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#### miamicuse

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OK I am adding an attic junction box and 1 new circuit which involves messing around with two 1/2" EMT conduits.

I have pulled out the existing #12 solid conductors and plan on using all new stranded conductors which are easier to pull.

Between the two 1/2" EMT conduits I need to feed five (6) circuits - all for standard receptacles and lighting purposes. I will be using tandem breakers and sharing the neutral conductors between circuits on opposite legs.

So circuits 1, 2, 3, 4, 5, 6 that would be six hot conductors. circuits 1, 2 will have a common neutral, 3 and 4 one neutral, and 5 and 6 one neutral. No need for ground conductors for EMT. Altogether I will have six hot and three neutral conductors between two 1/2" EMT conduits going to the same attic junction box. I think the only way I can do this is to put 3 conductors in one (circuits 1 & 2) and 6 conductors in the other (circuits 3, 4, 5, 6) right?

Which lead to the question, is six #12 stranded THHN conductors too much for a 1/2" EMT? The box fill chart says I can put in 9 #12s but that's before derating kicks in. The way I am reading it, if I put four circuits (six conductors) in one 1/2" EMT, and the code says that 4 to 6 current carrying conductors would need to derate by 20%, which means in my case my circuits 3, 4, 5, 6 canNOT be 20A but 15A breakers correct?

IF the above is correct, then would it be better for me to divide up the six circuits EQUALLY between the two 1/2" conduits? In other words, put circuits 1, 2, 3 in one conduit (circuit 1 has it's own neutral, circuits 2,3 MWBC), and circuits 4, 5, 6 in the other conduit (circuit 4 has it's own neutral, circuits 5, 6 MWBC). The total number of conductors between the two conduits is actually more (10 total instead of 9) but in each conduit will be 3 hot and 2 neutral. If I do it this way, do I still need to worry abiut derating? Do the neutral conductors count as "current carry conductors"?

#### rjniles

· A "Handy Husband"
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#12 THHN is derated from 30 amps not 20.

#### micromind

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Neutrals don't count for derating.

I'd pull all 6 circuits plus the 3 neutrals in one pipe and leave the other for a spare.

#### miamicuse

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So I don't need to worry about derating for the 20A circuits? I could fill all 9 #12s in one?

I don't think I can pull all 9 conductors in the 1/2" conduit though. I have done 6 before and it was really hard to pull and I only had two 90 degree bends.

#### Clutchcargo

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So I don't need to worry about derating for the 20A circuits? I could fill all 9 #12s in one?

I don't think I can pull all 9 conductors in the 1/2" conduit though. I have done 6 before and it was really hard to pull and I only had two 90 degree bends.
You need to add lubricant to the emt and conductors.

#### Arrow3030

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I would never advise 9 #12's in a 1/2" unless it's the only way (or under 2'). Maybe 9 #14's but I've never tried. You don't count the neutral in a MWBC because it carries the unbalanced load so it isn't current carrying (unless harmonics are involved). Your ampacity adjustment is 80% of 30A for #12 or 80% of 25A for #14. If you only have one MWBC in a conduit no adjustment is required.

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