Hi to all
We got our S85 yesterday. Being an engineer, I put it on charge at 30A instead of 40A to test how things are functioning. We have 242V at the outlet with the car on charge. We had the electrician put in #4 wiring, 52 feet underground from the breaker box instead of #6 so the feed side is cool into the garage outlet. The 14-50 outlet was just detectably warm after an hour at the plug faceplate, but the Tesla wiring was markedly warm- this concerns me a bit as the difference going from 30A to 40A is about 65% more energy dissipation in the cable (ratio of 40^2 to 30^2). The plug at the car was a bit warm too. I am going to put a thermocouple on the different areas and monitor, and report later on.
I share your concern if it's more than just warm to the touch at 30A. "Detectably warm" is fine, if you can't touch it, it's a bad thing. I use an infrared thermometer to read mine. I've had my UMC replaced once because of a melting problem at the adapter and my HPWC cable replaced because of a loose connection at the car.
The #4 is a bit overkill IMO, considering that even #8 is sufficient if THHN in conduit. At least you're erring on the safe side.