Anatomy of a Spark


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Anatomy of a Spark

Sparks created by an electrical arc are high powered but fleeting. The high energy release can melt and vaporize the metal in conductors and terminals. Arc flash is the light created from a high energy electric arc. High energy circuits, such as 3 phase AC systems, are capable of arc flashes where temperatures can reach or exceed 35,000ºF. The electrical energy vaporizes the melted metal from a solid to gaseous form. The molten metal and expanding plasma move outward with extreme force, an expansion in volume occurs that can be up to 69,000 times the original.

An arc occurs when the electrical resistance of a material like air breaks down or the amount of material between the voltage potentials decreases. As with our photographs for example, the air gap decreases as the conductors get closer together.

The sparks themselves are luminous particles of the materials (in this case copper from the wire strands) ejected from the point of arcing. Since the temperature of the arcs are about 10,800ºF and the melting temperature for copper is approximately 1983ºF the arc easily melts and vaporizes most common conductors.

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Unlike higher energy systems our example with 120 volt AC at 60 Hz  pictured decays quickly preventing the arc from developing enough energy to produce an expanding plasma cloud. High energy arc flash can be extremely hazardous and is an exposure potential for certain occupations. However as you can see with our lower voltage test the visible arc is still fairly spectacular when captured at 300 frames per second with a high speed camera.