Generator safety: carbon monoxide and placement
A backup generator is a lifesaver used correctly and a killer used wrong. The single most important rule is about carbon monoxide.
The 20-foot rule
Run a portable generator outdoors only, at least 20 feet from the house, with the exhaust pointed away from any door, window, or vent. This is the consistent guidance from both the CPSC and CDC. Never run one in a garage, carport, porch, basement, or shed — opening the door does not help.
Why carbon monoxide is so dangerous
Carbon monoxide is odorless, colorless, and tasteless. A single portable generator can produce roughly 100 times the CO of a car engine (NIST). Symptoms — headache, dizziness, nausea, weakness, confusion — mimic the flu, so people often don't realize they're being poisoned until it's severe. The CPSC attributes about 100 deaths a year to generator CO.
Safety checklist
- Place the generator at least 20 feet away, exhaust pointed away from the home.
- Install battery-backup CO alarms on every level and outside sleeping areas; test monthly.
- Prefer a unit with an automatic CO shut-off sensor.
- Never refuel a hot or running generator; let it cool to avoid fire.
- Use a transfer switch or interlock — never "backfeed" power through a wall outlet.
- Keep it dry; use an approved generator cover/canopy in wet weather.
Common questions
How far should a generator be from the house?
Both the CPSC and CDC advise operating a portable generator outdoors only, at least 20 feet from the home, with exhaust directed away from doors, windows, and vents.
Can I run a generator in the garage with the door open?
No. CPSC guidance is explicit that an open garage, carport, porch, basement, or shed is not safe — opening doors or windows does not provide enough ventilation to prevent lethal carbon monoxide buildup.
How dangerous is generator carbon monoxide?
Very. NIST notes a portable generator can emit roughly 100 times more carbon monoxide than a car, and the CPSC estimates about 100 people die each year from CO poisoning associated with portable generators.
Sources
- U.S. CPSC — portable generator CO safety
- CDC — carbon monoxide poisoning prevention
- NIST — generator CO emission research
External figures attributed to the bodies above; wattage estimates on this site are typical planning values to verify against your equipment.