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Model # 40346
MSRP: $4,739.00
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20kW Standby Generator With 200 Amp Automatic Transfer Switch By Briggs and Stratton

  • Reliable Engine Power - Commercial Grade Vanguard Engines
  • Manage the loads of up to two air conditioners while powering other household appliances
  • ACCM Managed Whole House Power system
  • Includes 200 Amp Automatic Service Entrance Rated Transfer Switch Nema 3R, Indoor/Outdoor Rated
  • Rust-resistant, Galvanneal steel enclosures
  • Automatically powers your home in seconds after sensing a power outage
  • Thermally protected fuel system which automatically shuts off the unit in the event of a fire
  • Featuring unique airflow technology, the standby generator's design pushes engine exhaust out the front of the unit and directly away from the house
  • Front exhaust allows the generator to be placed as close as 18" from the home or other structures for custom placement
  • 4 Year Limited Parts and Labor Warranty


Details and Specifications

20kW Standby Generator With 200 Amp Automatic Transfer Switch By Briggs and Stratton

A standby generator from Briggs & Stratton provides your home with backup electrical power. The 40346 is a 20-kilowatt, air-cooled generator packaged with a 200-amp automatic transfer switch. Connected to your home's existing electrical system and gaseous fuel supply lines, the fully automatic generator system starts and runs automatically within seconds of a power outage, providing electrical power to keep families and homes safe.

Adherence to National Fire Protection Association safety rules and National Electrical Codes allow placement as close as 18 inches to a home, offering maximum installation flexibility, especially where lot lines are tight and yards are small. These standby generators carry a four-year, limited parts and labor warranty.


Briggs & Stratton powers the 40346 with its own popular and reliable Vanguard 993 cc V-Twin overhead valve engine. The electronic engine governor incorporated into the generator design keeps the Vanguard operating at a constant 3600 RPM, even under heavy and changing loads, to keep the AC signal constant at 60 hertz. The air cooled engine has a fully pressured lubrication system and oil cooler, with a low oil pressure sensor that allows engine shut down to prevent damage.


The 20kW standby unit is factory configured to run on natural gas, but converts easily to liquid petroleum gas (propane) during installation by simply turning a selector screw with an Allen wrench. Operating on LP gas provides up to 20 kW of power. At half-load, the engine consumes about 2.3 gallons of LP fuel per hour. Natural gas supplies up to 18 kW of power, and consumption runs about 83 cubic feet per hour at half load. Fuel consumption varies along with the electrical load and is affected by altitude and ambient temperature.

Backup Power

Standby generators are permanently installed appliances that operate automatically without intervention. A power outage is sensed immediately and after a short delay to prevent unnecessary starts during momentary outages, the engine is started and brought up to speed. The automatic transfer switch disconnects the home from the utility supply lines and connects it to the generator, effectively isolating the home from the electric utility.

The generator's controller continuously regulates the voltage and frequency to provide power that meets or exceeds electric-utility standards and is suitable for sensitive electronics in addition to lighting and appliance loads, including air conditioners.

Transfer Switch

The included 200-amp automatic transfer switch is a service entrance rated switch that includes the service disconnect. It installs indoors or outdoors and is typically placed between the electric utility meter and the main service panel. In this configuration, the switch controls the source of power to the main circuit breaker panel by selecting between utility power or generator power, which eliminates the need for additional subpanels and allows the generator to supply power throughout the home.

The air conditioning control module, or ACCM, allows the operation of two air conditioners. The ACCM "imprints" the starting current requirements of the air conditioners to prevent generator overload conditions and ensure the units only start when there is enough power available.


The addition of a load control center adds a managed power option which allows the generator to supply power to all your home's high-voltage, high current appliances including dryers, hot water heaters, and well pumps.

Maintenance kits include everything necessary to keep your generator running and supplying power, even through extended outages with oil and air filters, filler funnel, and spark plugs. Cold weather kits add two oil warmers and a battery warmer for easier and more reliable starts in cold weather down to -25 Fahrenheit.

