Fuses

A fuse is a low-resistance resistor which is used to protect a circuit from damage in case of an overload, short circuit or power surge. When it detects abnormal current activity, it is deliberately designed to 'blow' (when the fuse element or filament is destroyed),thereby protecting more serious damage. Afterwards, it has to be replaced. The fuse element is usually made of zinc or copper alloys while the body can be ceramic, glass, plastic or fibreglass. There are a wide variety of fuses according to current and voltage ratings. When used for high-voltage applications, the fuse can be ceramic and contains a liquid like boric acid. In case of fire, the heat transforms the acid into a gas, which extinguishes the fire/arc. For lower voltage applications such as for domestic appliances, a cartridge (or ferrule) fuse is sufficient. Renewable fuses mean that only the fuse element has to be replaced as the body and terminals can be reused. Other fuses include slow blow, self-resetting and surface mount. Although fuses are being used less frequently in Consumer Units, they remain an important form of circuit protection in individual appliances as well as electric circuits and are found in all private and public buildings.