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 https://www.osha.gov.

July 7, 2003

David Touhey
Contract Risk Management, Inc.
P.O. Box 211
Concord, NH 03302-0211

Re: Whether GFCIs are required to have "open-neutral protection."

Dear Mr. Touhey:

We are writing in response to your letter of August 20, 2002, to the Occupational Safety and Health Administration (OSHA) regarding "open-neutral protection" in ground-fault circuit interrupter (GFCI) devices. We apologize for the long delay in providing this response.

We have paraphrased your questions as follows:

Question: To comply with OSHA requirements for construction work, do ground-fault circuit interrupters (GFCIs) without open-neutral protection have to be replaced with GFCIs that have this feature?


A GFCI is a fast-acting device that senses small current leakage to ground ("ground fault") and, detecting an imbalance between the hot and neutral circuits, "trips" -- that is, it shuts off the electricity in a fraction of a second, thereby preventing electrocution.

An "open-neutral" condition occurs when there is a break or other failure in the neutral conductor. When this occurs, there are some situations (depending on factors such as the extent of the failure and its location), in which the neutral conductor, or portion of it, will continue to be energized, but electrically powered equipment, such as an electric hand drill, may not operate. In addition, a GFCI powered by that conductor may not operate -- that is, it may not trip -- unless it is specifically designed to trip even if there is an open-neutral condition. Because the conductor (or portion of it) remains energized, there is a danger of a ground fault during an open-neutral condition. For purposes of this response, "open-neutral protection" refers to the ability of a GFCI to trip even if there is an open-neutral condition.

OSHA requirements
29 CFR 1926.404(b)(1)(i) states:

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 . . .

Under §1926.404(b)(1)(ii), when using GFCIs to comply with paragraph (b)(1)(i), the employer must use an "approved" GFCI. Under §1926.449, approved equipment is equipment that is "acceptable." Section 1926.449(a) defines acceptable equipment as follows:

(a) If it is accepted, or certified, or listed, or labeled, or otherwise determined to be safe by a qualified testing laboratory capable of determining the suitability of materials and equipment for installation and use in accordance with this standard;1
* * *

A GFCI that does not have "open-neutral protection" is permitted to be used under the OSHA standard if it is approved by a qualified testing laborabory in accordance with §1926.449(a).

Our research indicates that Underwriters Laboratories' (UL) has for a number of years required cord-connected GFCIs to be able to operate in the presence of an open-neutral condition. However, as far as we can determine, this is not, and has not been, a requirement for UL approval of permanently connected, outlet-type GFCIs (mounted in an outlet box).

If an employer has a cord-connected GFCI that was not approved by a qualified testing laboratory, it would have to replace it with an approved GFCI -- which, at least for UL approval, would have to have open-neutral protection.

Your letter raises the further question of an employer's OSHA obligations where it has a GFCI that was approved at one time, but would no longer qualify for approval under the testing laboratory's revised approval criteria. In that instance, under §§1926.404 and 1926.449, the employer would have to replace the item with a new one only if the testing laboratory that originally approved it has revoked its approval.

If you need any additional information, please contact us by fax at: U.S. Department of Labor, OSHA, Directorate of Construction, [Office of Construction Standards and 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.


Russell B. Swanson, Director
Directorate of Construction





1Section 1926.449 (b) and (c) explain other circumstances, which are not pertinent here, in which equipment is considered acceptable. [ back to text ]









2In your letter you stated that UL had recently amended its UL 943 standard for GFCIs to require GFCIs to work in the presence of a reverse line-load miswire condition. However, that is not the equivalent of an open-neutral condition. [ back to text ]