Thanks Bob...

The load is assumed to be unchanged and the same size cable as before is allowed to be used which is #2 Cu, so we are told by a PoCo rep who worked on it the fateful day that it kept popping on them.

Other than that, we know it feeds a bath house and an RV park. Heck, 7200V at 100A, that's 3000A at 240 and it ain't got but a 200A 120/240V Panel on the secondary side of it... I think it will be OK without getting any algebra involved.. [Linked Image]

Thanks for all the help.

-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI