Residual-current device, Electrical safety device used in household wiring.
A residual-current device (RCD), or residual-current circuit breaker (RCCB), is a device that quickly breaks an electrical circuit to prevent serious harm from an ongoing electric shock. Injury may still occur in some cases, for example if a human falls after receiving a shock, or if the person touches both conductors at the same time.RCD is the name used in the United Kingdom. In the United States and Canada, the terms ground fault circuit interrupter (GFCI), ground fault interrupter (GFI) or appliance leakage current interrupter (ALCI) (also known as a Leakage Current Detection Interrupter (LCDI)) are used.
If the RCD device has additional overcurrent protection integrated in the same device, it is referred to as RCBO.
An earth leakage circuit breaker (ELCB) may be a residual-current device, although an older type of voltage-operated earth leakage circuit breaker also exists.
These electrical wiring devices are designed to quickly and automatically disconnect a circuit when it detects that the electric current is not balanced between the supply and return conductors of a circuit.
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