ECN Forum Forums Code Related Discussion NEC & other Code issues Neutrals

Let's see if I can describe and ask this so that it makes sense to you all.

As I read the NEC 2002 Handbook, on a 208/120 3 phase circuit, coming from a 100 amp sub-panel with 12 breakers, it is proper (ok) to use one neutral for set:

Phase Breaker
A 1
B 3
C 5 these use one neutral

A 7
B 8
C 9 these use another neutral

A 11
B 13
C 15 these use a third neutral

Having said that, can I use the following set up?

Phase Breaker
A 1
B 3 this pair uses one neutral

C 5
A 7 this uses the second neutral

B 9
C 11 this uses the third neutral

A 13
B 15 this uses a fourth neutral

I hope this makes sense to you all.

Thanks

Steve

What you listed should be fine but if these circuits are going to share one raceway you will need to adjust the ampacity of the conductors as shown in table 310.15(B)(2)(a). In your second example there are 12 current carrying conductors but if you did it the way shown in the first example there are only 9 current carrying conductors depending on the type of load.

Curt

I see in the first example where you are using breakers 7-8-9 instead of 7-9-11. I hope this was a typo, and not reality.

Yes, the first example should have said breakers 7,9,11 and then breakers 13,15,17.

Thanks for catching that.