Electric arc

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An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, similar to the instant spark, resulting from a current flowing through normally nonconductive media such as air. An archaic term is voltaic arc as used in the phrase "voltaic arc lamp".

The various shapes of electric arc are emergent properties of nonlinear patterns of current and electric field. The arc occurs in the gas-filled space between two conductive electrodes (often made of carbon) and it results in a very high temperature, capable of melting or vaporizing virtually anything.

On a commercial basis, electric arcs are used for welding, plasma cutting, for electrical discharge machining, as an arc lamp in movie theater projectors and Followspots in stage lighting. Electric arc furnaces are used to produce steel and other substances. Calcium carbide is made in this way as it requires a large amount of energy to promote an endothermic reaction (at temperatures of 2500 °C).

Low-pressure electric arcs are used for lighting, e.g., fluorescent tubes, mercury and sodium street lamps, camera flash lamps, plasma displays, and neon signs.

Undesired or unintended electric arcing can have detrimental effects on Electric power transmission systems and electronic equipment.