I have a 4 inch pvc conduit that is underground going to a tran socket which then goes to a 400-amp disconnect that is fused at 400-amps. They are showing me on the drawings to pull 2 sets of 4-3/0 in the same conduit do you have to derate them as per 310-15 and if so what would you pull in that conduit. The voltage is 480/277 3 phase 4 wire service.
wire size
- Thread starter acid75070
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- Chapel Hill, NC
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- Retired Electrical Contractor
You do need to derate so you have to see the cost difference between pulling 2 sets of 3/0 ,or possibly 4/0 if you have to derate , and pulling 500 MCM's if your load is under 380amps.
Depending if your neutral is considered a current carrying conductor you would have to derate either 70 or 80%.
Check art. 310.15(B)(4) for the neutral conductor info.
Depending if your neutral is considered a current carrying conductor you would have to derate either 70 or 80%.
Check art. 310.15(B)(4) for the neutral conductor info.
chris kennedy
Senior Member
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- Miami Fla.
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- 60 yr old tool twisting electrician
acid75070 said:
8 250's would fit and give you 406A after derating.
What do you mean by tran socket?
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- New Jersey
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- Journeyman Electrician
acid75070 said:
Who is they? Didn't they know that they designed something less than 400 amps?
chris kennedy
Senior Member
- Location
- Miami Fla.
- Occupation
- 60 yr old tool twisting electrician
Thats why I asked what a tran socket is. 400A to a 400A meter base? Its rated for 320 continious?infinity said:
This sounds like CT's should be considered.
Ask the PE for plan B.
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