30 ccc's

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mcelweec@gmail.com

CMAC1
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here's my situation,i have 2 42ckt panels with 2 nipples in each going into a 6x6 trough.lets consider this as 168ccc,s,the majority of these are deflected into the panels ,some criss-cross,is this type of install subject to the 30ccc rule?.i have been installing load conductors like this for a number of years with no problem.imo it makes the install a lot neater,could this be subject to the two foot nipple rule as no conductor travels no more than two feet and dosent fill the trough by more than 20% in any section.
 
As long as there are not more than 30 ccc's traveling together more than 24" without spacing inside the wireway, you don't have to apply article 310.15(B)2.
Rick
 
The same rule applies to metal auxiliary gutters as metal wireways. Over 30 ccc's bundled or traveling without spacing are subject to derating.
Rick
 
I try to explain to the installers of this type of situation that boxes instead of wireways make more sense. The direction of entry and amount of conductors generally do not make a non compliant install.

From your description, it sounds as though you have not complied with the 31ccc requirement.
 
Pierre C Belarge said:
I try to explain to the installers of this type of situation that boxes instead of wireways make more sense. The direction of entry and amount of conductors generally do not make a non compliant install.

From your description, it sounds as though you have not complied with the 31ccc requirement.
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Pierre what about the exception that I posted?
 
Pierre C Belarge said:
I try to explain to the installers of this type of situation that boxes instead of wireways make more sense. The direction of entry and amount of conductors generally do not make a non compliant install.

From your description, it sounds as though you have not complied with the 31ccc requirement.
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The language of the title of 376.23B always perplexes me - it's a raceway, and at the same time it's not if used as an enclosure? ("pull-box" 314 - no derating there...) IMO there should be clearer language for using long sheet metal boxes that are also listed wireways. But since it is a wireway it applies.... due to 376.22B but, "only where" the CCC's exceed 30. Is that 'only where' as in any one place in the gutter? Or 'only where' there are more than 30 in the gutter total? IMO that is at any one place in the gutter....
 
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infinity said:
You also should take a look at 310.15(A)(2)Exception.
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Rob thats a great exception. I thought that only applied to ambient temperatures. Never thought it could be used for raceways and wire ways.

So with any conduit run longer that 100' i could actually use a 10' stick of pipe anywhere in the run and pack it full. Like at a panel enclosure to a wire way with all 42 circuits as ccc's, i could use a 2-1/2" conduit and put all 84 conductors in it.
So would 310.15(A)2 be the exception to 310.15(B)2 that is used as a rule with 376.22B
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Rick
 
RUWired said:
Rob thats a great exception. I thought that only applied to ambient temperatures. Never thought it could be used for raceways and wire ways.

So with any conduit run longer that 100' i could actually use a 10' stick of pipe anywhere in the run and pack it full. Like at a panel enclosure to a wire way with all 42 circuits as ccc's, i could use a 2-1/2" conduit and put all 84 conductors in it.
So would 310.15(A)2 be the exception to 310.15(B)2 that is used as a rule with 376.22B
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Rick
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It's based on the heat sink effect of the part of the conductors that aren't required to be derated. If you think about it, it does make sense. I don't see where this wouldn't apply to a trough.
 
infinity said:
OK why not? Is there something in Article 376 that would make the exception non-applicable?
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310.15 (A) (2) is intended to be used for circuits and feeders that pass thru different ambient tempertures. It has nothing to do with derating for conductor fill. If that were the case you could have an 8' wireway run 79' of conduit and not have to derate . Even if the conductors went thru the complete wireway filled with over 30 ccc's. Not the intention a 2' nipple is enough .
 
SEO said:
310.15 (A) (2) is intended to be used for circuits and feeders that pass thru different ambient tempertures. It has nothing to do with derating for conductor fill. If that were the case you could have an 8' wireway run 79' of conduit and not have to derate . Even if the conductors went thru the complete wireway filled with over 30 ccc's. Not the intention a 2' nipple is enough .
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I'm unsure what you mean by "intended" but that's not the way it's written. It says nothing about ambient temperature adjustment.

310.15(A)(2) Selection of Ampacity. Where more than one calculated or tabulated ampacity could apply for a given circuit length, the lowest value shall be used.
Exception: Where two different ampacities apply to adjacent portions of a circuit, the higher ampacity shall be permitted to be used beyond the point of transition, a distance equal to 3.0 m (10 ft) or 10 percent of the circuit length figured at the higher ampacity, whichever is less.
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For a better description of what I said look at the example in the 2005 handbook. If what you are saying is the case I wouldn't have to derate conductors in a wireway at all as long as it wasn't over 10 percent of the circuit length. I don't agree!:smile:
 
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