Say the power goes out on a freezing night, and you’ve got a generator ready to roll. This is exactly the moment when people make a mistake that can be deadly. Generators give off carbon monoxide (CO), a gas you can’t see or smell, and every year people get poisoned because a generator was running too close to a living space.
So what are the basics of generator carbon monoxide safety? Run it outdoors, far from the house, with the exhaust pointed away from windows, doors and vents, and keep working CO alarms inside. The rules are simple, and following them every single time is what keeps everyone safe.
Why is generator exhaust so dangerous?
Any engine that burns gasoline, propane or diesel makes carbon monoxide. A portable generator can put out CO at a much higher rate than a car, and in an enclosed space the gas can reach dangerous levels in minutes. Here’s the catch, though. It can also drift into your home through open doors, windows, vents and small gaps, even when the generator is outside.
Early symptoms of CO poisoning feel a lot like the flu: headache, dizziness, weakness, nausea or confusion. People who are asleep or intoxicated may never notice anything. If someone has these signs while a generator is running, get everyone outside into fresh air and call 911. Don’t go back in until emergency responders say it’s safe.
The core rules for running a generator safely
- Never run a generator indoors. That means garages, basements, crawl spaces, sheds and partly enclosed porches. Opening the garage door or turning on a fan doesn’t make it safe.
- Keep it well away from the house. A commonly cited guideline is at least 20 feet from the home, with the exhaust aimed away from windows, doors and vents. If your generator’s manual gives a longer distance, follow that one.
- Set it on level, dry ground. If it’s raining, use a proper cover made for generators. Never run one in standing water or unprotected rain, and never touch it with wet hands.
- Stay clear of open windows and air intakes, including your neighbor’s.
- Read the manual before the first storm, not during it, and learn where the shutoff is.
Why you need CO alarms inside your home
A generator parked outside is only half the plan. You also want working carbon monoxide alarms indoors as a backup. Put one on every level of your home and outside each sleeping area, and follow the maker’s placement advice. Test them monthly. Replace them on the schedule printed on the unit too, since the sensors wear out, commonly after about five to ten years.
Many alarms run on batteries, and some plug in with a battery backup, which matters during an outage. Like getting alerts on your phone when you’re away or asleep? Then smart smoke and carbon monoxide detectors are worth a look. If you’d like to compare even more models, we also have a roundup of smart smoke detectors with carbon monoxide sensing. Just remember that a smart alert only reaches you if your Wi-Fi is up, so make sure the alarm still sounds loudly on its own.
Fueling and operating it the safe way
Once the generator’s in the right spot, a few habits keep the rest of the job safe too.
- Turn the generator off and let it cool before you refuel, because gasoline spilled on a hot engine can ignite.
- Store fuel in approved containers, outside living spaces and away from anything that could ignite it, like water heaters and pilot lights.
- Use heavy-duty extension cords rated for outdoor use and for the load. Check them for fraying, and don’t run them under rugs.
- Don’t overload the generator. Add up the watts of what you plan to run and stay under the rating.
- Keep kids and pets away, since the engine and exhaust get very hot.
Why you shouldn’t wire a generator into your house yourself
Plugging a generator into a wall outlet with a homemade cord is called backfeeding, and it’s a serious hazard. It can send power back onto the grid and badly injure or even kill utility workers, and it can start fires in your own home. If you want to power your house circuits, a licensed electrician needs to install a transfer switch or interlock. Our article on safely connecting a portable generator to your house walks through your options in plain English.
Do generators with CO shutoff make a difference?
Some newer portable generators have built-in sensors that shut the engine off when CO builds up near the unit. That’s a handy extra layer of protection. It doesn’t replace the rules above, though. You still need to place the generator outdoors and far from the house, and you still need alarms inside. Shopping around? Our guide to portable generators with CO shutoff compares models that have this feature.
Want fewer risks? Think about the alternatives
Battery-based power stations and solar generators have no exhaust at all, so they don’t produce carbon monoxide. They can’t run everything for as long as a gas generator can. Still, for small needs like phones, lights, internet equipment or a medical device, they’re an option worth thinking about. To figure out what you’d actually need to power, our checklist on getting your home ready before the lights go out is a good place to begin.
Frequently asked questions
Can I run a generator in an open garage?
No. Carbon monoxide can still build up there and seep into the house. Always run the generator outdoors and far from the home.
Is a CO alarm enough on its own?
No. Alarms are your backup, not your main defense. The real protection is keeping the generator outside and away from the house.
What should I do if my CO alarm goes off?
Get everyone, pets included, outside right away and call 911 from outside. Don’t go back in until the home has been cleared.
The bottom line
Good generator carbon monoxide safety comes down to two habits: run it outdoors and far from the house, and keep working CO alarms inside. Those two steps prevent most generator poisonings, so check your alarms and your plan before the next outage.