GFCI stands for Ground Fault Circuit Interrupter. These are also referred to as GFIs, or Ground Fault Interrupters. A GFCI precisely monitors the balance of electrical current moving through a circuit. If an imbalance occurs, like in a short, the GFCI immediately cuts off the electricity. An imbalance means that the power flowing through the circuit differs from the power returning to it. A GFCI's purpose is to prevent fatal electrical shocks through elimination of sustained current draw when a short occurs.

Water and electricity do not mix, and there are many places in the home and outside where the two are required to be in fairly close proximity. All switches, sockets, breakers and circuits for those rooms and areas of the home should be GFCI protected for your family's safety.

About Ground Faults
Any electric path between a source of current and a grounded surface is referred to as a "ground-fault." A ground-fault occurs when current is "leaking" and escaping to the ground. How this occurs is significant in that, if your body provides a path to the ground for this leakage, you could be injured, burned, severely shocked, or electrocuted. Since water is such a good conductor, ground-faults are especially common in areas where water can provide a conduit for electricity to "escape" and find an alternate path to the ground.

Types

There are three basic types of GFCI devices:

Receptacle Type

This is the most common GFCI in residential homes. It is an inexpensive device that replaces the standard receptacle (outlet). It is completely compatible with any standard outlet and can be used to protect other outlets "downstream" (any outlet receiving power from the GFCI outlet).

Circuit Breaker Type

This type of GFCI is becoming more and more popular since it allows the builder/electrician to use standard (inexpensive) outlets in a room and simply wire the entire circuit with a single GFCI circuit breaker that gets installed in the panel box. The advantage of this breaker is that it applies to every fixture on the circuit - lights, outlets, fans, etc and also provides protection against overloads and simple short-circuits.

Portable Type

This is an outlet strip or other device which provides GFCI-level protection in a portable unit.

Where to Install GFCIs

Since around 1973, GFCI is required for most outdoor receptacles in homes built to comply with the National Electrical Code. In 1975 that was extended to bathroom receptacles and in 1978 garage wall outlets were added. It took until around 1987 for the code to include kitchen receptacles, so that is where many homeowners find themselves redoing their electrical to comply with current law. All receptacles in crawl spaces and unfinished basements are also required to have GFCI outlets or breakers (since 1990).

Obviously the newer GFCI circuit breakers make retrofitting a home with GFCI protection much easier than replacing each individual outlet in a system, especially if you aren't sure how your wiring is run in a given room. For homes protected by fuses (seriously consider upgrading your box), you are going to have to stick to GFCI receptacles and focus on the most critical areas like bathrooms, kitchens, crawl spaces and outdoor areas.

We have a separate article on Installing GFCI's, but most savvy consumers can do it themselves if they follow the instructions and make sure to completely disable the power going to the circuit before beginning. To test the receptacle GFCI after installation, simply plug something into the outlet (like a radio or light) and turn it on. Press the "TEST" button on the GFCI to ensure that the GFCI's "RESET" button pops out, and power to the device is cut. If the "RESET" button pops out but the light does not go out, the GFCI has been wired improperly. If the "RESET" button does not pop out, the GFCI is defective and should be replaced. Pressing the "RESET" button re-activates your circuit.

Conclusion

Ground Fault Circuit Interrupters are critical in any home. If you are doing any rewiring or simply updating your house to bring it up to code you should pay attention to where GFCIs may be required. This is one of the least expensive things you can do to provide an incredibly beneficial level of safety to your family.