers that will afford
adequate mechanical protection from vehicular traffic or accidental
contact by unauthorized personnel or that complies with paragraph
(g)(1)(vii)(A)(2) of this section, piping, ducts, or equipment foreign
to the electrical installation may not be located in this area;
(2) The space equal to the width and depth of the equipment shall
be kept clear of foreign systems unless protection is provided to avoid
damage from condensation, leaks, or breaks in such foreign systems.
This area shall extend from the top of the electric equipment to the
structural ceiling;
(3) Sprinkler protection is permitted for the dedicated space where
the piping complies with this section; and
(4) Control equipment that by its very nature or because of other
requirements in this subpart must be adjacent to or within sight of its
operating machinery is permitted in the dedicated space.
Note to paragraph (g)(1)(vii)(A) of this section: A dropped,
suspended, or similar ceiling that does not add strength to the
building structure is not considered a structural ceiling.
(B) Outdoor electric equipment shall be installed in suitable
enclosures and shall be protected from accidental contact by
unauthorized personnel, or by vehicular traffic, or by accidental
spillage or leakage from piping systems. No architectural appurtenance
or other equipment may be located in the working space required by
paragraph (g)(1)(i) of this section.
(2) Guarding of live parts. (i) Except as elsewhere required or
permitted by this standard, live parts of electric equipment operating
at 50 volts or more shall be guarded against accidental
contact by use of approved cabinets or other forms of approved
enclosures or by any of the following means:
(A) By location in a room, vault, or similar enclosure that is
accessible only to qualified persons;
(B) By suitable permanent, substantial partitions or screens so
arranged so that only qualified persons will have access to the space
within reach of the live parts. Any openings in such partitions or
screens shall be so sized and located that persons are not likely to
come into accidental contact with the live parts or to bring conducting
objects into contact with them;
(C) By placement on a suitable balcony, gallery, or platform so
elevated and otherwise located as to prevent access by unqualified
persons; or
(D) By elevation of 2.44 m (8.0 ft) or more above the floor or
other working surface.
(ii) In locations where electric equipment is likely to be exposed
to physical damage, enclosures or guards shall be so arranged and of
such strength as to prevent such damage.
(iii) Entrances to rooms and other guarded locations containing
exposed live parts shall be marked with conspicuous warning signs
forbidding unqualified persons to enter.
(h) Over 600 volts, nominal--(1) General. Conductors and equipment
used on circuits exceeding 600 volts, nominal, shall comply with all
applicable provisions of the paragraphs (a) through (g) of this section
and with the following provisions, which supplement or modify the
preceding requirements. However, paragraphs (h)(2), (h)(3), and (h)(4)
of this section do not apply to the equipment on the supply side of the
service point.
(2) Enclosure for electrical installations. (i) Electrical
installations in a vault, room, or closet or in an area surrounded by a
wall, screen, or fence, access to which is controlled by lock and key
or other approved means, are considered to be accessible to qualified
persons only. The type of enclosure used in a given case shall be
designed and constructed according to the hazards associated with the
installation.
(ii) For installations other than equipment described in paragraph
(h)(2)(v) of this section, a wall, screen, or fence shall be used to
enclose an outdoor electrical installation to deter access by persons
who are not qualified. A fence may not be less than 2.13 m (7.0 ft) in
height or a combination of 1.80 m (6.0 ft) or more of fence fabric and
a 305-mm (1-ft) or more extension utilizing three or more strands of
barbed wire or equivalent.
(iii) The following requirements apply to indoor installations that
are accessible to other than qualified persons:
(A) The installations shall be made with metal-enclosed equipment
or shall be enclosed in a vault or in an area to which access is
controlled by a lock;
(B) Metal-enclosed switchgear, unit substations, transformers, pull
boxes, connection boxes, and other similar associated equipment shall
be marked with appropriate caution signs; and
(C) Openings in ventilated dry-type transformers and similar
openings in other equipment shall be designed so that foreign objects
inserted through these openings will be deflected from energized parts.
(iv) Outdoor electrical installations having exposed live parts
shall be accessible to qualified persons only.
(v) The following requirements apply to outdoor enclosed equipment
accessible to unqualified employees:
(A) Ventilating or similar openings in equipment shall be so
designed that foreign objects inserted through these openings will be
deflected from energized parts;
(B) Where exposed to physical damage from vehicular traffic,
suitable guards shall be provided;
(C) Nonmetallic or metal-enclosed equipment located outdoors and
accessible to the general public shall be designed so that exposed nuts
or bolts cannot be readily removed, permitting access to live parts;
(D) Where nonmetallic or metal-enclosed equipment is accessible to
the general public and the bottom of the enclosure is less than 2.44 m
(8.0 ft) above the floor or grade level, the enclosure door or hinged
cover shall be kept locked; and
(E) Except for underground box covers that weigh over 45.4 kg (100
lb), doors and covers of enclosures used solely as pull boxes, splice
boxes, or junction boxes shall be locked, bolted, or screwed on.
(3) Work space about equipment. Sufficient space shall be provided
and maintained about electric equipment to permit ready and safe
operation and maintenance of such equipment. Where energized parts are
exposed, the minimum clear work space may not be less than 1.98 m (6.5
ft) high (measured vertically from the floor or platform) or less than
914 mm (3.0 ft) wide (measured parallel to the equipment). The depth
shall be as required in paragraph (h)(5)(i) of this section. In all
cases, the work space shall be adequate to permit at least a 90-degree
opening of doors or hinged panels.
(4) Entrance and access to work space. (i) At least one entrance
not less than 610 mm (24 in.) wide and 1.98 m (6.5 ft) high shall be
provided to give access to the working space about electric equipment.
(A) On switchboard and control panels exceeding 1.83 m (6.0 ft) in
width, there shall be one entrance at each end of such boards unless
the location of the switchboards and control panels permits a
continuous and unobstructed way of exit travel, or unless the work
space required in paragraph (h)(5)(i) of this section is doubled.
(B) Where one entrance to the working space is permitted under the
conditions described in paragraph (h)(4)(i)(A) of this section, the
entrance shall be located so that the edge of the entrance nearest the
switchboards and control panels is at least the minimum clear distance
given in Table S-2 away from such equipment.
(C) Where bare energized parts at any voltage or insulated
energized parts above 600 volts, nominal, to ground are located
adjacent to such entrance, they shall be suitably guarded.
(ii) Permanent ladders or stairways shall be provided to give safe
access to the working space around electric equipment installed on
platforms, balconies, mezzanine floors, or in attic or roof rooms or
spaces.
(5) Working space and guarding. (i)(vi) Except as elsewhere
required or permitted in this subpart, the minimum clear working space
in the direction of access to live parts of electric equipment may not
be less than specified in Table S-2. Distances shall be measured from
the live parts, if they are exposed, or from the enclosure front or
opening, if they are enclosed.
(ii) If switches, cutouts, or other equipment operating at 600
volts, nominal, or less, are installed in a room or enclosure where
there are exposed live parts or exposed wiring operating at over 600
volts, nominal, the high-voltage equipment shall be effectively
separated from the space occupied by the low-voltage equipment by a
suitable partition, fence, or screen. However, switches or other
equipment operating at 600 volts, nominal, or less, and serving only
equipment within the high-voltage vault, room, or enclosure may be
installed in the high-voltage enclosure, room, or vault if accessible
to qualified persons only.
(iii) The following requirements apply to the entrances to all
buildings, rooms, or enclosures containing exposed live parts or
exposed conductors operating at over 600 volts, nominal:
(A) The entrances shall be kept locked unless they are under the
observation of a qualified person at all times; and
(B) Permanent and conspicuous warning signs shall be provided,
reading substantially as follows:
"DANGER--HIGH VOLTAGE--KEEP OUT."
(iv) Illumination shall be provided for all working spaces about
electric equipment.
(A) The lighting outlets shall be arranged so that persons changing
lamps or making repairs on the lighting system will not be endangered
by live parts or other equipment.
(B) The points of control shall be located so that persons are
prevented from contacting any live part or moving part of the equipment
while turning on the lights.
(v) Unguarded live parts above working space shall be maintained at
elevations not less than specified in Table S-3.
(vi) Pipes or ducts that are foreign to the electrical installation
and that require periodic maintenance or whose malfunction would
endanger the operation of the electrical system may not be located in
the vicinity of service equipment, metal-enclosed power switchgear, or
industrial control assemblies. Protection shall be provided where
necessary to avoid damage from condensation leaks and breaks in such
foreign systems.
Note to paragraph (h)(5)(vi) of this section: Piping and other
facilities are not considered foreign if provided for fire
protection of the electrical installation.
Table S-2.--Minimum Depth of Clear Working Space at Electric Equipment, Over 600 V
----------------------------------------------------------------------------------------------------------------
Minimum clear distance for condition \2\ \3\
-----------------------------------------------------------------
Nominal voltage to ground Condition A Condition B Condition C
-----------------------------------------------------------------
m ft m ft m ft
----------------------------------------------------------------------------------------------------------------
601-2500 V.................................... 0.9 3.0 1.2 4.0 1.5 5.0
2501-9000 V................................... 1.2 4.0 1.5 5.0 1.8 6.0
9001 V-25 kV.................................. 1.5 5.0 1.8 6.0 2.8 9.0
Over 25-75 kV \1\............................. 1.8 6.0 2.5 8.0 3.0 10.0
Above 75 kV \1\............................... 2.5 8.0 3.0 10.0 3.7 12.0
----------------------------------------------------------------------------------------------------------------
Notes to Table S-2:
\1\ Minimum depth of clear working space in front of electric equipment with a nominal voltage to ground above
25,000 volts may be the same as that for 25,000 volts under Conditions A, B, and C for installations built
before April 16, 1981.
\2\ Conditions A, B, and C are as follows:
Condition A--Exposed live parts on one side and no live or grounded parts on the other side of the working
space, or exposed live parts on both sides effectively guarded by suitable wood or other insulating material.
Insulated wire or insulated busbars operating at not over 300 volts are not considered live parts.
Condition B--Exposed live parts on one side and grounded parts on the other side. Concrete, brick, and tile
walls are considered as grounded surfaces.
Condition C--Exposed live parts on both sides of the work space (not guarded as provided in Condition A) with
the operator between.
\3\ Working space is not required in back of equipment such as dead-front switchboards or control assemblies
that has no renewable or adjustable parts (such as fuses or switches) on the back and where all connections
are accessible from locations other than the back. Where rear access is required to work on the deenergized
parts on the back of enclosed equipment, a minimum working space 762 mm (30 in.) horizontally shall be
provided.
Table S-3.--Elevation of Unguarded Live Parts Above Working Space
------------------------------------------------------------------------
Elevation
Nominal voltage between phases ---------------------------------------
m ft
------------------------------------------------------------------------
601-7500 V...................... \1\ 2.81.......... \1\ 9.01.
7501 V-35 kV.................... 2.8............... 9.0.
Over 35 kV...................... 2.8 + 9.5 mm/kV 9.0 + 0.37 in./kV
over 35 kV. over 35 kV.
------------------------------------------------------------------------
\1\ The minimum elevation may be 2.6 m (8.5 ft) for installations built
before August 13, 2007. The minimum elevation may be 2.4 m (8.0 ft)
for installations built before April 16, 1981, if the nominal voltage
between phases is in the range of 601-6600 volts.
Sec. 1910.304 Wiring design and protection.
(a) Use and identification of grounded and grounding conductors--
(1) Identification of conductors. (i) A conductor used as a grounded
conductor shall be identifiable and distinguishable from all other
conductors.
(ii) A conductor used as an equipment grounding conductor shall be
identifiable and distinguishable from all other conductors.
(2) Polarity of connections. No grounded conductor may be attached
to any terminal or lead so as to reverse designated polarity.
(3) Use of grounding terminals and devices. A grounding terminal or
grounding-type device on a receptacle, cord connector, or attachment
plug may not be used for purposes other than grounding.
(b) Branch circuits--(1) Identification of multiwire branch
circuits. Where more than one nominal voltage system exists in a
building containing multiwire branch circuits, each ungrounded
conductor of a multiwire branch circuit, where accessible, shall be
identified by phase and system. The means of identification shall be
permanently posted at each branch-circuit panelboard.
(2) Receptacles and cord connectors. (i) Receptacles installed on
15- and 20-ampere branch circuits shall be of the grounding type except
as permitted for replacement receptacles in paragraph (b)(2)(iv) of
this section. Grounding-type receptacles shall be installed only on
circuits of the voltage class and current for which they are rated,
except as provided in Table S-4 and Table S-5.
(ii) Receptacles and cord connectors having grounding contacts
shall have those contacts effectively grounded except for receptacles
mounted on portable and vehicle-mounted generators in accordance with
paragraph (g)(3) of this section and replacement receptacles installed
in accordance with paragraph (b)(2)(iv) of this section.
(iii) The grounding contacts of receptacles and cord connectors
shall be grounded by connection to the equipment grounding conductor of
the circuit supplying the receptacle or cord connector. The branch
circuit wiring method shall include or provide an equipment grounding
conductor to which the grounding contacts of the receptacle or cord
connector shall be connected.
(iv) Replacement of receptacles shall comply with the following
requirements:
(A) Where a grounding means exists in the receptacle enclosure or a
grounding conductor is installed, grounding-type receptacles shall be
used and shall be connected to the grounding means or conductor;
(B) Ground-fault circuit-interrupter protected receptacles shall be
provided where replacements are made at receptacle outlets that are
required to be so protected elsewhere in this subpart; and
(C) Where a grounding means does not exist in the receptacle
enclosure, the installation shall comply with one of the following
provisions:
(1) A nongrounding-type receptacle may be replaced with another
nongrounding-type receptacle; or
(2) A nongrounding-type receptacle may be replaced with a ground-
fault circuit-interrupter-type of receptacle that is marked "No
Equipment Ground;" an equipment grounding conductor may not be
connected from the ground-fault circuit-interrupter-type receptacle to
any outlet supplied from the ground-fault circuit-interrupter
receptacle; or
(3) A nongrounding-type receptacle may be replaced with a
grounding-type receptacle where supplied through a ground-fault
circuit-interrupter; the replacement receptacle shall be marked "GFCI
Protected" and "No Equipment Ground;" an equipment grounding
conductor may not be connected to such grounding-type receptacles.
(v) Receptacles connected to circuits having different voltages,
frequencies, or types of current (ac or dc) on the same premises shall
be of such design that the attachment plugs used on these circuits are
not interchangeable.
(3) Ground-fault circuit interrupter protection for personnel. (i)
All 125-volt, single-phase, 15- and 20-ampere receptacles installed in
bathrooms or on rooftops shall have ground-fault circuit-interrupter
protection for personnel.
(ii) The following requirements apply to temporary wiring
installations that are used during maintenance, remodeling, or repair
of buildings, structures, or equipment or during similar construction-
like activities.
(A) All 125-volt, single-phase, 15-, 20-, and 30-ampere receptacle
outlets that are not part of the permanent wiring of the building or
structure and that are in use by personnel shall have ground-fault
circuit-interrupter protection for personnel.
Note 1 to paragraph (b)(3)(ii)(A) of this section: A cord
connector on an extension cord set is considered to be a receptacle
outlet if the cord set is used for temporary electric power.
Note 2 to paragraph (b)(3)(ii)(A) of this section: Cord sets and
devices incorporating the required ground-fault circuit-interrupter
that are connected to the receptacle closest to the source of power
are acceptable forms of protection.
(B) Receptacles other than 125 volt, single-phase, 15-, 20-, and
30-ampere receptacles that are not part of the permanent wiring of the
building or structure and that are in use by personnel shall have
ground-fault circuit-interrupter protection for personnel.
(C) Where the ground-fault circuit-interrupter protection required
by paragraph (b)(3)(ii)(B) of this section is not available for
receptacles other than 125-volt, single-phase, 15-, 20-, and 30-ampere,
the employer shall establish and implement an assured equipment
grounding conductor program covering cord sets, receptacles that are
not a part of the building or structure, and equipment connected by
cord and plug that are available for use or used by employees on those
receptacles. This program shall comply with the following requirements:
(1) A written description of the program, including the specific
procedures adopted by the employer, shall be available at the jobsite
for inspection and copying by the Assistant Secretary of Labor and any
affected employee;
(2) The employer shall designate one or more competent persons to
implement the program;
(3) Each cord set, attachment cap, plug, and receptacle of cord
sets, and any equipment connected by cord and plug, except cord sets
and receptacles which are fixed and not exposed to damage, shall be
visually inspected before each day's use for external defects, such as
deformed or missing pins or insulation damage, and for indications of
possible internal damage. Equipment found damaged or defective shall
not be used until repaired;
(4) The following tests shall be performed on all cord sets and
receptacles which are not a part of the permanent wiring of the
building or structure, and cord- and plug-connected equipment required
to be grounded:
(i) All equipment grounding conductors shall be tested for
continuity and shall be electrically continuous;
(ii) Each receptacle and attachment cap or plug shall be tested for
correct attachment of the equipment grounding conductor. The equipment
grounding conductor shall be connected to its proper terminal; and
(iii) All required tests shall be performed before first use;
before equipment is returned to service following any repairs; before
equipment is used after any incident which can be reasonably suspected
to have caused damage (for example, when a cord set is run over); and
at intervals not to exceed 3 months, except that cord sets and
receptacles which are fixed and not exposed to damage shall be tested
at intervals not exceeding 6 months;
(5) The employer shall not make available or permit the use by
employees of any equipment which has not met the requirements of
paragraph (b)(3)(ii)(C) of this section; and
(6) Tests performed as required in paragraph (b)(3)(ii)(C) of this
section shall be recorded. This test record shall identify each
receptacle, cord set, and cord- and plug-connected equipment that
passed the test and shall indicate the last date it was tested or the
interval for which it was tested. This record shall be kept by means of
logs, color coding, or other effective means and shall be maintained
until replaced by a more current record. The record shall be made
available on the jobsite for inspection by the Assistant Secretary and
any affected employee.
(4) Outlet devices. Outlet devices shall have an ampere rating not
less than the load to be served and shall comply with the following
provisions:
(i) Where connected to a branch circuit having a rating in excess
of 20 amperes, lampholders shall be of the heavy-duty type. A heavy-
duty lampholder shall have a rating of not less than 660 watts if of
the admedium type and not less than 750 watts if of any other type; and
(ii) Receptacle outlets shall comply with the following provisions:
(A) A single receptacle installed on an individual branch circuit
shall have an ampere rating of not less than that of the branch
circuit;
(B) Where connected to a branch circuit supplying two or more
receptacles or outlets, a receptacle may not supply a total cord- and
plug-connected load in excess of the maximum specified in Table S-4;
and
(C) Where connected to a branch circuit supplying two or more
receptacles or outlets, receptacle ratings shall conform to the values
listed in Table S-5; or, where larger than 50 amperes, the receptacle
rating may not be less than the branch-circuit rating. However,
receptacles of cord- and plug-connected arc welders may have ampere
ratings not less than the minimum branch-circuit conductor ampacity.
(5) Cord connections. A receptacle outlet shall be installed
wherever flexible cords with attachment plugs are used. Where flexible
cords are permitted to be permanently connected, receptacles may be
omitted.
Table S-4.--Maximum Cord- and Plug-Connected Load to Receptacle
------------------------------------------------------------------------
Receptacle Maximum
Circuit rating (amperes) rating load
(amperes) (amperes)
------------------------------------------------------------------------
15 or 20...................................... 15 12
20............................................ 20 16
30............................................ 30 24
------------------------------------------------------------------------
Table S-5.--Receptacle Ratings for Various Size Circuits
------------------------------------------------------------------------
Circuit rating (amperes) Receptacle rating (amperes)
------------------------------------------------------------------------
15........................................ Not over 15.
20........................................ 15 or 20.
30........................................ 30.
40........................................ 40 or 50.
50........................................ 50.
------------------------------------------------------------------------
(c) Outside conductors, 600 volts, nominal, or less. The following
requirements apply to branch-circuit, feeder, and service conductors
rated 600 volts, nominal, or less and run outdoors as open conductors.
(1) Conductors on poles. Conductors on poles shall have a
separation of not less than 305 mm (1.0 ft) where not placed on racks
or brackets. Conductors supported on poles shall provide a horizontal
climbing space not less than the following:
(i) Power conductors below communication conductors--762 mm (30
in.);
(ii) Power conductors alone or above communication conductors:
(A) 300 volts or less--610 mm (24 in.),
(B) Over 300 volts--762 mm (30 in.);
(iii) Communication conductors below power conductors--same as
power conductors; and
(iv) Communications conductors alone--no requirement.
