Ground-fault circuit interrupter

A protective electrical device that disconnects a circuit when it detects a mismatch between outgoing and returning current, indicating leakage from the intended path.

Differential current transformer: A transformer that detects the difference between currents in two conductors by measuring their combined magnetic effect. It senses the imbalance between a GFCI’s outgoing and returning currents.
Electrical safety: Practices and engineering measures that reduce injury, fire, and equipment damage from electricity. GFCIs are one measure for reducing shock risk from leakage current.
Arc-fault circuit interrupter: A protective device that detects dangerous electrical arcing and disconnects the circuit. An AFCI targets arcing faults, while a GFCI responds to current escaping the intended path.
Electric shock: The physiological effect of electric current passing through the body. Rapid disconnection can reduce the duration of some shocks, but cannot eliminate every shock hazard.
Residual-current device: A protective switch that disconnects a circuit when it detects residual current flowing outside the intended conductors. It uses the same leakage-current principle as a GFCI, with terminology common outside North America.
Ground-fault protection: Electrical protection that detects current escaping its intended circuit path and limits resulting hazards. GFCIs are a specific form of ground-fault protection for people and circuits.
Overcurrent protection: Protection that interrupts current exceeding a circuit’s rated limit because of overload or short circuit. A GFCI can trip at currents too small to trigger ordinary overcurrent protection.
Electrocution: Death caused by electric shock. GFCIs are intended to reduce the risk of fatal shock from certain leakage faults.
Trip threshold: The measured level at which a protective device initiates an interrupting action. A GFCI must distinguish dangerous leakage from small normal imbalances.
GFCI receptacle: A wall receptacle with integrated ground-fault sensing and a switch that disconnects its protected circuit. This common GFCI form provides protection at an outlet and sometimes downstream outlets.

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