For many years now, ground-fault circuit interrupter (GFCI) outlets have been a common site in bathrooms, kitchens, exterior receptacles and other areas where electricity might mix with water or other hazards to create potentially dangerous conditions. Now, you can take that protection with you while you work, in the form of portable GFCI cords and outlets. In fact, if you are a contractor, GFCI protection is an OSHA-required safety feature on every size and type of job site.

All of today’s electrical systems have a grounding system, designed to carry excess electricity safely to the ground to protect the people using the system. Should that ground system somehow fail, however, ground-fault circuit interrupters are the backup system. GFCIs continually measure and compare the amount of electrical current going to and returning from a piece of electrical equipment. Should the GFCI sense a difference between those two currents of anything in excess of approximately 5 milliamperes — a very tiny amount of electricity — it will interrupt the circuit to protect the user.

On construction sites where permanent electricity has not yet been installed or activated, temporary electrical services and portable generators are equipped with GFCI outlets for the protection of workers using 110-volt power tools, extension cords and other electrical devices. For professional contractors, tradespeople, or do-it-yourselfers who want or need that same level of electrical protection on 110-volt circuits being used for home improvement or home maintenance projects of any size, any of the portable GFCI components now on the market make it simple.

Portable GFCIs typically take one of two forms: outlets and cords. Portable GFCI outlets consist of a rugged, metal or high-impact plastic box that contains one or more GFCI-protected receptacles and a short, grounded cord. The box is hung on the wall, and the cord plugs into an adjacent standard, non-GFCI-equipped outlet. Most types have a hinged, spring-loaded cover to protect the receptacles when not in use, and are listed as “weather-resistant.” If the outlet will be directly exposed to rain, it must be listed as “waterproof.”

Another common type of portable GFCI outlet does not have a cord. Instead, it plugs directly into a standard, nonprotected outlet and provides a single, protected outlet. Most GFCIs of this type are intended for use in protected, interior environments. Portable GFCI outlets of either type are typically available with 14-gauge wire, for use with 15-amp circuits.

GFCI cords can provide a quick and easy way to provide protection to three tools or other devices at the same time. Looking like a short extension cord, one end has a standard male three-prong receptacle that plugs directly into any standard outlet, and the other end has a power block with three standard female outlets. In between the two ends is a sealed box containing the GFCI circuitry, which provides protection to the three outlets. Both 14-gauge and 12-gauge wiring is commonly available with cords of this type — the 12-gauge allows use on 20-amp circuits.

GFCI outlets of any type — including the ones permanently wired inside your home — have some very complex internal circuitry. For that reason, they need to be tested regularly to ensure that they are working correctly.

Every GFCI comes equipped with two small buttons, marked “test” and “reset.” Pressing the test button will trigger an artificial ground fault in the circuit, popping out the reset button and immediately shutting off the flow of electricity to that outlet and any other outlet or device that is downstream of it. Simply press the reset button to restore the flow.

Permanently wired GFCI outlets should be tested monthly, and portable ones should be tested immediately prior to each use.

Remodeling and repair questions? E-mail Paul at

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