2 ways:
1) have an electrician wire up a plug that connects to your house so all the plugs in your house work as if you’re on the grid when the generator is plugged into it. I assume they would make up a switch for safety reasons.
2) run a bunch of extension cords and plug in which appliances you want to power when you turn on your generator.
I haven’t done the first one yet but it has its advantages and disadvantages like convenience vs practicality
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