Employee Alarm Systems
The purpose of the employee alarm systems standard
29 CFR 1910.165 is to reduce the severity of workplace
accidents and injuries by ensuring that alarm systems
operate properly and procedures are in place to alert
employees to workplace emergencies.
This section will help you to
understand alarm system requirements for warning employees
when a hazardous condition or event occurs.
See the
Alarms Checklist [76 KB
PDF, 1 page].
Accessibility Assistance: Contact the OSHA Directorate of
Science, Technology and Medicine at 202-693-2300 for
assistance accessing OSHA PDF materials. |
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Does
the standard apply to me? |
OSHA's employee alarm
systems standard
29 CFR 1910.165 applies to all employers that
use an alarm system to satisfy any OSHA standard
that requires employers to provide an early
warning for emergency action, or reaction time for
employees to safely escape the work place, the
immediate work area, or both.
This standard also applies to you if an OSHA
standard specifically states that you must install
an employee alarm system. For example, some
standards that specifically require or reference
alarm systems include:
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29 CFR 1910.37, Maintenance, safeguards, and
operational features for exit routes
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29 CFR 1910.38, Emergency action plans
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29 CFR 1910.66, Powered platforms for
building maintenance
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29 CFR 1910.106, Flammable and combustible
liquids
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29 CFR 1910.120, Hazardous waste operations
and emergency response
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29 CFR 1910.157, Portable fire extinguishers
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29 CFR 1910.160, Fixed extinguishing
systems, general
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29 CFR 1910.161, Fixed extinguishing
systems, dry chemical
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29 CFR 1910.162, Fixed extinguishing
systems, gaseous agent
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29 CFR 1910.164, Fire detection systems
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Note:
This section applies to all emergency employee
alarms installed to meet a particular OSHA
standard. This section does not apply to those
discharge or supervisory alarms required on
various fixed extinguishing systems or to
supervisory alarms on fire suppression, alarm or
detection systems unless they are intended to be
employee alarm systems [29
CFR 1910.165(a)(1)].
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Types of alarm devices |
The employee alarm system shall
provide warning for necessary emergency action as called
for in the emergency action plan, or for reaction time for
safe escape of employees from the workplace or the
immediate work area, or both [29
CFR 1910.165(b)(1)]. An employee alarm system can be
any piece of equipment and/or device designed to inform
employees that an emergency exists or to signal the
presence of a hazard requiring urgent attention. National
Fire Protection Association (NFPA) 72, National Fire Alarm
Code, requires a fire alarm signal to be distinctive in
sound from other signals and can not be used for any other
purpose.
The two most common types of alarms are audible
and visual devices.
The employee alarm shall be
capable of being perceived above ambient noise or light
levels by all employees in the affected portions of the
workplace. Tactile devices may be used to alert those
employees who would not otherwise be able to recognize the
audible or visual alarm [29
CFR 1910.165(b)(2)].
Audible Alarms
Audible alarms include bells, horns, sirens, voice
announcement systems, and other devices that can be
distinguished above and apart from the normal sound level
within the workplace. Temporal and voice signals are
the most effective means.
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Use temporal coded signals. Temporal coding is
accomplished by interrupting a steady sound in the
following manner: .5 sec ON; .5 sec OFF; .5 sec
ON; .5 sec OFF, in a repeating cycle.
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Use a distinctive three-pulse temporal pattern to
signal an immediate emergency evacuation.
Standard Audible Emergency
Evacuation Signal. This signal shall
consist of a "three-pulse" temporal pattern. Three
successive "on" phases, lasting 0.5 second each,
must be separated by 0.5 second of "off" time.
Then, at the completion of the third "on" phase
there must be 1.5 seconds of "off" time before the
full cycle is repeated. Therefore, the total cycle
shall last 4.0 seconds (0.5 second "on," 0.5
second "off," 0.5 second "on," 0.5 second "off",
0.5 second "on," 1.5 seconds "off") [S3.41,
Audible Emergency Evacuation Signal,
American National Standard Institute (ANSI)].
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Only use this signal pattern to notify personnel
of the need to immediately evacuate the building.
Total evacuation is not always desirable or
necessary during an emergency but relocation of
the occupants from the affected area to a safe
area within the building, or their protection in
place.
Note: Audible
notification devices such as horns, bells, or
sirens are no longer recognized for new systems by
NFPA 72, National Fire Alarm Code – only
temporal signals or voice signals. For visual
signals, only strobe lights are now recognized by
NFPA 72 and the Americans with Disabilities Act
(ADA). The following
bells, horns and sirens, are only permitted in
existing systems.
