safety spotlight
Arc Flash Safety: Create a Plan for Compliance A
According to the National Fire Protection Agency (NFPA) 70E: Standard for Electrical Safety in the Workplace, arc flash is a “dangerous condition associated with the release of energy caused by an electrical arc.” In laymen’s terms, that translates into a sudden and dangerous blast of extreme heat, intense light, and pressure waves that happens when a high-voltage gap exists between a phase bus bar and another phase bus bar, neutral or a ground. Injuries are often devastating, as arc flash temperatures can reach 35,000° F, which is three times hotter than the surface of the sun. An arc flash also can produce noise reaching 140 decibels—about as loud as a gunshot—and molten metal shrapnel. Arc flash incidents can often be traced to human error or poorly maintained systems. Factors such as worn cable insulation, dirty or corroded contacts or electrical parts, a dropped tool, and occasionally an ill-fated rodent or bird, can all cause a catastrophic accident. Some plant managers may justify their decision to not provide workers with arc rated, flame resistant (AR/FR) clothing or safety training by suggesting that arc flash incidents are so rare that it’s not worth the expense. However, a 2013 report published in the May 31, 2013, edition of Industrial Safety & Hygiene News disputes that claim. It estimates that, on average, there are 30,000 arc flash incidents every year in the United States or about 5-10 per day. The report went on to say that those incidents resulted in annual totals of 7,000 burn injuries, 2,000 hospitalizations, and 400 fatalities. Costs incurred by arc flash damage can reach millions of dollars in employee claims, insurance costs, equipment replacement and lost productivity. Given the risk, frequency and severity of arc flash events, it is imperative that plants employ a host of mitigation
8 // July 2020
This is an example of the Emerson Appleton Plexpower Fiber panel board. Photos courtesy of Emerson, St. Louis, Missouri. processes to pave a safer path for workers who maintain electrical distribution, power control and protection systems.
DRESS FOR DURESS
In April 2014, OSHA issued a final rule on electric power generation, transmission and distribution, and electrical protective equipment. Under the rule, employers must protect their workers from hazards posed by flames and electric arc in the following ways: • Identify employees who will be working around these hazards. • Estimate the incident heat energy of any electric-arc hazard to which a worker would be exposed at various points along the power chain. Accuracy is es-
sential with such measurements, so plant managers who lack direct and extensive experience with arc flash incident energy assessment should always seek assistance from a qualified power systems engineer. • Ensure workers exposed to such hazards wear protective clothing and other protective equipment with an arc rating equal to or greater than the estimated heat energy. Wearing flame-resistant clothing can drastically improve the chance of walking away from an arc flash. Some of the different types of PPE that should be worn includes an arc flash suit, hardhat, leather footwear, rubber gloves, arc-rated face shield and more. Workers should always
