Enlarging mounting holes on lugs

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CustomElectricLLC

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Midlothian Texas
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Electrical Contractor
You guys think its a violation (most likely listing) to enlarge a mounting hole in a standard single conductor "chair" lug? Got into a back and fourth with a journeyman on my job about this. If it were say a 1/4 and you had to enlarge it to fit a 3/8 bolt through it, size of lug could be 6awg-250kcmil etc. Other than a listing violation I don't find anything wrong with it.
 
Been there, done that. I don't see an issue either and who will know after it's all bolted together. ;)
 
Many with 1/4" hole in them don't have enough meat around the hole to enlarge it to 3/8. Enlarging them to 5/16 is possible but there is little left around the hole.

I can't recall seeing any (general use lugs, some OEM's for a specific use may be an exception) that accept a 250 conductor that only have a 1/4 mounting hole in them either.
 
Thanks guys. Yeah had a GE transformer that came with odd sized mounting bolts for lugs that were larger than 3/8 and lug holes were little larger too. None the less got a bigger lug and all worked out. But like some have mentioned here 110.3 is a valid article that would be in violation of doing some like that. Even though we do it often out in the field. Guilty of it also. Thanks


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ptonsparky said:
Field engineering at its finest! Most of us have a drill, but not a section of copper bar.
Click to expand...

OK, maybe I overlooked that minor problem.

I’ve always worked for multinationals and so I could lay my hands on almost anything. The last distribution panel I installed needed sections of 2 x ¼” busbar to make the connections viable.

I would never agree to drilling out a lug.
 
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