Originally Posted by I_think_I_conduit
REALLY. I always assumed I could tape white wire with colored tape.
I understand "shoulds". But my question is about code.
As others have said, it is against code. You absolutely, positively, can not use a white wire for anything other than a neutral (grounded) conductor. Also you can not use a green wire for anything other than a ground (grounding) conductor. The only exception for this, as Speedy said, is in a multi conductor cable assembly, but if you are pulling separate conductors in conduit, then no.
Those two colors are the only specific colors that the code restricts (well there are a few other instances, but nothing you would ever need in residential wiring). You can use any other color you want for the hot conductors.
Industry standards are black, red, blue for 120/208/240 volts, and brown, orange, yellow for 277/480 volts, but those are not governed by code only standard industry practices.