Understanding 310.15 B (4)

[K2X]

I know there was another thread on this recently but i didn't really get it . So I thought I'd try and example to see if someone could explain it to me.

First question. If I was going to put 15 # 12's in 3/4 emt and pull it 80 ft with two 90's , would my arms hurt? I'm guessing yes.

Second question. If I had 15 #12's in a 3/4 emt, 5 blacks, (A phase), 2 reds,(B phase), and 7 whites, (grounded conductors), 1 green, (grounding conductor), do I count the grounded conductors according to
310.15 B (4)?? I'm not going to guess. My arms hurt.

Third question. 310.15 B(4)a. I think I understand balanced/ unbalanced load from like the A phase and the B phase but I don't seem to understand " Unbalanced current from other conductors of the same circuit "??

Thanks for any replys for all the help in the past.

 

[K2X]

I meant to say do i count the grounded conductors/neutrals on question #2. The panel is 120/208 three phase. Tnx..

 

[augie47]

with a 3 phase system, the only time the neutral carries the true unbalanced load is when it is shared by all 3 phases (A,B,&C) and the loads are linear.
In any other situation, you must count the neutral.
In your case, where each current carrying conductor has it's own neutral, that neutral will carry as much as it's phase conductor and definitely will count as current carrying.

 

[don_resqcapt19]

First, any time you have a grounded conductor for every ungrounded conductor, the grounded conductor counts as a curretnt carrying conductor.

If you are using a common grounded conductor with two ungrounded conductors of a 3 phase wye system, the grounded conductor is counted as a current carrying conductor.

The only time you don't count the grounded conductor is when you are using a multiwire circuit that uses each of the available hot legs and the majority of the load is linear.

 

[LarryFine]

First question. If I was going to put 15 # 12's in 3/4 emt and pull it 80 ft with two 90's , would my arms hurt? I'm guessing yes.

It may be impossible if you're working alone. It's not easy to set up 15 spools and have them pay out without fouling (tangling.)

Second question. If I had 15 #12's in a 3/4 emt, 5 blacks, (A phase), 2 reds,(B phase), and 7 whites, (grounded conductors), 1 green, (grounding conductor), do I count the grounded conductors according to
310.15 B (4)??

Yep, every one. Only a grounded shared by all (2 for 1ph, or 3 for 3ph) phases of the supply can be ignored (for CCC, not fill.)

Third question. 310.15 B(4)a. I think I understand balanced/ unbalanced load from like the A phase and the B phase but I don't seem to understand " Unbalanced current from other conductors of the same circuit "??

They're basically talking about the same thing.