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joeyww12000

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Chatsworth GA
I had earlier asked a question on Derating and got great answers, thank you. Im still having some trouble on understanding when I count a neutral as current carrying. Ive read 310.15 b (4) a-c and just want a clearer understanding of this matter. An answer to my question earlier was if I had 3 sets of conductors a/b/c/n/g of a 208/120 wye connected system in a raceway I would only have 9 that were current carrying, this being my 9 current phases. So can I assume that in all 208/120 systems my neutral is not counted as current carrying or does it depend on the load? How about 277/480 delta systems?
 
joeyww12000 said:
So can I assume that in all 208/120 systems my neutral is not counted as current carrying or does it depend on the load?

Generally, if you have all 3 phase conductors and a neutral (all connected at 120-volts, then the neutral is not counted as a CCC.

If you have A & B phases connected at 208-volts and C-phase connected at 120-volts then you will have 4 CCCs.

If you have A & B phases and a neutral (of a 208/120 system), then all 3 conductors are CCCs.

If you have A & B phases and a neutral (of a 120/240 system), then you only have 2 CCCs since the neutral will only carry the unbalanced load in this configuration.
 
joeyww12000 said:
So can I assume that in all 208/120 systems my neutral is not counted as current carrying or does it depend on the load?
Yes, unless a significant portion of the load is non-linear.
joeyww12000 said:
How about 277/480 delta systems?
T'aint no sech animul! ;) If there is 277 present, then you have a WYE configuration.
 
charlie b said:

Yes, unless a significant portion of the load is non-linear.

T'aint no sech animul! ;) If there is 277 present, then you have a WYE configuration.

Well, there is a chance you happen to have 277V to ground in a delta system, depending on system capacitance. But, that would just be a concidence.
 
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