what is an rccb
A residual-current device (RCD), or residual-current circuit breaker (RCCB), is a device to quickly disconnect current to prevent serious harm from an ongoing electric shock.Injury may still occur in some cases, for example if a person falls after receiving a shock.n earth leakage circuit breaker (ELCB) may be a residual-current device, although an older type of voltage-operated earth leakage circuit breaker also exists. In German speaking countries the device is sometimes known as FI where the F stands for fault (Fehler) and I for the symbol that represents Electric current.