Bells
Vibrating bells are
the most common signal device. Bells are
commonly used in schools for fire alarms.
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Horns
Horns produce a very
loud distinctive sound that immediately attracts
attention. Horns can be useful to call attention
to critical situations.
Signals other than those used for evacuation
purposes do not have to produce the temporal
coded signal.
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Sirens
Sirens produce a loud
piercing wail that makes them ideally suitable
for initiating a site-wide evacuation.
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Workplace Announcement System
Speakers can be used to
play a live or recorded voice message. They are
often ideally suited for large workplaces where
phased or guided evacuations are needed.
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Visual Alarms
Visual alarms use steady, flashing, or strobe lights to
alert workers to an emergency situation in areas where
noise levels are high, especially where ear protection
must be worn and audible signals may not be heard or may
be misunderstood. Visual signals also provide an
effective way to alert workers with hearing loss about
an emergency. Strobe lights are recognized as the most
effective means. Only strobe lights
are now recognized by NFPA 72 and the Americans with
Disabilities Act (ADA).
- Provide visible signals in restrooms, in other
general and common use areas, and in hallways and
lobbies. Common use areas also include:
- meeting and conference rooms,
- classrooms,
- cafeterias,
- filing and photocopy rooms,
- employee break rooms,
- dressing, examination, and treatment rooms, and
- similar spaces that are not used solely as employee
work areas.
[Americans with Disabilities Act Accessibility
Guidelines, ADAAG
4.28.1 General].
Note: It is not always
possible to fix the occupancy of a room or space
or anticipate its use by a person with a hearing
impairment. Visual alarms are particularly
important in those common use spaces where a
person may be alone.
Flashing/Steady Lights
These lights are well
suited for areas where ambient noise makes audible
signals difficult to hear. These types of lights
come with different colored covers for increased
attention and can be ordered with rotating or
flashing lights.
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Strobe Lights
Strobe lights use high
intensity flash tubes that are ideally suited for
areas where high ambient light levels make
traditional rotating or flashing lights difficult
to distinguish or where ambient noise makes
audible signals difficult to hear.
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Emergency action plan |
For an alarm system to be effective, you must have
an emergency action plan that addresses how
employees, including disabled workers, will be
informed that an emergency exists and how they
should respond. The alarm system must inform all
affected employees that an emergency exists and what
their immediate response should be based on the
alarm sequence. This plan should include:
- The preferred means of reporting emergencies, such
as manual pull box alarms, public address systems,
radio or telephones. The employer shall post emergency
telephone numbers near telephones, or employee notice
boards, and other conspicuous locations when
telephones serve as a means of reporting emergencies.
Where a communication system also serves as the
employee alarm system, all emergency messages shall
have priority over all non-emergency messages [29
CFR 1910.165(b)(4)].
- Procedures for sounding emergency alarms in the
workplace. For those employers with 10 or fewer
employees in a particular workplace, direct voice
communication is an acceptable procedure for sounding
the alarm provided all employees can hear the alarm.
Such workplaces do not need a back-up system [29
CFR 1910.165(b)(5)].
- A current list of key personnel, such as the plant
manager or physician, in order of priority, to notify
in the event of an emergency during off-duty hours.
Employee
Alarm Systems |
Comments |
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Is the emergency preparedness
plan reviewed and revised periodically? |
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Does each employee know the following? |
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How to report an emergency |
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The type and meaning of each
emergency alarm or signal |
The employee alarm system must use a
distinctive signal for each purpose and comply
with the requirements in
29 CFR 1910.165 [29
CFR 1910.38(d)].
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Evacuation routes |
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Assembly areas |
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First aid / medical kit
locations |
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Alarm pull box locations |
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Are the following emergency
phone numbers posted? |
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Local fire department |
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Hospitals and ambulances |
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Police departments |
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Emergency response team |
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Emergency agencies |
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Is the employee alarm system
recognizable and perceptible in all areas during
emergency conditions? |
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Are employee alarm systems
properly maintained and tested regularly? |
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Installation and restoration |
For alarm systems to provide adequate notification
in the event of an emergency, the employer shall
assure that all devices, components, combinations of
devices or systems constructed and installed to
comply with this standard are approved. Steam
whistles, air horns, strobe lights or similar
lighting devices, or tactile devices meeting the
requirements of this section are considered to meet
this requirement for approval [29
CFR 1910.165(c)(1)].
The employer should assure that the alarms which are
installed are:
- Capable of being heard, seen, or otherwise
perceived by everyone in the workplace; [29
CFR 1910.165(b)(2)].
