The power’s out, your portable generator’s humming in the yard, and you’re trying to figure out how to get that electricity to the furnace blower, the fridge or the sump pump. It’s tempting to hunt for a shortcut. Please don’t. The wrong connection can kill a utility worker, start a fire, or fill your home with carbon monoxide.
The good news? The safe ways to connect a portable generator to your house are simple, and none of them involves plugging into a wall outlet. For a few appliances, use outdoor-rated extension cords. For whole circuits, use a transfer switch or an interlock kit installed by a licensed electrician. Let’s go through each one.
The one connection you must never make
Never plug a generator into a wall outlet with a male-to-male cord, sometimes called a “suicide cord.” This is called backfeeding. Power flows backward through your home wiring and out to the utility lines, where it can electrocute line workers who think the lines are dead. It can also wreck your generator and appliances and start fires. Backfeeding without a transfer switch or interlock is dangerous, and it’s illegal in most places.
Powering a few items with heavy-duty extension cords
If you only need a handful of essentials, this is the easiest safe route. You simply run outdoor-rated extension cords from the generator to your appliances. A few ground rules make it work:
- Pick cords rated for outdoor use, with a wire gauge heavy enough for the load. Check the cord’s amp rating against what you’re plugging in, and use the shortest cord that reaches.
- Keep the generator outside and well away from the house. The standard guidance is at least 20 feet, with the exhaust pointed away from windows, doors and vents.
- Route cords so they aren’t pinched by a door or window, and keep any gap around them as small as you can so fumes and weather stay out. Never leave a door or window open near the generator just to pass a cord through.
- Never overload a cord, and replace any with cracked or frayed insulation.
That setup works fine for a fridge, a few lamps and some electronics. It gets awkward, though, with hardwired items like furnaces, well pumps or lights on a circuit. That’s where a transfer switch comes in.
Using a manual transfer switch for whole circuits
A transfer switch is a small panel installed next to your main electrical panel. It connects the circuits you choose to the generator and keeps them cut off from the utility, so power can’t flow back out. You plug the generator into an inlet on the outside of the house with a proper generator cord, then flip the switch.
Now you can power things like the fridge, furnace and some lights without cords snaking through the house. A licensed electrician should install it, and local codes may require a permit and inspection. To see what’s out there, read about transfer switches for portable generators.
What an interlock kit does
An interlock is a mechanical plate that fits on your main panel. It physically blocks the main breaker and the generator breaker from being on at the same time. Add a dedicated generator inlet and breaker, and you can power circuits right from your existing panel.
It’s often cheaper than a transfer switch, but there’s a trade-off. You have to follow the procedure exactly, and you’ll need to manage your load so you don’t overload the generator. Kits are panel-specific, so you need one made for your panel’s brand and model. A licensed electrician should install it, and some areas require a permit. Our guide to generator interlock kits for home panels explains what to look for.
Going hands-free with an automatic transfer switch
Have a standby generator? Then an automatic transfer switch (ATS) is the piece that makes it work on its own. It senses when utility power fails, starts the generator, moves your home onto it, and switches back when the grid returns. Professionals install it as part of a permanent system. For more, see automatic transfer switches for generators.
A safe generator setup checklist
- Place the generator outdoors only. Never in a garage, basement, crawl space, shed or porch, even with the door open.
- Keep it at least 20 feet from the house, with the exhaust directed away from windows and vents.
- Keep it dry. Use a generator tent or canopy made for the purpose, never a tarp that traps exhaust, and don’t run it in rain or snow without proper protection.
- Install working carbon monoxide alarms on every level and near bedrooms, with fresh batteries.
- Let it cool before refueling. Turn it off, wait, and store fuel in approved containers away from living spaces.
- Add up your loads so you don’t exceed the generator’s rated output.
Why is carbon monoxide the biggest risk?
Generator exhaust contains carbon monoxide, which you can’t see or smell. It can build up fast and cause serious illness or death. If you feel dizzy or nauseous, or get a headache while a generator’s running, get outside into fresh air and call 911.
Some portable models include automatic CO shutoff, which is a helpful extra layer, though it doesn’t replace proper placement. Our roundup of portable generators with CO shutoff covers that feature, and our guide to generator carbon monoxide safety goes into more detail.
When should you call an electrician?
For any transfer switch, interlock or inlet installation. A licensed electrician will make sure the equipment matches your panel, your generator and local code, and they can pull the permits. Tell your utility too, if your area requires it. If you’re ever unsure whether a setup is safe, stop and ask.
Frequently asked questions
Can I plug my generator into a wall outlet?
No. That’s backfeeding, and it can electrocute utility workers, damage your equipment and start fires. Use extension cords, a transfer switch or an interlock instead.
How far should a portable generator be from the house?
Standard guidance is at least 20 feet, with the exhaust pointed away from windows, doors and vents. Keep it outdoors only, never in a garage or shed.
Do I need an electrician to install a transfer switch?
Yes. A licensed electrician should handle any transfer switch, interlock or inlet installation, and local codes may require a permit and inspection.
The bottom line
Safely connecting a portable generator to your house means extension cords for a few appliances and a professionally installed transfer switch or interlock for whole circuits. Never backfeed through an outlet. And before the next storm, give our power outage checklist a read so the rest of your plan’s ready too.