trekkie,
why would there be any heat from induction with all the phases present?
You have more than just all phases in each conduit...you have an extra conductor from a single phase with no conductors of the other phases to cancel the fields. This would be the same as putting A in one conduit and B in another conduit. Remember this is a ferrous metal conduit. If the conduit was non-ferrous, you would not have the heating problem, but there still would be a violation of 310.4.
