Cirrcuit Breakers

A circuit breaker fulfils the same function as a fuse. If a current gets too high, it breaks the circuit. Current can not then flow and the reason for the high current can be investigated and corrected.

A circuit breaker through, has several advantages over a fuse

  • It can act more quickly

  • It is more reliable

  • It can be reset – each time a fuse acts to break a circuit, it must be replaced

  • The RCCB (residual current circuit breaker) is very sensitive

There are two main types of circuit breaker.

The MCB (miniature circuit breaker) acts to break the circuit at a set current – typically 1A, 13A or 30A.

The MCB might not prevent you being electrocuted. To prevent electrocution, use an RCCB. This cnsists of coils of wire wound in opposite directions on a soft iron core. If the currents are equal the magnetic fields cancel each other out. If there is a current leakage, there will be a net field in the coil. The residual magnetic field trips a relay and breaks the circuit very quickly.