Electrical Questions? Ask an Electrician Online.
Hello there and welcome to Just Answer. My name is XXXXX XXXXX I will be assisting you today. I am an engineer with over 30 years of electrical and electronic training, repair and installation experience. I will try and answer your question accurately and precisely so that we can get you on your way.
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.