Adjustment Factors/Derating of Conductors

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dcheser

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I am relocating a 30 circuit 120/240 breaker panel that primarily provides power to lighting circuits. We are moving the panel about 15 feet. The existing wiring has been pulled back and placed in a trough with terminals. I have roughly 30 hots and 30 neutrals. My question is do the neutrals count as current carrying conductors? My interpretation of the code is that they are and will factor in to the Derating percentage listed in Table 310.15(B)(2)(a) however I have an electrician who is telling me otherwise. Can anyone clear this up for me.......please.
 
dcheser said:
I am relocating a 30 circuit 120/240 breaker panel that primarily provides power to lighting circuits. We are moving the panel about 15 feet. The existing wiring has been pulled back and placed in a trough with terminals. I have roughly 30 hots and 30 neutrals. My question is do the neutrals count as current carrying conductors? My interpretation of the code is that they are and will factor in to the Derating percentage listed in Table 310.15(B)(2)(a) however I have an electrician who is telling me otherwise. Can anyone clear this up for me.......please.
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30 hots 30 neutrals =60 current carrying conductors
 
Convert to MWBC's and you'll only have 30 CCC's and you'd only have to derate to 45% instead of 35% unless there are other factors.
 
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See 310.15(B)(2) Adjustment Factors.
(a)More than 3 current carrying conductors in a raceway or cable

Also see 310.15(B)(4) Neutral Conductors





You may have a larger issue with
376.22(B) Adjustment Factors.

If your conductors are installed inside the wireway/trough in a manner that fits this section, your adjustment factor is 35%.

Who knows, depending on the size of your wireway, you may have an issue with 376.22(A) as well.
 
A/A Fuel GTX said:
Multiwire Branch Circuit.......Sharing the neutral with conductors from different phases.
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With the 120/240 volt panelboard our neutral is common across both phases. However the challenge is in properly protecting the conductors. I would have to pull one large neutral over from the trough to the new panelboard and try to get a distribution block in the trough. I think it may be just as easy to pull all 30 neutrals back. I'll just have to bust it up into 2 or 3 conduits and use either #8 or #10's. I guess there are several ways to skin this cat and each has its pro's and con's.

Thanks again for the feedback!!
 
like you say. many ways to skin that cat. since you can feed from alternate phases your neutrals probably wont count (see 310.15(B)(4) to confirm). Then you could use 30 #10s with a 18 amp ampacity on your 20 amp breakers.
 
augie47 said:
like you say. many ways to skin that cat. since you can feed from alternate phases your neutrals probably wont count (see 310.15(B)(4) to confirm). Then you could use 30 #10s with a 18 amp ampacity on your 20 amp breakers.
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That's assuming that he meets all the conditions of 240.2(B). Especially #1 The conductors being protected are not part of a multioutlet branch circuit supplying receptacles for cord and plug connected portable loads :) I'm thinking he might be supplying some receptacles with those #10's. ;)
 
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