MCB / Miniature circuit breaker

MCB means miniature circuit breaker, a resettable protective device that disconnects a circuit when it detects an electrical fault or overload. In a home consumer unit or distribution board, an MCB trips for overcurrent conditions such as an overloaded circuit or a short circuit. It protects the circuit wiring and connected equipment from damaging current, but it is not the same as an RCD, which provides residual-current protection against some electric-shock risks. For solar inverters, batteries, EV chargers and heat-pump circuits, the breaker rating is part of the circuit design and should match the cable, load and fault protection designed for that circuit. If an MCB trips repeatedly, the cause needs checking before it is reset again.