Electrical Repairs: GFCI

I got a call from a friend the other day because the outlets in his shop had stopped working and he had no idea why. When I got to his shop, my first check was his circuit breakers. Nothing was tripped, but when I put my tester on his outlets, sure enough, he had no power. A little poking around showed the problem to be a tripped GFCI outlet. One quick reset later, his power was restored and he was back to work.

A GFCI is a Ground Fault Circuit Interrupter. It is a safety device designed to shut off electrical power in the event of a ground fault, which is an electrical failure or fault where the energized (or "hot") wire comes into contact with something that provides a path back to the earth. This is a dangerous situation because that path back to the earth very frequently includes a person, and that person will receive a nasty and potentially lethal shock. To prevent this, the GFCI detects minuscule differences in current between the hot and neutral legs of a circuit and cuts power before a damaging shock can be delivered.

Water is the main contributor to electrical ground faults involving humans. The current US National Electrical Code requires GFCI protection for outlets outdoors, in garages, kitchens, bathrooms, and basically any place where there is a chance of water splashing an outlet. This requirement has reduced death by electrical shock by an estimated 50% since it was introduced in the 1970s.

There are two kinds of GFCI devices used in the USA. The newer style is built into a circuit breaker. It makes protecting an entire circuit simple and certain. It requires a bit more work to install, but assures protection for every outlet on the circuit. It is also the more expensive option.

The more common GFCI protection is built into an outlet. This device can be wired to protect all of the outlets down the circuit from it, so that only one outlet is required to protect all of a circuit. It's a bit more complex to set up, but is the more budget-friendly option.

GFCI devices are easily identified. They have buttons on the face that are marked "Test" and "Reset." The Test button is used to manually trip the protection, and these devices should be tested a few times a year. The Reset button resets the protection and restores power to the protected outlets on the circuit. This button is also used to restore power in case an actual ground fault triggers the protection.

Installing GFCI protecting devices is a bit more involved than a simple outlet swap; it involves changing a breaker or doing a fair bit of legwork to identify which outlet in a circuit needs replaced in order to ensure correct protection. If you're the slightest bit unsure of what you're doing, please contact a qualified electrician to handle this task.

Now you know what to check to keep yourself from being in the dark if you lose power to certain outlets but the breaker or fuse looks normal.

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