Undersize Lug

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Artemis

Member
When a conductor is shaved down to fit into an underside lug, what NEC article would that be in violation of the NEC?
 
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petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
there is no specific code that prohibits this. however, when you remove strands from a conductor you have made it a different size conductor which has a different ampacity.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
I dont actually think 110.14(A) covers it. To me that is talking about not damaging the conductor while making the connection. When you trim off strands you are changing/damaging the concductor prior to that. I would go with something like 240.4 - the conductor is now smaller than XX size and (presumably) not protected at its ampacity. If one could document/prove the size of the "new" conductor after the strands were removed, and it was done without damaging the remaining strands, I wouldnt have a problem with it if it was protected at its ampacity.
 
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jap

Senior Member
Occupation
Electrician
electrofelon said:
I dont actually think 110.14(A) covers it. To me that is talking about not damaging the conductor while making the connection. When you trim off strands you are changing/damaging the concductor prior to that. I would go with something like 240.4 - the conductor is now smaller than XX size and (presumably) not protected at its ampacity. If one could document/prove the size of the "new" conductor after the strands were removed, and it was done without damaging the remaining strands, I wouldnt have a problem with it if it was protected at its ampacity.
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That's a good one too.
I'll agree with that one also. :)

Jap>
 
G

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
petersonra said:
there is no specific code that prohibits this. however, when you remove strands from a conductor you have made it a different size conductor which has a different ampacity.
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Which, in and of itself, may or may not be a problem. If the conductors have been oversized for, say, voltage drop, the reduced conductor may still be protected by the OCPD. But still, I wouldn't do it. If the smaller conductor is sufficient, ampacity wise, I would use a Polaris block or something similar to change to a size that would fit the lug. When you trim wire strands it's hard to know what effective AWG size you end up with.
 
kwired

kwired

Electron manager
Location
NE Nebraska
electrofelon said:
I dont actually think 110.14(A) covers it. To me that is talking about not damaging the conductor while making the connection. When you trim off strands you are changing/damaging the concductor prior to that. I would go with something like 240.4 - the conductor is now smaller than XX size and (presumably) not protected at its ampacity. If one could document/prove the size of the "new" conductor after the strands were removed, and it was done without damaging the remaining strands, I wouldnt have a problem with it if it was protected at its ampacity.
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I agree in principle, now show me an inspector that will buy it.:)
 
G

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
kwired said:
I agree in principle, now show me an inspector that will buy it.:)
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I'm not sure what you mean, but I have reduced the size of large feeders from PV systems a long way from services right before connecting to a disco when the reduced size was sufficient for the required ampacity but not for voltage drop. Built and passed inspection. Not by trimming strands, though, if that's what you mean.
 
kwired

kwired

Electron manager
Location
NE Nebraska
ggunn said:
I'm not sure what you mean, but I have reduced the size of large feeders from PV systems a long way from services right before connecting to a disco when the reduced size was sufficient for the required ampacity but not for voltage drop. Built and passed inspection. Not by trimming strands, though, if that's what you mean.
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That is what I was talking about. If you can prove what the reduced CSA is after trimming and it is still above needed conductor ampacity then I see no reason it won't work. May appear as "hack" but in principle should still work.

I'm guessing you will find very few inspectors that will even listen to any kind of explanation of why this might be acceptable.
 
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