PURPOSE:  To reduce the number and severity of electric arc burn injuries in mining.

RESEARCH SUMMARY:  Systematic electric arc protection for industrial workers is specified by the National Electrical Code (NFPA 70) and the NFPA Standard for Electrical Safety in the Workplace (NFPA 70E). The scopes of NFPA 70 and NFPA 70E specifically exclude the underground mining industry due to its unique electrical needs and problems. 30CFR Parts 56, 57, 75, and 77 contain mining electrical safety provisions, but 30CFR does not require anything beyond rudimentary PPE for hazardous underground electrical maintenance work. Between 1990 and 2003, 2,326 traumatic mine electrical injuries occurred. The largest single category of electrical injury was burns from electrical arcing, which accounted for 893 (38%) of all electrical injuries. Electrical burn injuries of all types accounted for more than 21,500 lost work days. The project approach focuses on the development of a comprehensive program of engineering analysis and controls, management of work activities, training, and the use of personal protective equipment (PPE). Computer simulations are employed to estimate the arcing fault energy available from the power systems of representative mine and mineral processing plants. The systems selected represent the most dangerous mining industry sectors. Simulation results will allow the definition of boundaries or zones where protection from arc-flashes is needed for various equipment and circumstances. Findings thus far indicate a general lack of awareness of common arc-flash hazards in the mining industry. Accident reports show that two-thirds of arc-flash injuries involve circuit breakers, cables, hand tools, meters, and plugs. The equipment and PPE needed for safe troubleshooting in arc-prone situations are seldom used. Circuit breakers are often operated beyond their design parameters and many are repaired by third-party rebuilders using substandard components. Power system coordination is seldom optimum. Thirty-one victims of, or witnesses to, arc burn accidents have been interviewed. Victims now realize that their understanding of arc-flash hazards was inadequate. Many see their failure to wear arc–rated clothing, face and hand protection, use appropriate tools and meters, and work on live circuits as unsafe work practices that need to be altered by improved hazard recognition training. This project will produce practical guidelines to determine arc flash boundaries in mines and prep plants. Recommended improvements in work practices regarding the use of hand tools, meters, PPE, and other engineering controls will increase miners’ understanding of arc-flash hazards. Training guidelines will show how to most effectively present this information to the mining audience. Follow-on work will implement the guidelines as 10-minute and 30-minute training modules available to MSHA trainers. It is envisioned that the outcome of hazard recognition training, PPE, and improved work practices would be a dramatic reduction in the number and severity of arc-flash injuries in mining.