Have you considered connecting an analyzer or chart recorder to the circuit to find out what is actually going on? I have also used an "amprobe" in the past with the peak hold setting to help troubleshoot similar problems.
Calculations are great but I also like to find out what the actual...
We had a failure today of our GE Spectra Bus Duct. The failure appears to have originated at one of the insulated thru bolts. The bolts are spaced approx. every 10" throughout the length of the duct. They are 3/8-16 bolts with a Mylar type tube over the bolt, going thru the insulated bus bars...