National Fire Protection Association Standard 70E, Standard for Electrical Safety in the Workplace, (formerly Standard for Electrical Safety Requirements for Employee Workplaces), addresses the safety aspects of both facility conditions and safe work practices to assure employee safety from electrical hazards present in the workplace. This standard is a primary source document for electrical safety regulations promulgated by the Occupational Safety and Health Administration (OSHA) of the U.S. Department of Labor. The Standard was first issued in 1979, and the current edition was issued in June 2004. This article provides insight in understanding the opportunity and stake in reducing electrical injuries, the intent of the NFPA70E standard, and guidance in applying the requirements contained therein.
Today, it is generally recognized that electric shock and electric arc flash are separate and distinct electrical hazards, requiring different means for safeguarding workers exposed to electrical energy. Historically, electric shock, which involves the passage of electric current through the body, was viewed as the electrical hazard. From the data on occupational injuries and fatalities compiled by the U.S. Bureau of Labor Statistics, events involving electric shock are relatively easy to identify. Over the past decade electrocution has ranked in the top five causes of occupational fatalities. For electric arc burn events, it has been more difficult to segregate this data, since the heat or ignition sources for the burn injuries are often not easily sorted, or even noted on the accident report. Since the early 1980s, there has been a growing awareness that arc flash burn is a separate and distinct hazard. The 1995 edition of NFPA70E incorporated the concepts of arc flash hazard, arc flash hazard boundaries, and arc flash personal protective equipment, which had been introduced earlier in other technical literature. [1] [2] [3]. The 2000 and 2004 editions of NFPA70E continued to incorporate practical application of advancing knowledge on both electric shock and arc flash hazards.
In 2003, James Cawley and Gerald Homce of the U.S. National Institute for Occupational Safety and Health (NIOSH) provided the most in depth analysis to date of injuries and fatalities suffered from electrical hazards in the workplace. Their study [4] showed that 2,287 workers died and 32,807 sustained lost time due to electric shock or electrical burns between 1992 and 1998. This was the first study to differentiate electric shock from electrical burn injuries. Their study determined that contact with overhead lines during activity other than electrical system installation and maintenance is the largest category of workplace electrocutions in the U.S., a total of 39% of workplace electrocutions. Within this group, contact with a handheld object accounted for 22%, and contact indirectly through a piece of high reaching mobile equipment, such as cranes, drilling rigs, mobile work platforms, antennas, irrigation rigs, and raised truck beds, accounted for 17%.
