Article 310 Section 310.15 (B)(3) talkes about adjustment factors for more than 3 current carrying conductors in a raceway or cable.
The question that was given to me is that if you have 6 two wire circuits each with it's own neutral in the same conduit, can he use 310.15(B)(5)(a) and not count the neutrals. I said "No" because crudely put (a) is really talking about a Delta system and (b) and (c) are talking about a Wye system. Plus for his example none of the circuits shared the same neutral wire as it would if they were multi-wire circuits.
The code references are from the '11 NEC but it's worded the same in the '08 NEC, they just moved it around.
