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Standard Interpretations
05/15/2002 - Ground fault protection requirements for 120-volt and/or 240-volt circuits.
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• Standard Number: 1926.404(b); 1926.404(b)(1)(i); 1926.404(b)(1)(ii)

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.


May 15, 2002

Mr. Philip P. Mercuris
Master Builders of Iowa
221 Park Street
P.O. Box 695
Des Moines, Iowa 50303

Re: §1926.404(b); assured equipment grounding conductor program; ground-fault circuit interrupter; 240-volt circuits;

Dear Mr. Mercuris:

This is in response to your May 23, 2001, letter to the Occupational Safety and Health Administration (OSHA) in which you ask questions regarding the use of 220-volt (V) equipment for construction work. We apologize for the long delay in providing a response. Your questions have been paraphrased below.

Question (1): Does the requirement in 29 CFR 1926.404(b)(1)(i) to have either a ground-fault circuit interrupter protection (GFCI) or an assured equipment grounding conductor program (AEGCP) apply only to 120 V circuits, or does it also apply to a 240 V circuit?

Answer: Yes. §1926.404(b)(1)(i) provides:
(b) Branch circuits -- (1) Ground-fault protection - (i) General. The employer shall use either ground fault circuit interrupters as specified in paragraph (b)(1)(ii) of this section or an assured equipment grounding conductor program as specified in paragraph (b)(1)(iii) of this section to protect employees on construction sites. These requirements are in addition to any other requirements for equipment grounding conductors.
Under this provision, employers must provide protection against ground-fault by using either a GFCI or AEGCP. The provision, by its terms, is not limited to 120 V circuits. Employers are required to protect employees under this provision with respect to 240 V circuits as well.

Question (2): What are the requirements when a temporary service panel has both a 120 V and a 240 V circuit? Would protecting the 120 V circuit with a GFCI comply with the standard, or does the 240 V circuit also have to be protected by a GFCI or an assured equipment grounding conductor program?

Answer: The 240 V circuit must be protected as well. Installing a GFCI designed for a 120 V circuit in a panel that also has a 240 V circuit will not provide ground-fault protection to the 240 V circuit.

While technically the option of using GFCI under (b)(1)(ii) is available only for 120 V circuits, that limitation was put in the standard only because GFCIs for 240 V were generally unavailable when the standard was promulgated. Employers may choose to use GFCIs designed for 240 V to protect 240 V circuits; the technical violation of (b)(1)(ii) would be considered de minimis. De minimis violations are those which have no direct or immediate relationship to safety or health. Citations are not issued for de minimis violations.

Question (3): Does the requirement in §1926.404(b)(1)(i) to provide ground-fault protection apply where 240 V equipment, such as a welder, is hard-wired directly into a panel box?

Answer
No, since the circuit you describe has no outlet.

If you need any further clarification on this subject, please contact us by fax at: U.S. Department of Labor, OSHA, Directorate of Construction, [Office of Construction Standards and Compliance Guidance], fax # 202-693-1689. You can also contact us by mail at the above office, Room N3468, 200 Constitution Avenue, N.W., Washington, D.C. 20210, although there will be a delay in our receiving correspondence by mail.

Sincerely,



Russell B. Swanson, Director
Directorate of Construction

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