Rosslyn, VA, October 9, 2003 -- NEMA, the National Electrical Manufacturers Association, has released two papers that address the hazard of electric arc flash. The first paper, Avoid Arc Flash Occurrences by Following Industry Standards, is a general synopsis that introduces the hazard, industry codes, and standards that address the hazard, as well as the requirements that facilities must comply with in order to reduce injuries, occurrences, and down time. The second paper, Molded-Case Circuit Breakers Reduce Arc Flash Hazard Impact, technical in nature, identifies the impact on arc flash by molded-case circuit breakers and provides methods of determining the magnitude of the flash.
The Standard for Electrical Safety Requirements for Employee Workplaces (NFPA 70E-2000) defines arc flash hazard as "a dangerous condition associated with the release of energy caused by electric arc." Explosions can occur when an electric arc operates at temperatures of several thousand degrees Celsius and the arc creates pressure waves. Within a few milliseconds of arc ignition, the energy from this explosion can cause molten metal particles, equipment parts, and other loose items to be expelled from the arc area in addition to the expulsion of hot, ionized gas. The NFPA 70E also provides basic information regarding arc flash analysis. The 2002 National Electrical Code (NEC) Section 110.16 requires switchboards, panelboards, industrial control panels, and motor control centers to be field marked with a warning of possible flash hazard.
"Arc flash can cause extensive equipment damage," says NEMA President Malcolm O''Hagan. "Of even greater concern are serious injuries, such as trauma, hearing, and eyesight loss, or even death that may result if there are people nearby. Properly installed equipment that meets industry standards can make a significant difference in minimizing the degree of arc-burning incidents."
Electronic copies of both documents may be downloaded free of charge from NEMA''s Low Voltage Distribution Equipment website. Molded-Case Circuit Breakers Reduce Arc Flash Hazard Impact can be downloaded at www.nema.org/r/wp/arc-mccb/, and Avoid Arc Flash Occurrences by Following Industry Standards can be downloaded at www.nema.org/r/wp/arc-stds/.