fuse

In electricity, a wire or strip of metal designed to melt (thus breaking the circuit) when excessive current passes through. It is a safety device that halts surges of current that would otherwise damage equipment and cause fires. In explosives, a fuse is a cord impregnated with chemicals so that it burns slowly at a predetermined rate. It is used to set off a main explosive charge, sufficient length of fuse being left to allow the person lighting it to get away to safety.

In an electrical fuse, current flow converts electrical energy into heat energy, increasing the temperature of the fuse material. As more current flows, the temperature of the material rises; at a certain current the material melts, thus interrupting the current flow.

Different types of electrical equipment require differently-rated fuses depending upon how much current can flow without damaging the equipment. For example, some equipment requires a 13 amp fuse and some a 3 amp fuse.