The 20/20/20 rule for generators is a portable generator safety guideline: keep the generator at least 20 feet from any door or window, pointed so exhaust faces away, and install a CO detector with a 20-minute low-battery backup minimum.
The rule exists because carbon monoxide from a running generator accumulates fast — levels can reach dangerous concentrations indoors within minutes if the unit is placed too close to the home. The 20-foot clearance is the CPSC's minimum recommended distance, not a suggestion. DuroStar generators with built-in CO Alert technology automatically shut down when carbon monoxide reaches a dangerous threshold, but that sensor is a last line of defense, not a substitute for the 20-foot placement standard.
- Minimum safe distance from doors and windows: 20 feet, per CPSC guidelines for portable generators.
- CO Alert on DuroStar DX and MX series models triggers automatic shutdown before CO reaches lethal indoor levels.
- CO poisoning from portable generators causes an estimated 70+ deaths per year in the U.S., according to CPSC data.
- The 20-minute CO detector battery backup requirement ensures the alarm functions during a power outage — the exact scenario when a generator is running.