I have always counted the grounded conductor of a 120v 2wire circuit of a 120-208 3ph wye service as current carrying, is this correct? More and more I am seeing contractors using 2" pipes over 24in up to main pull boxes above the ceiling. Here is an example, a job I am doing a build-out on has a 42crt panel with two 2" conduits each of those have 20- 20a 120v 2wire gfci circuits in them. That is a total of 40 #10 Thhn wires, that would cause the derating to drop to 40% of the conductor. #10 is good for 40amps x 40% gives you 16amps. Which you could go to a 20a breaker for unless it is feeding multiple outlets... So back to the beginning of the question, Am I wrong in counting the grounded conductor as current carrying? And am I correct in not being able to go up on multi outlet branch circuits?