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Are your conductors copper or aluminum?
Please let me know so that we can continue.
Ok, your #10 conductors in MC are good for 30A. 50 feet is not a long run either.
Do you actually have 240V at the equipment? Or maybe 230 or 220?
Can you check that?
Yes, I measured 240VAC RMS between phases with Fluke digital meter at the receptacle with no load. With load, I see about 237VAC
Ok, for continuous loads, the NEC requires that you breaker (and wiring) be rated 125% of the full load of the equipment. 25A x 1.25 is 31.25A.
Your breaker and wiring should be rated for 40A - the next common size up from 31.25
That would be to comply with code, however, when it boils down to it, #10 conductors are good for 25A so I'm not sure why they are warm for such a short run.
Are you sure that the load is 6KW?
OK. I had 40A breaker originally but reduced it thinking 40A was too high.
I have a residential-type power meter in series with this load so I can watch power draw when charger is in use. From that I confirm 6kW, consistent with charger and car specs.
I calculate about 1W/ft power dissipation in the conduit from 0.9989 ohm/1000ft from table online. Don't know if that is enough to create a warm temp.