When an arc flash occurs, an enormous amount of concentrated energy explodes outward from the point of origin. There is an immediate high-intensity flash, which could cause vision damage or blindness. Temperatures within the arc can reach 35,000°F (19,426°C); the resulting thermal exposure can cause severe burns. The pressure wave from the blast can reach 200 lb/in2. Workers can be knocked down or thrown several feet, resulting in broken bones, brain and internal injuries, and hearing loss. Copper conductors vaporize. Material that isn’t vaporized becomes shrapnel, which can cause punctures and lacerations. Some arc flash injuries result in death.
Understanding arc-flash risks requires knowing the data. “Arc flash occurs five to 10 times a day in the U.S.,” said Joe Weigel, product manager for Square D Services at Schneider Electric. “Major injuries can be as serious as third- or fourth-degree burns. The average cost just for medical treatment is about $1.5 million. The total cost including litigation can easily be $8 million to $10 million, and in some cases even higher. There’s an average of about one fatality from arc flash per day.”
If there is a serious industrial arc flash incident, U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) will investigate. It will ask for the employer’s electrical safety training records and arc flash hazard assessment. If the employer is found negligent in either of these areas, OSHA could impose a significant fine. However, if the incident involves injuries or loss of life and the worker’s family chooses to sue, the employer’s situation could become much worse.
Read the full article in Fluke’s Electrical News about how to avoid electrical safety incidents and investigations.
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