davewill
Active Member
I agree with you that they should have used a 50a rated pigtail, but the one they used probably meets specs. A little searching finds that the 40a rated range cords generally have 10awg wire and the 50a rated ones have 8awg. Once you're past the wallbox, it's a different set of rules, and cables in air have different ratings than cables in wall or in conduit.10 gauge?!?! Seriously? I'm kind of angry at them just thinking about this, that they intentionally decided to build a device to use 40A continuous current draw and only used extremely undersized 10 gauge conductors. Regardless of how short, that's dangerously thin and resistive for that level of current. I'm not surprised at all that it feels hot. I would definitely keep the current turned down into the 20's, probably 24A, since 10 gauge is normally used for 30A circuits.
I'm also pretty sure the whole 80% rule no longer applies once you're out of the wall. However, if the cord is regularly getting that hot, they should have bumped it up...and the OP may want to do so for his own comfort and peace of mind. He could also simply set the JuiceBox for 30a and I'm sure it would be much cooler.
I just had to make a similar decision. I have an OpenEVSE and the J1772 cord and plug was rated for 40a, so I had my unit set to deliver 40a. The Rav4EV has the same charger as the original Model S, so it happily charged at 40a. Everything seemed OK, but I recently found that the plug was getting hot, and opened the housing to find that the wires inside had the insulation burnt off.
I bought a replacement cord and plug that was was more sturdily built and I now run the unit at 30a.
Here's the new one:
Funnily enough, it's Leviton branded, but the wire gauge is much thicker than the one I was using. It also has a much higher quality Yazaki branded plug which I've been using on my other EVSE for years. It's only rated for 30a, but unlike the one I was using, it really IS rated for that and specifically for EV use.
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