Ground fault circuit interrupters (GFCIs) have been around since the early 60s, yet there is much confusion about their use and how they operate. I believe that both the Occupational Safety and Health Administration (OSHA) and the National Electric Code (NEC) could be more user-friendly in their rules and regulations, which would help others better understand the use of GFCIs. There is no question about where GFCIs are required in dwellings, as outlined in NEC 210-8(a) and other than dwellings, 210-8(b). There is also a Table in the handbook (Table 210.1), that lists additional requirements. One very important area is also covered in Section 305-6. Confusion arises because some inspectors and electricians believe Article 305 only covers temporary power situations at construction sites.

First, you must understand that anytime you use electric power anywhere, for a short time, and then remove the equipment, you are using temporary power. OSHA and the NEC require that any extension cords, and cord- and plug-connected equipment used to construct, maintain, repair, and demolish (including alterations and painting), is required to have GFCI protection, or the assured equipment grounding conductor program (AEGC). OSHA exempts double-insulated tools from the assured equipment grounding conductor program.

The AEGC program and double-insulated tools are a very good effort toward electrical safety, yet it is still possible for a fatality to occur when using a tool in either of these two programs when GFCI protection is missing. There is an incident on record where a worker was killed while using a double-insulated tool. An internal wire became loose and stuck outside the case of the tool, which he apparently didn’t notice. When he came in contact with the hot wire and ground he was killed.

And it is possible that one could perform the assured equipment grounding conductor program, on a tool or cord, with just one strand of the conductor remaining attached. The tester would indicate there was continuity from the male grounding terminal on the plug to the female grounding terminal on the other end of the cord, or from the male grounding end of the cord to the grounding frame of the tool. Immediately after the designated person performed this test, he or she could then throw the cord or tool aside and have the single remaining strand break. You would then have a cord or tool with no grounding conductor, a potential for a fatal accident. GFCI protection would back up both of these situations and prevent a fatality.

Both OSHA and the NEC require GFCI protection for tools used on construction sites. OSHA seems to imply that if you use the AEGC program you are exempt from the GFCI requirement at construction sites {1926.404(b)(iii)(C)}. Yet, in its letters of interpretation OSHA indicates otherwise. The NEC only allows the AEGC in place of GFCI in industrial locations. The NEC at 305-6(a) calls for GFCI protection for all 15-, 20- and 30-amp (the 30-amp is new for the 1999 code), 125-volt receptacle outlets, when using temporary power on construction sites. Then in Exception 2 the NEC allows industrial locations to use the AEGC program, as outlined in 305-6(b)(2), in lieu of GFCI protection for these outlets. What if you are doing construction at the industrial site? Would you still be able to use this exception? OSHA’s interpretation of the rule (using the NEC as a standard) is construction activity is just that, no matter where it is conducted, and 1926.404 construction standards would apply. In a letter of interpretation on 1926.404, OSHA went so far as to explain that in an office environment, you would not need GFCI protection because insulated walls, flooring, and other materials surrounded you. Then, OSHA contrasts that with the concrete floors and steel structures in an industrial plant, where GFCI protection would be required.

Not to be overlooked in all this is that in the NEC section 305-6(b), all outlets other than 125 volt, 15, 20 and 30 amp, using temporary power requires either GFCI protection or the AEGC program. What that implies is if you are using 220-volt or 480-volt cord- and plug-connected equipment you must perform the AEGC program if you do not have GFCI protection for this equipment.

In OSHA 29 CFR 1910 Industrial Standards, Section 1910.334, Electrical Safety section, Subpart S, strangely mentions nothing at all about GFCI protection. The only requirement is that grounding-type tools be grounded and cords be inspected for the integrity of that conductor. Remember though, OSHA’s letters of interpretation, available on the Internet at, imply that when doing construction alterations and repairs at industrial locations, 1926 Construction Standards apply.

Now let’s try to make some sense of all this. First, we need to understand the dangers presented when using extension cords, and cord- and plug-connected equipment. At either a construction site or in an industrial environment, while using this electrical equipment, there is a lot of activity going on. Vehicle traffic of all kinds is present, installation and construction materials are being thrown about, welding sparks and slag are everywhere, and steel scrap and pipes are being cut and burned. All these activities could damage the cords. Meanwhile, we are pulling cords through mud and water, through and over scraps and construction equipment. All of this presents the danger of the equipment ground being broken and perhaps at the same time the ungrounded conductors being exposed or coming in contact with metal not grounded. The very surroundings would then put workers between these grounded sources—the earth itself, water, steel, concrete, etc.—and the voltage source. OSHA says deaths could actually be cut in half at these locations if we employ the use of GFCI’s.

Not to be overlooked is an extremely important requirement at 305-6(a). This, in my opinion, is the paragraph that explains in black and white that this requirement goes beyond your temporary power pole found at construction sites. An inspector pointed out that the first sentence clearly states that this section is only for construction sites because it specifically says: “… for outlets not part of the permanent wiring.” The very next sentence clearly indicates otherwise, as it states: “If a receptacle(s) is installed or exists as part of the permanent wiring of the building or structure and is used for temporary electric power, ground-fault circuit-interrupter protection for personnel shall be provided.” And OSHA, in a letter of interpretation clearly states, (GET COPY OF LETTER). What we’re saying here folks is, if the temporary power comes from an outlet on a construction power pole, or the outlet is permanently installed in a building, GFCI protection is required. If you are using an extension cord or plugging in cord- and plug-connected equipment, you are obtaining temporary power. In addition, if that outlet is permanently mounted and is not GFCI-protected, you may use cord sets or devices that contain GFCI protection identified for portable use. What does “identified for portable use” mean? It means you can not use the prohibited ubiquitous metal box with a standard GFCI receptacle.

You cannot even use a listed weatherproof box with a standard GFCI receptacle. A receptacle identified for portable use is one that has grounded conductor integrity protection. If you have an ordinary GFCI receptacle attached to a cord, and the grounded conductor is broken for any reason, you have lost the ability to detect a ground fault. Without the grounded conductor we have lost our 120-volt source to the receptacle and the ability to detect a ground fault. The “portable type” prevents such a situation from developing. If it loses its 120-volt source (by losing the grounded conductor) it cuts off all power to the outlet.

CORCORAN, owner of EMC Code Consultants in Burlington, Wash., is an expert instructor on OSHA industrial standards and electrical safety, grounding and bonding, and the National Electrical Code. He can be reached at (360) 757-3605.