MCB abbreviated as Miniature Circuit Breaker, is an automatically operated electronics switch. It detects the fault by detecting excessive amount of current flow in the circuit and breaks the circuit as soon as possible.

Initially, fuses were used instead of MCB. Fuses need to be replaced after a short circuit while MCB just has to be reset and it will start functioning. MCB offers greater operational safety and is convenient to use.


MCB is designed to protect against over current and over heating faults. When the current exceeds the predefined limit MCB automatically turns off and breaks the circuit. To restart the circuit MCB has to be turned on manually.

In case of over heating MCB takes 2 seconds to 2 minutes to trip.


  • Handling MCB is much safer than fuse for electrical appliances as well as for human beings.
  • In MCB, faulty wire trips off from original position which makes it very much easier to detect faults.
  • It provides a better interface by using a knob.
  • MCB is reusable and hence is cheaper then fuse.
  • It is more sensitive to current.
  • To return supply, you just have to push the knob.

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