HPWC wire gage

[Soolim]

#1 ALuminum is good to 100A with 75 degree terminations, and #3 CU (copper) likewise.

Be careful - your electrician might try telling you that what he did is fine because the car will never charge at more than 80A, so 90A is plenty good. This is incorrect! NEC 210.19(A)(1)(a) says otherwise - the circuit conductor rating must not be less than 125% of the continuous load. NEC 625 says all EV loads are treated as continuous loads, 80A * 125% = 100A. The conductor and terminations must be rated at 100A.

To put it in another way, regardless that the conductor is rated for 90C, simply use the 75C ampacity for your circuit rating. Apply the same method be it copper or aluminum wiring, then you are always safe. In my thinking, saving a few dollars on the wiring material is not worth the risk. The contractor may think otherwise, but we as the owner should demand what is right for us.

 

[Atebit]

Thanks for all the detailed information guys. I had a meeting today with my electrician...we looked over the ampacity tables, and discussed that the middle of the wire is not the same as the ends in terms of heat and with regard to what the wire is connecting to. I also mentioned again that the HPWC has to be considered to be a continuous load. So he's going to re-pull the wire, probably going with 2/0 AL from the main panel to the sub-panel in the garage and 3 AWG CU from sub-panel to the HPWC. I have no doubt he knows his trade, I just think this is his first EVSE install and it might not have been clear that he needs to treat it as a continuous load. So we're good!

 

[FlasherZ]

Glad to hear it!