Generator noise and neighbors: placement, campground rules and local limits

Run the generator outside, at least 20 feet from your home with the exhaust pointed away, because that is what carbon monoxide safety requires. Within that rule, you keep it quiet for neighbors by giving it as much open distance from them as your space allows, keeping the load light so the eco mode can slow the engine, and running it only in the hours your campground or town allows. In a national park, federal rules cap generator noise at 60 decibels on the A-weighted scale at 50 feet, and each park sets its own generator hours. At home, your city, county or HOA sets the rules.

The rest of this page explains each of those steps and where they come from. We have not measured any generator ourselves; every figure and rule below is quoted from the agency or maker that published it.

Safety comes before noise

Every quiet trick has to fit inside the carbon monoxide rules, so start there.

The CDC's generator fact sheet says: "Never use a generator inside your home or garage, even if doors and windows are open." It continues: "Only use generators outside, more than 20 feet away from your home, doors, and windows."

The Consumer Product Safety Commission puts it this way: "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."

Makers say the same in their manuals. Honda's EU1000i owner's manual tells owners to "Only run a generator OUTSIDE, far away from windows, doors, and vents with engine exhaust directed away from occupied structures", and to "Never operate a generator inside a house, garage, basement, crawl space, any type of vehicle, trailer, or boat, or any enclosed or partly enclosed space."

This matters for noise because the most tempting quiet fixes break these rules. Tucking a generator into a garage, a shed, a crawl space or a homemade box would muffle it, and every one of those is something the CDC, CPSC or Honda says never to do. Honda's manual is explicit: "Do not enclose the generator in any structure." Elsewhere it adds: "Do not enclose or cover the generator with boards or a tent, even when it is outside and away from of a building." It also says to keep the generator "at least 3 feet (1 meter) away from buildings" for fire safety, and not to "block intake or exhaust vents". So noise control happens with distance, direction, load and timing, never with walls around the machine.

What the figure on the box measures

Generator makers are unusual among appliance makers: several say how far away they measured. Two examples:

• Briggs & Stratton says it measures its PowerSmart and QuietPower inverter generators "running at ¼ load at 7 meters from the control panel side", and at that load and distance lists its P2200 at 59 dB(A).
• Champion lists its 2500-watt inverter at "53 dBA from 23 feet", without stating a load on that page.

Those two figures cannot be ranked against each other: one names a load and a side of the machine, the other names neither. The general problem of comparing figures taken under different conditions, and the difference between a reading at a distance and a sound power figure, are covered in why you cannot compare dB ratings across brands and sound power vs sound pressure. Our Honda generator decibels page lists each Honda figure with the load and distance Honda gives.

The key point for neighbors is that the box figure describes one spot, at one load. Your neighbor's bedroom window is a different spot, and your generator may not be at that load.

What distance does to the reading

The OSHA Technical Manual gives the rule for open space: "As a principle of physics, the sound pressure level decreases 6 dB, on a Z-weighted (i.e., unweighted) scale, each time the distance from the point source is doubled." That holds in what OSHA calls a free field, with no reflecting surfaces. OSHA adds that where surfaces reflect sound, it "decreases by less than 6 dB each time the distance from the sound source doubles."

For a generator, that has three practical consequences.

Doublings, not feet, are what count. Moving a generator from 20 feet to 40 feet from a listener is one doubling. Moving it from 100 feet to 120 feet is a small fraction of one. So the first stretch of distance does the most good, and it is worth using every bit of the space you have on the side away from your neighbors.

Walls give some of it back. A generator in a narrow side yard between two houses is in exactly the reflective kind of space OSHA describes, where the level falls off more slowly than the 6 dB rule. Open ground lets it fade faster.

A figure on the box is not a figure at the property line. Whatever distance the maker measured at, your neighbor hears the machine from wherever they are, through whatever is in between. A reading at 7 meters tells you nothing exact about what arrives at a window farther away, across a fence and between two walls. If you want to see what actually reaches a spot, our guide on how to measure noise at home explains how to take consistent readings with a phone and why they will not match the box.

Load changes the noise

Most inverter generators slow their engine when demand is light. The makers describe this in their own words:

• Honda's EU1000i manual says its Eco Throttle system "automatically reduces engine speed when loads are turned off or disconnected", and that the ON setting is "Recommended to minimize fuel consumption and further reduce noise levels when less than a full load is applied to the generator."
• Champion says its "smart Economy Mode" provides "quieter operation, extended engine life and better fuel economy."
• Briggs & Stratton says its PowerSmart mode "automatically adjusts engine speed to save fuel, run longer, and help keep sound levels as low as possible."

