SHUT IT DOWN...
POCO, may have only checked thier side of the equipment, most wont go any further. "NMJ" But wise to rule it out...
"prior electrician had bonded the grounded and grounding conductors to each sub-panel via installing lugs and bolting them to the main disconnect enclosure, rather than installing a single bus with enough openings for all the conductors."
Nothing wrong with that... So long as ground on ground bar, and neutral seperate in main panel, and bonded there, even in multiple services.
Anyway, I'm lost as to what feeds the affected area? But either way it sound to me that the panel on the left is either carrying load or fault current on the ground. This is a potentialy dangerous situation if left to continue for any period. In my professional opinion, it should be shut down until located. As it is a high fire or shock risk.
You could locate this a few different ways...
The hot spots are resistive, and creating heat due to current flow, but only a symtom of the real problem. But will need to be corrected any way. Don't fix this yet, it will aid you in locating the fault.
By now the whole kit and cabootle of the affected panels should be off.... Not kidding. Wait for the hot spots to cool! If they don't you have other problems, like current flowing out toward branch areas = BAD! (Bigger problems - loss of GEC, and the system found a better one for you...) If they do cool off... Attach a solidly connected insulated #6 between the panels with the hot spots, or better between the the best grounded portion of the panels closest to the GEC, and the other side of the affected panels. Then turn breakers on one at a time, and then back off while checking amperage on that #6 you installed. The one that gives you an amperage reading jump is the fault, if all of them give an amperage reading to some degree, the neutral is toast. Or a ground and neutral are connected down the line, and this is parralel current coming back.
I'll opt for neutral is toast! (with secondary screw up's.)
Good luck, but get on it quick.....