(2) Clearance from ground. Open conductors, open multiconductor
cables, and service-drop conductors of not over 600 volts, nominal,
shall conform to the minimum clearances specified in Table S-6.
Table S-66.--Clearances From Ground
----------------------------------------------------------------------------------------------------------------
Installations built before August 13, Installations built on or after
2007 August 13, 2007
Distance ----------------------------------------------------------------------------
Maximum voltage Conditions Voltage to ground Conditions
----------------------------------------------------------------------------------------------------------------
3.05 m (10.0 ft)................... < 600 V........... Above finished < 150 V........... Above finished
grade or grade or
sidewalks, or sidewalks, or
from any from any
platform or platform or
projection from projection from
which they might which they
be reached. (If might be
these areas are reached. (If
accessible to these areas are
other than accessible to
pedestrian other than
traffic, then pedestrian
one of the other traffic, then
conditions one of the
applies). other
conditions
applies.)
3.66 m (12.0 ft)................... < 600 V........... Over areas, other < 300 V........... Over residential
than public property and
streets, alleys, driveways. Over
roads, and commercial
driveways, areas subject
subject to to pedestrian
vehicular traffic or to
traffic other vehicular
than truck traffic other
traffic. than truck
traffic. (This
category
includes
conditions
covered under
the 3.05-m
(10.0-ft)
category where
the voltage
exceeds 150 V.)
4.57 m (15.0 ft)................... < 600 V........... Over areas, other 301 to 600 V...... Over residential
than public property and
streets, alleys, driveways. Over
roads, and commercial
driveways, areas subject
subject to truck to pedestrian
traffic. traffic or to
vehicular
traffic other
than truck
traffic. (This
category
includes
conditions
covered under
the 3.05-m
(10.0-ft)
category where
the voltage
exceeds 300 V.)
5.49 m (18.0 ft)................... < 600 V........... Over public < 600 V........... Over public
streets, alleys, streets,
roads, and alleys, roads,
driveways. and driveways.
Over commercial
areas subject
to truck
traffic. Other
land traversed
by vehicles,
including land
used for
cultivating or
grazing and
forests and
orchards.
----------------------------------------------------------------------------------------------------------------
(3) Clearance from building openings. (i) Service conductors
installed as open conductors or multiconductor cable without an overall
outer jacket shall have a clearance of not less than 914 mm (3.0 ft)
from windows that are designed to be opened, doors, porches, balconies,
ladders, stairs, fire escapes, and similar locations. However,
conductors that run above the top level of a window may be less than
914 mm (3.0 ft) from the window. Vertical clearance of final spans
above, or within 914 mm (3.0 ft) measured horizontally of, platforms,
projections, or surfaces from which they might be reached shall be
maintained in accordance with paragraph (c)(2) of this section.
(ii) Overhead service conductors may not be installed beneath
openings through which materials may be moved, such as openings in farm
and commercial buildings, and may not be installed where they will obstruct
entrance to these building openings.
(4) Above roofs. Overhead spans of open conductors and open
multiconductor cables shall have a vertical clearance of not less than
2.44 m (8.0 ft) above the roof surface. The vertical clearance above
the roof level shall be maintained for a distance not less than 914 mm
(3.0 ft) in all directions from the edge of the roof.
(i) The area above a roof surface subject to pedestrian or
vehicular traffic shall have a vertical clearance from the roof surface
in accordance with the clearance requirements of paragraph (c)(2) of
this section.
(ii) A reduction in clearance to 914 mm (3.0 ft) is permitted where
the voltage between conductors does not exceed 300 and the roof has a
slope of 102 mm (4 in.) in 305 mm (12 in.) or greater.
(iii) A reduction in clearance above only the overhanging portion
of the roof to not less than 457 mm (18 in.) is permitted where the
voltage between conductors does not exceed 300 if:
(A) The conductors do not pass above the roof overhang for a
distance of more than 1.83 m (6.0 ft), 1.22 m (4.0 ft) horizontally,
and
(B) The conductors are terminated at a through-the-roof raceway or
approved support.
(iv) The requirement for maintaining a vertical clearance of 914 mm
(3.0 ft) from the edge of the roof does not apply to the final
conductor span, where the conductors are attached to the side of a
building.
(d) Location of outdoor lamps. Lamps for outdoor lighting shall be
located below all energized conductors, transformers, or other electric
equipment, unless such equipment is controlled by a disconnecting means
that can be locked in the open position, or unless adequate clearances
or other safeguards are provided for relamping operations.
(e) Services--(1) Disconnecting means. (i) Means shall be provided
to disconnect all conductors in a building or other structure from the
service-entrance conductors. The service disconnecting means shall
plainly indicate whether it is in the open or closed position and shall
be installed at a readily accessible location nearest the point of
entrance of the service-entrance conductors.
(ii) Each service disconnecting means shall simultaneously
disconnect all ungrounded conductors.
(iii) Each service disconnecting means shall be suitable for the
prevailing conditions.
(2) Services over 600 volts, nominal. The following additional
requirements apply to services over 600 volts, nominal.
(i) Service-entrance conductors installed as open wires shall be
guarded to make them accessible only to qualified persons.
(ii) Signs warning of high voltage shall be posted where
unqualified employees might come in contact with live parts.
(f) Overcurrent protection--(1) 600 volts, nominal, or less. The
following requirements apply to overcurrent protection of circuits
rated 600 volts, nominal, or less.
(i) Conductors and equipment shall be protected from overcurrent in
accordance with their ability to safely conduct current.
(ii) Except for motor running overload protection, overcurrent
devices may not interrupt the continuity of the grounded conductor
unless all conductors of the circuit are opened simultaneously.
(iii) A disconnecting means shall be provided on the supply side of
all fuses in circuits over 150 volts to ground and cartridge fuses in
circuits of any voltage where accessible to other than qualified
persons so that each individual circuit containing fuses can be
independently disconnected from the source of power. However, a
current-limiting device without a disconnecting means is permitted on
the supply side of the service disconnecting means. In addition, a
single disconnecting means is permitted on the supply side of more than
one set of fuses as permitted by the exception in Sec.
1910.305(j)(4)(vi) for group operation of motors, and a single
disconnecting means is permitted for fixed electric space-heating
equipment.
(iv) Overcurrent devices shall be readily accessible to each
employee or authorized building management personnel. These overcurrent
devices may not be located where they will be exposed to physical
damage or in the vicinity of easily ignitable material.
(v) Fuses and circuit breakers shall be so located or shielded that
employees will not be burned or otherwise injured by their operation.
Handles or levers of circuit breakers, and similar parts that may move
suddenly in such a way that persons in the vicinity are likely to be
injured by being struck by them, shall be guarded or isolated.
(vi) Circuit breakers shall clearly indicate whether they are in
the open (off) or closed (on) position.
(vii) Where circuit breaker handles on switchboards are operated
vertically rather than horizontally or rotationally, the up position of
the handle shall be the closed (on) position.
(viii) Circuit breakers used as switches in 120-volt and 277-volt,
fluorescent lighting circuits shall be listed and marked "SWD."
(ix) A circuit breaker with a straight voltage rating, such as 240
V or 480 V, may only be installed in a circuit in which the nominal
voltage between any two conductors does not exceed the circuit
breaker's voltage rating. A two-pole circuit breaker may not be used
for protecting a 3-phase, corner-grounded delta circuit unless the
circuit breaker is marked 1[Phi]--3[Phi] to indicate such suitability.
A circuit breaker with a slash rating, such as 120/240 V or 480Y/277 V,
may only be installed in a circuit where the nominal voltage of any
conductor to ground does not exceed the lower of the two values of the
circuit breaker's voltage rating and the nominal voltage between any
two conductors does not exceed the higher value of the circuit
breaker's voltage rating.
(2) Feeders and branch circuits over 600 volts, nominal. The
following requirements apply to feeders and branch circuits energized
at more than 600 volts, nominal:
(i) Feeder and branch-circuit conductors shall have overcurrent
protection in each ungrounded conductor located at the point where the
conductor receives its supply or at a location in the circuit
determined under engineering supervision;
(A) Circuit breakers used for overcurrent protection of three-phase
circuits shall have a minimum of three overcurrent relays operated from
three current transformers. On three-phase, three-wire circuits, an
overcurrent relay in the residual circuit of the current transformers
may replace one of the phase relays. An overcurrent relay, operated
from a current transformer that links all phases of a three-phase,
three-wire circuit, may replace the residual relay and one other phase-
conductor current transformer. Where the neutral is not grounded on the
load side of the circuit, the current transformer may link all three
phase conductors and the grounded circuit conductor (neutral); and
(B) If fuses are used for overcurrent protection, a fuse shall be
connected in series with each ungrounded conductor;
(ii) Each protective device shall be capable of detecting and
interrupting all values of current that can occur at its location in
excess of its trip setting or melting point;
(iii) The operating time of the protective device, the available
short-circuit current, and the conductor used shall be coordinated to
prevent damaging or dangerous temperatures in conductors or conductor
insulation under short-circuit conditions; and
(iv) The following additional requirements apply to feeders only:
(A) The continuous ampere rating of a fuse may not exceed three
times the ampacity of the conductors. The long-time trip element
setting of a breaker or the minimum trip setting of an electronically
actuated fuse may not exceed six times the ampacity of the conductor.
For fire pumps, conductors may be protected for short circuit only; and
(B) Conductors tapped to a feeder may be protected by the feeder
overcurrent device where that overcurrent device also protects the tap
conductor.
(g) Grounding. Paragraphs (g)(1) through (g)(9) of this section
contain grounding requirements for systems, circuits, and equipment.
(1) Systems to be grounded. Systems that supply premises wiring
shall be grounded as follows:
(i) All 3-wire dc systems shall have their neutral conductor
grounded;
(ii) Two-wire dc systems operating at over 50 volts through 300
volts between conductors shall be grounded unless:
(A) They supply only industrial equipment in limited areas and are
equipped with a ground detector;
(B) They are rectifier-derived from an ac system complying with
paragraphs (g)(1)(iii), (g)(1)(iv), and (g)(1)(v) of this section; or
(C) They are fire-alarm circuits having a maximum current of 0.030
amperes;
(iii) AC circuits of less than 50 volts shall be grounded if they
are installed as overhead conductors outside of buildings or if they
are supplied by transformers and the transformer primary supply system
is ungrounded or exceeds 150 volts to ground;
(iv) AC systems of 50 volts to 1000 volts shall be grounded under
any of the following conditions, unless exempted by paragraph (g)(1)(v)
of this section:
(A) If the system can be so grounded that the maximum voltage to
ground on the ungrounded conductors does not exceed 150 volts;
(B) If the system is nominally rated three-phase, four-wire wye
connected in which the neutral is used as a circuit conductor;
(C) If the system is nominally rated three-phase, four-wire delta
connected in which the midpoint of one phase is used as a circuit
conductor; or
(D) If a service conductor is uninsulated;
(v) AC systems of 50 volts to 1000 volts are not required to be
grounded under any of the following conditions:
(A) If the system is used exclusively to supply industrial electric
furnaces for melting, refining, tempering, and the like;
(B) If the system is separately derived and is used exclusively for
rectifiers supplying only adjustable speed industrial drives;
(C) If the system is separately derived and is supplied by a
transformer that has a primary voltage rating less than 1000 volts,
provided all of the following conditions are met:
(1) The system is used exclusively for control circuits;
(2) The conditions of maintenance and supervision ensure that only
qualified persons will service the installation;
(3) Continuity of control power is required; and
(4) Ground detectors are installed on the control system;
(D) If the system is an isolated power system that supplies
circuits in health care facilities; or
(E) If the system is a high-impedance grounded neutral system in
which a grounding impedance, usually a resistor, limits the ground-
fault current to a low value for 3-phase ac systems of 480 volts to
1000 volts provided all of the following conditions are met:
(1) The conditions of maintenance and supervision ensure that only
qualified persons will service the installation;
(2) Continuity of power is required;
(3) Ground detectors are installed on the system; and
(4) Line-to-neutral loads are not served.
(2) Conductor to be grounded. The conductor to be grounded for ac
premises wiring systems required to be grounded by paragraph (g)(1) of
this section shall be as follows:
(i) One conductor of a single-phase, two-wire system shall be
grounded;
(ii) The neutral conductor of a single-phase, three-wire system
shall be grounded;
(iii) The common conductor of a multiphase system having one wire
common to all phases shall be grounded;
(iv) One phase conductor of a multiphase system where one phase is
grounded shall be grounded; and
(v) The neutral conductor of a multiphase system in which one phase
is used as a neutral conductor shall be grounded.
(3) Portable and vehicle-mounted generators. (i) The frame of a
portable generator need not be grounded and may serve as the grounding
electrode for a system supplied by the generator under the following
conditions:
(A) The generator supplies only equipment mounted on the generator
or cord- and plug-connected equipment through receptacles mounted on
the generator, or both; and
(B) The noncurrent-carrying metal parts of equipment and the
equipment grounding conductor terminals of the receptacles are bonded
to the generator frame.
(ii) The frame of a vehicle need not be grounded and may serve as
the grounding electrode for a system supplied by a generator located on
the vehicle under the following conditions:
(A) The frame of the generator is bonded to the vehicle frame;
(B) The generator supplies only equipment located on the vehicle
and cord- and plug-connected equipment through receptacles mounted on
the vehicle;
(C) The noncurrent-carrying metal parts of equipment and the
equipment grounding conductor terminals of the receptacles are bonded
to the generator frame; and
(D) The system complies with all other provisions of paragraph (g)
of this section.
(iii) A system conductor that is required to be grounded by the
provisions of paragraph (g)(2) of this section shall be bonded to the
generator frame where the generator is a component of a separately
derived system.
(4) Grounding connections. (i) For a grounded system, a grounding
electrode conductor shall be used to connect both the equipment
grounding conductor and the grounded circuit conductor to the grounding
electrode. Both the equipment grounding conductor and the grounding
electrode conductor shall be connected to the grounded circuit
conductor on the supply side of the service disconnecting means or on
the supply side of the system disconnecting means or overcurrent
devices if the system is separately derived.
(ii) For an ungrounded service-supplied system, the equipment
grounding conductor shall be connected to the grounding electrode
conductor at the service equipment. For an ungrounded separately
derived system, the equipment grounding conductor shall be connected to
the grounding electrode conductor at, or ahead of, the system
disconnecting means or overcurrent devices.
(iii) On extensions of existing branch circuits that do not have an
equipment grounding conductor, grounding-type receptacles may be
grounded to a grounded cold water pipe near the equipment if the
extension was installed before August 13, 2007. When any element of this
branch circuit is replaced, the entire branch circuit shall use an equipment
grounding conductor that complies with all other provisions of paragraph
(g) of this section.
(5) Grounding path. The path to ground from circuits, equipment,
and enclosures shall be permanent, continuous, and effective.
(6) Supports, enclosures, and equipment to be grounded. (i) Metal
cable trays, metal raceways, and metal enclosures for conductors shall
be grounded, except that:
(A) Metal enclosures such as sleeves that are used to protect cable
assemblies from physical damage need not be grounded; and
(B) Metal enclosures for conductors added to existing installations
of open wire, knob-and-tube wiring, and nonmetallic-sheathed cable need
not be grounded if all of the following conditions are met:
(1) Runs are less than 7.62 meters (25.0 ft);
(2) Enclosures are free from probable contact with ground, grounded
metal, metal laths, or other conductive materials; and
(3) Enclosures are guarded against employee contact.
(ii) Metal enclosures for service equipment shall be grounded.
(iii) Frames of electric ranges, wall-mounted ovens, counter-
mounted cooking units, clothes dryers, and metal outlet or junction
boxes that are part of the circuit for these appliances shall be
grounded.
(iv) Exposed noncurrent-carrying metal parts of fixed equipment
that may become energized shall be grounded under any of the following
conditions:
(A) If within 2.44 m (8 ft) vertically or 1.52 m (5 ft)
horizontally of ground or grounded metal objects and subject to
employee contact;
(B) If located in a wet or damp location and not isolated;
(C) If in electrical contact with metal;
(D) If in a hazardous (classified) location;
(E) If supplied by a metal-clad, metal-sheathed, or grounded metal
raceway wiring method; or
(F) If equipment operates with any terminal at over 150 volts to
ground.
(v) Notwithstanding the provisions of paragraph (g)(6)(iv) of this
section, exposed noncurrent-carrying metal parts of the following types
of fixed equipment need not be grounded:
(A) Enclosures for switches or circuit breakers used for other than
service equipment and accessible to qualified persons only;
(B) Electrically heated appliances that are permanently and
effectively insulated from ground;
(C) Distribution apparatus, such as transformer and capacitor
cases, mounted on wooden poles, at a height exceeding 2.44 m (8.0 ft)
above ground or grade level; and
(D) Listed equipment protected by a system of double insulation, or
its equivalent, and distinctively marked as such.
(vi) Exposed noncurrent-carrying metal parts of cord- and plug-
connected equipment that may become energized shall be grounded under
any of the following conditions:
(A) If in hazardous (classified) locations (see Sec. 1910.307);
(B) If operated at over 150 volts to ground, except for guarded
motors and metal frames of electrically heated appliances if the
appliance frames are permanently and effectively insulated from ground;
(C) If the equipment is of the following types:
(1) Refrigerators, freezers, and air conditioners;
(2) Clothes-washing, clothes-drying, and dishwashing machines, sump
pumps, and electric aquarium equipment;
(3) Hand-held motor-operated tools, stationary and fixed motor-
operated tools, and light industrial motor-operated tools;
(4) Motor-operated appliances of the following types: hedge
clippers, lawn mowers, snow blowers, and wet scrubbers;
(5) Cord- and plug-connected appliances used in damp or wet
locations, or by employees standing on the ground or on metal floors or
working inside of metal tanks or boilers;
(6) Portable and mobile X-ray and associated equipment;
(7) Tools likely to be used in wet and conductive locations; and
(8) Portable hand lamps.
(vii) Notwithstanding the provisions of paragraph (g)(6)(vi) of
this section, the following equipment need not be grounded:
(A) Tools likely to be used in wet and conductive locations if
supplied through an isolating transformer with an ungrounded secondary
of not over 50 volts; and
(B) Listed or labeled portable tools and appliances if protected by
an approved system of double insulation, or its equivalent, and
distinctively marked.
(7) Nonelectrical equipment. The metal parts of the following
nonelectrical equipment shall be grounded: frames and tracks of
electrically operated cranes and hoists; frames of nonelectrically
driven elevator cars to which electric conductors are attached; hand-
operated metal shifting ropes or cables of electric elevators; and
metal partitions, grill work, and similar metal enclosures around
equipment of over 750 volts between conductors.
(8) Methods of grounding fixed equipment. (i) Noncurrent-carrying
metal parts of fixed equipment, if required to be grounded by this
subpart, shall be grounded by an equipment grounding conductor that is
contained within the same raceway, cable, or cord, or runs with or
encloses the circuit conductors. For dc circuits only, the equipment
grounding conductor may be run separately from the circuit conductors.
(ii) Electric equipment is considered to be effectively grounded if
it is secured to, and in electrical contact with, a metal rack or
structure that is provided for its support and the metal rack or
structure is grounded by the method specified for the noncurrent-
carrying metal parts of fixed equipment in paragraph (g)(8)(i) of this
section. Metal car frames supported by metal hoisting cables attached
to or running over metal sheaves or drums of grounded elevator machines
are also considered to be effectively grounded.
(iii) For installations made before April 16, 1981, electric
equipment is also considered to be effectively grounded if it is
secured to, and in metallic contact with, the grounded structural metal
frame of a building. When any element of this branch circuit is
replaced, the entire branch circuit shall use an equipment grounding
conductor that complies with all other provisions of paragraph (g) of
this section.
(9) Grounding of systems and circuits of 1000 volts and over (high
voltage). If high voltage systems are grounded, they shall comply with
all applicable provisions of paragraphs (g)(1) through (g)(8) of this
section as supplemented and modified by the following requirements:
(i) Systems supplying portable or mobile high voltage equipment,
other than substations installed on a temporary basis, shall comply
with the following:
(A) The system shall have its neutral grounded through an
impedance. If a delta-connected high voltage system is used to supply
the equipment, a system neutral shall be derived.
(B) Exposed noncurrent-carrying metal parts of portable and mobile
equipment shall be connected by an equipment grounding conductor to the
point at which the system neutral impedance is grounded.
(C) Ground-fault detection and relaying shall be provided to
automatically deenergize any high voltage system component that has
developed a ground fault. The continuity of the equipment grounding
conductor shall be continuously monitored so as to deenergize
automatically the high voltage feeder to the portable equipment upon
loss of continuity of the equipment grounding conductor.
(D) The grounding electrode to which the portable equipment system
neutral impedance is connected shall be isolated from and separated in
the ground by at least 6.1 m (20.0 ft) from any other system or
equipment grounding electrode, and there shall be no direct connection
between the grounding electrodes, such as buried pipe, fence, and so
forth.
(ii) All noncurrent-carrying metal parts of portable equipment and
fixed equipment, including their associated fences, housings,
enclosures, and supporting structures, shall be grounded. However,
equipment that is guarded by location and isolated from ground need not
be grounded. Additionally, pole-mounted distribution apparatus at a
height exceeding 2.44 m (8.0 ft) above ground or grade level need not
be grounded.
Sec. 1910.305 Wiring methods, components, and equipment for general
use.
(a) Wiring methods. The provisions of this section do not apply to
conductors that are an integral part of factory-assembled equipment.
(1) General requirements. (i) Metal raceways, cable trays, cable
armor, cable sheath, enclosures, frames, fittings, and other metal
noncurrent-carrying parts that are to serve as grounding conductors,
with or without the use of supplementary equipment grounding
conductors, shall be effectively bonded where necessary to ensure
electrical continuity and the capacity to conduct safely any fault
current likely to be imposed on them. Any nonconductive paint, enamel,
or similar coating shall be removed at threads, contact points, and
contact surfaces or be connected by means of fittings designed so as to
make such removal unnecessary.
(ii) Where necessary for the reduction of electrical noise
(electromagnetic interference) of the grounding circuit, an equipment
enclosure supplied by a branch circuit may be isolated from a raceway
containing circuits supplying only that equipment by one or more listed
nonmetallic raceway fittings located at the point of attachment of the
raceway to the equipment enclosure. The metal raceway shall be
supplemented by an internal insulated equipment grounding conductor
installed to ground the equipment enclosure.
(iii) No wiring systems of any type may be installed in ducts used
to transport dust, loose stock, or flammable vapors. No wiring system
of any type may be installed in any duct used for vapor removal or for
ventilation of commercial-type cooking equipment, or in any shaft
containing only such ducts.
(2) Temporary wiring. Except as specifically modified in this
paragraph, all other requirements of this subpart for permanent wiring
shall also apply to temporary wiring installations.
(i) Temporary electrical power and lighting installations of 600
volts, nominal, or less may be used only as follows:
(A) During and for remodeling, maintenance, or repair of buildings,
structures, or equipment, and similar activities;
(B) For a period not to exceed 90 days for Christmas decorative
lighting, carnivals, and similar purposes; or
(C) For experimental or development work, and during emergencies.
(ii) Temporary wiring shall be removed immediately upon completion
of the project or purpose for which the wiring was installed.
(iii) Temporary electrical installations of more than 600 volts may
be used only during periods of tests, experiments, emergencies, or
construction-like activities.
(iv) The following requirements apply to feeders:
(A) Feeders shall originate in an approved distribution center.
(B) Conductors shall be run as multiconductor cord or cable
assemblies. However, if installed as permitted in paragraph
(a)(2)(i)(C) of this section, and if accessible only to qualified
persons, feeders may be run as single insulated conductors.
(v) The following requirements apply to branch circuits:
(A) Branch circuits shall originate in an approved power outlet or
panelboard.
(B) Conductors shall be multiconductor cord or cable assemblies or
open conductors. If run as open conductors, they shall be fastened at
ceiling height every 3.05 m (10.0 ft).
(C) No branch-circuit conductor may be laid on the floor.
(D) Each branch circuit that supplies receptacles or fixed
equipment shall contain a separate equipment grounding conductor if run
as open conductors.
(vi) Receptacles shall be of the grounding type. Unless installed
in a continuous grounded metallic raceway or metallic covered cable,
each branch circuit shall contain a separate equipment grounding
conductor and all receptacles shall be electrically connected to the
grounding conductor.
(vii) No bare conductors nor earth returns may be used for the
wiring of any temporary circuit.
(viii) Suitable disconnecting switches or plug connectors shall be
installed to permit the disconnection of all ungrounded conductors of
each temporary circuit. Multiwire branch circuits shall be provided
with a means to disconnect simultaneously all ungrounded conductors at
the power outlet or panelboard where the branch circuit originated.
Note to paragraph (a)(2)(viii) of this section. Circuit breakers
with their handles connected by approved handle ties are considered
a single disconnecting means for the purpose of this requirement.
(ix) All lamps for general illumination shall be protected from
accidental contact or breakage by a suitable fixture or lampholder with
a guard. Brass shell, paper-lined sockets, or other metal-cased sockets
may not be used unless the shell is grounded.
(x) Flexible cords and cables shall be protected from accidental
damage, as might be caused, for example, by sharp corners, projections,
and doorways or other pinch points.
(xi) Cable assemblies and flexible cords and cables shall be
supported in place at intervals that ensure that they will be protected
from physical damage. Support shall be in the form of staples, cables
ties, straps, or similar type fittings installed so as not to cause
damage.
(3) Cable trays. (i) Only the following wiring methods may be
installed in cable tray systems: armored cable; electrical metallic
tubing; electrical nonmetallic tubing; fire alarm cables; flexible
metal conduit; flexible metallic tubing; instrumentation tray cable;
intermediate metal conduit; liquidtight flexible metal conduit;
liquidtight flexible nonmetallic conduit; metal-clad cable; mineral-
insulated, metal-sheathed cable; multiconductor service-entrance cable;
multiconductor underground feeder and branch-circuit cable;
multipurpose and communications cables; nonmetallic-sheathed cable;
power and control tray cable; power-limited tray cable; optical fiber
cables; and other factory-assembled, multiconductor control, signal, or
power cables that are specifically approved for installation in cable
trays, rigid metal conduit, and rigid nonmetallic conduit.
(ii) In industrial establishments where conditions of maintenance
and supervision assure that only qualified persons will service the
installed cable tray system, the following cables may also be installed
in ladder, ventilated-trough, or ventilated-channel cable trays:
(A) Single conductor cable; the cable shall be No. 1/0 or larger
and shall be of a type listed and marked on the surface for use in
cable trays; where Nos. 1/0 through 4/0 single conductor cables are
installed in ladder cable tray, the maximum allowable rung spacing for
the ladder cable tray shall be 229 mm (9 in.); where exposed to direct
rays of the sun, cables shall be identified as being sunlight
resistant;
(B) Welding cables installed in dedicated cable trays;
(C) Single conductors used as equipment grounding conductors; these
conductors, which may be insulated, covered, or bare, shall be No. 4 or
larger; and
(D) Multiconductor cable, Type MV; where exposed to direct rays of
the sun, the cable shall be identified as being sunlight resistant.
(iii) Metallic cable trays may be used as equipment grounding
conductors only where continuous maintenance and supervision ensure
that qualified persons will service the installed cable tray system.
(iv) Cable trays in hazardous (classified) locations may contain
only the cable types permitted in such locations. (See Sec. 1910.307.)
(v) Cable tray systems may not be used in hoistways or where
subjected to severe physical damage.
(4) Open wiring on insulators. (i) Open wiring on insulators is
only permitted on systems of 600 volts, nominal, or less for industrial
or agricultural establishments, indoors or outdoors, in wet or dry
locations, where subject to corrosive vapors, and for services.
(ii) Conductors smaller than No. 8 shall be rigidly supported on
noncombustible, nonabsorbent insulating materials and may not contact
any other objects. Supports shall be installed as follows:
(A) Within 152 mm (6 in.) from a tap or splice;
(B) Within 305 mm (12 in.) of a dead-end connection to a lampholder
or receptacle; and
(C) At intervals not exceeding 1.37 m (4.5 ft), and at closer
intervals sufficient to provide adequate support where likely to be
disturbed.
(iii) In dry locations, where not exposed to severe physical
damage, conductors may be separately enclosed in flexible nonmetallic
tubing. The tubing shall be in continuous lengths not exceeding 4.57 m
(15.0 ft) and secured to the surface by straps at intervals not
exceeding 1.37 m (4.5 ft).
(iv) Open conductors shall be separated from contact with walls,
floors, wood cross members, or partitions through which they pass by
tubes or bushings of noncombustible, nonabsorbent insulating material.
If the bushing is shorter than the hole, a waterproof sleeve of
nonconductive material shall be inserted in the hole and an insulating
bushing slipped into the sleeve at each end in such a manner as to keep
the conductors absolutely out of contact with the sleeve. Each
conductor shall be carried through a separate tube or sleeve.
(v) Where open conductors cross ceiling joints and wall studs and
are exposed to physical damage (for example, located within 2.13 m (7.0
ft) of the floor), they shall be protected.
(b) Cabinets, boxes, and fittings--(1) Conductors entering boxes,
cabinets, or fittings. (i) Conductors entering cutout boxes, cabinets,
or fittings shall be protected from abrasion, and openings through
which conductors enter shall be effectively closed.
(ii) Unused openings in cabinets, boxes, and fittings shall be
effectively closed.
(iii) Where cable is used, each cable shall be secured to the
cabinet, cutout box, or meter socket enclosure. However, where cable
with an entirely nonmetallic sheath enters the top of a surface-mounted
enclosure through one or more nonflexible raceways not less than 457 mm
(18 in.) or more than 3.05 m (10.0 ft) in length, the cable need not be
secured to the cabinet, box, or enclosure provided all of the following
conditions are met:
(A) Each cable is fastened within 305 mm (12 in.) of the outer end
of the raceway, measured along the sheath;
(B) The raceway extends directly above the enclosure and does not
penetrate a structural ceiling;
(C) A fitting is provided on each end of the raceway to protect the
cable from abrasion, and the fittings remain accessible after
installation;
(D) The raceway is sealed or plugged at the outer end using
approved means so as to prevent access to the enclosure through the
raceway;
(E) The cable sheath is continuous through the raceway and extends
into the enclosure not less than 6.35 mm (0.25 in.) beyond the fitting;
(F) The raceway is fastened at its outer end and at other points as
necessary; and
(G) Where installed as conduit or tubing, the allowable cable fill
does not exceed that permitted for complete conduit or tubing systems.
(2) Covers and canopies. (i) All pull boxes, junction boxes, and
fittings shall be provided with covers identified for the purpose. If
metal covers are used, they shall be grounded. In completed
installations, each outlet box shall have a cover, faceplate, or
fixture canopy. Covers of outlet boxes having holes through which
flexible cord pendants pass shall be provided with bushings designed
for the purpose or shall have smooth, well-rounded surfaces on which
the cords may bear.
(ii) Where a fixture canopy or pan is used, any combustible wall or
ceiling finish exposed between the edge of the canopy or pan and the
outlet box shall be covered with noncombustible material.
(3) Pull and junction boxes for systems over 600 volts, nominal. In
addition to other requirements in this section, the following
requirements apply to pull and junction boxes for systems over 600
volts, nominal:
(i) Boxes shall provide a complete enclosure for the contained
conductors or cables.
(ii) Boxes shall be closed by suitable covers securely fastened in
place.
Note to paragraph (b)(3)(ii) of this section: Underground box
covers that weigh over 45.4 kg (100 lbs) meet this requirement.
(iii) Covers for boxes shall be permanently marked "HIGH
VOLTAGE." The marking shall be on the outside of the box cover and
shall be readily visible and legible.
(c) Switches--(1) Single-throw knife switches. Single-throw knife
switches shall be so placed that gravity will not tend to close them.
Single-throw knife switches approved for use in the inverted position
shall be provided with a locking device that will ensure that the
blades remain in the open position when so set.
(2) Double-throw knife switches. Double-throw knife switches may be
mounted so that the throw will be either vertical or horizontal.
However, if the throw is vertical, a locking device shall be provided
to ensure that the blades remain in the open position when so set.
(3) Connection of switches. (i) Single-throw knife switches and
switches with butt contacts shall be connected so that the blades are
deenergized when the switch is in the open position.
(ii) Single-throw knife switches, molded-case switches, switches
with butt contacts, and circuit breakers used as switches shall be
connected so that the terminals supplying the load are deenergized when
the switch is in the open position. However, blades and terminals
supplying the load of a switch may be energized when the switch is in
the open position where the switch is connected to circuits or equipment
inherently capable of providing a backfeed source of power. For such
installations, a permanent sign shall be installed on the switch enclosure
or immediately adjacent to open switches that read, "WARNING--LOAD SIDE
TERMINALS MAY BE ENERGIZED BY BACKFEED."
(4) Faceplates for flush-mounted snap switches. Snap switches
mounted in boxes shall have faceplates installed so as to completely
cover the opening and seat against the finished surface.
(5) Grounding. Snap switches, including dimmer switches, shall be
effectively grounded and shall provide a means to ground metal
faceplates, whether or not a metal faceplate is installed. However, if
no grounding means exists within the snap-switch enclosure, or where
the wiring method does not include or provide an equipment ground, a
snap switch without a grounding connection is permitted for replacement
purposes only. Such snap switches shall be provided with a faceplate of
nonconducting, noncombustible material if they are located within reach
of conducting floors or other conducting surfaces.
(d) Switchboards and panelboards--(1) Switchboards with exposed
live parts. Switchboards that have any exposed live parts shall be
located in permanently dry locations and shall be accessible only to
qualified persons.
(2) Panelboard enclosures. Panelboards shall be mounted in
cabinets, cutout boxes, or enclosures designed for the purpose and
shall be dead front. However, panelboards other than the dead front
externally-operable type are permitted where accessible only to
qualified persons.
(3) Knife switches mounted in switchboards or panelboards. Exposed
blades of knife switches mounted in switchboards or panelboards shall
be dead when open.
(e) Enclosures for damp or wet locations--(1) Cabinets, cutout
boxes, fittings, boxes, and panelboard enclosures. Cabinets, cutout
boxes, fittings, boxes, and panelboard enclosures in damp or wet
locations shall be installed so as to prevent moisture or water from
entering and accumulating within the enclosures and shall be mounted so
there is at least 6.35-mm (0.25-in.) airspace between the enclosure and
the wall or other supporting surface. However, nonmetallic enclosures
may be installed without the airspace on a concrete, masonry, tile, or
similar surface. The enclosures shall be weatherproof in wet locations.
(2) Switches, circuit breakers, and switchboards. Switches, circuit
breakers, and switchboards installed in wet locations shall be enclosed
in weatherproof enclosures.
(f) Conductors for general wiring--(1) Insulation. All conductors
used for general wiring shall be insulated unless otherwise permitted
in this subpart.
(2) Type. The conductor insulation shall be of a type that is
approved for the voltage, operating temperature, and location of use.
(3) Distinguishable. Insulated conductors shall be distinguishable
by appropriate color or other suitable means as being grounded
conductors, ungrounded conductors, or equipment grounding conductors.
(g) Flexible cords and cables--(1)Use of flexible cords and cables.
(i) Flexible cords and cables shall be approved for conditions of use
and location.
(ii) Flexible cords and cables may be used only for:
(A) Pendants;
(B) Wiring of fixtures;
(C) Connection of portable lamps or appliances;
(D) Portable and mobile signs;
(E) Elevator cables;
(F) Wiring of cranes and hoists;
(G) Connection of stationary equipment to facilitate their frequent
interchange;
(H) Prevention of the transmission of noise or vibration;
(I) Appliances where the fastening means and mechanical connections
are designed to permit removal for maintenance and repair;
(J) Data processing cables approved as a part of the data
processing system;
(K) Connection of moving parts; and
(L) Temporary wiring as permitted in paragraph (a)(2) of this
section.
(iii) If used as permitted in paragraphs (g)(1)(ii)(C),
(g)(1)(ii)(G), or (g)(1)(ii)(I) of this section, the flexible cord
shall be equipped with an attachment plug and shall be energized from
an approved receptacle outlet.
(iv) Unless specifically permitted otherwise in paragraph
(g)(1)(ii) of this section, flexible cords and cables may not be used:
(A) As a substitute for the fixed wiring of a structure;
(B) Where run through holes in walls, ceilings, or floors;
(C) Where run through doorways, windows, or similar openings;
(D) Where attached to building surfaces;
(E) Where concealed behind building walls, ceilings, or floors; or
(F) Where installed in raceways, except as otherwise permitted in
this subpart.
(v) Flexible cords used in show windows and showcases shall be Type
S, SE, SEO, SEOO, SJ, SJE, SJEO, SJEOO, SJO, SJOO, SJT, SJTO, SJTOO,
SO, SOO, ST, STO, or STOO, except for the wiring of chain-supported
lighting fixtures and supply cords for portable lamps and other
merchandise being displayed or exhibited.
(2) Identification, splices, and terminations. (i) A conductor of a
flexible cord or cable that is used as a grounded conductor or an
equipment grounding conductor shall be distinguishable from other
conductors. Types S, SC, SCE, SCT, SE, SEO, SEOO, SJ, SJE, SJEO, SJEOO,
SJO, SJT, SJTO, SJTOO, SO, SOO, ST, STO, and STOO flexible cords and
Types G, G-GC, PPE, and W flexible cables shall be durably marked on
the surface at intervals not exceeding 610 mm (24 in.) with the type
designation, size, and number of conductors.
(ii) Flexible cords may be used only in continuous lengths without
splice or tap. Hard-service cord and junior hard-service cord No. 14
and larger may be repaired if spliced so that the splice retains the
insulation, outer sheath properties, and usage characteristics of the
cord being spliced.
(iii) Flexible cords and cables shall be connected to devices and
fittings so that strain relief is provided that will prevent pull from
being directly transmitted to joints or terminal screws.
(h) Portable cables over 600 volts, nominal. This paragraph applies
to portable cables used at more than 600 volts, nominal.
(1) Conductor construction. Multiconductor portable cable for use
in supplying power to portable or mobile equipment at over 600 volts,
nominal, shall consist of No. 8 or larger conductors employing flexible
stranding. However, the minimum size of the insulated ground-check
conductor of Type G-GC cables shall be No. 10.
(2) Shielding. Cables operated at over 2,000 volts shall be
shielded for the purpose of confining the voltage stresses to the
insulation.
(3) Equipment grounding conductors. Grounding conductors shall be
provided.
(4) Grounding shields. All shields shall be grounded.
(5) Minimum bending radii. The minimum bending radii for portable
cables during installation and handling in service shall be adequate to
prevent damage to the cable.
(6) Fittings. Connectors used to connect lengths of cable in a run
shall be of a type that lock firmly together. Provisions shall be made to
prevent opening or closing these connectors while energized. Strain
relief shall be provided at connections and terminations.
(7) Splices. Portable cables may not be operated with splices
unless the splices are of the permanent molded, vulcanized, or other
approved type.
(8) Terminations. Termination enclosures shall be suitably marked
with a high voltage hazard warning, and terminations shall be
accessible only to authorized and qualified employees.
(i) Fixture wires--(1) General. Fixture wires shall be approved for
the voltage, temperature, and location of use. A fixture wire which is
used as a grounded conductor shall be identified.
(2) Uses permitted. Fixture wires may be used only:
(i) For installation in lighting fixtures and in similar equipment
where enclosed or protected and not subject to bending or twisting in
use; or
(ii) For connecting lighting fixtures to the branch-circuit
conductors supplying the fixtures.
(3) Uses not permitted. Fixture wires may not be used as branch-
circuit conductors except as permitted for Class 1 power limited
circuits and for fire alarm circuits.
(j) Equipment for general use--(1) Lighting fixtures, lampholders,
lamps, and receptacles. (i) Fixtures, lampholders, lamps, rosettes, and
receptacles may have no live parts normally exposed to employee
contact. However, rosettes and cleat-type lampholders and receptacles
located at least 2.44 m (8.0 ft) above the floor may have exposed
terminals.
(ii) Handlamps of the portable type supplied through flexible cords
shall be equipped with a handle of molded composition or other material
identified for the purpose, and a substantial guard shall be attached
to the lampholder or the handle. Metal shell, paper-lined lampholders
may not be used.
(iii) Lampholders of the screw-shell type shall be installed for
use as lampholders only. Where supplied by a circuit having a grounded
conductor, the grounded conductor shall be connected to the screw
shell. Lampholders installed in wet or damp locations shall be of the
weatherproof type.
(iv) Fixtures installed in wet or damp locations shall be
identified for the purpose and shall be so constructed or installed
that water cannot enter or accumulate in wireways, lampholders, or
other electrical parts.
