The difference between circuit breakers and fuses is that while a fuse has to be replaced when it is “blown,” a circuit breaker continues to function over and over again. A circuit breaker can also be manually switched to open a circuit so that you can make electrical repairs without the danger of electricity flowing through the circuit (and you!). Most homes nowadays are set up with circuit breaker boxes instead of fuse boxes. Some individual appliances might have their own fuse for additional protection for that appliance.

If the wires in a circuit carry too much current, it is possible for the wires in the circuit to build up an excess amount of heat. If the wires become hot enough, the insulation around the wire can burn off and then the exposed wire may ignite whatever is touching it. This is how electrical fires start. Fuses and circuit breakers prevent dangerous overloading of a circuit by building in an intentional weak spot in the circuit. The weak spot is the fuse or circuit breaker.