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Generators are the most dangerous thing most households ever buy, and the danger is not electrical. It is an invisible, odourless exhaust gas that reaches lethal concentrations in minutes in a space you would describe as well ventilated.
Key figures
- 20 feet Minimum generator distance from the home, outdoors
- 430 Average yearly US deaths from accidental carbon-monoxide poisoning
The rule, in one sentence
The Consumer Product Safety Commission’s guidance is to operate generators outdoors only, at least 20 feet from homes and buildings, with exhaust directed away from windows, doors and vents.
Twenty feet is not a formality. It is the distance the agency identified as keeping exhaust from being drawn back into a building.
The places people think are fine and are not
- An attached garage, with the door open.
- A carport or covered porch.
- A shed or an outbuilding.
- A crawl space or basement.
- Just outside a window, including under it.
Opening doors and windows does not provide enough ventilation to prevent lethal build-up. This is the single most repeated point in CPSC’s warnings, because it is the mistake that recurs after every storm.
It has no smell, no colour and no taste, and the early symptoms, headache, dizziness, nausea and confusion, are exactly what a tired person in a cold house expects to feel anyway. The CDC recorded an average of about 430 unintentional carbon monoxide deaths a year, concentrated in winter.
What to look for when buying
CPSC recommends choosing a portable generator with a carbon monoxide shut-off safety feature, which turns the engine off automatically when CO builds up nearby. Models certified to PGMA G300-2023 or UL 2201-2023 include that technology.
Two notes on the state of the rules. These are voluntary industry standards, not a federal requirement: the CPSC has proposed a mandatory rule but it is still a proposal. And a shut-off is a backstop, not a licence: the distance rule applies to a generator with the feature exactly as it does to one without.
Alarms, which are the other half
Battery-operated or battery-backed CO alarms on every level of the home, especially outside sleeping areas, are what tell you the plan failed.
- Test them before storm season and replace batteries.
- Know the expiry date: CO alarm sensors wear out, usually after seven to ten years, and the date is printed on the unit.
- If an alarm sounds, get everyone outside into fresh air first, then call emergency services from outside. Do not stop to investigate.
Running it safely, beyond the distance
- Keep it dry. Run it on a dry surface under an open canopy if it is raining, never in an enclosed space.
- Let it cool before refuelling. Petrol on a hot engine is how generator fires start.
- Store fuel properly, in approved containers, away from living space and any pilot light.
- Never backfeed. Plugging a generator into a wall socket energises the neighbourhood wiring and can kill line workers. A transfer switch installed by an electrician is the correct way to power circuits.
- Plug appliances directly into the generator with heavy-duty outdoor rated cords, and check the cords for damage.
Related reading: When the Power Goes and a Device Keeps You Alive and Price Fridge Battery Backup With a Real Runtime Plan.
Questions people ask
How far should a generator be from the house?
At least 20 feet, outdoors, with the exhaust directed away from windows, doors and vents, according to CPSC guidance.
Can I run a generator in the garage with the door open?
No. CPSC is explicit that opening doors and windows does not prevent lethal carbon monoxide build-up. A garage is an enclosed space.
Do generators with CO shut-off make it safe to use one closer to the house?
No. The shut-off is a backstop for when something goes wrong. The 20-foot rule still applies.
What do I do if the CO alarm goes off?
Get everyone outside into fresh air immediately, then call emergency services from outside. Do not go back in to look for the source.
Where these figures come from
- CPSC Warns of Generator, Carbon Monoxide and Fire Hazards Ahead of Hurricane Season US Consumer Product Safety Commission · cpsc.gov
- Carbon Monoxide Information Center US Consumer Product Safety Commission · cpsc.gov
- QuickStats: Average Annual Number of Deaths and Death Rates from Unintentional, Non-Fire-Related Carbon Monoxide Poisoning Morbidity and Mortality Weekly Report, CDC · cdc.gov
Figures last checked September 2026.
