Generator carbon monoxide safety: how far from the house?
Short answer: Run a portable generator outdoors only, at least 20 feet from your home, with the engine exhaust pointed away from doors, windows and vents. Never run it in a garage, basement, crawlspace or shed, even with the doors open. Put battery-powered CO alarms on every level of the house.
Why this matters more than sizing
A small gasoline generator produces as much carbon monoxide as hundreds of idling cars. CO has no color or smell, and at the concentrations a generator in a garage produces, people lose consciousness before they notice symptoms. The Consumer Product Safety Commission counts dozens of deaths from portable generator CO every year, most of them after storms, when people run generators in garages and basements to keep them dry or out of sight.
The rules
- Outdoors only. Not in a garage, carport with walls, basement, crawlspace, shed or porch, and not with doors or windows open "for ventilation".
- At least 20 feet from the house, the distance the CPSC recommends, with the exhaust pointed away from the house and from your neighbors' homes.
- CO alarms with battery backup on every level and outside sleeping areas. Test them before storm season.
- Rain: use a generator tent or canopy designed for it, never an enclosure that traps exhaust.
Symptoms
Headache, dizziness, weakness, nausea and confusion — easily mistaken for flu or exhaustion. If anyone feels sick while a generator is running, get everyone into fresh air immediately and call 911. The CDC notes that people who are asleep or intoxicated can die before they have symptoms.
CO-sensing shutoff
Many portable generators sold in recent years include a CO sensor that shuts the engine off when CO builds up around it, and a voluntary safety standard (ANSI/PGMA G300) and UL 2201 set requirements for this. It is a valuable backup, not permission to run a generator anywhere closer to the house.
The other hazards
- Backfeeding through an outlet can kill line workers. Use an interlock or transfer switch.
- Refueling a hot generator can ignite gasoline. Shut it off and let it cool.
- Cords: use outdoor-rated, heavy-gauge cords without damage, sized for the load.
Safety. If a CO alarm sounds, leave the house and call 911 or the fire department from outside. Do not go back in until responders say it is safe.