Ground fault
When electricity escapes its intended path and leaks to ground — the fault a GFCI is built to catch.
A ground fault is electricity taking an unintended shortcut to ground instead of returning on the neutral wire — through wet insulation, a damaged appliance, or a person. Even a tiny leak is dangerous: about 5 milliamps through a body can be harmful, far below what a normal breaker would notice. That's why wet areas need a [GFCI outlet](/glossary/gfci-outlet), which watches for that exact imbalance and cuts power in milliseconds. A GFCI that keeps tripping is usually reporting a real (often moisture-related) ground fault — see [why a GFCI keeps tripping](/guides/gfci-keeps-tripping).