A portable generator keeps essentials running in an outage, but its exhaust is one of the most dangerous things in a home during a storm. Almost every generator death is preventable with a few rules about where it runs and how it connects.
The CPSC reports about 85 deaths a year from carbon monoxide from portable generators. Run a generator outdoors only, at least 20 feet from the house, with the exhaust pointed away from doors, windows and vents; never in a garage, basement or crawl space, even with the door open. Keep battery-backed CO alarms working inside, and never plug a generator into a wall outlet.
Carbon monoxide
Generator exhaust contains carbon monoxide, a colorless, odorless gas that can kill within minutes at high concentrations. Opening doors or windows doesn't make an indoor or garage location safe. If you feel dizzy, sick or weak while a generator runs, get to fresh air immediately and call for help.
Recognize carbon monoxide poisoning
Early carbon monoxide symptoms mimic the flu: headache, dizziness, fatigue and nausea, per the CDC. Because the gas is colorless and odorless, people often blame a bug and lie down, then become too impaired to get out. Confusion, weakness and loss of consciousness follow as exposure continues.
Symptoms track both concentration and time. Sustained exposure around 70 parts per million (ppm) can bring on symptoms over a few hours, 150 ppm causes headache and nausea within hours, and 400 ppm produces serious symptoms within minutes, the thresholds documented under the UL 2034 alarm standard and in CPSC testing.
An engine running in an enclosed or partly enclosed space drives the concentration into that top band fast, which is why these deaths happen in minutes rather than hours. Twenty feet of open air between the generator and the house keeps the exhaust from reaching those levels indoors.
Placement
- Outdoors only, at least 20 feet from the house, as the CPSC advises.
- Exhaust pointed away from doors, windows and vents, including your neighbors'.
- Never in an enclosed or partly enclosed space: a garage, basement, crawl space, shed or porch.
CO alarms and CO-shutoff generators
Install battery-powered or battery-backup CO alarms on every level and outside sleeping areas, and test them before storm season; see the carbon monoxide detector guide. Some generators shut themselves off when carbon monoxide builds up around them, or emit less of it; when buying, look for one certified to a CO safety standard.
Connecting to the house
Never plug a generator into a household outlet to power the house. Backfeeding can energize utility lines, endangering line workers and neighbors, and can damage the generator and your wiring.
Connect through a transfer switch or a listed interlock installed by an electrician. See how many amps a generator produces for outlet and cord ratings.
Grounding and bonding
A portable generator is built with its neutral bonded to the frame, so the metal frame itself is the grounding reference. When you power equipment by plugging cords straight into the generator's own receptacles, that bonded frame is generally all the grounding the setup needs, and a separate driven ground rod is not usually required.
Grounding gets more involved only when the generator feeds the house through a transfer switch. Whether a ground rod applies then depends on how that switch handles the neutral, which is one more reason the transfer switch is an electrician's job. Follow your generator's manual and local electrical code, and let the installer match the grounding to the connection.
Cords
Use heavy-duty outdoor extension cords rated for the load, without cuts or damaged plugs, and keep them out of water and away from where people walk or drive.
Fueling and storage
Turn the generator off and let it cool before refueling; fuel spilled on hot engine parts can ignite. Store fuel in approved containers away from living areas and any flame.
Weather
Keep the generator dry. Run it on a dry surface under an open, canopy-like cover, never in standing water, and dry your hands before touching it.
Storm-season setup, before the power goes out
Do the setup while the power is still on, not in the dark during the storm.
- Have the transfer switch or interlock installed by an electrician now, so you are never tempted to backfeed a cord into an outlet mid-outage.
- Test every CO alarm and replace any unit that is past its rated life or signals end of life.
- Pick the run spot in advance: a firm, dry, open location at least 20 feet from the house, with the exhaust aimed away from every door, window and vent, including a neighbor's.
- Stage fuel safely in approved containers, stored away from living space and any flame or pilot light.
- Stage rated cords: heavy-duty outdoor extension cords sized for the load, with no cuts or damaged plugs.
During the outage, start and run the generator only in that outdoor spot, keep it dry, and shut it off to cool before every refuel.
Frequently asked questions
How far should a generator be from the house?
At least 20 feet, with the exhaust pointed away from doors, windows and vents, as the CPSC advises.
Can I run a generator in my garage with the door open?
No. Carbon monoxide can build up to deadly levels in a garage even with the door open.
Can I plug my generator into a wall outlet?
No. That backfeeds the house wiring and can energize utility lines. Use a transfer switch or interlock installed by an electrician.
Do I need a CO alarm if I use a generator?
Yes. Battery-powered or battery-backup CO alarms inside the home are essential whenever a generator runs nearby.
What are the symptoms of carbon monoxide poisoning?
Early signs are headache, dizziness, fatigue and nausea, which feel much like the flu, per the CDC. Confusion, weakness and loss of consciousness follow with continued exposure. If anyone feels these while a generator runs, get everyone to fresh air at once and call for help.
Does a portable generator need a ground rod?
Usually not. Portable generators have the neutral bonded to the frame, so cords plugged into the generator's own outlets are grounded through that frame without a separate rod. A separate grounding electrode may apply only when the unit feeds the house through a transfer switch, which is why that connection should be set up by an electrician following your manual and local code.
Can I run a generator under a canopy in the rain?
Yes, on a dry surface under an open, canopy-style cover made for generators, which keeps rain off while leaving all sides open for exhaust and airflow. Never run it in standing water or in an enclosed tent or box, and dry your hands before touching it. The canopy only handles weather; it does nothing to make carbon monoxide safe, so the 20-foot outdoor rule still applies.
Sources & References
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