(2) Receptacles, cord connectors, and attachment plugs (caps). (i)
All 15- and 20-ampere attachment plugs and connectors shall be
constructed so that there are no exposed current-carrying parts except
the prongs, blades, or pins. The cover for wire terminations shall be a
part that is essential for the operation of an attachment plug or
connector (dead-front construction). Attachment plugs shall be
installed so that their prongs, blades, or pins are not energized
unless inserted into an energized receptacle. No receptacles may be
installed so as to require an energized attachment plug as its source
of supply.
(ii) Receptacles, cord connectors, and attachment plugs shall be
constructed so that no receptacle or cord connector will accept an
attachment plug with a different voltage or current rating than that
for which the device is intended. However, a 20-ampere T-slot
receptacle or cord connector may accept a 15-ampere attachment plug of
the same voltage rating.
(iii) Nongrounding-type receptacles and connectors may not be used
for grounding-type attachment plugs.
(iv) A receptacle installed in a wet or damp location shall be
suitable for the location.
(v) A receptacle installed outdoors in a location protected from
the weather or in other damp locations shall have an enclosure for the
receptacle that is weatherproof when the receptacle is covered
(attachment plug cap not inserted and receptacle covers closed).
Note to paragraph (j)(2)(v) of this section. A receptacle is
considered to be in a location protected from the weather when it is
located under roofed open porches, canopies, marquees, or the like
and where it will not be subjected to a beating rain or water
runoff.
(vi) A receptacle installed in a wet location where the product
intended to be plugged into it is not attended while in use (for
example, sprinkler system controllers, landscape lighting, and holiday
lights) shall have an enclosure that is weatherproof with the
attachment plug cap inserted or removed.
(vii) A receptacle installed in a wet location where the product
intended to be plugged into it will be attended while in use (for
example, portable tools) shall have an enclosure that is weatherproof
when the attachment plug cap is removed.
(3) Appliances. (i) Appliances may have no live parts normally
exposed to contact other than parts functioning as open-resistance
heating elements, such as the heating elements of a toaster, which are
necessarily exposed.
(ii) Each appliance shall have a means to disconnect it from all
ungrounded conductors. If an appliance is supplied by more than one
source, the disconnecting means shall be grouped and identified.
(iii) Each electric appliance shall be provided with a nameplate
giving the identifying name and the rating in volts and amperes, or in
volts and watts. If the appliance is to be used on a specific frequency
or frequencies, it shall be so marked. Where motor overload protection
external to the appliance is required, the appliance shall be so
marked.
(iv) Marking shall be located so as to be visible or easily
accessible after installation.
(4) Motors. This paragraph applies to motors, motor circuits, and
controllers.
(i) If specified in paragraph (j)(4) of this section that one piece
of equipment shall be "within sight of" another piece of equipment,
the piece of equipment shall be visible and not more than 15.24 m (50.0
ft) from the other.
(ii) An individual disconnecting means shall be provided for each
controller. A disconnecting means shall be located within sight of the
controller location. However, a single disconnecting means may be
located adjacent to a group of coordinated controllers mounted adjacent
to each other on a multi-motor continuous process machine. The
controller disconnecting means for motor branch circuits over 600
volts, nominal, may be out of sight of the controller, if the
controller is marked with a warning label giving the location and
identification of the disconnecting means that is to be locked in the
open position.
(iii) The disconnecting means shall disconnect the motor and the
controller from all ungrounded supply conductors and shall be so
designed that no pole can be operated independently.
(iv) The disconnecting means shall plainly indicate whether it is
in the open (off) or closed (on) position.
(v) The disconnecting means shall be readily accessible. If more
than one disconnect is provided for the same equipment, only one need
be readily accessible.
(vi) An individual disconnecting means shall be provided for each
motor, but a single disconnecting means may be used for a group of
motors under any one of the following conditions:
(A) If a number of motors drive several parts of a single machine
or piece of apparatus, such as a metal or woodworking machine, crane,
or hoist;
(B) If a group of motors is under the protection of one set of
branch-circuit protective devices; or
(C) If a group of motors is in a single room within sight of the
location of the disconnecting means.
(vii) Motors, motor-control apparatus, and motor branch-circuit
conductors shall be protected against overheating due to motor
overloads or failure to start, and against short-circuits or ground
faults. These provisions do not require overload protection that will
stop a motor where a shutdown is likely to introduce additional or
increased hazards, as in the case of fire pumps, or where continued
operation of a motor is necessary for a safe shutdown of equipment or
process and motor overload sensing devices are connected to a
supervised alarm.
(viii) Where live parts of motors or controllers operating at over
150 volts to ground are guarded against accidental contact only by
location, and where adjustment or other attendance may be necessary
during the operation of the apparatus, suitable insulating mats or
platforms shall be provided so that the attendant cannot readily touch
live parts unless standing on the mats or platforms.
(5) Transformers. (i) Paragraph (j)(5) of this section covers the
installation of all transformers except the following:
(A) Current transformers;
(B) Dry-type transformers installed as a component part of other
apparatus;
(C) Transformers that are an integral part of an X-ray, high
frequency, or electrostatic-coating apparatus;
(D) Transformers used with Class 2 and Class 3 circuits, sign and
outline lighting, electric discharge lighting, and power-limited fire-
alarm circuits; and
(E) Liquid-filled or dry-type transformers used for research,
development, or testing, where effective safeguard arrangements are
provided.
(ii) The operating voltage of exposed live parts of transformer
installations shall be indicated by signs or visible markings on the
equipment or structure.
(iii) Dry-type, high fire point liquid-insulated, and askarel-
insulated transformers installed indoors and rated over 35kV shall be
in a vault.
(iv) Oil-insulated transformers installed indoors shall be
installed in a vault.
(v) Combustible material, combustible buildings and parts of
buildings, fire escapes, and door and window openings shall be
safeguarded from fires that may originate in oil-insulated transformers
attached to or adjacent to a building or combustible material.
(vi) Transformer vaults shall be constructed so as to contain fire
and combustible liquids within the vault and to prevent unauthorized
access. Locks and latches shall be so arranged that a vault door can be
readily opened from the inside.
(vii) Any pipe or duct system foreign to the electrical
installation may not enter or pass through a transformer vault.
Note to paragraph (j)(5)(vii) of this section. Piping or other
facilities provided for vault fire protection, or for transformer
cooling, are not considered foreign to the electrical installation.
(viii) Material may not be stored in transformer vaults.
(6) Capacitors. (i) All capacitors, except surge capacitors or
capacitors included as a component part of other apparatus, shall be
provided with an automatic means of draining the stored charge after
the capacitor is disconnected from its source of supply.
(ii) The following requirements apply to capacitors installed on
circuits operating at more than 600 volts, nominal:
(A) Group-operated switches shall be used for capacitor switching
and shall be capable of the following:
(1) Carrying continuously not less than 135 percent of the rated
current of the capacitor installation;
(2) Interrupting the maximum continuous load current of each
capacitor, capacitor bank, or capacitor installation that will be
switched as a unit;
(3) Withstanding the maximum inrush current, including
contributions from adjacent capacitor installations; and
(4) Carrying currents due to faults on the capacitor side of the
switch;
(B) A means shall be installed to isolate from all sources of
voltage each capacitor, capacitor bank, or capacitor installation that
will be removed from service as a unit. The isolating means shall
provide a visible gap in the electric circuit adequate for the
operating voltage;
(C) Isolating or disconnecting switches (with no interrupting
rating) shall be interlocked with the load interrupting device or shall
be provided with prominently displayed caution signs to prevent
switching load current; and
(D) For series capacitors, the proper switching shall be assured by
use of at least one of the following:
(1) Mechanically sequenced isolating and bypass switches;
(2) Interlocks; or
(3) Switching procedure prominently displayed at the switching
location.
(7) Storage Batteries. Provisions shall be made for sufficient
diffusion and ventilation of gases from storage batteries to prevent
the accumulation of explosive mixtures.
Sec. 1910.306 Specific purpose equipment and installations.
(a) Electric signs and outline lighting--(1) Disconnecting means.
(i) Each sign and outline lighting system, or feeder circuit or branch
circuit supplying a sign or outline lighting system, shall be
controlled by an externally operable switch or circuit breaker that
will open all ungrounded conductors. However, a disconnecting means is
not required for an exit directional sign located within a building or
for cord-connected signs with an attachment plug.
(ii) Signs and outline lighting systems located within fountains
shall have the disconnect located at least 1.52 m (5.0 ft) from the
inside walls of the fountain.
(2) Location. (i) The disconnecting means shall be within sight of
the sign or outline lighting system that it controls. Where the
disconnecting means is out of the line of sight from any section that
may be energized, the disconnecting means shall be capable of being
locked in the open position.
(ii) Signs or outline lighting systems operated by electronic or
electromechanical controllers located external to the sign or outline
lighting system may have a disconnecting means located within sight of
the controller or in the same enclosure with the controller. The
disconnecting means shall disconnect the sign or outline lighting
system and the controller from all ungrounded supply conductors. It
shall be designed so no pole can be operated independently and shall be
capable of being locked in the open position.
(iii) Doors or covers giving access to uninsulated parts of indoor
signs or outline lighting exceeding 600 volts and accessible to other
than qualified persons shall either be provided with interlock switches
to disconnect the primary circuit or shall be so fastened that the use
of other than ordinary tools will be necessary to open them.
(b) Cranes and hoists. This paragraph applies to the installation
of electric equipment and wiring used in connection with cranes,
monorail hoists, hoists, and all runways.
(1) Disconnecting means for runway conductors. A disconnecting
means shall be provided between the runway contact conductors and the
power supply. Such disconnecting means shall consist of a motor-circuit
switch, circuit breaker, or molded case switch. The disconnecting means
shall open all ungrounded conductors simultaneously and shall be:
(i) Readily accessible and operable from the ground or floor level;
(ii) Arranged to be locked in the open position; and
(iii) Placed within view of the runway contact conductors.
(2) Disconnecting means for cranes and monorail hoists. (i) Except
as provided in paragraph (b)(2)(iv) of this section, a motor-circuit
switch, molded case switch, or circuit breaker shall be provided in the
leads from the runway contact conductors or other power supply on all
cranes and monorail hoists.
(ii) The disconnecting means shall be capable of being locked in
the open position.
(iii) Means shall be provided at the operating station to open the
power circuit to all motors of the crane or monorail hoist where the
disconnecting means is not readily accessible from the crane or
monorail hoist operating station.
(iv) The disconnecting means may be omitted where a monorail hoist
or hand-propelled crane bridge installation meets all of the following
conditions:
(A) The unit is controlled from the ground or floor level;
(B) The unit is within view of the power supply disconnecting
means; and
(C) No fixed work platform has been provided for servicing the
unit.
(3) Limit switch. A limit switch or other device shall be provided
to prevent the load block from passing the safe upper limit of travel
of any hoisting mechanism.
(4) Clearance. The dimension of the working space in the direction
of access to live parts that may require examination, adjustment,
servicing, or maintenance while alive shall be a minimum of 762 mm (2.5
ft). Where controls are enclosed in cabinets, the doors shall either
open at least 90 degrees or be removable.
(c) Elevators, dumbwaiters, escalators, moving walks, wheelchair
lifts, and stairway chair lifts. The following requirements apply to
elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and
stairway chair lifts.
(1) Disconnecting means. Elevators, dumbwaiters, escalators, moving
walks, wheelchair lifts, and stairway chair lifts shall have a single
means for disconnecting all ungrounded main power supply conductors for
each unit.
(2) Control panels. Control panels not located in the same space as
the drive machine shall be located in cabinets with doors or panels
capable of being locked closed.
(3) Type. The disconnecting means shall be an enclosed externally
operable fused motor circuit switch or circuit breaker capable of being
locked in the open position. The disconnecting means shall be a listed
device.
(4) Operation. No provision may be made to open or close this
disconnecting means from any other part of the premises. If sprinklers
are installed in hoistways, machine rooms, or machinery spaces, the
disconnecting means may automatically open the power supply to the
affected elevators prior to the application of water. No provision may
be made to close this disconnecting means automatically (that is, power
may only be restored by manual means).
(5) Location. The disconnecting means shall be located where it is
readily accessible to qualified persons.
(i) On elevators without generator field control, the disconnecting
means shall be located within sight of the motor controller. Driving
machines or motion and operation controllers not within sight of the
disconnecting means shall be provided with a manually operated switch
installed in the control circuit adjacent to the equipment in order to
prevent starting. Where the driving machine is located in a remote
machinery space, a single disconnecting means for disconnecting all
ungrounded main power supply conductors shall be provided and be
capable of being locked in the open position.
(ii) On elevators with generator field control, the disconnecting
means shall be located within sight of the motor controller for the
driving motor of the motor-generator set. Driving machines, motor-
generator sets, or motion and operation controllers not within sight of
the disconnecting means shall be provided with a manually operated
switch installed in the control circuit to prevent starting. The
manually operated switch shall be installed adjacent to this equipment.
Where the driving machine or the motor-generator set is located in a
remote machinery space, a single means for disconnecting all ungrounded
main power supply conductors shall be provided and be capable of being
locked in the open position.
(iii) On escalators and moving walks, the disconnecting means shall
be installed in the space where the controller is located.
(iv) On wheelchair lifts and stairway chair lifts, the
disconnecting means shall be located within sight of the motor
controller.
(6) Identification and signs. (i) Where there is more than one
driving machine in a machine room, the disconnecting means shall be
numbered to correspond to the identifying number of the driving machine
that they control.
(ii) The disconnecting means shall be provided with a sign to
identify the location of the supply-side overcurrent protective device.
(7) Single-car and multicar installations. On single-car and
multicar installations, equipment receiving electrical power from more
than one source shall be provided with a disconnecting means for each
source of electrical power. The disconnecting means shall be within
sight of the equipment served.
(8) Warning sign for multiple disconnecting means. A warning sign
shall be mounted on or next to the disconnecting means where multiple
disconnecting means are used and parts of the controllers remain
energized from a source other than the one disconnected. The sign shall
be clearly legible and shall read "WARNING--PARTS OF THE CONTROLLER
ARE NOT DEENERGIZED BY THIS SWITCH."
(9) Interconnection between multicar controllers. A warning sign
worded as required in paragraph (c)(8) of this section shall be mounted
on or next to the disconnecting means where interconnections between
controllers are necessary for the operation of the system on multicar
installations that remain energized from a source other than the one
disconnected.
(10) Motor controllers. Motor controllers may be located outside
the spaces otherwise required by paragraph (c) of this section,
provided they are in enclosures with doors or removable panels capable
of being locked closed and the disconnecting means is located adjacent
to or is an integral part of the motor controller. Motor controller
enclosures for escalators or moving walks may be located in the
balustrade on the side located away from the moving steps or moving
treadway. If the disconnecting means is an integral part of the motor
controller, it shall be operable without opening the enclosure.
(d) Electric welders--disconnecting means--(1) Arc welders. A
disconnecting means shall be provided in the supply circuit for each
arc welder that is not equipped with a disconnect mounted as an
integral part of the welder. The disconnecting means shall be a switch
or circuit breaker, and its rating may not be less than that necessary
to accommodate overcurrent protection.
(2) Resistance welders. A switch or circuit breaker shall be
provided by which each resistance welder and its control equipment can
be disconnected from the supply circuit. The ampere rating of this
disconnecting means may not be less than the supply conductor ampacity.
The supply circuit switch may be used as the welder disconnecting means
where the circuit supplies only one welder.
(e) Information technology equipment--(1) Disconnecting means. A
means shall be provided to disconnect power to all electronic equipment
in an information technology equipment room. There shall also be a
similar means to disconnect the power to all dedicated heating,
ventilating, and air-conditioning (HVAC) systems serving the room and
to cause all required fire/smoke dampers to close.
(2) Grouping. The control for these disconnecting means shall be
grouped and identified and shall be readily accessible at the principal
exit doors. A single means to control both the electronic equipment and
HVAC system is permitted.
(3) Exception. Integrated electrical systems covered by Sec.
1910.308(g) need not have the disconnecting means required by paragraph
(e)(1) of this section.
(f) X-Ray equipment. This paragraph applies to X-ray equipment.
(1) Disconnecting means. (i) A disconnecting means shall be
provided in the supply circuit. The disconnecting means shall be
operable from a location readily accessible from the X-ray control. For
equipment connected to a 120-volt branch circuit of 30 amperes or less,
a grounding-type attachment plug cap and receptacle of proper rating
may serve as a disconnecting means.
(ii) If more than one piece of equipment is operated from the same
high-voltage circuit, each piece or each group of equipment as a unit
shall be provided with a high-voltage switch or equivalent
disconnecting means. The disconnecting means shall be constructed,
enclosed, or located so as to avoid contact by employees with its live
parts.
(2) Control. The following requirements apply to industrial and
commercial laboratory equipment.
(i) Radiographic and fluoroscopic-type equipment shall be
effectively enclosed or shall have interlocks that deenergize the
equipment automatically to prevent ready access to live current-
carrying parts.
(ii) Diffraction- and irradiation-type equipment shall have a pilot
light, readable meter deflection, or equivalent means to indicate when
the equipment is energized, unless the equipment or installation is
effectively enclosed or is provided with interlocks to prevent access
to live current-carrying parts during operation.
(g) Induction and dielectric heating equipment. This paragraph
applies to induction and dielectric heating equipment and accessories
for industrial and scientific applications, but not for medical or
dental applications or for appliances.
(1) Guarding and grounding. (i) The converting apparatus (including
the dc line) and high-frequency electric circuits (excluding the output
circuits and remote-control circuits) shall be completely contained
within enclosures of noncombustible material.
(ii) All panel controls shall be of dead-front construction.
(iii) Doors or detachable panels shall be employed for internal
access. Where doors are used giving access to voltages from 500 to 1000
volts ac or dc, either door locks shall be provided or interlocks shall
be installed. Where doors are used giving access to voltages of over
1000 volts ac or dc, either mechanical lockouts with a disconnecting
means to prevent access until circuit parts within the cubicle are
deenergized, or both door interlocking and mechanical door locks, shall
be provided. Detachable panels not normally used for access to such
parts shall be fastened in a manner that will make them difficult to
remove (for example, by requiring the use of tools).
(iv) Warning labels or signs that read "DANGER--HIGH VOLTAGE--KEEP
OUT" shall be attached to the equipment and shall be plainly visible
where persons might contact energized parts when doors are opened or
closed or when panels are removed from compartments containing over 250
volts ac or dc.
(v) Induction and dielectric heating equipment shall be protected
as follows:
(A) Protective cages or adequate shielding shall be used to guard
work applicators other than induction heating coils.
(B) Induction heating coils shall be protected by insulation or
refractory materials or both.
(C) Interlock switches shall be used on all hinged access doors,
sliding panels, or other such means of access to the applicator, unless
the applicator is an induction heating coil at dc ground potential or
operating at less than 150 volts ac.
(D) Interlock switches shall be connected in such a manner as to
remove all power from the applicator when any one of the access doors
or panels is open.
(vi) A readily accessible disconnecting means shall be provided by
which each heating equipment can be isolated from its supply circuit.
The ampere rating of this disconnecting means may not be less than the
nameplate current rating of the equipment. The supply circuit
disconnecting means is permitted as a heating equipment disconnecting
means where the circuit supplies only one piece of equipment.
(2) Remote control. (i) If remote controls are used for applying
power, a selector switch shall be provided and interlocked to provide
power from only one control point at a time.
(ii) Switches operated by foot pressure shall be provided with a
shield over the contact button to avoid accidental closing of the
switch.
(h) Electrolytic cells. This paragraph applies to the installation
of the electrical components and accessory equipment of electrolytic
cells, electrolytic cell lines, and process power supply for the
production of aluminum, cadmium, chlorine, copper, fluorine, hydrogen
peroxide, magnesium, sodium, sodium chlorate, and zinc. Cells used as a
source of electric energy and for electroplating processes and cells
used for production of hydrogen are not covered by this paragraph.
(1) Application. Installations covered by paragraph (h) of this
section shall comply with all applicable provisions of this subpart,
except as follows:
(i) Overcurrent protection of electrolytic cell dc process power
circuits need not comply with the requirements of Sec. 1910.304(f);
(ii) Equipment located or used within the cell line working zone or
associated with the cell line dc power circuits need not comply with
the provisions of Sec. 1910.304(g); and
(iii) Electrolytic cells, cell line conductors, cell line
attachments, and the wiring of auxiliary equipment and devices within
the cell line working zone need not comply with the provisions of Sec.
1910.303 or Sec. 1910.304(b) and (c).
(2) Disconnecting means. If more than one dc cell line process
power supply serves the same cell line, a disconnecting means shall be
provided on the cell line circuit side of each power supply to
disconnect it from the cell line circuit. Removable links or removable
conductors may be used as the disconnecting means.
