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Arc flash has become a major concern in electrical safety. NFPA 70E concentrates on it and electrical workers are learning about it. So, what exactly is arc flash and how can it be prevented?

Arc flash is high temperature conductive plasma formed when a short circuit fault occurs between at least two energized conductors. It occurs when a phase-to-phase fault or phase-to-ground fault causes energized conductors to go beyond their rated voltage and current limits. If the protective device allows this condition to happen, conductors will explode or "arc flash," producing a flash of light, loud noise and temperatures exceeding 5,000° F.

When this happens, hot gases are released and molten metal is projected outward from the fault area. An arc flash can happen in as little as 1/1,000 of a second, creating a shock wave that can hurl loose items from the area outward. The shock wave produced from the instantaneous heating of air could be great enough to knock someone completely off their feet. Personnel standing in the area could be seriously injured with loss of sight, loss of hearing and severe burns; injuries can be severe enough to cause death. In fact, arc flash can cause instant death.

Why now?

Even though arc flashing has been in existence for as long as electricity, why does this topic seem to be at the top of everyone's list today? With the high demands on electrical energy in the industrial environment, arc flash accidents are increasing. Some reports indicate as many as 10 to 15 serious arc flash incidents happen each day in the United States. This is causing concern about personal safety. Authorities are vigorously investigating arc flash and its causes. The results provide a better understanding of arc flash, quantify its potential hazards and encourage the adoption of safer work practices.

The Occupational Safety and Health Administration (OSHA) can enforce safer workplace practices with their standards. When an accident occurs due to an arc flash, OSHA likely will cite the employer with non-compliance of 29CFR 1910.335(a)(1)(i) and 29CFR 1910.132(d)(1), which requires proper protective equipment usage and requires the employer to perform an assessment of workplace hazards.

In 1976 the National Fire Protection Association (NFPA) formed a committee to write and publish their first workplace safety standard concerning electrical safety. In 2004 the NFPA 70E, "Standard for Electrical Safety in the Workplace," was approved and adopted for use. Even though OSHA has not incorporated the NFPA 70E in the Code of Federal Regulations, they still use it as a "how to comply" manual.

An employer is not mandated to comply with the NFPA 70E, but OSHA has been able to show that conforming to the standard helps maintain compliance with mandated OSHA regulations. OSHA contends that compliance with NFPA 70E can prevent or lessen the risk of injury and has been able to use this as a baseline to prove if an employer has acted reasonably.