The topic of the NEMA14-50 socket has come up a lot lately. When seeing one, someone might want to assume that they could get 50amps of current out of one. For instance, check these specs/features: Leviton 125/250V Flush Mount Receptacle - Industrial Plugs - Leviton 279 - LevitonProducts.com So that "50 Amp" feature can be misleading. I think that describes the max capability of the physical connector, but current can be more limited by the equipment behind it. For instance, there could be a 40 or 50 amp breaker. If a 40 amp breaker, code says you shouldn't draw more than 32 amps. If a 50 amp breaker, code says no more than 40 amps. This page says: So, I think there are some NEMA 14-50 with 40 amp breaker installed out there. Also, various adapters may provide a NEMA 14-50 even though there is a smaller than 50 amp breaker behind it. For instance, this Y cable is called "MAXIMIZER RV 50-AMP GENERATOR ADAPTER" yet it provides far less than 50 amps of capability. Various cable adapters, like those from EVnut will also let you plug NEMA14-50 equipment into 30 amp sockets. Also, the EAA Avcon to NEMA14-50 adapter box mentioned on the EVnut site above lets you get a NEMA14-50 socket that has equipment behind it that typically only pulls about 25 amps, not 50. The Tesla MC240 is listed as "30 amp capable", and some have wondered "why not 40" or "even 50", and I think the above illustrates why it is safer for it to not use more than 30. Some home made kits have been able to adapt Avcon to Roadster without using the MC240, but one needs to be careful about how much current you try to pull through the Avcon cable. 25 amps is probably most appropriate. 30 or 32 amps is pushing it. 40 amps is probably too much. If you have a home installed NEMA14-50 not adapted from another socket, and you know it has a 50 amp breaker, and suitable wiring gauge, then yes, 40 amps can work, but if on the road at an unfamiliar NEMA14-50 or Avcon it is probably best to stick to lower current.