How loud is a whole-home generator?

Generator makers publish sound levels on their spec sheets, usually in A-weighted decibels, dB(A), measured 23 feet (7 meters) from the unit. Here is what the current sheets say:

• Generac 26 kW Guardian: 67 dB(A) at normal load, 57 dB(A) in Quiet-Test low-speed exercise, per its spec sheet.
• Generac 20, 22 and 24 kW Guardian: 67 dB(A) at normal load; 55 or 57 dB(A) in Quiet-Test depending on the model, per the 20/22/24 kW sheet.
• Generac 10, 14 and 18 kW Guardian: 61, 65 and 65 dB(A) at normal load; 57, 55 and 55 in Quiet-Test, per the 10/14/18 kW sheet.
• Kohler 26RCA: 56 dB(A) during engine exercise and 67 dB(A) in normal operation and full-speed diagnostics, per its spec sheet.
• Kohler 20RCA: 66 dB(A) average during weekly exercise and 70 dB(A) in normal operation, per its spec sheet.
• Briggs and Stratton PP26: 62 dB(A) in low idle mode and 67 dB(A) in normal operation, per the PP26 sheet. Ask your installer at what distance that figure is measured.

For a reference point, the National Institute on Deafness and Other Communication Disorders lists normal conversation at 60 to 70 dBA. So at 23 feet, most of these units running a full house sound roughly like a conversation, and the self-test on several of them is quieter than that.

The big 22 to 26 kW units land within a few decibels of each other at normal load. Brand choice matters less for sound than where the unit sits and which way it faces.

Ask your installer for the sound sheet on each model quoted

Spec sheet numbers are real, but they are measured a particular way, and your yard is not a test site.

• Which side. Generac says its sound levels are taken from the front of the generator, and that levels from other sides may be higher depending on the installation.
• Which point. Kohler says its figures are the lowest of 8 points measured around the generator, and that other points may vary with the installation.
• How far. The 23 foot distance is a test standard. On a villa or a narrow side yard, the neighbor's bedroom window may be closer, and sound is louder up close.
• What is around it. A hard wall behind the unit can reflect sound. Open lawn and plants soften it. Two homes close together can funnel it.
• What else is running. During an outage, your generator is running the air conditioner, whose outdoor condenser makes its own noise, and the neighbors' units may be running too.

Because the brands measure differently, a 1 or 2 decibel difference on paper is not a reliable reason to choose one over another. Compare models by size, fuel use, warranty and service support first, then use sound to break a tie.

If noise is your main worry, ask the installer whether you can hear a running unit of the model you are considering, perhaps during a scheduled self-test at another customer's home or a showroom. Hearing it at the distance of your neighbor's window tells you more than any number.

Ask to hear the model you are considering

Most of the sound a generator makes in a normal year comes from its automatic self-test, called exercise. It keeps the engine lubricated and checks the system so it is ready for a real outage. You control when it happens.

• Generac. The 26 kW spec sheet says the unit exercises for 5 minutes every other week by default, with weekly or monthly settings available. The owner manual lets you set the day of the week and the hour and minute. In Quiet-Test mode the engine runs at operating speed for about five seconds, then drops to a lower speed for the rest of the five minutes. Loads do not transfer to the generator during exercise unless utility power is lost.
• Kohler. The owner manual describes an unloaded weekly exercise of 20 minutes with complete system diagnostics, and intervals of weekly or every two weeks. The 26RCA also offers EcoExercise, a 90 second unloaded run with diagnostics that Kohler says reduces fuel use and minimizes sound disruption.

Practical tips for picking the time:

• A weekday mid-morning, when most neighbors are out or awake, is a common choice.
• Avoid early mornings, evenings, and the times your neighbors are on their lanais.
• Avoid the time a neighbor's own generator exercises, so the street does not get two at once.
• If your unit has Wi-Fi, Generac notes the exercise timer adjusts for Daylight Saving Time on its own. Without it, the time resets when the battery is disconnected.

Ask your installer to set the exercise time with you at startup, and to show you how to change it.

Set the self-test time together at startup

The district ARC manuals say a permanently fixed generator's exhaust must be directed away from adjacent neighboring properties. It is listed with the other generator rules in the District 1 and District 8 manuals: rear or side placement, 2 feet from property lines, not visible from the street, and screening no taller than the unit.

That rule is about fumes, but it helps with sound too. The exhaust outlet is one of the louder parts of a running generator, and Kohler's owner manual notes that cooling air mixes with the engine exhaust and leaves through the exhaust outlet. Point that outlet toward open space, such as your own back lawn or a golf course edge, and less of the sound lands on the neighbor's wall.

On a typical lot the installer considers:

• Which side of the unit the exhaust leaves from, which varies by brand and model.
• Which way the unit can face while still meeting the manufacturer's clearances of 3 feet at the front and ends and 5 feet from windows and doors.
• Where the neighbors' windows, lanais and bedrooms are, not just the property line.
• Whether the unit can sit near your own air conditioner condenser, so equipment noise is grouped in one place.

The ARC application should show the exhaust direction on the site plan. Our ARC approval page covers what else goes in the packet.

Have the exhaust direction drawn on your site plan

Distance and orientation do most of the work. Screening helps a little, as long as it does not trap heat or break the clearance rules.

• Distance. Every extra foot between the generator and the neighbor's window helps. The ARC's 2 foot minimum from property lines is a floor, not a target.
• A fence, within the rules. The manuals allow a screening fence no taller than the generator. A solid fence between the unit and the neighbor can soften direct sound, and it also hides the unit from view as the ARC requires.
• Plants, with space. Landscaping can screen the unit, but Generac's guidance calls for 3 feet of clearance at the front and both ends, including trees, shrubs and bushes, and 5 feet of open space above. Plant beyond those lines.
• Never boxed in. Generators need airflow. Kohler warns not to block the cooling air inlets or mount anything above them. A tight enclosure can overheat the unit, which shuts it down when you need it most.
• Not under a deck. Generac says not to install a unit under a wooden deck or platform.
• Keep it clean. Generac's continuous-use guidance includes clearing the enclosure louvers at each daily stop on a long run. A clear unit runs cooler and more evenly.

Aftermarket sound kits and walls exist, but they have to meet the manufacturer's clearance and airflow requirements and the ARC's screening height. Ask your installer before adding anything around the unit.

Ask which screening fits your clearances

In a close-knit community, the best noise control is a conversation.

Before the install. Tell your neighbors what is coming, where it will sit, and when the self-test will run. Most people mind a five minute hum every other week far less when they know what it is and when to expect it.

After the install. Listen to your own self-test from the neighbor's side of the property line. If it seems loud, ask your installer whether the exercise mode or time can be adjusted. A change in how the unit sounds, such as a new rattle or a louder run, is also worth a service call. Generac's continuous-use guidance asks owners on long runs to stop every 24 hours to check oil and look over the unit, and that stop is a good moment to notice anything unusual.

During an outage. Context changes. When the whole street is dark and hot, a running generator is a reassuring sound to most people. A few habits keep it friendly:

• Check on neighbors, especially anyone on oxygen or living alone. The CDC advises checking on older adults at least twice a day in hot weather.
• Offer a cold drink or a place to charge a phone.
• Keep the unit maintained so it runs smoothly through a long outage. See our maintenance page.

A well-placed, well-kept generator is a good neighbor. One request gets you a free in-home estimate from a licensed local installer who will plan the placement with your street in mind.

Book a free estimate that plans for your neighbors