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.