(3) Portable electric equipment. (i) The frames and enclosures of
portable electric equipment used within the cell line working zone may
not be grounded, unless the cell line circuit voltage does not exceed
200 volts DC or the frames are guarded.
(ii) Ungrounded portable electric equipment shall be distinctively
marked and shall employ plugs and receptacles of a configuration that
prevents connection of this equipment to grounding receptacles and that
prevents inadvertent interchange of ungrounded and grounded portable
electric equipment.
(4) Power supply circuits and receptacles for portable electric
equipment. (i) Circuits supplying power to ungrounded receptacles for
hand-held, cord- and plug-connected equipment shall meet the following
requirements:
(A) The circuits shall be electrically isolated from any
distribution system supplying areas other than the cell line working
zone and shall be ungrounded;
(B) The circuits shall be supplied through isolating transformers
with primaries operating at not more than 600 volts between conductors
and protected with proper overcurrent protection;
(C) The secondary voltage of the isolating transformers may not
exceed 300 volts between conductors; and
(D) All circuits supplied from the secondaries shall be ungrounded
and shall have an approved overcurrent device of proper rating in each
conductor.
(ii) Receptacles and their mating plugs for ungrounded equipment
may not have provision for a grounding conductor and shall be of a
configuration that prevents their use for equipment required to be
grounded.
(iii) Receptacles on circuits supplied by an isolating transformer
with an ungrounded secondary:
(A) Shall have a distinctive configuration;
(B) Shall be distinctively marked; and
(C) May not be used in any other location in the facility.
(5) Fixed and portable electric equipment. (i) The following need
not be grounded:
(A) AC systems supplying fixed and portable electric equipment
within the cell line working zone; and
(B) Exposed conductive surfaces, such as electric equipment
housings, cabinets, boxes, motors, raceways and the like that are
within the cell line working zone.
(ii) Auxiliary electric equipment, such as motors, transducers,
sensors, control devices, and alarms, mounted on an electrolytic cell
or other energized surface shall be connected to the premises wiring
systems by any of the following means:
(A) Multiconductor hard usage or extra hard usage flexible cord;
(B) Wire or cable in suitable nonmetallic raceways or cable trays;
or
(C) Wire or cable in suitable metal raceways or metal cable trays
installed with insulating breaks such that they will not cause a
potentially hazardous electrical condition.
(iii) Fixed electric equipment may be bonded to the energized
conductive surfaces of the cell line, its attachments, or auxiliaries.
If fixed electric equipment is mounted on an energized conductive
surface, it shall be bonded to that surface.
(6) Auxiliary nonelectrical connections. Auxiliary nonelectrical
connections such as air hoses, water hoses, and the like, to an
electrolytic cell, its attachments, or auxiliary equipment may not have
continuous conductive reinforcing wire, armor, braids, or the like.
Hoses shall be of a nonconductive material.
(7) Cranes and hoists. (i) The conductive surfaces of cranes and
hoists that enter the cell line working zone need not be grounded. The
portion of an overhead crane or hoist that contacts an energized
electrolytic cell or energized attachments shall be insulated from
ground.
(ii) Remote crane or hoist controls that may introduce hazardous
electrical conditions into the cell line working zone shall employ one
or more of the following systems:
(A) Isolated and ungrounded control circuit;
(B) Nonconductive rope operator;
(C) Pendant pushbutton with nonconductive supporting means and with
nonconductive surfaces or ungrounded exposed conductive surfaces; or
(D) Radio.
(i) Electrically driven or controlled irrigation machines--(1)
Lightning protection. If an irrigation machine has a stationary point,
a grounding electrode system shall be connected to the machine at the
stationary point for lightning protection.
(2) Disconnecting means. (i) The main disconnecting means for a
center pivot irrigation machine shall be located at the point of
connection of electrical power to the machine or shall be visible and
not more than 15.2 m (50 ft) from the machine.
(ii) The disconnecting means shall be readily accessible and
capable of being locked in the open position.
(iii) A disconnecting means shall be provided for each motor and
controller.
(j) Swimming pools, fountains, and similar installations. This
paragraph applies to electric wiring for and equipment in or adjacent
to all swimming, wading, therapeutic, and decorative pools and
fountains; hydro-massage bathtubs, whether permanently installed or
storable; and metallic auxiliary equipment, such as pumps, filters, and
similar equipment. Therapeutic pools in health care facilities are
exempt from these provisions.
(1) Receptacles. (i) A single receptacle of the locking and
grounding type that provides power for a permanently installed swimming
pool recirculating pump motor may be located not less than 1.52 m (5
ft) from the inside walls of a pool. All other receptacles on the
property shall be located at least 3.05 m (10 ft) from the inside walls
of a pool.
(ii) Receptacles that are located within 4.57 m (15 ft), or 6.08 m
(20 ft) if the installation was built after August 13, 2007, of the
inside walls of the pool shall be protected by ground-fault circuit
interrupters.
(iii) Where a pool is installed permanently at a dwelling unit, at
least one 125-volt, 15- or 20-ampere receptacle on a general-purpose
branch circuit shall be located a minimum of 3.05 m (10 ft) and not
more than 6.08 m (20 ft) from the inside wall of the pool. This
receptacle shall be located not more than 1.98 m (6.5 ft) above the
floor, platform, or grade level serving the pool.
Note to paragraph (j)(1) of this section: In determining these
dimensions, the distance to be measured is the shortest path the
supply cord of an appliance connected to the receptacle would follow
without piercing a floor, wall, or ceiling of a building or other
effective permanent barrier.
(2) Lighting fixtures, lighting outlets, and ceiling suspended
(paddle) fans. (i) In outdoor pool areas, lighting fixtures, lighting
outlets, and ceiling-suspended (paddle) fans may not be installed over
the pool or over the area extending 1.52 m (5 ft) horizontally from the
inside walls of a pool unless no part of the lighting fixture of a
ceiling-suspended (paddle) fan is less than 3.66 m (12 ft) above the
maximum water level. However, a lighting fixture or lighting outlet
that was installed before April 16, 1981, may be located less than 1.52
m (5 ft) measured horizontally from the inside walls of a pool if it is
at least 1.52 m (5 ft) above the surface of the maximum water level and
is rigidly attached to the existing structure. It shall also be
protected by a ground-fault circuit interrupter installed in the branch
circuit supplying the fixture.
(ii) Lighting fixtures and lighting outlets installed in the area
extending between 1.52 m (5 ft) and 3.05 m (10 ft) horizontally from
the inside walls of a pool shall be protected by a ground-fault circuit
interrupter unless installed 1.52 m (5 ft) above the maximum water
level and rigidly attached to the structure adjacent to or enclosing
the pool.
(3) Cord- and plug-connected equipment. Flexible cords used with
the following equipment may not exceed 0.9 m (3 ft) in length and shall
have a copper equipment grounding conductor with a grounding-type attachment
plug:
(i) Cord- and plug-connected lighting fixtures installed within
4.88 m (16 ft) of the water surface of permanently installed pools; and
(ii) Other cord- and plug-connected, fixed or stationary equipment
used with permanently installed pools.
(4) Underwater equipment. (i) A ground-fault circuit interrupter
shall be installed in the branch circuit supplying underwater fixtures
operating at more than 15 volts. Equipment installed underwater shall
be identified for the purpose.
(ii) No underwater lighting fixtures may be installed for operation
at over 150 volts between conductors.
(iii) A lighting fixture facing upward shall have the lens
adequately guarded to prevent contact by any person.
(5) Fountains. All electric equipment, including power supply
cords, operating at more than 15 volts and used with fountains shall be
protected by ground-fault circuit interrupters.
(k) Carnivals, circuses, fairs, and similar events. This paragraph
covers the installation of portable wiring and equipment, including
wiring in or on all structures, for carnivals, circuses, exhibitions,
fairs, traveling attractions, and similar events.
(1) Protection of electric equipment. Electric equipment and wiring
methods in or on rides, concessions, or other units shall be provided
with mechanical protection where such equipment or wiring methods are
subject to physical damage.
(2) Installation. (i) Services shall be installed in accordance
with applicable requirements of this subpart, and, in addition, shall
comply with the following:
(A) Service equipment may not be installed in a location that is
accessible to unqualified persons, unless the equipment is lockable;
and
(B) Service equipment shall be mounted on solid backing and
installed so as to be protected from the weather, unless the equipment
is of weatherproof construction.
(ii) Amusement rides and amusement attractions shall be maintained
not less than 4.57 m (15 ft) in any direction from overhead conductors
operating at 600 volts or less, except for the conductors supplying the
amusement ride or attraction. Amusement rides or attractions may not be
located under or within 4.57 m (15 ft) horizontally of conductors
operating in excess of 600 volts.
(iii) Flexible cords and cables shall be listed for extra-hard
usage. When used outdoors, flexible cords and cables shall also be
listed for wet locations and shall be sunlight resistant.
(iv) Single conductor cable shall be size No. 2 or larger.
(v) Open conductors are prohibited except as part of a listed
assembly or festoon lighting installed in accordance with Sec.
1910.304(c).
(vi) Flexible cords and cables shall be continuous without splice
or tap between boxes or fittings. Cord connectors may not be laid on
the ground unless listed for wet locations. Connectors and cable
connections may not be placed in audience traffic paths or within areas
accessible to the public unless guarded.
(vii) Wiring for an amusement ride, attraction, tent, or similar
structure may not be supported by another ride or structure unless
specifically identified for the purpose.
(viii) Flexible cords and cables run on the ground, where
accessible to the public, shall be covered with approved nonconductive
mats. Cables and mats shall be arranged so as not to present a tripping
hazard.
(ix) A box or fitting shall be installed at each connection point,
outlet, switch point, or junction point.
(3) Inside tents and concessions. Electrical wiring for temporary
lighting, where installed inside of tents and concessions, shall be
securely installed, and, where subject to physical damage, shall be
provided with mechanical protection. All temporary lamps for general
illumination shall be protected from accidental breakage by a suitable
fixture or lampholder with a guard.
(4) Portable distribution and termination boxes. Employers may only
use portable distribution and termination boxes that meet the following
requirements:
(i) Boxes shall be designed so that no live parts are exposed to
accidental contact. Where installed outdoors, the box shall be of
weatherproof construction and mounted so that the bottom of the
enclosure is not less than 152 mm (6 in.) above the ground;
(ii) Busbars shall have an ampere rating not less than the
overcurrent device supplying the feeder supplying the box. Busbar
connectors shall be provided where conductors terminate directly on
busbars;
(iii) Receptacles shall have overcurrent protection installed
within the box. The overcurrent protection may not exceed the ampere
rating of the receptacle, except as permitted in Sec. 1910.305(j)(4)
for motor loads;
(iv) Where single-pole connectors are used, they shall comply with
the following:
(A) Where ac single-pole portable cable connectors are used, they
shall be listed and of the locking type. Where paralleled sets of
current-carrying single-pole separable connectors are provided as input
devices, they shall be prominently labeled with a warning indicating
the presence of internal parallel connections. The use of single-pole
separable connectors shall comply with at least one of the following
conditions:
(1) Connection and disconnection of connectors are only possible
where the supply connectors are interlocked to the source and it is not
possible to connect or disconnect connectors when the supply is
energized; or
(2) Line connectors are of the listed sequential-interlocking type
so that load connectors are connected in the following sequence:
(i) Equipment grounding conductor connection;
(ii) Grounded circuit-conductor connection, if provided; and
(iii) Ungrounded conductor connection; and so that disconnection is
in the reverse order; or
(3) A caution notice is provided adjacent to the line connectors
indicating that plug connection must be in the following sequence:
(i) Equipment grounding conductor connection;
(ii) Grounded circuit-conductor connection, if provided; and
(iii) Ungrounded conductor connection; and indicating that
disconnection is in the reverse order; and
(B) Single-pole separable connectors used in portable professional
motion picture and television equipment may be interchangeable for ac
or dc use or for different current ratings on the same premises only if
they are listed for ac/dc use and marked to identify the system to
which they are connected;
(v) Overcurrent protection of equipment and conductors shall be
provided; and
(vi) The following equipment connected to the same source shall be
bonded:
(A) Metal raceways and metal sheathed cable;
(B) Metal enclosures of electrical equipment; and
(C) Metal frames and metal parts of rides, concessions, trailers,
trucks, or other equipment that contain or support electrical
equipment.
(5) Disconnecting means. (i) Each ride and concession shall be
provided with a fused disconnect switch or circuit breaker located
within sight and within 1.83 m (6 ft) of the operator's station.
(ii) The disconnecting means shall be readily accessible to the
operator, including when the ride is in operation.
(iii) Where accessible to unqualified persons, the enclosure for
the switch or circuit breaker shall be of the lockable type.
(iv) A shunt trip device that opens the fused disconnect or circuit
breaker when a switch located in the ride operator's console is closed
is a permissible method of opening the circuit.
Sec. 1910.307 Hazardous (classified) locations.
(a) Scope--(1) Applicability. This section covers the requirements
for electric equipment and wiring in locations that are classified
depending on the properties of the flammable vapors, liquids or gases,
or combustible dusts or fibers that may be present therein and the
likelihood that a flammable or combustible concentration or quantity is
present. Hazardous (classified) locations may be found in occupancies
such as, but not limited to, the following: aircraft hangars, gasoline
dispensing and service stations, bulk storage plants for gasoline or
other volatile flammable liquids, paint-finishing process plants,
health care facilities, agricultural or other facilities where
excessive combustible dusts may be present, marinas, boat yards, and
petroleum and chemical processing plants. Each room, section or area
shall be considered individually in determining its classification.
(2) Classifications. (i) These hazardous (classified) locations are
assigned the following designations:
(A) Class I, Division 1
(B) Class I, Division 2
(C) Class I, Zone 0
(D) Class I, Zone 1
(E) Class I, Zone 2
(F) Class II, Division 1
(G) Class II, Division 2
(H) Class III, Division 1
(I) Class III, Division 2
(ii) For definitions of these locations, see Sec. 1910.399.
(3) Other sections of this subpart. All applicable requirements in
this subpart apply to hazardous (classified) locations unless modified
by provisions of this section.
(4) Division and zone classification. In Class I locations, an
installation must be classified as using the division classification
system meeting paragraphs (c), (d), (e), and (f) of this section or
using the zone classification system meeting paragraph (g) of this
section. In Class II and Class III locations, an installation must be
classified using the division classification system meeting paragraphs
(c), (d), (e), and (f) of this section.
(b) Documentation. All areas designated as hazardous (classified)
locations under the Class and Zone system and areas designated under
the Class and Division system established after August 13, 2007 shall
be properly documented. This documentation shall be available to those
authorized to design, install, inspect, maintain, or operate electric
equipment at the location.
(c) Electrical installations. Equipment, wiring methods, and
installations of equipment in hazardous (classified) locations shall be
intrinsically safe, approved for the hazardous (classified) location,
or safe for the hazardous (classified) location. Requirements for each
of these options are as follows:
(1) Intrinsically safe. Equipment and associated wiring approved as
intrinsically safe is permitted in any hazardous (classified) location
for which it is approved;
(2) Approved for the hazardous (classified) location. (i) Equipment
shall be approved not only for the class of location, but also for the
ignitable or combustible properties of the specific gas, vapor, dust,
or fiber that will be present.
Note to paragraph (c)(2)(i) of this section: NFPA 70, the
National Electrical Code, lists or defines hazardous gases, vapors,
and dusts by "Groups" characterized by their ignitable or
combustible properties.
(ii) Equipment shall be marked to show the class, group, and
operating temperature or temperature range, based on operation in a 40-
degree C ambient, for which it is approved. The temperature marking may
not exceed the ignition temperature of the specific gas or vapor to be
encountered. However, the following provisions modify this marking
requirement for specific equipment:
(A) Equipment of the nonheat-producing type, such as junction
boxes, conduit, and fittings, and equipment of the heat-producing type
having a maximum temperature not more than 100[deg] C (212[deg] F) need
not have a marked operating temperature or temperature range;
(B) Fixed lighting fixtures marked for use in Class I, Division 2
or Class II, Division 2 locations only need not be marked to indicate
the group;
(C) Fixed general-purpose equipment in Class I locations, other
than lighting fixtures, that is acceptable for use in Class I, Division
2 locations need not be marked with the class, group, division, or
operating temperature;
(D) Fixed dust-tight equipment, other than lighting fixtures, that
is acceptable for use in Class II, Division 2 and Class III locations
need not be marked with the class, group, division, or operating
temperature; and
(E) Electric equipment suitable for ambient temperatures exceeding
40[deg] C (104[deg] F) shall be marked with both the maximum ambient
temperature and the operating temperature or temperature range at that
ambient temperature; and
(3) Safe for the hazardous (classified) location. Equipment that is
safe for the location shall be of a type and design that the employer
demonstrates will provide protection from the hazards arising from the
combustibility and flammability of vapors, liquids, gases, dusts, or
fibers involved.
Note to paragraph (c)(3) of this section: The National
Electrical Code, NFPA 70, contains guidelines for determining the
type and design of equipment and installations that will meet this
requirement. Those guidelines address electric wiring, equipment,
and systems installed in hazardous (classified) locations and
contain specific provisions for the following: wiring methods,
wiring connections; conductor insulation, flexible cords, sealing
and drainage, transformers, capacitors, switches, circuit breakers,
fuses, motor controllers, receptacles, attachment plugs, meters,
relays, instruments, resistors, generators, motors, lighting
fixtures, storage battery charging equipment, electric cranes,
electric hoists and similar equipment, utilization equipment,
signaling systems, alarm systems, remote control systems, local loud
speaker and communication systems, ventilation piping, live parts,
lightning surge protection, and grounding.
(d) Conduits. All conduits shall be threaded and shall be made
wrench-tight. Where it is impractical to make a threaded joint tight, a
bonding jumper shall be utilized.
(e) Equipment in Division 2 locations. Equipment that has been
approved for a Division 1 location may be installed in a Division 2
location of the same class and group. General-purpose equipment or
equipment in general-purpose enclosures may be installed in Division 2
locations if the employer can demonstrate that the equipment does not
constitute a source of ignition under normal operating conditions.
(f) Protection techniques. The following are acceptable protection
techniques for electric and electronic equipment in hazardous
(classified) locations.
(1) Explosionproof apparatus. This protection technique is
permitted for equipment in the Class I, Division 1 and 2 locations for
which it is approved.
(2) Dust ignitionproof. This protection technique is permitted for
equipment in the Class II, Division 1 and 2 locations for which it is approved.
(3) Dust-tight. This protection technique is permitted for
equipment in the Class II, Division 2 and Class III locations for which
it is approved.
(4) Purged and pressurized. This protection technique is permitted
for equipment in any hazardous (classified) location for which it is
approved.
(5) Nonincendive circuit. This protection technique is permitted
for equipment in Class I, Division 2; Class II, Division 2; or Class
III, Division 1or 2 locations.
(6) Nonincendive equipment. This protection technique is permitted
for equipment in Class I, Division 2; Class II, Division 2; or Class
III, Division 1 or 2 locations.
(7) Nonincendive component. This protection technique is permitted
for equipment in Class I, Division 2; Class II, Division 2; or Class
III, Division 1 or 2 locations.
(8) Oil immersion. This protection technique is permitted for
current-interrupting contacts in Class I, Division 2 locations as
described in the Subpart.
(9) Hermetically sealed. This protection technique is permitted for
equipment in Class I, Division 2; Class II, Division 2; and Class III,
Division 1 or 2 locations.
(10) Other protection techniques. Any other protection technique
that meets paragraph (c) of this section is acceptable in any hazardous
(classified) location.
(g) Class I, Zone 0, 1, and 2 locations--(1) Scope. Employers may
use the zone classification system as an alternative to the division
classification system for electric and electronic equipment and wiring
for all voltage in Class I, Zone 0, Zone 1, and Zone 2 hazardous
(classified) locations where fire or explosion hazards may exist due to
flammable gases, vapors, or liquids.
(2) Location and general requirements. (i) Locations shall be
classified depending on the properties of the flammable vapors,
liquids, or gases that may be present and the likelihood that a
flammable or combustible concentration or quantity is present. Where
pyrophoric materials are the only materials used or handled, these
locations need not be classified.
(ii) Each room, section, or area shall be considered individually
in determining its classification.
(iii) All threaded conduit shall be threaded with an NPT (National
(American) Standard Pipe Taper) standard conduit cutting die that
provides \3/4\-in. taper per foot. The conduit shall be made wrench
tight to prevent sparking when fault current flows through the conduit
system and to ensure the explosionproof or flameproof integrity of the
conduit system where applicable.
