How far should a generator be from the house? Outdoors, at least 20 feet from windows, doors, and vents (CDC, Ready.gov). A NJ lineman on generator CO safety.
How far should a generator be from the house? A portable generator should run outdoors only, at least 20 feet from any window, door, vent, or attached garage, with the exhaust pointed away from the house. That is the CDC and Ready.gov guidance, and your generator manual may ask for more. Follow whichever number is bigger. Never run it in a garage, basement, crawlspace, shed, or enclosed porch, even with the door open. Put battery-backed carbon monoxide alarms on every level of the house before you need them.
The rest of this page is why that matters right after a storm, when people are tired and the cord only reaches so far.
I'm Mike, a union electrical lineman in New Jersey with 22+ years on the job. I've done mutual aid in multiple states over the years and seen the devastation Mother Nature brings. After storms I see the same setup mistakes on ordinary streets: machine under a bedroom window, garage door "cracked open," someone saying they will only run it for a minute.
If you can smell exhaust indoors, shut it down and fix placement. Smell is not a safe "detector." CO itself is colorless and odorless. Exhaust smell means the plume is already going the wrong way.
Storm cleanup is messy. People are tired, wet, and trying to save a freezer. The machine gets parked wherever the cord reaches. That is how exhaust ends up pointed at a window that was closed during the wind and then cracked for "fresh air."
An attached garage with the big door up is not outdoor space. It feeds living space through doors, duct leaks, and the wall itself. CDC, CPSC, and EPA all land on the same line: generators stay outside, far from openings.
Public safety floor: CDC says never run a generator less than 20 feet from any window, door, or vent. Ready.gov says outdoors and at least 20 feet from windows, doors, and attached garages. NFPA says to measure that 20 feet from the generator to the building.
That 20 feet is a floor, not a target. Your manual may add more. Follow both. Farther is better than cozy. Aim exhaust away from the structure and away from the neighbor's bedroom wall if houses sit close. Wind matters too: a spot that is fine on a calm afternoon can push exhaust at the house when the wind swings overnight.
A practical way to set it up before a storm:
Do not bury the unit under a tarp that traps exhaust. Use a rain cover built for your model, or a temporary shelter that leaves the exhaust and intake free. Wet machines and wet cords are shock hazards on top of the CO problem.
| Myth | Reality |
|---|---|
| "Door open = outdoors" | Still an enclosed or semi-enclosed space. CO builds and drifts inside. |
| "Just for a minute while I plug in" | Short runs still produce CO. People get hit while loading freezers and walking back through the door. |
| "I will smell it" | CO has no smell. Exhaust odor is a late, incomplete signal. |
| "CO alarm upstairs is enough" | Put alarms on every level, outside sleeping areas (CPSC home guidance). Test batteries. |
Fair question, and it deserves a straight answer.
First, the car is not safe there either. The CDC says never run a car or truck inside a garage attached to a house, even with the garage door open. A carport attached to the house puts the tailpipe against the house too. A car idling there without trouble is not proof the spot is safe.
Second, a generator puts out far more CO. U.S. cars started getting catalytic converters in 1975 to clean up exhaust, as CPSC staff noted in a 2006 briefing on portable generators, and a car's exhaust leaves through one fixed tailpipe. A typical portable generator engine does not have that kind of exhaust cleanup. CPSC's public warning puts it plainly: "One generator produces as much CO as hundreds of cars." If you are shopping, CPSC points to models with a CO shut-off feature, and UL 2201 certified models also have reduced CO emissions. Distance still applies.
Third, the exhaust does not stay put. A generator sits in one spot for hours under load, often overnight. The wind shifts and exhaust drifts into windows, doors, vents, and gaps around the house. Bath fans, the range hood, and the dryer push air out, and replacement air comes back in through whatever openings it finds.
That is why the number is 20 feet: the CDC says more than 20 feet from windows, doors, and vents, and Ready.gov says at least 20 feet from windows, doors, and attached garages. A 30 minute daytime test with a quiet alarm says little about hour nine at 2 a.m.
CDC lists the common symptoms of CO poisoning as headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion. They often get described as "flu-like." The tell is the pattern: several people (or the dog) feel off at the same time, and they feel better after time outside.
People who are asleep or drunk can die from CO before they ever notice symptoms. That is the whole reason the alarm matters more than how you feel.
If an alarm sounds or someone has those symptoms while a generator or any fuel-burning device is running:
Buy and install CO alarms on a calm week, not at 9 p.m. after the lights die. CPSC says to put battery-operated or battery-backup alarms on every level and outside sleeping areas, and to test them monthly. Replace units by the manufacturer date on the back. Smoke alarms are not CO alarms. You want both.
Plug-in CO alarms run on house power. When the power goes out, they switch to a backup battery, usually a 9V. That backup is meant to be short. Kidde's manual for its plug-in CO and gas combo alarm calls the 9V "short term back-up during a power outage," says to replace the battery if the alarm has been on backup for an extended period, and warns that the alarm will not detect CO once the battery is depleted. It gives no hour count, and real battery life varies by model and battery.
My planning assumption is that a plug-in alarm's 9V backup is measured in days, not weeks. That is a planning estimate, not a manufacturer spec. In a multi-day outage, it can run down during the same stretch the generator runs the most.
What to do:
Use outdoor-rated cords with the gauge matched to amperage and distance, and keep them out of standing water. Refuel after cooldown. Store fuel per local code, away from living space.
If the only place the cord reaches puts the generator under a bedroom window, change the cord, not the safety margin.
Cords to individual appliances are one thing. Tying a generator into your house wiring is another. If you connect a generator to the house, the main breaker on your panel has to be open first. Otherwise your generator's power goes back out through the service drop to the transformer and onto the lines, where it can hurt the lineman working to get you back on.
An electrician-installed transfer switch or interlock makes that automatic so you cannot forget. Never backfeed through a dryer outlet. I am not going to give wiring steps here: hire an electrician for anything that ties into your panel.
Be honest about needs versus wants. Needs: fridge and freezer cold, phones charged, internet a few hours a day, lights, and any medical device that has to stay up. Wants: the whole house running like nothing happened. Wants are where generators end up idling all night next to a bedroom.
At my house, an EcoFlow DELTA 3 Ultra stays indoors for the essentials: the internet and a few electronics. The freezers and the furnace run off a gas generator we keep outdoors. That split means the combustion machine does the heavy work outside, and the quiet indoor loads do not depend on it.
A power station like that keeps essentials running. It does not power a whole home, and it does not have to. If a battery station covers phones, a router, or a CPAP overnight, run the generator for the heavy stuff, then shut it down so exhaust is not running while people sleep.
Size the battery side with the power station runtime calculator. For the bigger decision, see generator vs power station and multi-day battery backup.
Ice storms and cold snaps bring the same bad setups: a generator under an eave for "cover" and combustion heat improvised indoors. For winter, read ice storm power, heat, and CO and indoor propane heater safety. The same CO alarm stack applies.
Outdoors and at least 20 feet from windows, doors, vents, and attached garages (CDC, Ready.gov). Follow your manual if it asks for more. Point exhaust away. If exhaust odor enters the house, shut down and move it farther.
No. Garages trap CO and feed living space. CDC guidance: never inside a home, basement, or garage, even with doors and windows open.
Yes. Outside placement fails when wind shifts, someone moves the machine closer, or a second combustion source (heater, vehicle) is in play. Alarms on every level, outside sleeping areas.
For quiet indoor loads, a battery station has no engine exhaust. It still needs honest watt-hour math. Use the runtime calculator. Heavy loads like freezers and a furnace may still need the outdoor generator.
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