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12 kW 1 Fortress Standby Generator - Back-up power for small to medium sized homes

Briggs and Stratton 040579


  • Symphony II ®
  • Now 60% Quieter*
  • Streamlined, Space-Saving Design
  • Durable Enclosure

See More


Featuring a 10-year limited warranty including parts, labor and travel for all 10 years, this generator will be ready to run when it's needed most.

Symphony II ®
Thanks to Symphony® II Power Management System, a smaller home generator system by Briggs & Stratton can meet all your needs and save you money in the process.

Now 60% Quieter*
Powered by our high-quality Vanguard engine, improved muffler design and re-engineered alternator intake ducting, the new 12kW is 60% quieter than our old 12kW.

Streamlined, Space-Saving Design
With the streamlined, compact design, the new 12kW is 50% smaller than our previous 12kW generator.

Durable Enclosure
Designed to weather the elements, the system's enclosure is made from automotive-grade Galvanneal steel to resist rust. Its advanced powder coat paint process results in years of protection against chips and abrasions.

Flexible Placement 3
Have a tight lot line" Worried about your curb appeal" Install your generator as close as 18" from your home. Our generators are in compliance with the stringent National Fire Protection Agency 37 standard.

Superior Customer Support
Shopping for the right standby generator for your home can be confusing, but Briggs & Stratton will be with you every step of the way. Complete our web form below or visit the Customer Support portal to get your questions answered.

Financing Solution
We have partnered with Synchrony to provide financing solutions that fit your needs. Special financing* is available on qualified Briggs & Stratton Standby Generators on the Briggs & Stratton Standby Power Credit Card. *Subject to credit approval Minimum monthly payments required.

10 Year Parts, Labor & Travel Limited Warranty
Warranty included with the generator, a $995 value. Click here for details. 1 This 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). 2 See operator's manual or BRIGGSandSTRATTON.com for complete warranty details. 3 Installations 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.


  • Symphony II ®
  • Now 60% Quieter*
  • Streamlined, Space-Saving Design
  • Durable Enclosure
  • Flexible Placement 3
  • Superior Customer Support
  • Financing Solution
  • 10 Year Parts, Labor & Travel Limited Warranty
Model 040579
Running kW (NG)* 11,000
Running Amps (NG)* 45.8
Engine Displacement (cc) 627
NG Fuel Consumption at 50% Load** (BTU/hr) 50% Load 116.9 ft 3 /hr
Length (in) 28
Height (in) 37.2
Warranty (Product)*** 10 Year Parts, Labor & Travel Limited Warranty
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
Engine Series Vanguard
Alternator Type Computer Friendly
Running kW (LP)* 12,000
Running Amps (LP)* 50
Engine Brand Briggs & Stratton
Voltage (V) 120/240V AC, Single Phase, 1.0 pf
LP Fuel Consumption at 50% Load** (BTU/hr) 50% Load = 1.7 gal/hr
Width (in) 26
Weight (lbs) 318
Weekly Exerciser Yes
Operation Fully Automatic
Battery Charger Yes

Professional delivery and installation is available for every product we sell. We would be happy to coordinate delivery and installation for you.

Extended warranties are usually very inexpensive and can save you thousands in the future. It's simple and inexpensive to purchase extended warranties and one of the smartest ways to protect your investment.

Lawn equipment can be large, heavy and expensive. You probably don't have the special tools or expertise needed to fix them in a crisis. If you can spare a few thousand dollars without batting an eyelash for new lawn equipment should they break tomorrow, don't buy a warranty. But if you're like most of us, protect yourself by purchasing inexpensive extended warranties when you buy a new product and save yourself big money in the long run.