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The full form of MCB is miniature circuit breaker. It is an automatically operated switch which
trips down and protects an electric circuit from damage, when current flowing through it
exceeds the maximum limit. It can be reset back to its ‘ON’ position and the circuit will once
again be complete and start working.

A fuse or MCB works in case of:
a) short circuit
b) Overloading of current.
a) Short-circuit:
It is a problem in an electrical circuit where two or more wires that are not supposed to
come in contact with each other touch. A short circuit can result in a very high current
flowing through the circuit.

b) Overloading:
 An overloaded circuit is an electric circuit that is carrying more current than it is designed
to handle, creating a danger of fire through overheating.

 Overloading happens when too many appliances which work on high power are
connected through the same socket.

Advantage of MCB over fuse is:
a) MCB trips down the switch automatically during electrical faults whereas fuse melts
itself to protect the circuit.
b) MCB can be restored by putting switch back whereas fuse needs to be replaced