(iv) Equipment provided with threaded entries for field wiring
connection shall be installed in accordance with paragraph
(g)(2)(iv)(A) or (g)(2)(iv)(B) of this section.
(A) For equipment provided with threaded entries for NPT threaded
conduit or fittings, listed conduit, conduit fittings, or cable
fittings shall be used.
(B) For equipment with metric threaded entries, such entries shall
be identified as being metric, or listed adaptors to permit connection
to conduit of NPT-threaded fittings shall be provided with the
equipment. Adapters shall be used for connection to conduit or NPT-
threaded fittings.
(3) Protection techniques. One or more of the following protection
techniques shall be used for electric and electronic equipment in
hazardous (classified) locations classified under the zone
classification system.
(i) Flameproof "d"--This protection technique is permitted for
equipment in the Class I, Zone 1 locations for which it is approved.
(ii) Purged and pressurized--This protection technique is permitted
for equipment in the Class I, Zone 1 or Zone 2 locations for which it
is approved.
(iii) Intrinsic safety--This protection technique is permitted for
equipment in the Class I, Zone 0 or Zone 1 locations for which it is
approved.
(iv) Type of protection "n"--This protection technique is
permitted for equipment in the Class I, Zone 2 locations for which it
is approved. Type of protection "n" is further subdivided into nA,
nC, and nR.
(v) Oil Immersion "o"--This protection technique is permitted for
equipment in the Class I, Zone 1 locations for which it is approved.
(vi) Increased safety "e"--This protection technique is permitted
for equipment in the Class I, Zone 1 locations for which it is
approved.
(vii) Encapsulation "m"--This protection technique is permitted
for equipment in the Class I, Zone 1 locations for which it is
approved.
(viii) Powder Filling "q"--This protection technique is permitted
for equipment in the Class I, Zone 1 locations for which it is
approved.
(4) Special precaution. Paragraph (g) of this section requires
equipment construction and installation that will ensure safe
performance under conditions of proper use and maintenance.
(i) Classification of areas and selection of equipment and wiring
methods shall be under the supervision of a qualified registered
professional engineer.
(ii) In instances of areas within the same facility classified
separately, Class I, Zone 2 locations may abut, but not overlap, Class
I, Division 2 locations. Class I, Zone 0 or Zone 1 locations may not
abut Class I, Division 1 or Division 2 locations.
(iii) A Class I, Division 1 or Division 2 location may be
reclassified as a Class I, Zone 0, Zone 1, or Zone 2 location only if
all of the space that is classified because of a single flammable gas
or vapor source is reclassified.
Note to paragraph (g)(4) of this section: Low ambient conditions
require special consideration. Electric equipment depending on the
protection techniques described by paragraph (g)(3)(i) of this
section may not be suitable for use at temperatures lower than -20
[deg]C (-4 [deg]F) unless they are approved for use at lower
temperatures. However, at low ambient temperatures, flammable
concentrations of vapors may not exist in a location classified
Class I, Zone 0, 1, or 2 at normal ambient temperature.
(5) Listing and marking. (i) Equipment that is listed for a Zone 0
location may be installed in a Zone 1 or Zone 2 location of the same
gas or vapor. Equipment that is listed for a Zone 1 location may be
installed in a Zone 2 location of the same gas or vapor.
(ii) Equipment shall be marked in accordance with paragraph
(g)(5)(ii)(A) and (g)(5)(ii)(B) of this section, except as provided in
(g)(5)(ii)(C).
(A) Equipment approved for Class I, Division 1 or Class 1, Division
2 shall, in addition to being marked in accordance with (c)(2)(ii), be
marked with the following:
(1) Class I, Zone 1 or Class I, Zone 2 (as applicable);
(2) Applicable gas classification groups; and
(3) Temperature classification; or
(B) Equipment meeting one or more of the protection techniques
described in paragraph (g)(3) of this section shall be marked with the
following in the order shown:
(1) Class, except for intrinsically safe apparatus;
(2) Zone, except for intrinsically safe apparatus;
(3) Symbol "AEx;"
(4) Protection techniques;
(5) Applicable gas classification groups; and
(6) Temperature classification, except for intrinsically safe
apparatus.
Note to paragraph (g)(5)(ii)(B) of this section: An example of
such a required marking is "Class I, Zone 0, AEx ia IIC T6." See
Figure S-1 for an explanation of this marking.
(C) Equipment that the employer demonstrates will provide
protection from the hazards arising from the flammability of the gas or
vapor and the zone of location involved and will be recognized as
providing such protection by employees need not be marked.
Note to paragraph (g)(5)(ii)(C) of this section: The National
Electrical Code, NFPA 70, contains guidelines for determining the
type and design of equipment and installations that will meet this
provision.
[GRAPHIC] [TIFF OMITTED] TR14FE07.000
Sec. 1910.308 Special systems.
(a) Systems over 600 volts, nominal. This paragraph covers the
general requirements for all circuits and equipment operated at over
600 volts.
(1) Aboveground wiring methods. (i) Aboveground conductors shall be
installed in rigid metal conduit, in intermediate metal conduit, in
electrical metallic tubing, in rigid nonmetallic conduit, in cable
trays, as busways, as cablebus, in other identified raceways, or as
open runs of metal-clad cable suitable for the use and purpose. In
locations accessible to qualified persons only, open runs of Type MV
cables, bare conductors, and bare busbars are also permitted. Busbars
shall be either copper or aluminum. Open runs of insulated wires and
cables having a bare lead sheath or a braided outer covering shall be
supported in a manner designed to prevent physical damage to the braid
or sheath.
(ii) Conductors emerging from the ground shall be enclosed in
approved raceways.
(2) Braid-covered insulated conductors--open installations. The
braid on open runs of braid-covered insulated conductors shall be flame
retardant or shall have a flame-retardant saturant applied after
installation. This treated braid covering shall be stripped back a safe
distance at conductor terminals, according to the operating voltage.
(3) Insulation shielding. (i) Metallic and semiconductor insulation
shielding components of shielded cables shall be removed for a distance
dependent on the circuit voltage and insulation. Stress reduction means
shall be provided at all terminations of factory-applied shielding.
(ii) Metallic shielding components such as tapes, wires, or braids,
or combinations thereof, and their associated conducting and
semiconducting components shall be grounded.
(4) Moisture or mechanical protection for metal-sheathed cables.
Where cable conductors emerge from a metal sheath and where protection
against moisture or physical damage is necessary, the insulation of the
conductors shall be protected by a cable sheath terminating device.
(5) Interrupting and isolating devices. (i) Circuit breaker
installations located indoors shall consist of metal-enclosed units or
fire-resistant cell-mounted units. In locations accessible only to
qualified employees, open mounting of circuit breakers is permitted. A
means of indicating the open and closed position of circuit breakers
shall be provided.
(ii) Where fuses are used to protect conductors and equipment, a
fuse shall be placed in each ungrounded conductor. Two power fuses may
be used in parallel to protect the same load, if both fuses have
identical ratings, and if both fuses are installed in an identified
common mounting with electrical connections that will divide the
current equally. Power fuses of the vented type may not be used
indoors, underground, or in metal enclosures unless identified for the
use.
(iii) Fused cutouts installed in buildings or transformer vaults
shall be of a type identified for the purpose. Distribution cutouts may
not be used indoors, underground, or in metal enclosures. They shall be
readily accessible for fuse replacement.
(iv) Where fused cutouts are not suitable to interrupt the circuit
manually while carrying full load, an approved means shall be installed
to interrupt the entire load. Unless the fused cutouts are interlocked
with the switch to prevent opening of the cutouts under load, a
conspicuous sign shall be placed at such cutouts reading: "WARNING--DO
NOT OPERATE UNDER LOAD."
(v) Suitable barriers or enclosures shall be provided to prevent
contact with nonshielded cables or energized parts of oil-filled
cutouts.
(vi) Load interrupter switches may be used only if suitable fuses
or circuits are used in conjunction with these devices to interrupt
fault currents.
(A) Where these devices are used in combination, they shall be
coordinated electrically so that they will safely withstand the effects
of closing, carrying, or interrupting all possible currents up to the
assigned maximum short-circuit rating.
(B) Where more than one switch is installed with interconnected
load terminals to provide for alternate connection to different supply
conductors, each switch shall be provided with a conspicuous sign
reading: "WARNING--SWITCH MAY BE ENERGIZED BY BACKFEED."
(vii) A means (for example, a fuseholder and fuse designed for the
purpose) shall be provided to completely isolate equipment for
inspection and repairs. Isolating means that are not designed to
interrupt the load current of the circuit shall be either interlocked
with an approved circuit interrupter or provided with a sign warning
against opening them under load.
(6) Mobile and portable equipment. (i) A metallic enclosure shall
be provided on the mobile machine for enclosing the terminals of the
power cable. The enclosure shall include provisions for a solid
connection for the grounding terminal to effectively ground the machine
frame. The method of cable termination used shall prevent any strain or
pull on the cable from stressing the electrical connections. The
enclosure shall have provision for locking so only authorized qualified
persons may open it and shall be marked with a sign warning of the
presence of energized parts.
(ii) All energized switching and control parts shall be enclosed in
effectively grounded metal cabinets or enclosures. Circuit breakers and
protective equipment shall have the operating means projecting through
the metal cabinet or enclosure so these units can be reset without
locked doors being opened. Enclosures and metal cabinets shall be
locked so that only authorized qualified persons have access and shall
be marked with a sign warning of the presence of energized parts.
Collector ring assemblies on revolving-type machines (shovels,
draglines, etc.) shall be guarded.
(7) Tunnel installations. This paragraph applies to installation
and use of high-voltage power distribution and utilization equipment
that is portable or mobile, such as substations, trailers, cars, mobile
shovels, draglines, hoists, drills, dredges, compressors, pumps,
conveyors, and underground excavators.
(i) Conductors in tunnels shall be installed in one or more of the
following:
(A) Metal conduit or other metal raceway;
(B) Type MC cable; or
(C) Other approved multiconductor cable.
(ii) Multiconductor portable cable may supply mobile equipment.
(iii) Conductors and cables shall also be so located or guarded as
to protect them from physical damage. An equipment grounding conductor
shall be run with circuit conductors inside the metal raceway or inside
the multiconductor cable jacket. The equipment grounding conductor may
be insulated or bare.
(iv) Bare terminals of transformers, switches, motor controllers,
and other equipment shall be enclosed to prevent accidental contact
with energized parts.
(v) Enclosures for use in tunnels shall be drip-proof,
weatherproof, or submersible as required by the environmental
conditions.
(vi) Switch or contactor enclosures may not be used as junction
boxes or raceways for conductors feeding through or tapping off to
other switches, unless special designs are used to provide adequate
space for this purpose.
(vii) A disconnecting means that simultaneously opens all
ungrounded conductors shall be installed at each transformer or motor
location.
(viii) All nonenergized metal parts of electric equipment and metal
raceways and cable sheaths shall be effectively grounded and bonded to
all metal pipes and rails at the portal and at intervals not exceeding
305 m (1000 ft) throughout the tunnel.
(b) Emergency power systems. This paragraph applies to circuits,
systems, and equipment intended to supply power for illumination and
special loads in the event of failure of the normal supply.
(1) Wiring methods. Emergency circuit wiring shall be kept entirely
independent of all other wiring and equipment and may not enter the
same raceway, cable, box, or cabinet or other wiring except either
where common circuit elements suitable for the purpose are required, or
for transferring power from the normal to the emergency source.
(2) Emergency illumination. Emergency illumination shall include
all required means of egress lighting, illuminated exit signs, and all
other lights necessary to provide illumination. Where emergency
lighting is necessary, the system shall be so arranged that the failure
of any individual lighting element, such as the burning out of a light
bulb, cannot leave any space in total darkness.
(3) Signs. (i) A sign shall be placed at the service entrance
equipment indicating the type and location of on-site emergency power
sources. However, a sign is not required for individual unit equipment.
(ii) Where the grounded circuit conductor connected to the
emergency source is connected to a grounding electrode conductor at a
location remote from the emergency source, there shall be a sign at the
grounding location that shall identify all emergency and normal sources
connected at that location.
(c) Class 1, Class 2, and Class 3 remote control, signaling, and
power-limited circuits--(1) Classification. Class 1, Class 2, and Class
3 remote control, signaling, or power-limited circuits are
characterized by their usage and electrical power limitation that
differentiates them from light and power circuits. These circuits are
classified in accordance with their respective voltage and power
limitations as summarized in paragraphs (c)(1)(i) through (c)(1)(iii)
of this section.
(i) A Class 1 power-limited circuit shall be supplied from a source
having a rated output of not more than 30 volts and 1000 volt-amperes.
(ii) A Class 1 remote control circuit or a Class 1 signaling
circuit shall have a voltage not exceeding 600 volts; however, the
power output of the source need not be limited.
(iii) The power source for a Class 2 or Class 3 circuit shall be
listed equipment marked as a Class 2 or Class 3 power source, except as
follows:
(A) Thermocouples do not require listing as a Class 2 power source;
and
(B) A dry cell battery is considered an inherently limited Class 2
power source, provided the voltage is 30 volts or less and the capacity
is less than or equal to that available from series-connected No. 6
carbon zinc cells.
(2) Marking. A Class 2 or Class 3 power supply unit shall be
durably marked where plainly visible to indicate the class of supply
and its electrical rating.
(3) Separation from conductors of other circuits. Cables and
conductors of Class 2 and Class 3 circuits may not be placed in any
cable, cable tray, compartment, enclosure, manhole, outlet box, device
box, raceway, or similar fitting with conductors of electric light,
power, Class 1, nonpower-limited fire alarm circuits, and medium power
network-powered broadband communications cables unless a barrier or
other equivalent form of protection against contact is employed.
(d) Fire alarm systems--(1) Classifications. Fire alarm circuits
shall be classified either as nonpower limited or power limited.
(2) Power sources. The power sources for use with fire alarm
circuits shall be either power limited or nonpower limited as follows:
(i) The power source of nonpower-limited fire alarm (NPLFA)
circuits shall have an output voltage of not more than 600 volts,
nominal; and
(ii) The power source for a power-limited fire alarm (PLFA) circuit
shall be listed equipment marked as a PLFA power source.
(3) Separation from conductors of other circuits. (i) Nonpower-
limited fire alarm circuits and Class 1 circuits may occupy the same
enclosure, cable, or raceway provided all conductors are insulated for
maximum voltage of any conductor within the enclosure, cable, or
raceway. Power supply and fire alarm circuit conductors are permitted
in the same enclosure, cable, or raceway only if connected to the same
equipment.
(ii) Power-limited circuit cables and conductors may not be placed
in any cable, cable tray, compartment, enclosure, outlet box, raceway,
or similar fitting with conductors of electric light, power, Class 1,
nonpower-limited fire alarm circuit conductors, or medium power
network-powered broadband communications circuits.
(iii) Power-limited fire alarm circuit conductors shall be
separated at least 50.8 mm (2 in.) from conductors of any electric
light, power, Class 1, nonpower-limited fire alarm, or medium power
network-powered broadband communications circuits unless a special and
equally protective method of conductor separation is employed.
(iv) Conductors of one or more Class 2 circuits are permitted
within the same cable, enclosure, or raceway with conductors of power-
limited fire alarm circuits provided that the insulation of Class 2
circuit conductors in the cable, enclosure, or raceway is at least that
needed for the power-limited fire alarm circuits.
(4) Identification. Fire alarm circuits shall be identified at
terminal and junction locations in a manner that will prevent
unintentional interference with the signaling circuit during testing
and servicing. Power-limited fire alarm circuits shall be durably
marked as such where plainly visible at terminations.
(e) Communications systems. This paragraph applies to central-
station-connected and non-central-station-connected telephone circuits,
radio and television receiving and transmitting equipment, including
community antenna television and radio distribution systems, telegraph,
district messenger, and outside wiring for fire and burglar alarm, and
similar central station systems. These installations need not comply
with the provisions of Sec. 1910.303 through Sec. 1910.308(d), except
for Sec. 1910.304(c)(1) and Sec. 1910.307.
(1) Protective devices. (i) A listed primary protector shall be
provided on each circuit run partly or entirely in aerial wire or
aerial cable not confined within a block.
(ii) A listed primary protector shall be also provided on each
aerial or underground circuit when the location of the circuit within
the block containing the building served allows the circuit to be
exposed to accidental contact with electric light or power conductors
operating at over 300 volts to ground.
(iii) In addition, where there exists a lightning exposure, each
interbuilding circuit on premises shall be protected by a listed
primary protector at each end of the interbuilding circuit.
(2) Conductor location. (i) Lead-in or aerial-drop cables from a
pole or other support, including the point of initial attachment to a
building or structure, shall be kept away from electric light, power,
Class 1, or nonpower-limited fire alarm circuit conductors so as to
avoid the possibility of accidental contact.
(ii) A separation of at least 1.83 m (6 ft) shall be maintained
between communications wires and cables on buildings and lightning
conductors.
(iii) Where communications wires and cables and electric light or
power conductors are supported by the same pole or run parallel to each
other in-span, the following conditions shall be met:
(A) Where practicable, communication wires and cables on poles
shall be located below the electric light or power conductors; and
(B) Communications wires and cables may not be attached to a
crossarm that carries electric light or power conductors.
(iv) Indoor communications wires and cables shall be separated at
least 50.8 mm (2 in.) from conductors of any electric light, power,
Class 1, nonpower-limited fire alarm, or medium power network-powered
broadband communications circuits, unless a special and equally
protective method of conductor separation, identified for the purpose,
is employed.
(3) Equipment location. Outdoor metal structures supporting
antennas, as well as self-supporting antennas such as vertical rods or
dipole structures, shall be located as far away from overhead
conductors of electric light and power circuits of over 150 volts to
ground as necessary to prevent the antenna or structure from falling
into or making accidental contact with such circuits.
(4) Grounding. (i) If exposed to contact with electric light and
power conductors, the metal sheath of aerial cables entering buildings
shall be grounded or shall be interrupted close to the entrance to the
building by an insulating joint or equivalent device. Where protective
devices are used, they shall be grounded in an approved manner.
(ii) Masts and metal structures supporting antennas shall be
permanently and effectively grounded without splice or connection in
the grounding conductor.
(iii) Transmitters shall be enclosed in a metal frame or grill or
separated from the operating space by a barrier, all metallic parts of
which are effectively connected to ground. All external metal handles
and controls accessible to the operating personnel shall be effectively
grounded. Unpowered equipment and enclosures are considered to be
grounded where connected to an attached coaxial cable with an
effectively grounded metallic shield.
(f) Solar photovoltaic systems. This paragraph covers solar
photovoltaic systems that can be interactive with other electric power
production sources or can stand alone with or without electrical energy
storage such as batteries. These systems may have ac or dc output for
utilization.
(1) Conductors of different systems. Photovoltaic source circuits
and photovoltaic output circuits may not be contained in the same
raceway, cable tray, cable, outlet box, junction box, or similar
fitting as feeders or branch circuits of other systems, unless the
conductors of the different systems are separated by a partition or are
connected together.
(2) Disconnecting means. Means shall be provided to disconnect all
current-carrying conductors of a photovoltaic power source from all
other conductors in a building or other structure. Where a circuit
grounding connection is not designed to be automatically interrupted as
part of the ground-fault protection system, a switch or circuit breaker
used as disconnecting means may not have a pole in the grounded
conductor.
(g) Integrated electrical systems--(1) Scope. Paragraph (g) of this
section covers integrated electrical systems, other than unit
equipment, in which orderly shutdown is necessary to ensure safe
operation. An integrated electrical system as used in this section
shall be a unitized segment of an industrial wiring system where all of
the following conditions are met:
(i) An orderly shutdown process minimizes employee hazard and
equipment damage;
(ii) The conditions of maintenance and supervision ensure that only
qualified persons will service the system; and
(iii) Effective safeguards are established and maintained.
(2) Location of overcurrent devices in or on premises. Overcurrent
devices that are critical to integrated electrical systems need not be
readily accessible to employees as required by Sec. 1910.304(f)(1)(iv)
if they are located with mounting heights to ensure security from operation
by nonqualified persons.
0
7. Section 1910.399 is revised to read as follows:
Sec. 1910.399 Definitions applicable to this subpart.
