The minimum service is 240v 100a (single phase) by code. 200a is becoming the standard and 320/400a is not unusual in these 3500 sq/ft and up McMansions they build. The only time I see much under 200a is if they have a significant use of natural gas. My house is 200a and I had to use the optional calculation to come up with that number when I pulled the permits for my addition. I suppose LED lighting should reduce that a little but lighting is really a pretty small part of the load on an "all electric" house. The heavy hitters are the water heater, range, spa and toaster wire heat. The last is really only practical in southern climates where the heat is not used enough to justify a heat pump. That is probably changing now since the heat pump option is becoming a lot cheaper on A/C systems, almost standard. I actually haven't had my toaster wire heat on in the 5+ years I have had this system. I know that because the installer screwed up and didn't connect the heat call from the thermostat. I tried it right before Christmas because my 92 year old FIL was over and he gets cold. We still got along without it using the 1.44kw heater in the electric fireplace. I since fixed the problem but I am thinking I should have left it alone, just so it doesn't get turned on by accident
