isn’t what you may think. Going into houses is +110VAC and -110VAC. To get 220V, you connect between +110VAC and -110VAC. You do that connection through a double breaker, and it takes up two adjacent slots in the breaker panel.

An electrician would, of course, know this. When you do it yourself, it’s far too easy to make a mistake and get injured or killed if you do it wrong.

I have skin grafts from burns when I did it wrong.