An MCB, or miniature circuit breaker, is an isolating component installed within a supply board which is designed to automatically trip the circuit if a fault is detected. This means that the power supply is cut off to prevent damage to the circuit, which is typically triggered by an overload or short. A bimetallic strip within the unit heats and bends if a continuous overcurrent comes into contact with it which then trips the switch. There are different MCB types for various applications with a wide range of amp ratings and trip curves available to suit any installation requirements.