Ground-fault circuit-interrupters, or GFCIs, are life-saving devices found on electrical receptacles (outlets), circuit breakers, extension cords, and other electrical equipment. They detect imbalances in the electrical current and quickly shut off the power to minimize the risk of shock. For example, if you're drying your hair in the bathroom and some water splashes into your hair dryer and creates a short circuit, the GFCI the dryer is plugged into will likely turn itself off—in a tiny fraction of a second.
(Actually, most hair dryers have their own GFCI-like devices built into the cords, so you're doubly protected, but this doesn't mean you should use your dryer in the bathtub.)
Where You Need a GFCI
The National Electrical Code, or NEC, has specific GFCI requirements for dwelling units. Article 210.8 states that ground-fault circuit-interrupters shall be used for all 125-volt, single-phase, 15- and 20-amp receptacles installed in the following locations:
- Bathrooms: All receptacles
- Garages and accessory buildings: Defined as structures that have a floor located at or below grade level not intended as habitable rooms and limited to storage areas, work areas, and areas of similar use.
- Outdoors: All receptacles, with one exception: receptacles that are not readily accessible and are supplied by a dedicated branch circuit for electric snow-melting or deicing equipment.
- Unfinished basements: Unfinished basements are defined as portions or areas of the basement not intended as habitable rooms and limited to storage areas, work areas, etc...
- Exceptions: Receptacle supplying only a permanently installed fire alarm or burglar alarm system, receptacles that are not readily accessible, receptacles on a dedicated branch circuit and labeled for use with a plug-in equipment (ex: sump pump).
- Crawl spaces - Unfinished areas located at or below grade level; same GFCI requirements as basements.
- Kitchens - All receptacles serving countertop areas and any receptacle within 4 feet of a sink.
- Laundry, utility, and wet bar sinks - Where receptacles are placed within six feet of the outside edge of the sink.
- Pool/spa areas: GFCI protection for lights and lighting outlets; receptacles for pumps; all receptacles within 20 feet of a pool, spa, or fountain; and power supply for a pool cover.
Tips for Meeting GFCI Requirements
While the NEC is the leading authority on all things electrical, your local building authority has the final word on GFCI requirements (and everything else in your house); check with your local building department for specific rules for installations in your area. GFCI requirements apply to GFCI protection. This doesn't mean you need a GFCI receptacle at every location. You can provide GFCI protection for an entire circuit with a GFCI circuit breaker. Also, a single GFCI receptacle can be wired to protect itself and every receptacle downstream on the same circuit. This allows you to install one GFCI receptacle at the beginning of the circuit and use standard receptacles for the rest—where allowed by local code.