What Is a GFCI Outlet?

A ground-fault circuit interrupter: an outlet that compares the current flowing out with the current coming back, and trips in a fraction of a second if any is leaking to ground. Code requires them near water: bathrooms, kitchens, garages, laundry rooms, and outdoors. One GFCI can protect a chain of ordinary-looking outlets downstream, which is why a dead bedroom outlet is sometimes fixed by a Reset button in the garage.

The downstream protection is the part that trips people up. A GFCI wired at the start of a circuit protects everything after it, and the protected outlets look completely normal (some just carry a small "GFCI protected" sticker). So when an outlet goes dead and the breaker looks fine, the fix is often a hunt: press Reset on every GFCI in the bathrooms, kitchen, garage, basement, and outside, then retest.

A GFCI that trips the moment you reset it is doing its job: something plugged in is leaking current, or the wiring is. Unplug everything on the circuit and try once more. If it still will not hold, or the buttons feel dead, the device itself may have worn out (they do, after 10–15 years or a lightning-adjacent life). Replacement is about $20 in parts, but it is live-wiring work, and misdiagnosing which wires are line versus load leaves you unprotected. That one is a fair job for a licensed electrician.