Reducing the flash hazard

Electrical workers are commonly exposed to three types of hazards: electrical shock, electrical burns resulting from contact and arc flash, and arc blast. Electrical burns that result from contact with energized parts occur due to current flow through the body. Burns as a result of arc flash occur due to radiant heat given off by an electrical arc. Lastly, arc blast is the result of the heating effects of an arc flash which produce tremendous pressures through the expansion of destroyed circuit materials. Of these three, electrical shock and electrical contact burns are the hazards of which most personnel are aware. An arc fault is the result of current flowing through air between conductors in phase-to-phase, single phase-to-ground, or multiple phase-to-ground configurations (i.e. a three-phase bolted fault). Arc faults can release large amounts of energy in an extremely short amount of time in the form of radiant heat, intense light, and high pressure waves. The radiant heat given off travels at the speed of light and can reach temperatures of 35,000degF. In recent years, the dangers and impact of arc flash have been studied and are now becoming better understood. However, the electrical industry is still in the process of studying the effects of arc blast and ways to mitigate its risks. This article is limited to the review of arc-flash hazards, their analysis, and corresponding ways to reduce incident energy in low-voltage systems.