The flip side is in the same manual. Honda says that when appliances are turned on, "the engine returns to the proper speed to power the electrical load", and that with high loads connected at once, owners should turn the Eco Throttle off. So the quiet you get from eco mode depends on keeping the load light. In practice:

1. Turn eco mode on whenever the manual allows it.
2. Stagger big loads. Do not start the microwave, the kettle and an air conditioner together.
3. Run the loud jobs, such as charging large batteries or running a space heater, during the hours when noise matters least.
4. Choose a generator sized so that your usual load is well below its maximum. Our guides to the quietest generators for camping and RVs, quiet inverter generators under $1,000 and backup generators for a home note which load each published figure describes.

Placement at home

Here is a placement order that keeps carbon monoxide safety first.

1. Outside only, with the 20 foot rule as the minimum. Follow the CDC and CPSC distances above. Do not trade distance from your own house for distance from your neighbor's; if 20 feet from your house puts it close to their window, talk to them before the outage, not during it.
2. Exhaust away from every building. CPSC says exhaust facing away from homes; Honda says directed away from occupied structures. Think about your neighbor's house too, not only your own.
3. Open ground over narrow gaps. Per OSHA, reflective surfaces slow the drop in level. A spot in the open, away from both houses, is better for noise and for exhaust.
4. No enclosures. Honda says not to enclose the generator in any structure and not to block its vents.
5. Mind the wind. Honda's EU1000i manual says to "Place the generator so that the muffler is pointed in the same direction as the wind is blowing and the exhaust is directed away from buildings, other structures, or vehicles." Check your own manual's diagram for where the muffler is, and keep that end aimed away from windows on both properties.

Campground rules

National parks have a federal rule and park by park schedules.

The federal rule is 36 CFR 2.12. It prohibits "Operating motorized equipment or machinery such as an electric generating plant, motor vehicle, motorized toy, or an audio device, such as a radio, television set, tape deck or musical instrument, in a manner: (i) That exceeds a noise level of 60 decibels measured on the A-weighted scale at 50 feet; or, if below that level, nevertheless; (ii) makes noise which is unreasonable, considering the nature and purpose of the actor's conduct, location, time of day or night, purpose for which the area was established, impact on park users, and other factors that would govern the conduct of a reasonably prudent person under the circumstances."

Two things stand out. The limit is measured at 50 feet, which no generator figure we have seen uses. And the second clause means a generator under 60 decibels can still break the rule if it is unreasonable for the time and place. Our room by room page, how quiet is quiet enough, sets the 50 foot limit beside other official reference points.

Generator hours are set by each park, and sometimes by each campground within it. Three examples from the parks' own regulation pages:

• Yosemite: "Generator use is allowed only from 7 am to 9 am, noon to 2 pm, and 5 pm to 7 pm. Generator use is not allowed at other times." Quiet hours are 10 pm to 6 am.
• Zion: "Generators are not permitted in Watchman Campground." At South Campground or Lava Point Campground, generators may be used "only between the hours of 8 am - 10 am and 6 pm - 8 pm." Zion's page also says quiet hours "are enforced for people, pets, and property (like radios or generators)."
• Assateague Island: "Generator use during quiet hours is prohibited." It adds that "Generator use is prohibited in Bayside Loop B, Oceanside walk-in and group camping sites 24 hours a day", and repeats the federal limit: "Generator noise levels must not exceed 60 decibels at 50 feet as measured on the A-weighted scale."

The National Park Service's camping etiquette page adds a reminder that applies outside the listed hours too: "courtesy does not end when quiet hours do."

State parks, national forests and private campgrounds set their own rules, so read the rules for the specific campground before you pack the generator.

Local noise ordinances and HOAs

At home, generator noise usually falls under a city or county noise ordinance, and sometimes under homeowners association rules as well. The EPA notes that "State and local governments have acquired the responsibility of responding to many noise pollution matters." That is why there is no single national answer: ordinances differ in their limits, their quiet hours, where the level is measured and whether emergency power during an outage is treated differently.

Before you need the generator:

1. Find your city or county code online and search it for "noise" and "generator".
2. Read your HOA's rules if you have one; some address generators, fuel storage or equipment placement.
3. If you are considering a permanent unit, our guide to quiet home standby generators covers the weekly exercise run that neighbors hear most.
4. Talk to the neighbors whose windows face your planned spot.

We did not measure any generator for this page. Every figure, rule and quotation comes from the government agency, park or manufacturer named, and each source is listed on this page.