Option 1: extension cords to each appliance
The simplest setup. The generator stays outdoors, at least 20 feet from the house, and heavy-duty outdoor extension cords rated for the load run inside to the fridge, a lamp, a phone charger. It can’t power hard-wired loads such as a furnace fan, a well pump or anything on 240V.
Option 2: an inlet and an interlock (installed by an electrician)
An electrician installs a power inlet on the outside wall and an interlock on your main panel. The interlock physically prevents the main breaker and the generator breaker from being on at the same time, so the house is connected to the grid or to the generator, never both. You then choose which circuits to run.
Option 3: a transfer switch (installed by an electrician)
A manual transfer switch moves selected circuits between utility and generator power. Like the interlock, it ensures your home is on one source or the other, which is what prevents backfeeding. Standby generators use automatic transfer switches.
Why not a wall outlet?
A double-ended cord in a wall outlet sends generator power backwards through your panel onto the utility lines. Generac’s support guidance: utility workers may assume lines are de-energized and can be seriously injured or killed; generator power can clash with returning utility power, causing fires and damage; and it violates codes in most jurisdictions.
Size the generator first
Whichever option you choose, the generator must cover your running load and your biggest motor’s start. Well pumps, central AC and electric dryers often need 240V, which only some portable generators supply. Check your list in the planner.
Sources: Generac support: why you should never back-feed your electric panel; CPSC, May 27 2026. Permits and code requirements vary by location; your electrician will know them.
Last reviewed 2026-09-26. Sources · How we calculate