Whitepapers

Electrocution is the obvious danger faced by anyone working on or near live electrical equipment and it is clearly important to understand shock hazards and wear appropriate protection. However, most electrical accidents are not the result of direct electric shocks. A particularly hazardous type of shorting fault-an arc fault-occurs when the insulation or air separation between high voltage conductors is compromised. Under these conditions, a plasma arc-an “arc flash”-may form between the conductors, unleashing a potentially explosive release of thermal energy. An arc flash can result in considerable damage to equipment and serious injuries to nearby personnel. A study carried out by the US Department of Labor found that, during a 7-year period, 2576 US workers died and over 32,000 suffered injuries from electrical shock and burn injuries. 77 % of recorded electrical injuries were due to arc flash incidents. According to statistics compiled by CapSchell Inc (Chicago), every day, in the US alone, there are 5-10 ten arc flash incidents, some fatal. NFPA 70E is the leading internationally recognized safety standard for electrical safety in the workplace. The Canadian Standards Association has developed its own set of standards based on NFPA 70E: CSA Z462. These standards define a set of safe requirements for personnel working on electrical equipment. To comply with the standards, employers must carry out a hazard risk assessment and ensure that all employees working in a potential arc-flash hazard zone use appropriate equipment and wear the right protective clothing. Although it is not the responsibility of the thermographer to put in place the appropriate safety procedures, it is important to recognize and understand their need, and to ensure that the correct procedures, equipment and protective clothing are used.