![]() ![]() Restricted approach distance applies to fixed conductors and movable conductors under a person’s control. Movable conductor distance almost always applies to overhead distribution and transmission lines. The limited approach distance applies to movable and fixed conductors. They are based upon nominal phase-to-phase voltage (or three phase equivalent) of the energized equipment. They are also usually found on an arc flash label. The shock boundaries are contained in Tables 130.4(E)(a) and (b) in the NFPA 70E. Distance is a key element common to both hazards. Arc flash (and blast) injury is determined by distance, energy magnitude, exposure time, exposure area and PPE calorie rating. Electric shock injury is determined by distance, voltage and current magnitude, exposure time, pathway and PPE voltage rating. It will always come to you!Īlthough much different, the two have some common characteristics. It is only present when an event occurs that triggers the release of energy. ![]() Arc flash and blast are a function of the discharge of incident energy from an electrical fault. It requires touching or coming close enough to be touched by it.Īrc flash hazard boundaries are determined by calculation and vary according to energy level, and several electrical and physical characteristics. It is present whenever a circuit is energized and present if a circuit becomes energized. Shock is both a persistent and potential hazard. The nominal voltage varies slightly, but it is consistent. Shock hazard boundaries are determined by voltage and do not vary. If you determine the risk is unacceptable, either take steps to lower that risk to an acceptable level or make an informed decision not to perform the inspection at all.Īmong the safety considerations when performing thermography on electrical equipment are the shock and arc flash approach boundaries applicable to both qualified and unqualified personnel. These elements may also cause you to determine a task is an unacceptable risk.
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