I am installing 41 # 10 thhn wires in a conduit. 20am ckt. Using #10 because of derating. 50 % from 310-15b2. This is for a lighting dimmer. All ckts have there own neutral. I do not believe I need to count the neutrals. 310-b4. Am I right? Also Table C-1 says I can put 63 # 10's in a 2inch emt. Would you use 2" or bump it up to 2.5"? I have never installed this many wire in a conduit. and would like to know if the extra room would make life easier. Thanks.
1.5 or 2" emt / 41 # 10 thhn wires in a conduit
- Thread starter arnettda
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Rewire
Senior Member
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- Lake of the Ozarks
I believe you need to count the neutrals
BryanMD
Senior Member
do your neutral conductors not carry current?
(neat trick if you can)
(neat trick if you can)
Rewire
Senior Member
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- Lake of the Ozarks
If each circuit has its own neutral then it can only carry full current and must be counted,if I read your post correctly you are not using MWBC so you are not sharing a neutral.
Hopefully your 41st wire is an equipment ground.
As stated above, if you have a seperate neutral per circuit, it counts in your derating, howver, 40 #10 would result of 40% of 40 amp rating or 16 amps. I would think if your loads don't exceed 16 amps you are still good to go.
As stated above, if you have a seperate neutral per circuit, it counts in your derating, howver, 40 #10 would result of 40% of 40 amp rating or 16 amps. I would think if your loads don't exceed 16 amps you are still good to go.
Rewire
Senior Member
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- Lake of the Ozarks
MWBC = multi wire branch circuit
Yes it is an equipment ground. And the derated value just applies to the amount of load you can apply to it? Also would you use the 1.5 or 2" Thanks to all who have replied.
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- New Jersey
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- Journeyman Electrician
So you have 40 CCC's and an EGC? Is that why your derated value is 16 amps? (40a*40%=16a).
Personally I would use more than one conduit.
Personally I would use more than one conduit.
Load doesn't matter... derating is about circuit ampacity. He'd have to put all the circuits on 15A breakers...
William1978
Senior Member
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- N.C.
15a breakers on #10 wire and run the 2" so it will be easer to pull.
Rewire
Senior Member
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- Lake of the Ozarks
I am trying to picture the wire rack with 41 rolls of # 10 and trying to keep them spooling even,always have one backlash.
I have 120 ckts total. Abut 60 feet between locations. 2 seperate floors. Will have 6 conduits all together. Or would I be better going with even more conduits.
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- New Jersey
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- Journeyman Electrician
Personally, for ease of pulling I would use only 1" conduit and fill accordingly. You could still do it your way and install 40 CCC's, in one conduit, with an adjusted ampacity of 16 amps and protect them at 20 amps.
William1978
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- N.C.
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- New Jersey
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- Journeyman Electrician
Given that the runs are kind of short I might consider running 1.25" EMT but as aforementioned I would forgo using any larger conduit to make pulling easier.
Rewire
Senior Member
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- Lake of the Ozarks
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Provided the condition of 240.4(B)(1) is met for all 20 circuits?which is to say they "...are not part of a multi-outlet branch circuit supplying receptacles for cord-and-plug connected portable loads." Otherwise they will have to be protected at 15A.
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- New Jersey
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- Journeyman Electrician
Since these are not multi-receptacle circuits and 16 amps is not a standard size, 240.4(B) would permit the next standard size OCPD which is 20 amps.
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