Add a wireless monitor and keep track of your generator from indoors and eliminate trips outside during inclement weather.


The exterior cabinet is made from rustresistant Galvanneal steel and painted in a process similar to that used by the automotive industry for years of corrosion- free use. It rests on a prepared gravel bed or concrete pad, is 47 inches wide and 29 inches deep. At just 69db, the generator produces noise similar to a central air conditioning unit.

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Product Specifications

Model Number 40346
Manufacturer Briggs & Stratton
Rated Watts 20 LP/18 NG
Rated Amps 83.3 LP/75 NG
Voltage 120/240V Single Phase
A/C Ton Rating 2 - 5 Ton
Enclosure Galvanneal Steel
UL Listed UL 2200
Decibel Rating 69.1 dB(A)
Starting System Automatic
Low Oil Alert Yes
Hour Meter Yes
Battery Requirement Group 26, 12V, 540CCA
Mounting Pad Included
Product Weight 500 lbs.
Shipping Weight 643 lbs.
Dimensions (Inches) 48L x 34W x 31H (BASE 50.5 x 32.9)
Engine Brand Vanguard V-Twin
Engine Size 993cc
Engine RPM 3600 RPM
Cooling System Air Cooled
Alternator Type Brushed, Computer Friendly
Frequency 60 Hz
Auto Voltage Regulation Automatic
Fuel Type LP/NG
NG Power Capacity 18kW
LP Power Capacity 20kW
NG Consumption @ Full Load 260 cu.ft/hr
NG Consumption @ 1/2 Load 187 cu.ft/hr
LP Consumption @ Full Load 3.75 gal/hr
LP Consumption @ 1/2 Load 2.31 gal/hr
Transfer Switch
Transfer Switch Model 71046
Transfer Switch Amps 200 Amps
Transfer Switch Circuits Whole Panel
ATS Poles 2 Pole
Warranty Information
Consumer Warranty 4 Year/1600hrs Limited
Commercial Warranty None
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Product Reviews

  1. Best Purchase I have made

    Posted by Jon H on 30th Sep 2014

    I purchased the Briggs and Stratton 20kw generator Last June. When the Electrician installed the service he commented on how well this unit was built. He stated that usually the power lugs are plastic and he has a hard time with getting it wired in, but on this unit they were well made. In Nov at Thanksgiving the House next to me burnt down it messed up my Service. While they worked on repairing my service the House ran on my generator and I mean the whole house. I live in a area that has a lot of Oak trees and the limbs are always knocking down the power lines. Without hesitation the Generator starts and powers the house. I choose the Briggs based on all the generator service professional in my area recommendation, for easy to work on and maintain. Meaning parts are easy to get to saving time and money. Also the service from Norwall was second to none

  2. Excellent Generator and Great Service from Norwall

    Posted by RP on 18th Jun 2013

    I got it installed before the hurricane Sandy and it worked tirelessly for 10 days! Easy to service. Norwall delivered it on time.

  3. Excellent Generator

    Posted by Mark A. on 17th Nov 2012

    Had this installed in a new house I had built. Approx sq. ft. is 2700 with a 5 ton ac unit. 2 weeks after moving in we lost power and about 5 - 8 seconds later we had power from the generator. worked as advertised. As far as I'm concerned, it paid for itself already. Just having it on stand-by is great relief. I'd recommend this to anyone.

  4. Great Generator

    Posted by Nathan H on 11th Nov 2012

    Exactly what I expected, installation was straight forward and look forward to having plenty of power during next storm which may cause balckout in my area.

  5. 9 Days of Sandy's Torment

    Posted by A&J Electrical Inst., LLC on 8th Nov 2012

    This generator was installed in a home approximately 4K sf. Burned a little bit of oil.

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All generators include 24 hour delivery notification and residential delivery. Liftgate service is available on all air-cooled generators and some liquid cooled units – Please call for verification. Free Shipping is curbside service only. Curbside service means the freight company will deliver to your address and lower your generator to the ground. The freight company will not back down driveways, place a generator in a building or where it is being installed. You are responsible for arranging the movement and setting of the generator.

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