Yeah, if the wire is sized according to NEC you will see a very noticeable temperature rise when it’s loaded for a while. Moving to the next size up wire helps, but not all that much. Wire isn’t really ‘good’ for a particular amount of current. The current it handles is generally limited by how hot the insulation can get before melting. And for short durations, it’s a lot. Most things in your house don’t take that much power for that long, so you wouldn’t notice it. With a 14-50, you probably can’t oversize the conductor that much anyways. You’re always limited to the weakest link in the chain. So if the breaker is only listed to accept up to #4, you can’t use anything larger than that. The receptacle and breaker should be marked with the conductor size range they are listed for. But as long as the wire wasn’t shredded during install, and the screws are tight on both ends, a bit warm is totally expected and normal. It should never be burning hot to the touch, but it is generally going to be fairly warm. A better outlet isn’t a bad idea, but the regular ones should be OK so long as you don’t unplug it a dozen times a day. They will get loose over time and slowly get hotter and hotter. I would assume Tesla would have put a temp sensor in the 14-50 plug on the wall connector to throttle charge power should it become too hot, but I’m not sure. If you see goop on wires into breakers, they’re probably aluminum. It’s required by code to use anti corrosion goop on aluminum conductors, and aluminum is typically used on larger capacity circuits since it’s much cheaper than copper. So it’s really just an aluminum wire thing and not a high current thing.
