Re: Clearance from Electrical Panels
This is another case in which language fails us. There is no clear answer, nor can there be. It fits into a category that I once coined as, ?precision ambiguity.? Into this category we can place all phrases (1) That are vague, and (2) For which the exact nature of the vagueness can be precisely described. In this specific instance, the ?precisely ambiguous? phrase is ?likely to require.? Many arguments can be put forth, with regard to the intended meaning of this phrase. Few can be effectively refuted. So where does that leave us?
I suggest that we turn our attention to the purpose of 110.26. If you touch 120 volts, and if the current exceeds the ?let go? value, and if your hands therefore refuse to obey the ?let go command? given to them by your brain, one thing that might keep you alive is having the weight of your body (i.e., as it collapses from loss of muscle control) pull your hands away from the circuit. If you don?t have enough clearance, your body won?t be able to fall far enough away. Many of you have had personal experiences related in some way to this process, whereas I (fortunately) have not. But as a design engineer, I will always fight to provide working clearance, even though its need may seem (on paper, at least) questionable. My simple reason is that some electrician might someday be pressured by his or her boss to work something live, even though I thought it should only be worked de-energized.
I now refer the reader back to my initial posing within this topic.