The Low Voltage Distribution Equipment (LVDE) Section of NEMA, the National Electrical Manufacturers Association, has published a white paper on arc-flash analysis that highlights the need for utility system parameters in the selection of personal protective equipment (PPE).

NFPA 70E, Electrical Standard for Safety in the Workplace, defines arc flash hazard as: "a dangerous condition associated with the release of energy caused by an electric arc." It is an explosion involving an electric arc operating at temperatures of several thousand degrees Celsius and a pressure wave created by the arc. Within a few milliseconds, the energy from this explosion can cause severe burns and loss of hearing, eyesight, taste, and smell. Molten metal particles, equipment parts, and other loose items are expelled from the arc area. Extensive equipment damage frequently results in extended downtime for an installation. More devastating are the trauma, hearing and eyesight loss, and burns to personnel in the area which can result in catastrophic injuries or even death.

The increasing awareness for the need to perform arc-flash analysis is driven by changes to the 2002 National Electrical Code, which added requirements for markings to alert qualified persons on the potential of arc-flash hazards. NFPA 70E provides tables for determining the level of PPE. These tables apply only to specific parameters, whereas an arc-flash analysis will permit the selection of PPE suitable for each location.

Utilities have traditionally provided a conservative fault current value, but this may not provide the "worst-case" arc-flash condition. The white paper identifies the parameters that the utilities should provide so that an accurate analysis can be conducted. By providing these parameters, and notifying users of system changes, the utilities can assist the user in ensuring that safe practices consistent with NFPA 70E are maintained.

View the white paper here.