12kW1 Standby Generator with 200 Amp Automatic Transfer Switch

Model Number: 040400

Turn on the performance with our new Briggs & Stratton 12kW1 home generator system. Its streamlined design meets the power needs of your whole house, with a more compact, affordable unit. The 12kW1 is ideal for medium-sized houses.

MSRP: 3,299.00

Learn more about this unit (PDF)

PlugPlugPlugManaged Whole House Power

Not all appliances are powered equally. Some, such as your central air conditioner, electric clothes dryer, electric stovetop, oven, or whirlpool tub, require a large amount of power to start up or operate properly.

The Symphony® II Power Management orchestrates these high-demand appliances with lower-demand items to give you true whole-house power with a smaller, more affordable generator.

Product Ratings

  • Did you know that each week, 3.5 million Americans will experience a power outage in their home? Watch this video to learn about the benefits of owning a standby generator!

  • More Access to Air Conditioners

    Briggs & Stratton automatic transfer switches can manage the load of up to two 4-ton air conditioners while powering other household appliances.

  • Streamlined Space Saving Design

    With the streamlined, compact design, the new 12 kW is 50% smaller than our previous 12kW generator.

  • Natural Gas Pressure Requirements

    Rated for operation in areas with low natural gas pressure. This standby generator can operate at 3.5'' to 7'' water column.

  • Durable Outdoor Enclosure

    Galvaneal steel provides years of rust proof, outdoor protection--perfect for extreme weather conditions.

  • Limited 3 Year Parts and Labor Warranty2

    Your Briggs & Stratton guarantee of quality and performance – one of the best in the industry.

  • Briggs & Stratton Engine

    Application-engineered to stringent specifications, these premium Briggs & Stratton engines will provide years of long-lasting, reliable standby power.

  • Turnkey Extras

    Systems include a battery charger, hour meter, and installation base.

1This generator is rated in accordance with UL (Underwriters Laboratories) 2200 (stationary engine generator assemblies) and CSA (Canadian Standards Association) standard C22.2 No. 100-04 (motors and generators).
2Warranty details available at
3Installations must strictly comply with all applicable codes, industry standards, laws, regulations and provided installation manual. Running engines give off carbon monoxide, an odorless, colorless, poisonous gas so it is important to keep exhaust gas away from any windows, doors, ventilation intakes or crawl spaces. The installation manual contains specific instructions related to generator placement in addition to NFPA 37, including the requirement that Carbon monoxide detectors be installed and maintained in your home.
4Review local codes to determine if a transfer switch with separate service entrance disconnect is required.
Not for prime power or use where standby systems are legally required, for serious life safety or health hazards, or where lack of power, hampers rescue or fire-fighting operations.

  • Have a question? Search our FAQs to find answers related to model specifications, routine maintenance, repair or troubleshooting. Search FAQs »

  • Find genuine Briggs & Stratton repair and/or maintenance parts for your engine or outdoor power equipment to ensure future performance. Purchase Parts »

12kW1 Standby Generator with 200 Amp Automatic Transfer Switch
Running Watts (LP) 12000
Running Watts (NG) 11000
Engine Brand Briggs & Stratton
Engine Series Professional Series™
CC 803
Operation Fully Automatic
Voltage (V) 120/240
Alternator Type Brushless, Computer-friendly
LP Fuel Consumption 1.42 gal/hr (LP) 119 ft3/hr (NG)
NG Fuel Consumption 2.36 gal/hr (LP) 197 ft3/hr (NG)
Weekly Exerciser Yes
Battery/Battery Charger Yes
Overcrank Protection Yes
Hour Meter Yes
Diagnostic Alerts with Remote System Status Low Oil Shutdown, Engine Does Not Start, Low Frequency, Engine Overspeed, Low Voltage, Low Battery Voltage, Oil Temp High, Transfer Switch Fault
Length (in) 34.6
Width (in) 39.4
Height (in) 38.5
Weight (lbs) 535
Warranty (Product) 3 Year Limited Parts and Labor
BTU's/Hour @ 1/2 load 102,000 (NG)
Enclosure Gray

*NG = Natural Gas; LP = Liquid Propane. **Fuel consumption rates are estimated based on normal operating conditions at 1/2 load. Generator operation may be greatly affected by elevation and the cycling operation of multiple electrical appliances - fuel flow rates may vary depending on these factors.

12kW1 Cold Weather Kit Ensures smooth starting and reliable operation in the winter months with the Briggs & Stratton™ Cold Weather kit. The thermostatically controlled battery warmer and oil heater activate as the temperature drops. Each kit includes a battery warmer and oil heater. View Generator Accessory
Maintenance Kit

Briggs & Stratton maintenance kits help you complete scheduled and preventative maintenance on your standby generator. The maintenance kit contains oil and air filters, synthetic oil and spark plugs.

12kW1 Remote System Status Panel

Receive diagnostic alerts from inside the comfort of your home from the hardwired panel. Alerts include: Low Oil Shutdown, Engine Does Not Start, Low Frequency, Engine Overspeed, Low Voltage, Low Battery Voltage, Oil Temp High, Transfer Switch Fault.

10-20kW1 Load Control Center

Used in addition to your transfer switch, this upgrade allows you to manage the power demands of multiple high wattage appliances, while the generator continues to power the essential loads throughout your home.

Dual 200A Symphony® II Transfer Switch

The Dual 200A Symphony® II Transfer Switch provides power to more of your household appliances. Featuring our patented Symphony® II Power Management, the 200 amp automatic transfer switch manages the load of 1 or 2 air conditioners while keeping household appliances powered. Flexible, indoor/outdoor transfer switch placement makes it …

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