Thanks for the help.
Yoopersup, regarding your mention of the derateing leads me to another question. The conductors on the primary side will be 500’s according to what Greg pointed me to (forgot about the step up). However the secondary side of the transformer fit into the adjustment factor because there are four conductors – three phase conductors and one neutral – and my flex is over 24”long. 310.15(B)(4) addresses the neutral conductor. If my loads consist of nonlinear loads I have to count it as a current carrying conductor. If my loads are not non linear than I don’t need to count it. How do I know if my loads are nonlinear? 1/3rd from this panel will be 277v lighting and the other 2/3rds will be small 277v blower motors. I have an identical setup next to this one but it will be a 480 to 120/208 transformer feeding two 400 amp panels and all the circuits will be for wall outlets. I know you can’t say for sure but what’s your feeling, is this nonlinear loading? If it’s nonlinear than I need to derate and I’m up to 600’s to get into the 400amp breaker but the breaker only accepts 500’s, still no good. I guess I may have to see if I can special order parallel lugs like Edward mentioned. Not what I wanted to do for this installation, but may be forced to.
Thanks
Mic
