Does it make sense to install a wall charger with a 40 amp breaker? Can't you pull that with the portable charger and and a dryer plug?
As noted by others, a dryer plug is a 30a plug so this would be a code violation to put on a 40a circuit. You could downgrade the breaker to 30a, but naturally my preference is for as much capacity as possible. You can always charge slower in software from the car if you feel the need, but it is good to have max charge speed available for the unforeseen situations.
If you're doing DIY on wall charger... going from what I know about my wall charger, the first gen 80A beast... you want to be sure of using anti-oxidant electrical connection lube / coating smeared on the stripped wire ends, and torquing down the wiring lugs to a specified setting. Not doing either of these things correctly can create too much heat at these connections over time.
I don't see any reasons to use an anti-oxidant on the connections. This generally applies (and is good advice) on aluminum wire, but the Wall Connector IS NOT RATED for aluminum wire - using it would be dangerous! Copper wire does not need anti-oxidant. The correct torque is good advice though.
No. A “dryer plug” uses a 30A circuit and the car will draw 24A. With a 40 or 50A circuit and a NEMA 14-50 outlet, a Gen 2 UMC will draw 32A. But a 14-50 is really meant for a 50A circuit unless it’s in an enclosed space like an oven. You wouldn’t want someone plugging their RV into one that’s only in a 40A circuit, or a Gen 1 UMC for that matter.
The 40a vs 50a thing on a 14-50 gets thrown around a lot, but I want to be very clear: It is fully NEC code compliant (2017 code) to put a 14-50 receptacle on a 40a circuit as long as that is the only receptacle on the circuit (which is a requirement for EV use anyway), and the intended load (the UMC Gen 2 in this case) is not going to draw more than 32a continuous (which is the case with a UMC Gen 2).
Now, generally, I would always wire up a 14-50 with sufficient ampacity wire (generally 6 AWG) to support 50a just for future proofing (and I probably would also put it on a 50a breaker), but there are cases where putting it on say 8 AWG NM cable (romex) on a 40a breaker would be completely fine.
Others have sometimes recommended (and I agree with them) that labeling the receptacle that it is only on a 40a circuit (good for 32a continuous) would be a good idea, but it is NOT a code requirement. The UMC gen 2 will draw a max of 32a and be totally happy on a 40a circuit. The issue comes in if someone later plugs in a different EVSE that draws 40a continuously.
The wire terminals on the connector are very very hard to get larger gauge wire into so I would recommend that you pre-bend the wires, loosen up the terminals as far as they will go without forcing them, then feed the wire in as far as possible.
In this case if his electrician wired him on a 40a breaker, there is a good chance they only wired it with 8 AWG NM (Romex) cable. Or maybe at best 6 AWG. So I don't think landing the wires will be too difficult under the Wall Connector.
I think the original poster can probably successfully do this themselves. It really is not rocket science if you are somewhat handy. I would just throw in that you need to make sure that the wall connector is firmly mechanically connected to the wall so it wont rip off the wall or anything. i.e. It needs to be screwed into wood.
If the circuit that was added was inspected already, I am not even sure this installation would require a permit (check with your local authority having jurisdiction). It may be classed similarly to installing new wall outlets or light fixtures.
Do be absolutely sure to set the max power draw via the rotary dial correctly per the install instructions table. Note that on a 40a circuit you can only draw 32 amps from the Wall Connector due to the 125% oversizing rule.
