Working Clearance

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egurdian

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Are the 3ft working-clearance in front of a tranformer required? - :roll: The question comes from the fact that no one in his right mind will open and work on an energized (dry type) transformer in an electrical closet.
 
Re: Working Clearance

The NEC requirement for "working space" is based on equipment needing servicing or adjustment "while energized". I doubt you will get the AHJ to say you never really need working space since you can always turn the equipment off. There are services performed on transformers while they are energized, such as infrared scanning. With this in mind I would say you need the clearance.
 
Re: Working Clearance

I also believe you need the clearance.

I have never taken the cover off while energized but I have certainly turned them on with the cover off.

If you need to change taps you want to check voltages before closing it up.
 
Re: Working Clearance

I attended a seminar last year that was presented by a major manufacturer of transformers, and discussed this issue with the very knowledgeable speaker. I was in favor of requiring working clearance, and he disagreed and said that no one should take the cover off a transformer or work on it while energized, ever. I asked what his response would be if I submitted a proposal to require working clearance, and he said that he would oppose it.

I agree that in the real world there are times when it is necessary to work in a transformer that is energized, and that therefore it should be under the scope of 110.26 and 110.34. However,
450.13 gives us two situations where transformers need not even be readily accessible. Clear as mud to me...

Douglas Hansen
Code Check
 
Re: Working Clearance

Ryan, look at 110.26(A)for the same reason Grant gave earlier.

Back to the transformers, I have opened energized transformers in hospitals for infrared scanning and other reasons before.


Roger
 
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