How to Use a Generator to Power Your House Safely
The safest way to power a house with a portable generator is to run it outdoors, far from the home, and connect it through a properly installed transfer switch or interlock kit. If you have no switch, skip the house wiring entirely and plug individual appliances into the generator with heavy-duty outdoor extension cords. Never plug a generator into a wall outlet, and never run it in a garage or near a window.
Westinghouse iGen8200TFcBest overall
Westinghouse WGen11500TFcTri-fuel whole-house backup
Westinghouse WGen11500DFcDual-fuel big backupSafety rules to settle before you start
Most generator injuries come from three things: carbon monoxide (CO), electric shock and fire. CO is invisible and odorless, and a generator's exhaust can build it up in minutes inside a closed space. The rules below cover those risks.
Read your owner's manual too. It lists the exact clearances, fuel types and grounding steps for your unit.
- Run the generator outdoors only, never in a garage, basement, shed or under a porch, even with the door open.
- Keep it well away from the house, with the exhaust pointing away from windows, doors and vents. Many manuals call for at least 20 feet, so check yours.
- Place it on dry, level ground under a canopy built for generators. Never run it in rain or standing water without cover.
- Install battery-powered CO alarms on every level of the home and near sleeping areas.
- Let the engine cool before refueling, and store fuel in approved containers away from the generator and any flame.
- Wear hearing protection if you work near an open-frame unit for long stretches, since some models are loud.
Size the generator to what you want to run
Start by deciding what must stay on. A typical outage list includes the refrigerator, a few lights, a sump pump, the furnace fan or a window air conditioner, and phone chargers. Check the nameplate on each item for its running watts, and add them up.
Running watts are what the generator can hold for hours. Peak (starting) watts cover the short surge when a motor kicks on, such as a fridge compressor or sump pump. Choose a unit whose running watts cover your total, and keep the peak figure in mind for motor loads. Do not size by the peak number alone.
Our best generator page shows how the numbers vary. The Westinghouse iGen8200TFc lists 6600 running watts and 8200 peak watts on gasoline. The Westinghouse WGen 11500W Tri-Fuel lists 11500 running and 14500 peak watts. A bigger unit can carry more at once, but it weighs more too: 230 lb for the WGen 11500W versus 134.5 lb for the iGen8200TFc.
Three ways to connect a generator to a house
How you connect the generator matters as much as which one you own. Here is how the common methods compare.
The one method to rule out is a homemade cord with a plug on both ends. People sometimes call it "plugging a generator into the house." It energizes the home's wiring and can send power back out to the utility lines, which can seriously injure or kill line workers. It also creates a fire and shock risk inside your home.
| Method | What it powers | Install needed | Main caution |
|---|---|---|---|
| Transfer switch | Selected circuits from the panel | Licensed electrician | Match switch rating to the generator's outlet |
| Interlock kit | Panel circuits, one source at a time | Licensed electrician, often a permit | Follow the kit's breaker sequence exactly |
| Extension cords | Individual appliances | None | Cord gauge and length must suit each load |
| Dual-male "backfeed" cord | Whole house | Never do this | Backfeeds the grid and can cause fatal shock or fire |
How to use a transfer switch or interlock kit
A transfer switch or interlock kit lets the generator feed your home panel without any chance of power flowing back to the grid. Have a licensed electrician install it, and check local permit rules first. This is not a casual weekend wiring job.
Many home-backup generators include an outlet made for this setup. The Westinghouse iGen8200TFc lists a 120/240V 14-50R 50A outlet and describes itself as transfer switch or interlock kit ready. The Westinghouse WGen 11500W models list 50A and 30A outlets for the same purpose. The Generac 12500W Tri-Fuel lists both a 14-50R outlet and an L14-30R twist-lock outlet. Match the outlet on your generator to the inlet on your switch.
- Place the generator outside, well away from the house, and connect a power cord rated for its outlet to the home's inlet box.
- Turn off or unplug large loads in the house, and switch the main breaker off (for an interlock kit, follow the kit's steps).
- Start the generator and let it run for a minute or two until it settles.
- Move the transfer switch to generator power, or slide the interlock into place and turn on the generator breaker.
- Turn on circuits one at a time, starting with the biggest motor loads, such as the sump pump or well pump.
- When utility power returns, reverse the order: turn off circuits, switch back to utility power, then shut down the generator.
Using a generator without a transfer switch
If you have no switch, the simplest safe approach is to run appliances straight from the generator's own outlets. Put the generator outside, run cords to the refrigerator, a lamp or a space heater fan, and keep everything else unplugged.
Use outdoor-rated, heavy-gauge extension cords with a rating at or above the load they carry. Thin or very long cords overheat and lose power. Uncoil them fully, keep them out of puddles and doorways where they can be pinched, and never run them under rugs. Replace any cord with cracked insulation or bent prongs.
Check the plug type before you buy cords. A standard 120V duplex outlet suits lamps and small appliances. Larger loads may need the generator's 30A or 50A outlet and a cord made for it. Plug in GFCI-protected outlets for anything near damp ground when the unit provides them. Several models on our spec sheets list four GFCI outlets, for example, but confirm this for your own generator.
Bring cords inside through the narrowest gap you can, and keep that gap away from the exhaust. A better option for many homes is to add an inlet and switch later, so you are not threading cords through windows.
Pick a unit that fits the job
For whole-house backup through a switch, look for a 240V outlet, a CO shutoff sensor and enough running watts for your list. Our best generator page compares these specs side by side, including CO sensor listings and runtime at 25% load.
For smaller loads like lights, a fridge and electronics, an inverter model can be a better fit because it runs quieter and produces cleaner power. See our best power inverter generator page for options. The Westinghouse iGen8200TFc lists 60 dBA and less than 3% THD, which suits sensitive electronics, and it has a CO sensor. Fuel type matters too: tri-fuel models like the iGen8200TFc run on gasoline, propane or natural gas, which gives more choices in a long outage.
Running it day to day during an outage
Check oil and fuel before every start, and refill only when the engine is off and cool. Spilled fuel near a hot engine is a real fire risk.
Run the generator only as long as you need it and keep the load below its running watts. If it trips a breaker or the engine bogs down, switch something off instead of forcing it. Rotate loads: the fridge can run for stretches while you charge devices, then you switch to other items.
Check your CO alarm batteries regularly. If an alarm sounds, or anyone feels dizzy, nauseous or has a headache, move outside to fresh air and call emergency services. Shut the generator down only if you can do it safely from outside.
Frequently asked questions
Can I run my generator in the garage with the door open?
No. CO can still drift into the house and build up quickly. Keep the generator outdoors and away from openings.
Do I need a permit to install a transfer switch?
Often yes. Rules vary by city and county, so ask your local building department before work begins and use a licensed electrician.
How often should I test my generator?
Follow your manual, but running it under light load now and then helps catch problems before an outage. Always do this outdoors with a CO alarm in the home.
What is the difference between running watts and peak watts?
Running watts are the power the generator sustains. Peak watts are the brief surge it can deliver for motor startup.
Can a power inverter generator power a house?
Larger inverter models with a suitable outlet can feed a switch or interlock kit. Smaller ones fit best with individual appliances through cords.