The full form of MCB is Miniature Circuit Breaker. It is a type of electronics switch which can be operated automatically. It is capable of detecting a fault present within a circuit by detecting the current flows that are present in the excessive amount in the circle. If a current is present in such an amount, it could break the circuit anytime. Sometimes, fuses are used as an alternative to the MCBs. However, the MCBs are a better option as you just need to reset it and it starts working again. It is designed in a way to protect against faults that occur due to overheating.