Generator Conduit Bonding

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SB75

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So I have a 1.5 meg generator feeding a switchgear. At the generator I have a 2500 amp 600 volt breaker. Per plans we have installed 8 parallel runs of 3x750mcm and a 350mcm ground copper in 4" coated rigid in a underground concrete in cased duct bank. The conduits stub up in the bottomless enclosures so I have no metal contact to any of the raceways. Due to the overcurrent protection rating I need a 350mcm bonding conductor to bond the raceways, however I have been unable to find a bonding bushing with a lug on it bigger than 250mcm. I am also under the impression to change the lugs on the bushings would destroy the UL listing of the bushing. Any suggestions or is there something I am misinterpretating?
 
SB75 said:
I am also under the impression to change the lugs on the bushings would destroy the UL listing of the bushing. Any suggestions or is there something I am misinterpretating?
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When you modify a listed part like this ULs position is it is up to the AHJ to determine if the modification has changed the product so much to fail it or require a UL field evaluation.

That said I can't imagine any inspector having a problem with changing the lug. Like Dave I would do it in a heartbeat.
 
My AHJ is a very knowledgeable about the code and we have a good relationship. I could call him about anything, however he is very black and white and does not distinguish between intent and written word. He understands that I have an issue but will not make a judgement call as to the acceptability. If I change anything it will have to be with a written letter from a engineer validating the situation. There will be no shortcuts. Back to my issue I could not even find a feed through bonding lug larger than 250mcm. I know that I'm not the first to need a bond this large somebody has to have a good fix or explanation as to why everything stops at 250mcm.
 
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