When you install 120V, single phase circuits in a raceway, each with a separate neutral, do you count the neutrals when applying the provisions of 310.15(B)(2)(a)? or does 310.15(B)(4)(a) apply to this situation?

Each neutral carries the same current at the associated phase conductor and therefore must be counted as current carrying conductors.
Don(resqcapt19)

In a word... yes. If you have a shared neutral on a single phase multiwire circuit it would not count.

Steve,

Isn't that on linear loads?

Non-linear loads using a multiwire method ( N-A-B-C ), the neutral is considered a current carrying conductor. 220-22 FPN#2, 310-15(b)(4)(c).

Absolutely. Each neut carries the full load.

[This message has been edited by electure (edited 12-09-2001).]