400amp 480v service

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Dm09

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I am installing a 400amp 3phase480v service, the transformer is 400'from the building .I am thinking of running 3sets of 4/0 AL in 4" PVC. Is this suitable as per nec
 
are you saying 3 core 4/0 ? if this is what you are saying 4" is very big

you need to clarify you mean six 4/0 single core cables or three core ?
 
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I planned on 12-4/0 cables xhhw if my math is correct this should be about 30%fill in a 4" pvc
 
Dm09 said:
I am installing a 400amp 3phase480v service, the transformer is 400'from the building .I am thinking of running 3sets of 4/0 AL in 4" PVC. Is this suitable as per nec
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Yes it's code compliant. For #4/0 compact strand aluminum you're allowed 18 conductors in 4" Sch 40 PVC.
 
Although compliant, a few other things to consider: I am not sure I would want to pull 12 conductors in a single pipe. Although the derating doesn't hurt you since you are presumably upsizing for VD, it just seems like a hassle all around. Also, you may want to look at your lug configurations. 400 amp equipment likely only has two hole lugs so you would have to transition from 3 down to 2 conductors which is added time and expense. If it's CT metered, then a 6067L mounting base has three holes (at least the brand I get) so you would be ok and could just go two sets from the CT to the Disco.
 
As Electrofelon stated this might not be the best design but it is code compliant. Given what he's stated two sets of a large conductor size might be better.
 
For a 400 amp service, we typically pull 750AL XHHW in 4" and use the round up rule to call it a 400 amp service.

It's far simpler to deal with 4 wires in a head, than twelve smaller ones, in my opinion.
 
If the neutral conductor is current carrying, you would have 12 current carrying conductors and the ampacity of the circuit would only be 307.5 amps. If the neutral is not current carrying the ampacity would be 430.5 and compliant.
 
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