Thermal magnetic circuit breakers incorporate both techniques with the electromagnet responding instantaneously to large surges in current ( short circuits ) and the bimetallic strip responding to less extreme but longer - term over-current conditions .
Thermal magnetic circuit breakers are the type found in most distribution boards .
Thermal magnetic circuit breakers , which are the type found in most distribution boards , incorporate both techniques with the electromagnet responding instantaneously to large surges in current ( short circuits ) and the bimetallic strip responding to less extreme but longer - term over-current conditions .