How Far Should a Generator Be From the House?

A portable generator belongs outside, more than 20 feet from the house and from its windows, doors and vents, with the exhaust pointed away. It never belongs in a garage, even with the door open, and a battery-powered or battery backup carbon monoxide alarm should be working in your home before you start it. Three federal agencies give that same number, though each words it a little differently.

Carbon monoxide is the reason for the distance. It is a colorless, odorless gas, so you will not notice it building up. The U.S. Consumer Product Safety Commission reports that more than 100 of the yearly U.S. deaths from carbon monoxide tied to consumer products are linked to portable generators.

Follow your local officials and your generator’s manual first. When in doubt, don’t run it, and if anyone feels sick, get outside and call 911.

What the agencies say about distance

The CDC’s carbon monoxide poisoning basics page names windows, doors and vents:

Only use generators outside, more than 20 feet away from any windows, doors, and vents.

Source: CDC, “Carbon Monoxide (CO) Poisoning Basics” (cdc.gov), accessed November 2026.

The CPSC’s carbon monoxide page measures from the home itself and adds the exhaust direction:

Never use portable generators inside homes or garages, even if doors and windows are open. Use generators outside only, at least 20 feet away from homes with exhaust facing away.

Source: CPSC, “Carbon Monoxide” (cpsc.gov), accessed November 2026.

Ready.gov’s power outage page lists attached garages and includes the fuel:

Generators and fuel should always be used outdoors and at least 20 feet away from windows, doors and attached garages.

Source: Ready.gov, “Power Outages” (ready.gov), accessed November 2026.

All three use 20 feet. The CPSC measures from homes, Ready.gov from windows, doors and attached garages, and the CDC from windows, doors and vents. The cautious reading takes all of them together: 20 feet from the house itself, which also clears every opening in it, with the exhaust facing the other way. The CDC’s wording is “more than” 20 feet, so treat 20 as the floor, not a mark to land on exactly.

How to pick the spot

Do this before the outage if you can, or while there is still daylight. A tape measure helps, though pacing it off works.

1. Find every opening on the outside of the house. Windows and doors are easy to spot. Also look for vents, such as a dryer, bathroom or crawl space vent, and for the garage door, since the CDC names vents and Ready.gov names attached garages.
2. Pick a spot more than 20 feet from the house itself. Measuring from the wall, as the CPSC’s “from homes” wording does, keeps you at least that far from every window, door and vent in it. If a neighbor’s house is close to your property line, keep the same distance from theirs.
3. Turn the generator so the exhaust faces away from the home, as the CPSC instructs. Distance alone is not enough if the exhaust points at a window.
4. Leave room around the generator. OSHA’s fact sheet on portable generators, written for workers but about the same equipment, says:

Make sure a generator has 3 to 4 feet of clear space on all sides and above it to ensure adequate ventilation.

Source: OSHA, “Using Portable Generators Safely” (osha.gov), accessed November 2026.

The same fact sheet sets a limit on the spot itself:

Do not use a generator outdoors if its placement near doors, windows, and vents could allow CO to enter and build up in occupied spaces.

Source: OSHA, “Using Portable Generators Safely” (osha.gov), accessed November 2026.

If you are still choosing a generator or a power station, the generator section of our binder resources covers what to look for.

If your yard is too small for 20 feet

Do not run the generator closer. None of the agency pages above gives a shorter distance, and the CDC’s wording is “more than 20 feet.” Closing windows, angling the exhaust or adding an alarm are extra precautions, and none of the sources offers them as a substitute for the distance.

Look for another spot on your property that does give you the room, even if it takes a longer cord. If there is no such spot, plan a different way through the outage instead of compromising on placement. Ready.gov points people to local officials:

Check with local officials about heating and cooling locations open near you.

Source: Ready.gov, “Power Outages” (ready.gov), accessed November 2026.

A warming or cooling location, or a stay with family who have power, may be the safer plan. Our guide on how to stay warm without power covers options for cold weather, and the hurricane preparation guide helps if the outage arrives with a storm and a decision about leaving.

Rain and wet ground

Water brings a shock risk on top of the exhaust. Ready.gov says:

Keep the generator dry and protected from rain or flooding. Touching a wet generator or devices connected to one can cause electrical shock.

Source: Ready.gov, “Power Outages” (ready.gov), accessed November 2026.

OSHA is more specific about the setup:

Keep a generator dry; do not use it in the rain or wet conditions. If needed, protect a generator with a canopy.

Source: OSHA, “Using Portable Generators Safely” (osha.gov), accessed November 2026.

Use ground fault circuit interrupters (GFCIs), especially where electrical equipment is used in or around wet or damp locations.

