Fuse

Fuse, safety device placed in an electric circuit to prevent overloading. It usually comprises a wire of low-melting-point metal mounted in or on an insulated frame. Current passing through the wire heats it, and excessive current heats the wire to the point that it melts, breaking the circuit. In most domestic plugs, the fuse consists of a cylinder of glass capped at each end by metal, with a wire running between the metal caps. Similar, but larger, cartridge fuses are used in industry.