How to Safely Set Up a Generator

Gasoline-powered portable generators produce carbon monoxide gas and, if they’re used indoors or too close to your home, that odorless, colorless CO exhaust can be fatal. The CPSC found that from 2012 to 2022, generators alone were associated with roughly 750 non-fire CO poisoning deaths.

The only safe spot to operate a generator is outdoors, a minimum distance of 20 feet from your house. Direct the engine exhaust away from windows, doors, air conditioning units, or other structures, including garages and sheds. Don’t assume that opening your doors and windows makes it safe to place the generator any closer to your home. That’s not enough ventilation to protect you, the CPSC says.

Driveways, stone patios, and level patches of grass are all good places to put your generator. And if it’s raining or snowing, you’ll need to shield the generator with a generator tent or cover. You can find model-specific covers online, but it’s fine to grab a generic generator tent at a home center, too.

Do not place your generator in the following spaces:
• The garage, even if you leave the door open. Opening doors or windows won’t provide enough ventilation to prevent the buildup of lethal levels of CO.
• An outside porch or carport. The CPSC says that’s still too close to your home.
• The attic
• The basement
• A crawl space
• A shed, or any other building that a person or an animal could enter.

One of the easiest and most important safeguards, according to the CPSC, is to make sure you have working, battery-powered carbon monoxide detectors on each level of your home and outside bedroom areas. (Electricity-powered models with a battery backup work well, too, in the event of an outage.) Test the devices monthly, and never ignore the alarm. If there’s a buildup of CO that eludes the sensors on the generator, the warning from an inexpensive stand-alone CO detector could be a lifesaver.

See our article on the best carbon monoxide detectors and information about how to buy the right CO detector for your home. And read more on how to use your generator safely.

Without a transfer switch, you can only use a portable generator’s built-in outlets, which can power some appliances and electronics through an extension cord (for more, see below). That means you won’t be able to power hardwired appliances such as a furnace, central air conditioner, or well pump. For those, you’ll need a transfer switch.

To make sure your generator can handle the appliances you want to power, check our interactive guide. Keep in mind that some appliances, like refrigerators, turn on and off during operation or use variable power that may cause temporary surges, so you’ll need to account for this additional peak power demand to keep all your devices running smoothly.

Extension cords can pose hazards, particularly if used outdoors or to carry the load of high-wattage appliances. For maximum safety, check the owner’s manual for each appliance you need to power to see which gauge (thickness) of cord it recommends. Make sure that the cords you use are rated for indoor and outdoor use. Check the cord labels for the maximum wattage that they’re safely rated to carry. Then make sure those ratings match the ratings of the appliances you plan to power.

Use the thickest extension cords for the appliances that draw the most current—such as portable heaters or large window air conditioners, says Paolo Fu, who leads generator testing for Consumer Reports. Thicker extension cords—that is, cords with lower gauge numbers—can handle more current. Devote higher-gauge (thinner) cords to devices that draw less current, like a laptop or a small lamp.

For large appliances like a refrigerator or window air conditioner, use one extension cord and one generator outlet, Fu recommends. For smaller appliances and electronics, like the light by your bedside and your phone or computer charger, you can get away with using a power strip attached to the extension cord from the generator outlet. Make sure the power strip has a surge protector for sensitive machines, such as computers or medical equipment, as voltage can fluctuate depending on the generator and its operating conditions.

While CR doesn’t recommend connecting multiple extension cords in a series to get the length you need, if you do, make sure they’re of the same gauge. If you put two cords together of different gauges, you’ll only get the capability of the lower gauge cord. Keep in mind that creating a "daisy chain" of multiple extension cords can be a potential fire or trip hazard.

Be aware that the farther from the power source you go—when you use longer power cords—voltage drop could be an issue for the items you want to power. But don’t be tempted to place the generator closer to the house than the 20 feet the CPSC recommends, and be mindful that you won’t be able to power everything with a portable generator. "Make sure you only hook up things that are necessities in an emergency," Fu says.

Don’t run extension cords under rugs or allow them to become pinched in windows or doors. Use a rubber doorstop to prevent doors from closing all the way and crimping the cords.

Portable generators run on gasoline, and most can hold a maximum of about 8 gallons. Stock up on gasoline and store it in ANSI-approved containers, which have special pressure-relieving mechanisms. Mix the gas with fuel stabilizer and store it outside the house.

Note that powering a generator takes a lot more fuel than, say, a lawn mower. The top-rated Predator 10,000-watt 72624 is a standard generator with a 10-gallon tank and a run time ranging from 13 to 21 hours. That means running it for two days straight could take more than 30 gallons of gasoline. That’s six large 5-gallon containers.

Never fill a generator while it’s running. The National Fire Protection Association warns that if you accidentally spill gasoline on the generator’s hot muffler, it could ignite.

If you’re shopping for a new portable generator, consider a model that can also run on propane, like the DuroMax XP10000HX, which gives you additional options for powering your generator. There are also conversion kits for other models that allow you to use either propane or natural gas, but installing the kit is a project that takes real DIY skill or professional help.

"Make sure to start your generator before you need it to ensure that it is working properly," says Fu. "You don’t want to be stuck with no power and no generator."

In particular, if you’re pulling a generator from storage that hasn’t been used in a while, make sure to give it the maintenance it needs so that it starts. Maintenance steps may include changing the oil and spark plug after a certain amount of run time, checking the starter battery (if the generator has an electric start button), and making sure it has been drained of gas before storage, says Fu.

Following the proper storage and maintenance steps for your generator helps ensure it works when you need it. You don’t want to be stuck before a storm with a generator that has bad gas, a bad spark plug, low to no oil, or a bad electric starter. Instructions for maintenance and preparation for long-term storage can be found in your user manual.

You can also check out our video on generator maintenance. Each step ensures your generator starts up the next time you need it and helps extend your generator’s lifespan.