Source: OSHA, “Using Portable Generators Safely” (osha.gov), accessed November 2026.

A canopy does not change the placement rules. The generator still sits in your 20-foot spot, exhaust facing away, with its clear space around it, and bad weather is not a reason to move it closer to the house or into an enclosed space.

Alarms and symptoms

Set up your alarms before you start the generator. The CDC says:

When using a generator, use a battery-powered or battery backup CO detector in your home.

Source: CDC, “Carbon Monoxide (CO) Poisoning Basics” (cdc.gov), accessed November 2026.

The CPSC says where they go:

Install battery-operated CO alarms or CO alarms with battery backup on every level of the home and outside sleeping areas.

Source: CPSC, “Carbon Monoxide” (cpsc.gov), accessed November 2026.

Battery power matters because a plug-in alarm goes dark with the rest of the house during an outage. If you are shopping, the smoke and carbon monoxide alarm entry in our binder resources lists what to look for, our roundup of the best carbon monoxide detectors compares options, and our guide on what to do when a carbon monoxide alarm is beeping covers the moment one goes off.

The CPSC lists the symptoms and the response:

Know the symptoms of carbon monoxide poisoning: headache, dizziness, weakness, nausea, vomiting, sleepiness, and confusion. If you suspect CO poisoning, get outside to fresh air immediately, and then call 911.

Source: CPSC, “Carbon Monoxide” (cpsc.gov), accessed November 2026.

If anyone in the house has those symptoms while a generator is running, follow that order: outside first, then 911.

Cords, refueling and backfeeding

Ready.gov covers connecting and fueling:

Always connect the generator to appliances with heavy-duty extension cords.

Source: Ready.gov, “Power Outages” (ready.gov), accessed November 2026.

Let the generator cool before refueling. Fuel spilled on hot engine parts can ignite.

Source: Ready.gov, “Power Outages” (ready.gov), accessed November 2026.

Ready.gov’s distance line covers “generators and fuel,” so decide where the fuel will sit as well. Our guide to storing fuel for emergencies covers containers and storage.

Do not plug a generator into a wall outlet or tie it into the house wiring yourself. OSHA explains the danger to people working on the lines:

Attaching a generator directly to a building electrical system without a properly installed transfer switch can energize wiring systems for great distances. This creates a risk of electrocution for utility workers and others in the area.

Source: OSHA, “Using Portable Generators Safely” (osha.gov), accessed November 2026.

OSHA’s fact sheet says a generator should be connected to a structure only when a qualified electrician has installed it with a transfer switch. For the cords, fuel and controls of your particular unit, Ready.gov’s advice is to “Follow manufacturer’s instructions carefully.”

Portable versus permanently installed

Everything above is about portable generators, the kind you wheel out of a shed. A permanently installed standby generator has its own installation rules and clearances, and this article does not cover them. The installer, the unit’s manual and your local code set that distance.

Related questions

Two questions tend to follow placement. Will a generator hurt your electronics? Our guide on whether a generator can damage electronic devices covers what causes problems and what does not. If the outage comes at night, the guide to what to do during a power outage at night covers the parts that get harder in the dark.

Frequently asked questions

Can I run a generator in the garage with the door open?

No. The CDC and the CPSC both say never to use a generator inside a home or garage, even if doors and windows are open. OSHA lists garages, crawl spaces and basements as enclosed spaces where a generator should never run.

Is 10 feet from the house far enough?

No. The agencies say 20 feet, and the CDC says “more than 20 feet.” None of the sources allows a shorter distance.

How far should a generator be from a neighbor’s house?

Use the same distance. The CDC’s wording covers “any windows, doors, and vents,” so the cautious reading treats a neighbor’s house the same as yours, with the exhaust pointed away from both.

Do I need a carbon monoxide alarm if the generator is outside?

Yes. The CDC says to use a battery-powered or battery backup CO detector in your home whenever you use a generator. Good placement lowers the risk, and the alarm is your warning if something still goes wrong.

Can I cover a generator with a tarp while it runs?

The federal text we collected does not mention tarps, so we will not give a rule it does not support. OSHA does say to keep a generator dry, to protect it with a canopy if needed, and to keep 3 to 4 feet of clear space on all sides and above it. A covering that closes the generator in works against that clear space, so check your manual before improvising.

Can I measure from the wall instead of the window or door?

Yes, and it is the cautious choice. The CPSC measures from homes, and a spot more than 20 feet from the wall is also that far from every window, door and vent in it.

Keep the plan where you can find it

The spot, the cord length and the alarm locations are easier to settle on a calm day than during an outage. The Family Emergency Binder has a Power Outage page with the generator carbon monoxide steps, so the rules are on paper before the lights go out.