Jea48: the wiring in our houses here is 120V and 240 comes into the house and is split out normally. I did have an error in my response in that we are not obligated to only have 120V here. I currently have a 240V line to the kitchen where an old electric stove used to be, another for a heat pump, and a 3rd for the dryer to the laundry room. I could choose to run a 240V line to the attic for an isolation transformer if I had to. For that matter, I could also choose to drop an entire 2nd house circuit immediately after the meter and skip the main breaker panel altogether; my response was more thinking of limiting the invasive electric/structure work that would be required here. My apologies for the confusion my original response probably caused...