- Supervised if they were installed after January 1,
1981 and contain circuitry that is capable of being
supervised. These systems must also provide positive
notification to assigned personnel whenever a
deficiency exists in the system [29
CFR 1910.165(d)(4)].
Alarm Selection Guidelines
To get the most from an alarm
system, follow these guidelines when selecting devices:
- Make sure the alarm's sound is as different
from the background noise and light as possible.
Audible alarms should exceed the ambient noise
level by at least six decibels. The light
intensity for visual alarms should be at least
75 candela.
- Use alarms with integrated audible and
visual signals to accommodate the hearing and
visually impaired, and for areas where a person
may be working alone. This includes areas such
as restrooms, storage areas, offices, and
similar areas. (These devices are available for
about the same cost as an audible or visual
signal alone).
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Did you know? |
Research indicates high-intensity xenon strobe
lamps to be the most effective and white light
the most discernible. Colored lamps,
particularly red, were found to be ineffective
even at very high intensities. |
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- Avoid using strobe devices that flash at rates
above five flashes per second (fps). Rates above five
fps can trigger seizures in people with certain forms
of epilepsy. When multiple devises are used, either
synchronize or reduce their flash rate so that the
combined rate does not exceed five fps.
Protection of Alarms
To make sure devices stay
operable, follow these guidelines:
- Alarm system components that may be exposed to
corrosive environments should be either made or coated
with a non-corrosive material.
- Position alarm devices away from or out of contact
with materials or equipment which may cause physical
damage.
- Alarms that are installed outdoors and need to be
shielded from the weather to work properly must be
protected with a canopy, hood, or other suitable
device.
- All devices should be securely mounted to a solid
surface, such as screwed to a junction box with a
mounting plate or other appropriate method that
prevents them from putting pressure or stress on
attached wires or tubing.
Alarm Placement Guidelines
To ensure your alarm system
provides adequate coverage, follow these guidelines when
placing alarm devices:
- Put at least one visual alarm in each room and any
other general usage areas (guest restrooms, meeting
rooms) which may be occupied by those with hearing
impairments. You may need more than one alarm per room
for those that exceed the manufacturer's spacing
requirements. For example, if your alarm is rated for
50 feet, install alarms so they are evenly spaced with
no more then 50 feet between devices.
- Mount visual and audible devices 80 inches above
the highest floor level within the space or six inches
below the ceiling, whichever is lower.
- Manually activated devices for use in conjunction
with alarms must also be:
Unobstructed, conspicuous, and readily
accessible [29
CFR 1910.165(e)]. Make available an emergency
communications system such as a public address
system, telephone, portable radio unit, or other
means to notify employees of the emergency and to
contact local law enforcement, the fire
department, and others [29
CFR 1910.165(b)(4)].
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Maintenance and testing |
Employee alarm systems are important life safety
devices and must be maintained in an operating
condition at all times except during repairs or
maintenance [29
CFR 1910.165(d)(1)].
Routine Test and Maintenance
- Test the reliability and adequacy of
non-supervised employee alarm systems every two
months. Use a different actuation device in each test
of a multi-actuation device system [29
CFR 1910.165(d)(2)].
- Maintain or replace power supplies as often as
necessary to ensure a fully operational condition.
Provide a back-up means of alarm when systems are out
of service, such as employee runners or telephones [29
CFR 1910.165(d)(3)].
- Use properly trained persons to service, maintain,
and test employee alarms [29
CFR 1910.165(d)(5)].
- Do a visual check to ensure that employee alarm
devices are not obstructed/installed in a manner that
would prevent sound or light from reaching or entering
the protected areas.
- Restore all employee alarm systems to normal
operating condition as soon as possible after each
test or alarm. Spare alarm devices and components must
be readily available in sufficient quantities and
locations for prompt restoration of the system [29
CFR 1910.165(c)(2)].
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Employee training and education |
Employees must know what types of emergencies may
occur and what course of action they must take. Make
sure all your employees understand the function and
elements of your emergency action plan, including
types of potential emergencies, reporting
procedures, alarm systems, evacuation plans, and
shutdown procedures. Discuss any special hazards
your workplace may have such as flammable materials,
toxic chemicals, radioactive sources, and/or
water-reactive substances.
Your training should address the following:
- Individual roles and responsibilities;
- Threats, hazards, and protective actions;
- Location and operation of manually activated pull
stations and communication equipment;
- Emergency response procedures;
- Evacuation, shelter, and accountability
procedures;
- Location and use of common emergency equipment;
and
- Emergency shutdown procedures.
When your employees know how to
sound an alarm and/or notify emergency personnel at the
first sign of an emergency, it may make the difference
between life and death.
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