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Lessening the Danger Zone

Aug. 25, 2003

Between five and 10 times a day, an arc flash explosion occurs in electrical equipment somewhere in the United States that sends a burn victim to a special burn center, according to statistics compiled by CapSchell Inc., a Chicago-based research and consulting firm that specializes in preventing workplace injuries and deaths. Recently, Palatine, IL-based Square D/Schneider Electric (www.SquareD.com) presented a sobering demonstration to a gathering of media professionals about this very topic.An arc flash occurs when insulation or isolation between electrified conductors is breached or can no longer withstand the applied voltage. As employees work on or near energized conductors or circuits, movement near or contact with the equipment (or a failure of the equipment) may cause a phase-to-ground and/or a phase-to-phase fault. Temperatures well over 5,000 degrees F. and a powerful explosion can be produced by this arc flash.Of course, the best way to prevent arc flash incidents from occurring is to de-energize equipment before beginning work. Newer (2000) industry standards contained in the National Fire Protection Association’s (NFPA) 70E standard, which are being aggressively monitored for compliance by the Occupational Safety and Health Administration (OSHA), have been designed to protect workers and the workplace in the few instances where turning off all power could create a greater hazard to people or processes.However, suppliers such as Square D/Schneider Electric, are also approaching the issue with specially designed components. Square D/Schneider Electric, for example, has just released a Masterpact Low Arc Flash circuit breaker that has been specially designed and tuned to provide balanced protection for both overcurrent and arc flash. Installing safety products like infrared windows and remote racking systems in electrical equipment may also help keep workers out of the arc flash danger zone around electrical equipment.The process of complying with the new NFPA 70E standards for minimizing arc flash incidents presents you with an opportunity to re-examine your electrical system and procedures, gain a better understanding of potential weaknesses, instill new work practices to better protect employees, and minimize financial risks to your company.