GFCI (Ground Fault Circuit Interrupter)
Also known as: ground fault circuit interrupter, GFI
Outlet or breaker that detects current leakage to ground and trips the circuit within milliseconds. Required by code in wet locations (kitchens, baths, outdoors).
A GFCI monitors current flow and trips when it detects an imbalance (current going somewhere other than the intended return path — typically through a person to ground). The trip happens in 5-25 milliseconds at very low current levels (4-6 mA), fast enough to prevent serious electric shock.
NEC requires GFCI protection in: kitchens, bathrooms, garages, outdoor outlets, basements, laundry areas, and any outlet within 6 feet of a sink. Older homes often lack GFCI protection in these locations and may need retrofit. GFCI outlets can also protect downstream outlets when wired correctly.
GFCIs are mechanically more complex than standard outlets and have a finite lifespan — most last 10-15 years before nuisance tripping or outright failure. The TEST and RESET buttons on every GFCI should be tested monthly per manufacturer guidance; in practice, most homeowners never do, so many GFCIs fail silently. For service businesses, GFCI replacement is a straightforward and frequently-needed residential service.
Related terms
AFCI (Arc Fault Circuit Interrupter)
Breaker that detects dangerous electrical arcs and trips the circuit. Required by NEC in most residential bedrooms, living areas, and habitable rooms since 2014.
Electrical conduit
Tube or pipe protecting electrical wiring. Required in commercial installations and exposed-to-damage residential locations. Material affects cost, flexibility, and code compliance.