Acceptable. An installation or equipment is acceptable to the
Assistant Secretary of Labor, and approved within the meaning of this
Subpart S:
(1) If it is accepted, or certified, or listed, or labeled, or
otherwise determined to be safe by a nationally recognized testing
laboratory recognized pursuant to Sec. 1910.7; or
(2) With respect to an installation or equipment of a kind that no
nationally recognized testing laboratory accepts, certifies, lists,
labels, or determines to be safe, if it is inspected or tested by
another Federal agency, or by a State, municipal, or other local
authority responsible for enforcing occupational safety provisions of
the National Electrical Code, and found in compliance with the
provisions of the National Electrical Code as applied in this subpart;
or
(3) With respect to custom-made equipment or related installations
that are designed, fabricated for, and intended for use by a particular
customer, if it is determined to be safe for its intended use by its
manufacturer on the basis of test data which the employer keeps and
makes available for inspection to the Assistant Secretary and his
authorized representatives.
Accepted. An installation is "accepted" if it has been inspected
and found by a nationally recognized testing laboratory to conform to
specified plans or to procedures of applicable codes.
Accessible. (As applied to wiring methods.) Capable of being
removed or exposed without damaging the building structure or finish,
or not permanently closed in by the structure or finish of the
building. (See "concealed" and "exposed.")
Accessible. (As applied to equipment.) Admitting close approach;
not guarded by locked doors, elevation, or other effective means. (See
"Readily accessible.")
Ampacity. The current, in amperes, that a conductor can carry
continuously under the conditions of use without exceeding its
temperature rating.
Appliances. Utilization equipment, generally other than industrial,
normally built in standardized sizes or types, that is installed or
connected as a unit to perform one or more functions.
Approved. Acceptable to the authority enforcing this subpart. The
authority enforcing this subpart is the Assistant Secretary of Labor
for Occupational Safety and Health. The definition of "acceptable"
indicates what is acceptable to the Assistant Secretary of Labor, and
therefore approved within the meaning of this subpart.
Armored cable (Type AC). A fabricated assembly of insulated
conductors in a flexible metallic enclosure.
Askarel. A generic term for a group of nonflammable synthetic
chlorinated hydrocarbons used as electrical insulating media. Askarels
of various compositional types are used. Under arcing conditions, the
gases produced, while consisting predominantly of noncombustible
hydrogen chloride, can include varying amounts of combustible gases
depending upon the askarel type.
Attachment plug (Plug cap)(Cap). A device that, by insertion in a
receptacle, establishes a connection between the conductors of the
attached flexible cord and the conductors connected permanently to the
receptacle.
Automatic. Self-acting, operating by its own mechanism when
actuated by some impersonal influence, as, for example, a change in
current strength, pressure, temperature, or mechanical configuration.
Bare conductor. See Conductor.
Barrier. A physical obstruction that is intended to prevent contact
with equipment or live parts or to prevent unauthorized access to a
work area.
Bathroom. An area including a basin with one or more of the
following: a toilet, a tub, or a shower.
Bonding (Bonded). The permanent joining of metallic parts to form
an electrically conductive path that ensures electrical continuity and
the capacity to conduct safely any current likely to be imposed.
Bonding jumper. A conductor that assures the necessary electrical
conductivity between metal parts required to be electrically connected.
Branch circuit. The circuit conductors between the final
overcurrent device protecting the circuit and the outlets.
Building. A structure that stands alone or is cut off from
adjoining structures by fire walls with all openings therein protected
by approved fire doors.
Cabinet. An enclosure designed either for surface or flush
mounting, and provided with a frame, mat, or trim in which a swinging
door or doors are or can be hung.
Cable tray system. A unit or assembly of units or sections and
associated fittings forming a rigid structural system used to securely
fasten or support cables and raceways. Cable tray systems include
ladders, troughs, channels, solid bottom trays, and other similar
structures.
Cablebus. An assembly of insulated conductors with fittings and
conductor terminations in a completely enclosed, ventilated, protective
metal housing.
Cell line. An assembly of electrically interconnected electrolytic
cells supplied by a source of direct current power.
Cell line attachments and auxiliary equipment. Cell line
attachments and auxiliary equipment include, but are not limited to,
auxiliary tanks, process piping, ductwork, structural supports, exposed
cell line conductors, conduits and other raceways, pumps, positioning
equipment, and cell cutout or bypass electrical devices. Auxiliary
equipment also includes tools, welding machines, crucibles, and other
portable equipment used for operation and maintenance within the
electrolytic cell line working zone. In the cell line working zone,
auxiliary equipment includes the exposed conductive surfaces of
ungrounded cranes and crane-mounted cell-servicing equipment.
Center pivot irrigation machine. A multi-motored irrigation machine
that revolves around a central pivot and employs alignment switches or
similar devices to control individual motors.
Certified. Equipment is "certified" if it bears a label, tag, or
other record of certification that the equipment:
(1) Has been tested and found by a nationally recognized testing
laboratory to meet nationally recognized standards or to be safe for
use in a specified manner; or
(2) Is of a kind whose production is periodically inspected by a
nationally recognized testing laboratory and is accepted by the
laboratory as safe for its intended use.
Circuit breaker. A device designed to open and close a circuit by
nonautomatic means and to open the circuit automatically on a
predetermined overcurrent without damage to itself when properly
applied within its rating.
Class I locations. Class I locations are those in which flammable
gases or vapors are or may be present in the air in quantities
sufficient to produce explosive or ignitable mixtures. Class I
locations include the following:
(1) Class I, Division 1. A Class I, Division 1 location is a
location:
(i) In which ignitable concentrations of flammable gases or vapors
may exist under normal operating conditions; or
(ii) In which ignitable concentrations of such gases or vapors may
exist frequently because of repair or maintenance operations or because
of leakage; or
(iii) In which breakdown or faulty operation of equipment or
processes might release ignitable concentrations of flammable gases or
vapors, and might also cause simultaneous failure of electric
equipment.
Note to the definition of "Class I, Division 1:" This
classification usually includes locations where volatile flammable
liquids or liquefied flammable gases are transferred from one
container to another; interiors of spray booths and areas in the
vicinity of spraying and painting operations where volatile
flammable solvents are used; locations containing open tanks or vats
of volatile flammable liquids; drying rooms or compartments for the
evaporation of flammable solvents; locations containing fat and oil
extraction equipment using volatile flammable solvents; portions of
cleaning and dyeing plants where flammable liquids are used; gas
generator rooms and other portions of gas manufacturing plants where
flammable gas may escape; inadequately ventilated pump rooms for
flammable gas or for volatile flammable liquids; the interiors of
refrigerators and freezers in which volatile flammable materials are
stored in open, lightly stoppered, or easily ruptured containers;
and all other locations where ignitable concentrations of flammable
vapors or gases are likely to occur in the course of normal
operations.
(2) Class I, Division 2. A Class I, Division 2 location is a
location:
(i) In which volatile flammable liquids or flammable gases are
handled, processed, or used, but in which the hazardous liquids,
vapors, or gases will normally be confined within closed containers or
closed systems from which they can escape only in the event of
accidental rupture or breakdown of such containers or systems, or as a
result of abnormal operation of equipment; or
(ii) In which ignitable concentrations of gases or vapors are
normally prevented by positive mechanical ventilation, and which might
become hazardous through failure or abnormal operations of the
ventilating equipment; or
(iii) That is adjacent to a Class I, Division 1 location, and to
which ignitable concentrations of gases or vapors might occasionally be
communicated unless such communication is prevented by adequate
positive-pressure ventilation from a source of clean air, and effective
safeguards against ventilation failure are provided.
Note to the definition of "Class I, Division 2:" This
classification usually includes locations where volatile flammable
liquids or flammable gases or vapors are used, but which would
become hazardous only in case of an accident or of some unusual
operating condition. The quantity of flammable material that might
escape in case of accident, the adequacy of ventilating equipment,
the total area involved, and the record of the industry or business
with respect to explosions or fires are all factors that merit
consideration in determining the classification and extent of each
location.
Piping without valves, checks, meters, and similar devices would
not ordinarily introduce a hazardous condition even though used for
flammable liquids or gases. Locations used for the storage of
flammable liquids or liquefied or compressed gases in sealed
containers would not normally be considered hazardous unless also
subject to other hazardous conditions.
Electrical conduits and their associated enclosures separated
from process fluids by a single seal or barrier are classed as a
Division 2 location if the outside of the conduit and enclosures is
a nonhazardous location.
(3) Class I, Zone 0. A Class I, Zone 0 location is a location in
which one of the following conditions exists:
(i) Ignitable concentrations of flammable gases or vapors are
present continuously; or
(ii) Ignitable concentrations of flammable gases or vapors are
present for long periods of time.
Note to the definition of "Class I, Zone 0:" As a guide in
determining when flammable gases or vapors are present continuously
or for long periods of time, refer to Recommended Practice for
Classification of Locations for Electrical Installations of
Petroleum Facilities Classified as Class I, Zone 0, Zone 1 or Zone
2, API RP 505-1997; Electrical Apparatus for Explosive Gas
Atmospheres, Classifications of Hazardous Areas, IEC 79-10-1995;
Area Classification Code for Petroleum Installations, Model Code--
Part 15, Institute for Petroleum; and Electrical Apparatus for
Explosive Gas Atmospheres, Classifications of Hazardous (Classified)
Locations, ISA S12.24.01-1997.
(4) Class I, Zone 1. A Class I, Zone 1 location is a location in
which one of the following conditions exists:
(i) Ignitable concentrations of flammable gases or vapors are
likely to exist under normal operating conditions; or
(ii) Ignitable concentrations of flammable gases or vapors may
exist frequently because of repair or maintenance operations or because
of leakage; or
(iii) Equipment is operated or processes are carried on of such a
nature that equipment breakdown or faulty operations could result in
the release of ignitable concentrations of flammable gases or vapors
and also cause simultaneous failure of electric equipment in a manner
that would cause the electric equipment to become a source of ignition;
or
(iv) A location that is adjacent to a Class I, Zone 0 location from
which ignitable concentrations of vapors could be communicated, unless
communication is prevented by adequate positive pressure ventilation
from a source of clean air and effective safeguards against ventilation
failure are provided.
(5) Class I, Zone 2. A Class I, Zone 2 location is a location in
which one of the following conditions exists:
(i) Ignitable concentrations of flammable gases or vapors are not
likely to occur in normal operation and if they do occur will exist
only for a short period; or
(ii) Volatile flammable liquids, flammable gases, or flammable
vapors are handled, processed, or used, but in which the liquids,
gases, or vapors are normally confined within closed containers or
closed systems from which they can escape only as a result of
accidental rupture or breakdown of the containers or system or as the
result of the abnormal operation of the equipment with which the
liquids or gases are handled, processed, or used; or
(iii) Ignitable concentrations of flammable gases or vapors
normally are prevented by positive mechanical ventilation, but which
may become hazardous as the result of failure or abnormal operation of
the ventilation equipment; or
(iv) A location that is adjacent to a Class I, Zone 1 location,
from which ignitable concentrations of flammable gases or vapors could
be communicated, unless such communication is prevented by adequate
positive-pressure ventilation from a source of clean air, and effective
safeguards against ventilation failure are provided.
Class II locations. Class II locations are those that are hazardous
because of the presence of combustible dust. Class II locations include
the following:
(1) Class II, Division 1. A Class II, Division 1 location is a
location:
(i) In which combustible dust is or may be in suspension in the air
under normal operating conditions, in quantities sufficient to produce
explosive or ignitable mixtures; or
(ii) Where mechanical failure or abnormal operation of machinery or
equipment might cause such explosive or ignitable mixtures to be
produced, and might also provide a source of ignition through
simultaneous failure of electric equipment, through operation of
protection devices, or from other causes; or
(iii) In which combustible dusts of an electrically conductive
nature may be present.
Note to the definition of "Class II, Division 1:" This
classification may include areas of grain handling and processing
plants, starch plants, sugar-pulverizing plants, malting
plants, hay-grinding plants, coal pulverizing plants, areas where
metal dusts and powders are produced or processed, and other similar
locations that contain dust producing machinery and equipment
(except where the equipment is dust-tight or vented to the outside).
These areas would have combustible dust in the air, under normal
operating conditions, in quantities sufficient to produce explosive
or ignitable mixtures. Combustible dusts that are electrically
nonconductive include dusts produced in the handling and processing
of grain and grain products, pulverized sugar and cocoa, dried egg
and milk powders, pulverized spices, starch and pastes, potato and
wood flour, oil meal from beans and seed, dried hay, and other
organic materials which may produce combustible dusts when processed
or handled. Dusts containing magnesium or aluminum are particularly
hazardous, and the use of extreme caution is necessary to avoid
ignition and explosion.
(2) Class II, Division 2. A Class II, Division 2 location is a
location where:
(i) Combustible dust will not normally be in suspension in the air
in quantities sufficient to produce explosive or ignitable mixtures,
and dust accumulations will normally be insufficient to interfere with
the normal operation of electric equipment or other apparatus, but
combustible dust may be in suspension in the air as a result of
infrequent malfunctioning of handling or processing equipment; and
(ii) Resulting combustible dust accumulations on, in, or in the
vicinity of the electric equipment may be sufficient to interfere with
the safe dissipation of heat from electric equipment or may be
ignitable by abnormal operation or failure of electric equipment.
Note to the definition of "Class II, Division 2:" This
classification includes locations where dangerous concentrations of
suspended dust would not be likely, but where dust accumulations
might form on or in the vicinity of electric equipment. These areas
may contain equipment from which appreciable quantities of dust
would escape under abnormal operating conditions or be adjacent to a
Class II Division 1 location, as described above, into which an
explosive or ignitable concentration of dust may be put into
suspension under abnormal operating conditions.
Class III locations. Class III locations are those that are
hazardous because of the presence of easily ignitable fibers or
flyings, but in which such fibers or flyings are not likely to be in
suspension in the air in quantities sufficient to produce ignitable
mixtures. Class III locations include the following:
(1) Class III, Division 1. A Class III, Division 1 location is a
location in which easily ignitable fibers or materials producing
combustible flyings are handled, manufactured, or used.
Note to the definition of "Class III, Division 1:" Such
locations usually include some parts of rayon, cotton, and other
textile mills; combustible fiber manufacturing and processing
plants; cotton gins and cotton-seed mills; flax-processing plants;
clothing manufacturing plants; woodworking plants, and
establishments; and industries involving similar hazardous processes
or conditions.
Easily ignitable fibers and flyings include rayon, cotton
(including cotton linters and cotton waste), sisal or henequen,
istle, jute, hemp, tow, cocoa fiber, oakum, baled waste kapok,
Spanish moss, excelsior, and other materials of similar nature.
(2) Class III, Division 2. A Class III, Division 2 location is a
location in which easily ignitable fibers are stored or handled, other
than in the process of manufacture.
Collector ring. An assembly of slip rings for transferring electric
energy from a stationary to a rotating member.
Competent Person. One who is capable of identifying existing and
predictable hazards in the surroundings or working conditions that are
unsanitary, hazardous, or dangerous to employees and who has
authorization to take prompt corrective measures to eliminate them.
Concealed. Rendered inaccessible by the structure or finish of the
building. Wires in concealed raceways are considered concealed, even
though they may become accessible by withdrawing them. (See Accessible.
(As applied to wiring methods.))
Conductor--(1) Bare. A conductor having no covering or electrical
insulation whatsoever.
(2) Covered. A conductor encased within material of composition or
thickness that is not recognized by this subpart as electrical
insulation.
(3) Insulated. A conductor encased within material of composition
and thickness that is recognized by this subpart as electrical
insulation.
Conduit body. A separate portion of a conduit or tubing system that
provides access through one or more removable covers to the interior of
the system at a junction of two or more sections of the system or at a
terminal point of the system. Boxes such as FS and FD or larger cast or
sheet metal boxes are not classified as conduit bodies.
Controller. A device or group of devices that serves to govern, in
some predetermined manner, the electric power delivered to the
apparatus to which it is connected.
Covered conductor. See Conductor.
Cutout. (Over 600 volts, nominal.) An assembly of a fuse support
with either a fuseholder, fuse carrier, or disconnecting blade. The
fuseholder or fuse carrier may include a conducting element (fuse
link), or may act as the disconnecting blade by the inclusion of a
nonfusible member.
Cutout box. An enclosure designed for surface mounting and having
swinging doors or covers secured directly to and telescoping with the
walls of the box proper. (See Cabinet.)
Damp location. See Location.
Dead front. Without live parts exposed to a person on the operating
side of the equipment
Deenergized. Free from any electrical connection to a source of
potential difference and from electrical charge; not having a potential
different from that of the earth.
Device. A unit of an electrical system that is intended to carry
but not utilize electric energy.
Dielectric heating. The heating of a nominally insulating material
due to its own dielectric losses when the material is placed in a
varying electric field.
Disconnecting means. A device, or group of devices, or other means
by which the conductors of a circuit can be disconnected from their
source of supply.
Disconnecting (or Isolating) switch. (Over 600 volts, nominal.) A
mechanical switching device used for isolating a circuit or equipment
from a source of power.
Electrolytic cell line working zone. The cell line working zone is
the space envelope wherein operation or maintenance is normally
performed on or in the vicinity of exposed energized surfaces of
electrolytic cell lines or their attachments.
Electrolytic cells. A tank or vat in which electrochemical
reactions are caused by applying energy for the purpose of refining or
producing usable materials.
Enclosed. Surrounded by a case, housing, fence, or walls that will
prevent persons from accidentally contacting energized parts.
Enclosure. The case or housing of apparatus, or the fence or walls
surrounding an installation to prevent personnel from accidentally
contacting energized parts, or to protect the equipment from physical
damage.
Energized. Electrically connected to a source of potential
difference.
Equipment. A general term including material, fittings, devices,
appliances, fixtures, apparatus, and the like, used as a part of, or in
connection with, an electrical installation.
Equipment grounding conductor. See Grounding conductor, equipment.
Explosion-proof apparatus. Apparatus enclosed in a case that is
capable of withstanding an explosion of a specified gas or vapor that
may occur within it and of preventing the ignition of a specified gas
or vapor surrounding the enclosure by sparks, flashes, or explosion of
the gas or vapor within, and that operates at such an external temperature
that it will not ignite a surrounding flammable atmosphere.
Exposed. (As applied to live parts.) Capable of being inadvertently
touched or approached nearer than a safe distance by a person. It is
applied to parts not suitably guarded, isolated, or insulated. (See
Accessible and Concealed.)
Exposed. (As applied to wiring methods.) On or attached to the
surface, or behind panels designed to allow access. (See Accessible.
(As applied to wiring methods.))
Exposed. (For the purposes of Sec. 1910.308(e).) Where the circuit
is in such a position that in case of failure of supports or
insulation, contact with another circuit may result.
Externally operable. Capable of being operated without exposing the
operator to contact with live parts.
Feeder. All circuit conductors between the service equipment, the
source of a separate derived system, or other power supply source and
the final branch-circuit overcurrent device.
Fitting. An accessory such as a locknut, bushing, or other part of
a wiring system that is intended primarily to perform a mechanical
rather than an electrical function.
Fountain. Fountains, ornamental pools, display pools, and
reflection pools.
Note to the definition of "fountain:" This definition does not
include drinking fountains.
Fuse. (Over 600 volts, nominal.) An overcurrent protective device
with a circuit opening fusible part that is heated and severed by the
passage of overcurrent through it. A fuse comprises all the parts that
form a unit capable of performing the prescribed functions. It may or
may not be the complete device necessary to connect it into an
electrical circuit.
Ground. A conducting connection, whether intentional or accidental,
between an electric circuit or equipment and the earth, or to some
conducting body that serves in place of the earth.
Grounded. Connected to the earth or to some conducting body that
serves in place of the earth.
Grounded, effectively. Intentionally connected to earth through a
ground connection or connections of sufficiently low impedance and
having sufficient current-carrying capacity to prevent the buildup of
voltages that may result in undue hazards to connected equipment or to
persons.
Grounded conductor. A system or circuit conductor that is
intentionally grounded.
Grounding conductor. A conductor used to connect equipment or the
grounded circuit of a wiring system to a grounding electrode or
electrodes.
Grounding conductor, equipment. The conductor used to connect the
noncurrent-carrying metal parts of equipment, raceways, and other
enclosures to the system grounded conductor, the grounding electrode
conductor, or both, at the service equipment or at the source of a
separately derived system.
Grounding electrode conductor. The conductor used to connect the
grounding electrode to the equipment grounding conductor, to the
grounded conductor, or to both, of the circuits at the service
equipment or at the source of a separately derived system.
Ground-fault circuit-interrupter. A device intended for the
protection of personnel that functions to deenergize a circuit or a
portion of a circuit within an established period of time when a
current to ground exceeds some predetermined value that is less than
that required to operate the overcurrent protective device of the
supply circuit.
