What is a fuse?

   In electricity, a fuse is a device that prevents dangerously high currents —ones that might cause fires or otherwise damage parts of the circuit—from passing through a circuit. The fuse consists of a piece of wire or metal that has a low melting point, such as tin or lead. It is placed in the circuit so that all the electricity in the circuit must pass through it before reaching the other components. If a high current passes through it, the temperature of the fuse wire will rise sufficiently to melt the wire and thus cause the circuit to break. A fuse thus damaged is known as a burned-out fuse. It must be replaced by a new fuse. Overloading a circuit (putting too many appliances or lights on a single circuit) will cause too high a current to pass through the wire, and the fuse will burn out. The fuse is a protective device. Nothing else should be used in its place, and a burned-out fuse should always be replaced by a fuse of the same size and rating as the burned-out one.