Hypothetical question, How does the derating picture change if I have a 208v 3 phase service rather than single phase?
If you are using the three phase system and a grounded conductor for each circuit the grounded conductor is a current carrying conductor. If you are using 2 phases with a common grounded conductor, the grounded conductor is a current carrying conductor. If you are using a three phases with a common grounded conductor the grounded conductor is not a current carrying conductor if a majority of the load is linear, and is a current carrying conductor if a majority of the load is non-linear.
Don
