A protective device that monitors leakage current between live conductors and earth in elevator circuits, tripping the supply when leakage exceeds a safe threshold.
Full Definition
A ground fault interrupter (GFI) or residual current circuit breaker (RCCB) in elevator installations monitors the difference between current flowing in the live and neutral conductors. When this imbalance — caused by current leaking to earth through insulation breakdown, moisture ingress, or contact with grounded metal — exceeds the trip threshold (typically 30 mA for personnel protection), the device opens the circuit within milliseconds. In elevator machine rooms and hoistways, GFIs protect maintenance personnel from electric shock when working on live equipment. They must be tested regularly by pressing the test button; a failed test indicates either a faulty device or a persistent earth leakage fault requiring investigation.
