Just when I think people are beginning to understand what is involved with electrical safety, I get a series of calls that convince me otherwise. Other than for the determination of PPE category or incident energy, the requirements in NFPA 70E®, Standard for Electrical Safety in the Workplace® do not really include a time constraint for the conditions of conducting energized work. However, it seems that many want to include time in their safety consideration. How long can someone leave a site unattended before they have to verify an electrically safe work condition (ESWC)? How long can an employee work on electrical equipment before they have to establish an ESWC? How long does someone have to be inside the arc-flash boundary before they have to don PPE? How long do energized electrical parts have to be exposed before they must considered to be an electrical hazard?
Those are just some of the actual questions that I have been asked. I am not aware of a method to determine that sticking a screwdriver into energized electrical equipment for only few seconds is considered safe. I am not sure that leaving an area for a ten minute smoke break is insufficient time for someone else to enter the area and do something unanticipated. I am not convinced that quickly walking through the arc-flash boundary removes the possibility of an arc flash occurring. I do not know the length of time necessary to avert an incident when “only” operating an internal switch after opening an enclosure.
How suddenly does a screwdriver slip from a terminal to initiate an arc flash or electrocution? How swiftly can an employee run when an arc flash occurs near them? How quickly can an employee react to prevent an injury after dropping a screw into switchgear? How long must electrical current pass through an employee’s body before a shock becomes an electrocution?
There are many electrical safety aspects that rely on common sense. Use yourself as a litmus test. If you think you could be injured so does your employee. If you wouldn’t feel comfortable doing what is being proposed neither will your employee. If you think something could go wrong it possibly will. Do you really believe that putting your employee at risk only for a short time, removes the chance of an incident occurring? If you are asking these types of questions to get around providing protection for your employee, choose safety.
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Next time: The act of establishing an electrically safe work condition (ESWC) or a properly established ESWC.