Every supply has a capacity to bear a maximum load, i.e., the power that can be supplied has a limit. Sometimes, the number of appliances which are switched on at the same time have power more than the capacity of the line. This is called overloading. In this situation, wires of the supply get heated due to extremely large current flowing through them and the circuit may catch fire. To avoid this fire, we use an electric fuse in the circuit.
