How to plan safe generator use before an outage
For portable generator safety, run the generator only outdoors, at least 20 feet from the house, with the exhaust pointing away from doors, windows and vents. Buy a model with automatic CO shut-off. Power your home's circuits only through a transfer switch or interlock fitted by a licensed electrician.
Portable generator safety features to buy first
Choose the safety feature first and the wattage second. CPSC's annual average for 2017 to 2019 was about 100 U.S. consumer deaths a year from generator carbon monoxide. It calls portable generators one of the leading causes of CO deaths after storms.
Look for a CO shut-off that stops the engine when the gas builds up nearby. CPSC names two certifications: PGMA G300-2023 and UL 2201-2023. UL 2201 models also put out less CO. In a 2024 release, CPSC said it estimated earlier certified designs would cut deaths by 87% (PGMA G300-2018) and 100% (UL 2201).
For size, Consumer Reports says you need at least 5,000 watts to connect to a transfer switch and run several appliances. Beyond that, buy the smallest unit that covers your essentials, because smaller models use less gas.
You also need:
- Heavy-duty extension cords rated for outdoor use, if you'll plug appliances in directly.
- Battery or battery-backup CO alarms on every level and outside sleeping areas.
- A transfer switch or interlock, if you want to run hardwired items like a well pump. A generator on its own only powers things with a standard plug.
Safe place to run a generator
Pick the spot now, in daylight, and mark it. It must be outdoors, at least 20 feet from the house and from any attached garage, with the exhaust aimed away from your home and your neighbor's. Close nearby windows and seal vent openings in the exhaust path.
These places are never safe, even with doors and windows open:
- Inside the house or basement
- The garage, shed or crawlspace
- A porch or carport
Plan for the weather too. Ready.gov says to keep the generator dry, since touching a wet unit or wet connected devices can cause shock. Follow the owner's manual for rain cover, so that you never pull it under a roofline or into the garage to stay dry.
Never plug a generator into a wall outlet or your panel without a transfer switch or interlock. Backfeeding this way can send power out to the utility lines, where it can injure line workers, and it can start a fire in your home. Treat any cord with a plug on both ends as a hazard.
How to make a portable generator safety plan
- Mark the outdoor spot
Measure 20 feet from the house and from any attached garage. Check that exhaust will blow away from doors, windows and vents.
- List your essentials
Write down what must run in an outage, such as the fridge, sump pump or medical devices. This sets the size you need.
- Buy a certified model
Look for CO shut-off and PGMA G300-2023 or UL 2201-2023 certification. Buy before storm season.
- Decide how you'll connect
Use heavy-duty extension cords for a few appliances, or get quotes from licensed electricians for a transfer switch or interlock.
- Check your alarms
Make sure CO and smoke alarms work on battery power. Test them monthly.
- Do a test run
Start the generator at the marked spot and run the cords. Let it cool fully before you store or refuel it.
- Teach the household
Agree that if a CO alarm sounds, everyone goes outside and calls 911.
Transfer switch for a portable generator: what it costs
| Item | About what it costs | What it covers |
|---|---|---|
| Manual transfer switch, installed | $400 to $1,300 | Angi range cited by The Pricer; more circuits and harder panel access push it up |
| Interlock work | $400 to $850 | HomeGuide range cited by The Pricer; a cheaper setup, less convenient |
| Electrician install (Consumer Reports) | $200 to $400, plus upwards of $300 for parts | One outlet's estimate, so get your own quotes |
| Permit | $80 to $450 | Local rules vary |
| Portable generator | Varies by watts and features | Compare models with CO shut-off |
Older wiring or a panel in poor shape can add to the bill, and an electrician may need to fix those first.
Portable generator safety mistakes
- Thinking an open garage door makes it safe. CPSC says opening doors and windows doesn't give enough ventilation.
- Refueling a hot engine. Let it cool first, because fuel on hot parts can ignite.
- Skipping test runs. Check and maintain the unit before storm season, following the manual.
- Ignoring early symptoms. Headache, dizziness or nausea during an outage could be CO. Get outside and call 911.
What homeowners say about generator carbon monoxide risks
Buy the generator before you need it, and a snow blower too if you get heavy snow. Owners say both are nearly impossible to find once a storm is in the forecast. (Reddit)
How far should a generator be from the house? More answers
How far should a generator be from the house?
CPSC says at least 20 feet, outdoors, with the exhaust pointing away from windows, doors and vents. Keep it away from attached garages as well.
Can I run a generator in the garage with the door open?
No. CPSC says never to run one in a garage, and opening doors or windows doesn't give enough ventilation. Porches and carports aren't safe either.
Do I need a transfer switch for a portable generator?
You need one, or an interlock, to power circuits in your panel. If you only plug in a few appliances with heavy-duty cords, you don't. Have a licensed electrician do any panel work and pull any required permit.
Sources: CPSC, Ready.gov, nbcdfw.com, thepricer.org
General guidance for U.S. homes, not professional advice. For gas, electrical and structural work, call a licensed pro.