Overloading can take place when the live wire and the neutral wire come into direct contact. (This
occurs when the insulation of wires is damaged or there is a fault in the appliance.)Due to this a short-circuit occurs resulting in abrupt increase of current in the circuit.
Using an electric fuse prevents the electric circuit and the appliance from a possible damage by stopping the flow of unduly high electric current. The Joule heating that takes place in the fuse melts it to break the electric circuit.