Buying my first house on friday!. Right now, it has 2 NEMA 14-50 outlets (one for my Tesla, one for another electric car when my parents or other friends come). I have 200 amps breaker. If eventually I change one of the 15-50 outlet for a 100 amps circuit to plug the HPWC, so it charges at amps will it work? Everything else in the house is also electric (heat, in cold weathers of Canada), stove etc. If not I guess the next step is to upgrade to 400 amps breaker? How does that cost?