Wire fill and deration

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pepevegac

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My next question is that if you have a conduit with 6 #10 current carrying conductors, this conductors are rated for 80% of it's max amperage right. So there is a foreman who am working with right now that is running a 1 " emt and he says that you could run 16#10 in a 1" and still be rated for 80%. is this right or does this 16 wires fall under the catergory of 50% based on 310.15B2a. Thanks
 

infinity

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You need to determine how many CCC's (current carrying conductors) are in the conduit and them apply the derating factors listed in 310.15(B)(2). The fact that the conduit has 16 conductors is almost meaningless in the derating calculation.
 

charlie b

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The 40% rule for conduit fill is based on the likelihood that the cables will jam, during the process of trying to pull them through the conduit. It has nothing to do with whether any of them will carry current (for example, EGCs don't normally carry current), and it has nothing to do with ampacity or derating factors. As Rob said, the derating factor you use depends on how many conductors you have to count as being "current carrying." That depends, in part, on how they are connected (i.e., whether there are any multi-wire branch circuits involved).
 

pepevegac

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then if you have 3 lighting circuits (blk, red, blue, neutral) and two receptacle circuits (bk, red, neutral). would the neutrals count as current carrying conductors? sorry I became a little confused with this rule having to do with the # of CCCs and the percentage allowed.
 

infinity

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then if you have 3 lighting circuits (blk, red, blue, neutral) and two receptacle circuits (bk, red, neutral). would the neutrals count as current carrying conductors? sorry I became a little confused with this rule having to do with the # of CCCs and the percentage allowed.


What is the system type and voltage? What type of lighting? If this is florescent lighting fed from a 3 phase WYE system your scenario would likely have seven current carrying conductors.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
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What is the system type and voltage? What type of lighting? If this is florescent lighting fed from a 3 phase WYE system your scenario would likely have seven current carrying conductors.
I count six, unless you're including the lighting neutral because of harmonics.
 
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