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.

February 4, 1992

MEMORANDUM FOR:     BYRON R. CHADWICK
                   REGIONAL ADMINISTRATOR

THROUGH:            LEO CAREY, DIRECTOR
                   OFFICE OF FIELD PROGRAMS

FROM:               PATRICIA K. CLARK, DIRECTOR 
                   DIRECTORATE OF COMPLIANCE PROGRAMS

SUBJECT:            Magna Electrical Construction Co., Inc. Letter
                   Requesting Ground Fault Circuit Interrupter Information

This is in response to your November 18 memorandum forwarding the Magna Electrical Construction Company's request for information on OSHA requirements for testing ground fault circuit interrupters (GFCIs) at construction sites. I apologize for the delay in responding to your inquiry.

Section 1926.404(b)(1) does not require GFCIs to be tested. However, 1926.20(b)(2) does require the frequent and regular inspections of equipment. The instructions included with the devices indicate that they should be tested monthly. If an employer can demonstrate, for example, by means of logs or procedures, that he or she tests GFCIs monthly and promptly replaces those found defective, then a serious citation may not be appropriate for defective GFCIs found upon inspection, provided the faulty devices are replaced promptly.

In regard to Magna's remaining two questions concerning the proper procedures for testing GFCIs, I have attached the Electrical/Electronic Technical Note 91-1 which outlines the acceptable test procedure.