So, after some debate over load calculations and a final setup of my new breaker panels I finally have HPWC #2 installed. (Yes, two Model S here.) Both units are [email protected] (Still have to mount the cable holder for the new one on the left) With both running at full power I still only see a 2-3% voltage drop, which confirms that everything is installed well and the transformer feeding my panel can handle the load fine. With these and all other loads I peaked at over 60kW draw so far without issue. I have 400A service here. Under normal conditions I don't see both chargers running simultaneously for very long anyway. It's more of a convenience thing for preconditioning and such and not having to switch which car is plugged in beforehand since they have their own chargers. There is a 30A outlet we've been using for the second vehicle's UMC for a while, but this is better. For the detail oriented, everyone involved agreed that NEC 625.23's declaration that a portable lockout method for the circuit was insufficient for an HPWC was stupid. All agreed that the 100A breakers and the lock on the breaker panel door were sufficient. The entire panel feeding the HPWCs in my case can be locked out via the adjacent permanently installed transfer switch's off position anyway.