I was turned down on an inspection on a 400a overhead service. I ran 500mcm copper @ 75deg its good for 380a and I thought I could apply the next size up rule to the line side of the meter socket. As well as the fact that the load is no where near 400a I figured the wire could be derated a little. Is my thinking incorrect? The panel is is mounted on a ag building. Thank you for reading, any feedback would be appreciated.
400a service conductors
- Thread starter Pjm 63
- Start date
- Status
- Location
- Connecticut
- Occupation
- Engineer
Sounds like a violation of 230.90(A).
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Please explain that David. Some other member had said his instructor cited that article but the exception #2 clearly allows 240.4(B) or (C) and 240.6 to be used.
- Location
- Connecticut
- Occupation
- Engineer
Dennis, you are correct, thanks. I should know better than to try to go from memory without the code in front of me first thing in the morning.:happysad:
kingpb
Senior Member
- Location
- SE USA as far as you can go
- Occupation
- Engineer, Registered
When I hear OH install of 500KCMIL, and turned down inspection, I have to wonder if it is related to the way in which the conductors are run overhead, and fastened to the structure. 500KCMIL is heavy cable, and if it is going very far you have sag and tension issues to deal with. Wouldn't think the 380A cable on 400A CB is the issue.
I wouldn't do anything though until I get the Code violation by article reference, otherwise your flying blind.
I wouldn't do anything though until I get the Code violation by article reference, otherwise your flying blind.
The only code violation he called me for was that 500 was only good for 380a at 75degree and can't be used according to 310.16. the overhead run is only 23'
and he had no problem with the mounting of the conduit. I don't understand the inspectors logic and thought i was well within the legal size as far as the conductor goes. thank you for your feed back. any sugestions on how to correct the inspector.
and he had no problem with the mounting of the conduit. I don't understand the inspectors logic and thought i was well within the legal size as far as the conductor goes. thank you for your feed back. any sugestions on how to correct the inspector.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Very simple. Show him art. 240.4(B) and see what he has to say about it.
kingpb
Senior Member
- Location
- SE USA as far as you can go
- Occupation
- Engineer, Registered
Does the breaker have an adjustable trip setting, whereby it is set at 400A? If so, this could be the issue.
Was there a calculation done to show that the load is less than the 380A? If not then do one, then this could be used to help the inspector back-peddle into admitting that in fact 240.4(B) is applicable.
Was there a calculation done to show that the load is less than the 380A? If not then do one, then this could be used to help the inspector back-peddle into admitting that in fact 240.4(B) is applicable.
Show him 230.90(A) Exception #2 first.
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