Circuit breaker

A circuit breaker is a resettable automatic protective device that switches off a circuit when it detects a fault, overload or other overcurrent condition. In a home consumer unit or distribution board, it may protect a circuit feeding a solar inverter, battery inverter, EV chargepoint, heat pump or other fixed equipment. It protects the circuit wiring and connected equipment from excessive current, but it is not the same as an RCD, which responds to residual current and provides protection against some electric-shock risks. MCB is a common circuit-breaker type for final circuits, while an RCBO combines MCB-style overcurrent protection with residual-current protection. A circuit breaker noted on a schedule, certificate or manual should be read with the circuit design, cable rating, equipment instructions and fault-protection requirements rather than treated as a user-selected accessory. If a breaker trips repeatedly, the circuit and connected equipment need checking before it is reset again.