"The engineer's first problem in any design situation is to discover what the problem really is." Unk. OSHA recognizes NFPA 70E as a standard for safe work practice, but does not directly enforce it. NFPA 70E is not a code suitable for adoption by building authorities, but rather a standard practice. Understanding arc flash labels, boundaries, and personal protective equipment can be complex but our latest. They also lead to business disruption and severely damage expensive equipment. There are 30,000 arc flash incidents per year leading to 7,000 burn injuries, and 400 fatalities. Work practices are not within the scope of the NEC. The electrical shock from arc flash accidents can be deadly. I would be less comfortable if there were active controls regularly operating circuit breakers, and less comfortable still if breakers or switches were being operated manually. It may not make sense to require PPE just walking past a passive panel or switchboard. A little reasonable judgement needs to be applied. No code or standard can cover every situation. It comes down to practicality, company policies and insurance requirements. Where your restricted and limited shock boundaries are 12 inches and 42 inches respectively, the arc flash boundary might be 50 feet, or it might be 1 inch. The arc flash boundary is independent of the shock protection boundaries. As exemplified in the QM2 case, things do fail spontaneously, but that is relatively rare. We must utilize proper PPE for arc flash protection when inside this boundary. Most electrical failures result from human interaction or as a result of automatic operation of the equipment.
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