I have 125amps coming into my house from PGE and my panel is 125amps and has a few free breaker slots. Currently I have a 240v oven, 24v clothes drier, 240v floor heating and 240v EV car charger (plus the usual 110 appliances: laundry, dishwasher, garbage disposal etc). Now I want to add an AC unit which they tell me will require 30amps. Now based on some load calculation table that the city permit folks want me to fill it seems I will go over the 125amps. They give you demand-factor reduction, take into account that you will not use AC and floor heating at same time etc - but taking all that into account and I still go over 125 amps by a little - the total is 135amps.
One solution is to use a DPDT switch that switches between either my EV car charger or my AC. Note I am okay with using 2 breakers in my main panel - one for AC and one for EV car. Alternatively I can use a generator interlock to solve my problem - I don't fully get how that works and would need some guidance.
Would either of the above two solutions pass code? Can EV charging 24v outlet into which I plug my car go through a DPDT switch? Or is there a rule against it like needing a dedicated circuit?
If legal could someone please draw a diagram for the DPDT switch and also for the generator interlock + subpanel. The DPDT switch seems simpler.