Portable generator safety: 20 feet from the house, exhaust pointed away, never in the garage

Why it’s so dangerous

Generator exhaust contains carbon monoxide (CO), a gas you can’t see or smell. CPSC says an average of nearly 100 people die in the U.S. each year from CO poisoning caused by portable generators, and that exposure can happen so fast that people pass out before they notice nausea, dizziness or weakness. Its hurricane season warning calls portable generators one of the leading causes of CO deaths after storms. [S1] [S2]

Inside a closed space, CPSC says a generator can build up high CO levels within minutes, and the gas can linger for hours after the engine shuts off. You can be exposed even when you don’t smell exhaust. [S3]

CDC lists the common symptoms as headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion, and warns that people who are asleep or drunk can die before they have any. For all unintentional CO poisoning not linked to fires, from any source, CDC counts more than 400 deaths, more than 100,000 emergency department visits and more than 14,000 hospital stays a year in the U.S. [S4]

Where the generator goes

• Outside only. Never run it inside a home, garage, basement, crawlspace, shed or other enclosed space. CPSC says opening doors or windows won’t provide enough ventilation, and the Red Cross adds that fans won’t prevent CO buildup either. NFPA says never in an attached garage, even with the door open. [S1] [S3] [S7] [S8]
• At least 20 feet away. CPSC says at least 20 feet from the house. NFPA says at least 20 feet from all doors, windows and vent openings, measured from the generator to the building. CDC says more than 20 feet from windows, doors and vents. [S1] [S2] [S4] [S7]
• Not on the porch or in the carport. CPSC says both are too close to the home. [S1]
• Exhaust aimed away. Point the exhaust away from your home and from other buildings’ entrances, and close windows and seal vents that are near the generator or in the path of its exhaust. [S1] [S2] [S7]
• Room to breathe. OSHA’s fact sheet asks for 3 to 4 feet of clear space on all sides and above the generator. [S9]
• Stay upwind. NFPA says not to stand or sit downwind of the exhaust: if you can smell it, you’re breathing it. [S7]

Distance check

Measure from the generator to the nearest door, window or vent of any building people use, yours or a neighbor’s.

Under 20 feet is too close by every source here. Exactly 20 feet meets the CPSC and NFPA wording (“at least”), but CDC says more than 20 feet, so a few more feet covers all of them. Distance alone isn’t the whole rule: the exhaust still needs to point away, and nearby windows should be closed. [S1] [S4] [S7]

Rain and snow

Wet weather is when people are tempted to pull a generator into the garage. Don’t. CPSC says to follow the manufacturer’s instructions for wet weather, which may include an NFPA-rated noncombustible generator tent, or may tell you to wait until the rain or snow passes. [S1] [S2]

CPSC’s safety alert says that if you must run it while it’s wet out, set it on a dry surface under an open, canopy-like structure where water can’t reach it or puddle or drain under it, still away from openings to the house. Dry your hands before touching it. Ready.gov adds that touching a wet generator, or devices plugged into one, can shock you. [S3] [S6]

Plugging things in

• Into the generator. Plug appliances straight into the generator, or use heavy-duty extension cords made for outdoor use. [S3] [S6] [S7] [S8]
• Rated for the load. CPSC says each cord’s wattage rating should exceed the total wattage of everything plugged into it. [S3] [S8]
• Three prongs, no damage. Check the whole cord for cuts or tears, and make sure the plug has all three prongs, especially the grounding pin. [S3] [S7] [S8] [S9]
• Long enough. The cord has to reach without pulling the generator closer to the house. CDC suggests a cord more than 20 feet long. If it runs through a window or doorway, protect it from being pinched or crushed. [S3] [S5]
• Ground-fault protection. OSHA recommends GFCIs, especially in wet or damp spots. Our GFCI guide covers how to test one. [S9]
• Don’t overload it. The Red Cross says even a properly connected generator can overload and overheat, so stagger the things you run. [S8] [S9]

Sizing, from the Red Cross: add up the watts on the appliance labels and the bulbs you want to run, then divide watts by volts to get amps. Pick a generator that makes more amps than that, since some machines draw up to 3 times as much power when they start. [S8]

Never plug it into a wall outlet

Plugging a generator into a wall outlet to power the house wiring is called backfeeding. CPSC says it puts utility workers and neighbors served by the same transformer at risk of electrocution, and it bypasses some of the house’s built-in circuit protection. OSHA says a generator attached to a building without a transfer switch can energize wiring for great distances. [S3] [S8] [S9]

If you want the generator to power house circuits, NFPA and the Red Cross say to have a qualified electrician install a properly rated transfer switch that meets the National Electrical Code and your state and local codes. [S7] [S8] [S9]

Fuel and refueling

• Off and cool first. Turn the generator off and let it cool before refueling. Fuel spilled on hot engine parts can ignite. [S3] [S6] [S7] [S8]
• The right container. Store fuel in a labeled container meant for it. CPSC says non-glass safety containers. [S3] [S7] [S8]
• Not in the house. Keep fuel outside living areas, and not near a fuel-burning appliance such as a gas water heater in a garage. OSHA adds to keep it away from heat sources, including the generator itself. [S3] [S8] [S9]
• Check local limits. The Red Cross says local laws may limit how much fuel you can store and where, so ask your fire department. [S8]

CO alarms and CO shut-off

CPSC asks for battery-operated CO alarms, or plug-in alarms with battery backup, on every level and outside sleeping areas. Interconnected alarms are best, because when one sounds they all do. Test them monthly. Its safety alert says to look for alarms certified to UL 2034, IAS 6-96 or CSA 6.19.01. CDC says to replace a detector when the manufacturer says to, or every 5 years. Our CO alarm guide covers placement. [S1] [S2] [S3] [S4]

If you’re choosing a generator, CPSC says to look for a CO shut-off feature, which turns the generator off when CO builds up nearby. It says models certified to PGMA G300-2023 or UL 2201-2023 include CO safety technology, and UL 2201 models also give off less CO. Every portable generator made or imported since May 14, 2007 has to carry a danger label. [S1] [S2] [S3]

What’s happening?

Pick the closest match to highlight what the sources say to do next.

Before the next outage

Run through this once, while the power is still on. Our emergency water guide covers the rest of an outage kit. Ready.gov says a closed refrigerator keeps food cold for about four hours and a full freezer for about 48. [S6]

Quick answers