![]() 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. Equipment is exhibiting symptoms of impending failure.Refer to NFPA 70E 130.4, 130.5 and Informative Annex F, and OSHA 1910.132. the applicable PPE (Personal Protective Equipment) that may be required in the presence of both existing and potential shock and arc flash hazards.Īlong with maintaining a safe working distance, it also is imperative to perform a thorough risk assessment to evaluate all recognized hazards, minimize the risk to an acceptable level, and include all hazards, not just the electrical hazards.the requirements for performing thermography in the presence of these hazards, and.the qualifications required if it is necessary to cross them,.How to identify these boundaries and when they apply,.Among the safety considerations when performing thermography on electrical equipment are approach boundaries applicable to these hazards and the precautions necessary for the safety of both qualified and unqualified personnel. Shock and arc flash are the electrical hazards addressed by the NFPA 70E electrical safety standard in the workplace and relevant OSHA regulations. ![]() Although it’s an advantage to evaluate systems while energized, the disadvantage is the potential exposure to the two primary electrical hazards – shock and arc flash. Some 70 years later, thermal scanning of electrical systems was capable of testing electrical systems and equipment in an energized, operating condition and detect hot spots and identify areas that require corrective action to prevent failures. ![]() Therefore, it often cannot detect conditions that can cause insulation to deteriorate or fail prematurely. The problem is that a megohmmeter is only effective in evaluating insulation condition in a deenergized state. The first instrument invented for testing electrical systems was the Megger megohmmeter patented in 1905 for evaluating insulation, arguably the most important component in an electrical system. ![]()
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