I agree, I thought I had mentioned the cheap portable L2 EVSEs(like the Ebusbar) which are 16a and I was thinking of using on a 20a circuit, yes 20a circuit=16a continuous. Clipper Creek makes it easy as their model numbers indicate circuit required not output current, therefore if you have a 20a circuit then get the ClipperCreek with the 20 in it's model numberLeftieBiker said:12 gauge wiring can provide 20 amps, but as the maximum load, not the maximum sustained load. That gauge wiring would require a 16 amp EVSE, not 20 amp.
AntroX-True while 12 gauge wiring may be able to support 20a, something like a EVSE is rated as continuous duty and therefore subject to the 80% rule. Extension cords being freestanding and not in a wall(where they could trap heat) are generally rated 20a for 12g and 15a for 14 gauge. Breakers also can be an issue, a 20a breaker will get VERY warm and possibly trip running 20a continuous, they do make continuous rated breakers but they are very rare and by far not the norm. I regularly run 19a on a 20a breaker and the breaker itself gets very warm, I only do this for an hour or so and the wiring feeding the outlet is in metal conduit, lastly I do it with the breaker panel door open to dissipate the heat but it's not really a good practice to overheat a breaker in this manner