Guarded. Covered, shielded, fenced, enclosed, or otherwise
protected by means of suitable covers, casings, barriers, rails,
screens, mats, or platforms to remove the likelihood of approach to a
point of danger or contact by persons or objects.
Health care facilities. Buildings or portions of buildings in which
medical, dental, psychiatric, nursing, obstetrical, or surgical care
are provided.
Note to the definition of "health care facilities:" Health
care facilities include, but are not limited to, hospitals, nursing
homes, limited care facilities, clinics, medical and dental offices,
and ambulatory care centers, whether permanent or movable.
Heating equipment. For the purposes of Sec. 1910.306(g), the term
"heating equipment" includes any equipment used for heating purposes
if heat is generated by induction or dielectric methods.
Hoistway. Any shaftway, hatchway, well hole, or other vertical
opening or space that is designed for the operation of an elevator or
dumbwaiter.
Identified (as applied to equipment). Approved as suitable for the
specific purpose, function, use, environment, or application, where
described in a particular requirement.
Note to the definition of "identified:" Some examples of ways
to determine suitability of equipment for a specific purpose,
environment, or application include investigations by a nationally
recognized testing laboratory (through listing and labeling),
inspection agency, or other organization recognized under the
definition of "acceptable."
Induction heating. The heating of a nominally conductive material
due to its own I\2\R losses when the material is placed in a varying
electromagnetic field.
Insulated. Separated from other conducting surfaces by a dielectric
(including air space) offering a high resistance to the passage of
current.
Insulated conductor. See Conductor, Insulated.
Interrupter switch. (Over 600 volts, nominal.) A switch capable of
making, carrying, and interrupting specified currents.
Irrigation Machine. An electrically driven or controlled machine,
with one or more motors, not hand portable, and used primarily to
transport and distribute water for agricultural purposes.
Isolated. (As applied to location.) Not readily accessible to
persons unless special means for access are used.
Isolated power system. A system comprising an isolating transformer
or its equivalent, a line isolation monitor, and its ungrounded circuit
conductors.
Labeled. Equipment is "labeled" if there is attached to it a
label, symbol, or other identifying mark of a nationally recognized
testing laboratory:
(1) That makes periodic inspections of the production of such
equipment, and
(2) Whose labeling indicates compliance with nationally recognized
standards or tests to determine safe use in a specified manner.
Lighting outlet. An outlet intended for the direct connection of a
lampholder, a lighting fixture, or a pendant cord terminating in a
lampholder.
Line-clearance tree trimming. The pruning, trimming, repairing,
maintaining, removing, or clearing of trees or cutting of brush that is
within 305 cm (10 ft) of electric supply lines and equipment.
Listed. Equipment is "listed" if it is of a kind mentioned in a
list that:
(1) Is published by a nationally recognized laboratory that makes
periodic inspection of the production of such equipment, and
(2) States that such equipment meets nationally recognized
standards or has been tested and found safe for use in a specified
manner.
Live parts. Energized conductive components.
Location--(1) Damp location. Partially protected locations under
canopies, marquees, roofed open porches, and like locations, and
interior locations subject to moderate degrees of moisture, such as some
basements, some barns, and some cold-storage warehouses.
(2) Dry location. A location not normally subject to dampness or
wetness. A location classified as dry may be temporarily subject to
dampness or wetness, as in the case of a building under construction.
(3) Wet location. Installations underground or in concrete slabs or
masonry in direct contact with the earth, and locations subject to
saturation with water or other liquids, such as vehicle-washing areas,
and locations unprotected and exposed to weather.
Medium voltage cable (Type MV). A single or multiconductor solid
dielectric insulated cable rated 2001 volts or higher.
Metal-clad cable (Type MC). A factory assembly of one or more
insulated circuit conductors with or without optical fiber members
enclosed in an armor of interlocking metal tape, or a smooth or
corrugated metallic sheath.
Mineral-insulated metal-sheathed cable (Type MI). Type MI, mineral-
insulated metal-sheathed, cable is a factory assembly of one or more
conductors insulated with a highly compressed refractory mineral
insulation and enclosed in a liquidtight and gastight continuous copper
or alloy steel sheath.
Mobile X-ray. X-ray equipment mounted on a permanent base with
wheels or casters or both for moving while completely assembled.
Motor control center. An assembly of one or more enclosed sections
having a common power bus and principally containing motor control
units.
Nonmetallic-sheathed cable (Types NM, NMC, and NMS). A factory
assembly of two or more insulated conductors having an outer sheath of
moisture resistant, flame-retardant, nonmetallic material.
Oil (filled) cutout. (Over 600 volts, nominal.) A cutout in which
all or part of the fuse support and its fuse link or disconnecting
blade are mounted in oil with complete immersion of the contacts and
the fusible portion of the conducting element (fuse link), so that arc
interruption by severing of the fuse link or by opening of the contacts
will occur under oil.
Open wiring on insulators. Open wiring on insulators is an exposed
wiring method using cleats, knobs, tubes, and flexible tubing for the
protection and support of single insulated conductors run in or on
buildings, and not concealed by the building structure.
Outlet. A point on the wiring system at which current is taken to
supply utilization equipment.
Outline lighting. An arrangement of incandescent lamps or electric
discharge lighting to outline or call attention to certain features,
such as the shape of a building or the decoration of a window.
Overcurrent. Any current in excess of the rated current of
equipment or the ampacity of a conductor. It may result from overload,
short circuit, or ground fault.
Overhaul means to perform a major replacement, modification,
repair, or rehabilitation similar to that involved when a new building
or facility is built, a new wing is added, or an entire floor is
renovated.
Overload. Operation of equipment in excess of normal, full-load
rating, or of a conductor in excess of rated ampacity that, when it
persists for a sufficient length of time, would cause damage or
dangerous overheating. A fault, such as a short circuit or ground
fault, is not an overload. (See Overcurrent.)
Panelboard. A single panel or group of panel units designed for
assembly in the form of a single panel; including buses, automatic
overcurrent devices, and with or without switches for the control of
light, heat, or power circuits; designed to be placed in a cabinet or
cutout box placed in or against a wall or partition and accessible only
from the front. (See Switchboard.)
Permanently installed decorative fountains and reflection pools.
Pools that are constructed in the ground, on the ground, or in a
building in such a manner that the fountain or pool cannot be readily
disassembled for storage, whether or not served by electrical circuits
of any nature. These units are primarily constructed for their
aesthetic value and are not intended for swimming or wading.
Permanently installed swimming, wading, and therapeutic pools.
Pools that are constructed in the ground or partially in the ground,
and all other capable of holding water in a depth greater than 1.07 m
(42 in.). The definition also applies to all pools installed inside of
a building, regardless of water depth, whether or not served by
electric circuits of any nature.
Portable X-ray. X-ray equipment designed to be hand-carried.
Power and control tray cable (Type TC). A factory assembly of two
or more insulated conductors, with or without associated bare or
covered grounding conductors under a nonmetallic sheath, approved for
installation in cable trays, in raceways, or where supported by a
messenger wire.
Power fuse. (Over 600 volts, nominal.) See Fuse.
Power-limited tray cable (Type PLTC). A factory assembly of two or
more insulated conductors under a nonmetallic jacket.
Power outlet. An enclosed assembly, which may include receptacles,
circuit breakers, fuseholders, fused switches, buses, and watt-hour
meter mounting means, that is intended to supply and control power to
mobile homes, recreational vehicles, or boats or to serve as a means
for distributing power needed to operate mobile or temporarily
installed equipment.
Premises wiring. (Premises wiring system.) The interior and
exterior wiring, including power, lighting, control, and signal circuit
wiring together with all of their associated hardware, fittings, and
wiring devices, both permanently and temporarily installed, that
extends from the service point of utility conductors or source of power
(such as a battery, a solar photovoltaic system, or a generator,
transformer, or converter) to the outlets. Such wiring does not include
wiring internal to appliances, fixtures, motors, controllers, motor
control centers, and similar equipment.
Qualified person. One who has received training in and has
demonstrated skills and knowledge in the construction and operation of
electric equipment and installations and the hazards involved.
Note 1 to the definition of "qualified person:" Whether an
employee is considered to be a "qualified person" will depend upon
various circumstances in the workplace. For example, it is possible
and, in fact, likely for an individual to be considered
"qualified" with regard to certain equipment in the workplace, but
"unqualified" as to other equipment. (See 1910.332(b)(3) for
training requirements that specifically apply to qualified persons.)
Note 2 to the definition of "qualified person:" An employee
who is undergoing on-the-job training and who, in the course of such
training, has demonstrated an ability to perform duties safely at
his or her level of training and who is under the direct supervision
of a qualified person is considered to be a qualified person for the
performance of those duties.
Raceway. An enclosed channel of metal or nonmetallic materials
designed expressly for holding wires, cables, or busbars, with
additional functions as permitted in this standard. Raceways include,
but are not limited to, rigid metal conduit, rigid nonmetallic conduit,
intermediate metal conduit, liquidtight flexible conduit, flexible
metallic tubing, flexible metal conduit, electrical metallic tubing,
electrical nonmetallic tubing, underfloor raceways, cellular concrete floor
raceways, cellular metal floor raceways, surface raceways, wireways,
and busways.
Readily accessible. Capable of being reached quickly for operation,
renewal, or inspections, so that those needing ready access do not have
to climb over or remove obstacles or to resort to portable ladders,
chairs, etc. (See Accessible.)
Receptacle. A receptacle is a contact device installed at the
outlet for the connection of an attachment plug. A single receptacle is
a single contact device with no other contact device on the same yoke.
A multiple receptacle is two or more contact devices on the same yoke.
Receptacle outlet. An outlet where one or more receptacles are
installed.
Remote-control circuit. Any electric circuit that controls any
other circuit through a relay or an equivalent device.
Sealable equipment. Equipment enclosed in a case or cabinet that is
provided with a means of sealing or locking so that live parts cannot
be made accessible without opening the enclosure. The equipment may or
may not be operable without opening the enclosure.
Separately derived system. A premises wiring system whose power is
derived from a battery, a solar photovoltaic system, or from a
generator, transformer, or converter windings, and that has no direct
electrical connection, including a solidly connected grounded circuit
conductor, to supply conductors originating in another system.
Service. The conductors and equipment for delivering electric
energy from the serving utility to the wiring system of the premises
served.
Service cable. Service conductors made up in the form of a cable.
Service conductors. The conductors from the service point to the
service disconnecting means.
Service drop. The overhead service conductors from the last pole or
other aerial support to and including the splices, if any, connecting
to the service-entrance conductors at the building or other structure.
Service-entrance cable. A single conductor or multiconductor
assembly provided with or without an overall covering, primarily used
for services, and is of the following types:
(1) Type SE. Type SE, having a flame-retardant, moisture resistant
covering; and
(2) Type USE. Type USE, identified for underground use, having a
moisture-resistant covering, but not required to have a flame-retardant
covering. Cabled, single-conductor, Type USE constructions recognized
for underground use may have a bare copper conductor cabled with the
assembly. Type USE single, parallel, or cable conductor assemblies
recognized for underground use may have a bare copper concentric
conductor applied. These constructions do not require an outer overall
covering.
Service-entrance conductors, overhead system. The service
conductors between the terminals of the service equipment and a point
usually outside the building, clear of building walls, where joined by
tap or splice to the service drop.
Service entrance conductors, underground system. The service
conductors between the terminals of the service equipment and the point
of connection to the service lateral.
Service equipment. The necessary equipment, usually consisting of
one or more circuit breakers or switches and fuses, and their
accessories, connected to the load end of service conductors to a
building or other structure, or an otherwise designated area, and
intended to constitute the main control and cutoff of the supply.
Service point. The point of connection between the facilities of
the serving utility and the premises wiring.
Shielded nonmetallic-sheathed cable (Type SNM). A factory assembly
of two or more insulated conductors in an extruded core of moisture-
resistant, flame-resistant nonmetallic material, covered with an
overlapping spiral metal tape and wire shield and jacketed with an
extruded moisture-, flame-, oil-, corrosion-, fungus-, and sunlight-
resistant nonmetallic material.
Show window. Any window used or designed to be used for the display
of goods or advertising material, whether it is fully or partly
enclosed or entirely open at the rear and whether or not it has a
platform raised higher than the street floor level.
Signaling circuit. Any electric circuit that energizes signaling
equipment.
Storable swimming or wading pool. A pool that is constructed on or
above the ground and is capable of holding water to a maximum depth of
1.07 m (42 in.), or a pool with nonmetallic, molded polymeric walls or
inflatable fabric walls regardless of dimension.
Switchboard. A large single panel, frame, or assembly of panels on
which are mounted, on the face or back, or both, switches, overcurrent
and other protective devices, buses, and (usually) instruments.
Switchboards are generally accessible from the rear as well as from the
front and are not intended to be installed in cabinets. (See
Panelboard.)
Switch--(1) General-use switch. A switch intended for use in
general distribution and branch circuits. It is rated in amperes, and
it is capable of interrupting its rated current at its rated voltage.
(2) General-use snap switch. A form of general-use switch
constructed so that it can be installed in device boxes or on box
covers, or otherwise used in conjunction with wiring systems recognized
by this subpart.
(3) Isolating switch. A switch intended for isolating an electric
circuit from the source of power. It has no interrupting rating, and it
is intended to be operated only after the circuit has been opened by
some other means.
(4) Motor-circuit switch. A switch, rated in horsepower, capable of
interrupting the maximum operating overload current of a motor of the
same horsepower rating as the switch at the rated voltage.
Switching devices. (Over 600 volts, nominal.) Devices designed to
close and open one or more electric circuits. Included in this category
are circuit breakers, cutouts, disconnecting (or isolating) switches,
disconnecting means, interrupter switches, and oil (filled) cutouts.
Transportable X-ray. X-ray equipment installed in a vehicle or that
may readily be disassembled for transport in a vehicle.
Utilization equipment. Equipment that utilizes electric energy for
electronic, electromechanical, chemical, heating, lighting, or similar
purposes.
Ventilated. Provided with a means to permit circulation of air
sufficient to remove an excess of heat, fumes, or vapors.
Volatile flammable liquid. A flammable liquid having a flash point
below 38 [deg]C (100 [deg]F), or a flammable liquid whose temperature
is above its flash point, or a Class II combustible liquid having a
vapor pressure not exceeding 276 kPa (40 psia) at 38 [deg]C (100
[deg]F) and whose temperature is above its flash point.
Voltage (of a circuit). The greatest root-mean-square (rms)
(effective) difference of potential between any two conductors of the
circuit concerned.
Voltage, nominal. A nominal value assigned to a circuit or system
for the purpose of conveniently designating its voltage class (as 120/
240 volts, 480Y/277 volts, 600 volts). The actual voltage at which a
circuit operates can vary from the nominal within a range that permits
satisfactory operation of equipment.
Voltage to ground. For grounded circuits, the voltage between the
given conductor and that point or conductor of the circuit that is
grounded; for ungrounded circuits, the greatest voltage between the
given conductor and any other conductor of the circuit.
Watertight. So constructed that moisture will not enter the
enclosure.
Weatherproof. So constructed or protected that exposure to the
weather will not interfere with successful operation. Rainproof,
raintight, or watertight equipment can fulfill the requirements for
weatherproof where varying weather conditions other than wetness, such
as snow, ice, dust, or temperature extremes, are not a factor.
Wireways. Sheet-metal troughs with hinged or removable covers for
housing and protecting electric wires and cable and in which conductors
are laid in place after the wireway has been installed as a complete
system.
0
8. Appendix A to Subpart S is revised to read as follows:
Appendix A--References for Further Information
The references contained in this appendix provide nonmandatory
information that can be helpful in understanding and complying with
Subpart S of this Part. However, compliance with these standards is
not a substitute for compliance with Subpart S of this Part.
ANSI/API RP 500-1998 (2002) Recommended Practice for
Classification of Locations for Electrical Installations at
Petroleum Facilities Classified as Class I Division 1 and Division
2.
ANSI/API RP 505-1997 (2002) Recommended Practice for
Classification of Locations for Electrical Installations at
Petroleum Facilities Classified as Class I, Zone 0, Zone 1 and Zone
2.
ANSI/ASME A17.1-2004 Safety Code for Elevators and Escalators.
ANSI/ASME B30.2-2005 Overhead and Gantry Cranes (Top Running
Bridge, Single or Multiple Girder, Top Running Trolley Hoist).
ANSI/ASME B30.3-2004 Construction Tower Cranes.
ANSI/ASME B30.4-2003 Portal, Tower, and Pedestal Cranes.
ANSI/ASME B30.5-2004 Mobile And Locomotive Cranes.
ANSI/ASME B30.6-2003 Derricks.
ANSI/ASME B30.7-2001 Base Mounted Drum Hoists.
ANSI/ASME B30.8-2004 Floating Cranes And Floating Derricks.
ANSI/ASME B30.11-2004 Monorails And Underhung Cranes.
ANSI/ASME B30.12-2001 Handling Loads Suspended from Rotorcraft.
ANSI/ASME B30.13-2003 Storage/Retrieval (S/R) Machines and
Associated Equipment.
ANSI/ASME B30.16-2003 Overhead Hoists (Underhung).
ANSI/ASME B30.22-2005 Articulating Boom Cranes.
ANSI/ASSE Z244.1-2003 Control of Hazardous Energy Lockout/Tagout
and Alternative Methods.
ANSI/ASSE Z490.1-2001 Criteria for Accepted Practices in Safety,
Health, and Environmental Training.
ANSI/IEEE C2-2002 National Electrical Safety Code.
ANSI K61.1-1999 Safety Requirements for the Storage and Handling
of Anhydrous Ammonia.
ANSI/UL 913-2003 Intrinsically Safe Apparatus and Associated
Apparatus for Use in Class I, II, and III, Division 1, Hazardous
(Classified) Locations.
ASTM D3176-1989 (2002) Standard Practice for Ultimate Analysis
of Coal and Coke.
ASTM D3180-1989 (2002) Standard Practice for Calculating Coal
and Coke Analyses from As-Determined to Different Bases.
NFPA 20-2003 Standard for the Installation of Stationary Pumps
for Fire Protection.
NFPA 30-2003 Flammable and Combustible Liquids Code.
NFPA 32-2004 Standard for Drycleaning Plants.
NFPA 33-2003 Standard for Spray Application Using Flammable or
Combustible Materials.
NFPA 34-2003 Standard for Dipping and Coating Processes Using
Flammable or Combustible Liquids.
NFPA 35-2005 Standard for the Manufacture of Organic Coatings.
NFPA 36-2004 Standard for Solvent Extraction Plants.
NFPA 40-2001 Standard for the Storage and Handling of Cellulose
Nitrate Film.
NFPA 58-2004 Liquefied Petroleum Gas Code.
NFPA 59-2004 Utility LP-Gas Plant Code.
NFPA 70-2002 National Electrical Code. (See also NFPA 70-2005.)
NFPA 70E-2000 Standard for Electrical Safety Requirements for
Employee Workplaces. (See also NFPA 70E-2004.)
NFPA 77-2000 Recommended Practice on Static Electricity.
NFPA 80-1999 Standard for Fire Doors and Fire Windows.
NFPA 88A-2002 Standard for Parking Structures.
NFPA 91-2004 Standard for Exhaust Systems for Air Conveying of
Vapors, Gases, Mists, and Noncombustible Particulate Solids.
NFPA 101-2006 Life Safety Code.
NFPA 496-2003 Standard for Purged and Pressurized Enclosures for
Electrical Equipment.
NFPA 497-2004 Recommended Practice for the Classification of
Flammable Liquids, Gases, or Vapors and of Hazardous (Classified)
Locations for Electrical Installations in Chemical Process Areas.
NFPA 505-2006 Fire Safety Standard for Powered Industrial Trucks
Including Type Designations, Areas of Use, Conversions, Maintenance,
and Operation.
NFPA 820-2003 Standard for Fire Protection in Wastewater
Treatment and Collection Facilities.
NMAB 353-1-1979 Matrix of Combustion-Relevant Properties and
Classification of Gases, Vapors, and Selected Solids.
NMAB 353-2-1979 Test Equipment for Use in Determining
Classifications of Combustible Dusts.
NMAB 353-3-1980 Classification of Combustible Dust in Accordance
with the National Electrical Code.
Appendices B and C [Removed]
0
9. Appendices B and C to Subpart S are removed.
[FR Doc. E7-1360 Filed 2-9-07; 8:45 am]
BILLING CODE 4510-26-P
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