What is MCB (miniature circuit breaker)

  • MCB is a mechanical device operate automatic operation designed to connect and disconnect the electrical circuit in the ordinary and extraordinary situation suitable both for A.C and D.C voltage.
  • The main function of the MCB to protect equipment or circuits from overhead and short circuit. The size of MCB is small and usually, use for a household appliance and domestic.

  • The average fix ampere rating from 6amp up to 125amp. It can be reset back to the normal condition after the trip but cannot adjust ampere rating.

Miniature circuit breaker

Miniature circuit breaker


  • An electric current requires two wires to complete the circuit.
  • From source via the in wire to the load and from there via out wire back to the electrical source.
  • The current in these two wire current is so longer identical.
  • In the MCB both currents are run through 2 small coils mounted in such a way that magnetic filed produced are annihilating each other.
  • A small mechanical switch near these coil trips however when the fields are no longer identical and therefore result in the electromagnetic field and tripping of the circuits occur.

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