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?
Generator Conduit Bonding
- Thread starter SB75
- Start date
- Status
- Occupation
- Licensed Electrician
Welcome to the forum.
UL listing gets lost when you take the thing out of the wrapper if you follow their logic to its conclusion. I'd get a lug that fits and put it on the bushing.
UL listing gets lost when you take the thing out of the wrapper if you follow their logic to its conclusion. I'd get a lug that fits and put it on the bushing.
- Location
- Massachusetts
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.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Some of the manufactures say contact them for lug sizes not shown. Best I can think of.
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