Generator Safety Basics
The CDC's rule: run a generator outdoors, more than 20 feet from any window, door, or vent — never in a garage, basement, breezeway, or carport, even with the door open. Pair the distance with a battery-powered carbon monoxide alarm indoors as a backup, not a replacement.
The one thing to know: The CDC's rule, backed by CPSC/NIST/UL testing: run a generator outdoors, more than 20 feet from any window, door, or vent — never in a garage, basement, breezeway, or carport, even with the door open. Nearly half of non-fatal generator CO poisonings during hurricanes involved units running within 7 feet of the home. Pair distance with a battery-powered CO alarm indoors.
Why 20 feet specifically
The distance isn't an arbitrary round number — it comes from CDC testing conducted with the CPSC, NIST, and UL, which examined how carbon monoxide from generator exhaust travels and concentrates near a home. The CDC found nearly half of non-fatal CO poisonings during hurricane-related power outages involved generators running within just 7 feet of the home, well inside a safe margin, which is part of why the published recommendation sets the floor well beyond that at 20 feet.
What "outdoors" does not include
- Garages — even with the door fully open, CO can build up and drift into the home.
- Basements and crawl spaces — enclosed by definition, regardless of ventilation attempts.
- Breezeways, carports, and covered porches — partial enclosure is still enough to trap dangerous CO concentrations near doors and windows.
The backup layer: a CO alarm
Carbon monoxide is odorless and colorless, and early symptoms — headache, dizziness, nausea, confusion — mimic fatigue or the flu, which is why relying on how you feel is not a reliable warning system. A battery-powered CO alarm is the CDC's recommended companion to the distance rule: it catches the case where wind, nearby structures, or a mistake in setup bring exhaust closer than planned.
Practical gear for following the rule
Research-based picks (how we evaluate) — live Amazon search links, no prices or ratings, an honest drawback on each.
Kidde CO Alarm, Battery-Powered
Battery-powered carbon monoxide alarm, no wiring required
The CDC explicitly recommends a battery-backup CO alarm alongside — not instead of — the 20-foot generator distance rule.
Best for: Every household running a generator or using any combustion heat source indoors
Watch out: Battery CO alarms need their own battery checks; don't let this be the only thing you rely on if the generator is used incorrectly (indoors, in a garage, too close).
Check price on AmazonUS Wire 25-Foot 12-Gauge Outdoor Extension Cord
12-gauge, 25 ft, outdoor-rated, lighted ends
The practical tool that actually lets you keep a generator 20+ feet from the house while still reaching your appliances.
Best for: Meeting the CDC's 20-foot generator distance without daisy-chaining thin indoor cords
Watch out: Match gauge and length to your generator's rated load — an undersized cord for the distance/wattage can overheat.
Check price on AmazonOther generator safety basics
- Never run a generator indoors under any circumstances, including "just for a few minutes."
- Keep the generator dry and let it cool before refueling to avoid fire risk.
- Use a properly rated outdoor extension cord long enough to maintain real distance — don't run the generator closer just because a shorter cord is on hand.
Frequently Asked Questions
The CDC recommends more than 20 feet from any window, door, or vent, running outdoors only. Testing found nearly half of non-fatal carbon monoxide poisonings during hurricanes involved generators running within 7 feet of a home.
No. The CDC is explicit that generators should never run in a garage, basement, breezeway, carport, or other enclosed or partially enclosed space, even with doors and windows open — carbon monoxide can still build up to lethal levels.
Yes. The CDC recommends a battery-powered CO alarm as a companion to the distance rule, not a replacement for it. It's the backup in case wind direction, nearby structures, or an unnoticed mistake bring exhaust closer than planned.
No — CO is odorless and colorless, and early symptoms (headache, dizziness, nausea, confusion) resemble the flu or fatigue, which is part of why it's so dangerous. A working CO alarm is the reliable early-warning method, not symptom recognition alone.
Never run a generator indoors under any circumstances, keep it dry, let it cool before refueling, and use an appropriately rated outdoor extension cord long enough to maintain real distance rather than running the generator closer just to reach a shorter cord.