Whole-House Generator Installation in O'Fallon, MO

Power outages in O'Fallon can last hours or days. A standby generator from ElectricSTL turns on automatically the moment Ameren cuts out — no extension cords, no manual starting, no food spoilage. We install Generac and Kohler whole-house generators throughout O'Fallon and St. Charles County, fully permitted.

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Why O'Fallon Homeowners Choose Standby Generators

Much of O'Fallon was built during St. Charles County's rapid growth from 1990 to 2015. As one of Missouri's fastest-growing cities, O'Fallon has a high concentration of newer homes with growing electrical loads from EVs and home additions. St. Louis storms — ice storms, severe thunderstorms, and the occasional tornado — can knock out power for days. A permanently installed standby generator means your heat, AC, refrigerator, sump pump, and medical equipment keep running automatically, regardless of what's happening outside.

Generac & Kohler Generator Installation in O'Fallon

We install Generac and Kohler standby generators — the two most reliable brands on the market. Both connect permanently to your natural gas or propane line, so there's no refueling. Sizing ranges from 11kW (essential circuits only) to 26kW+ (whole-house coverage). We size your generator based on a load calculation during the free estimate.

What's Included in Every O'Fallon Generator Installation

Every generator installation in O'Fallon includes: generator placement and pad installation, automatic transfer switch wiring, gas line connection (coordinated with Laclede Gas/Spire), all required St. Charles County permits, licensed inspection, and a startup walkthrough so you understand how the system works.

Generator Installation Cost in O'Fallon

A Generac or Kohler standby generator installed in O'Fallon typically costs $4,500–$12,000+ depending on generator size (11kW–26kW), transfer switch type, and gas line work required. We provide detailed, itemized estimates at no charge — call (314) 408-5647.

Common Questions

Generator FAQs for O'Fallon, MO

A whole-house standby generator installed in O'Fallon typically costs $4,500–$12,000+ depending on size (11kW–26kW) and gas line work. ElectricSTL provides free, detailed estimates.

A 14kW–20kW generator covers most O'Fallon homes including essentials plus central HVAC. Larger homes or homes with EV chargers may need 22kW–26kW. We size your generator based on a load calculation.

Yes. A standby generator monitors your utility power and starts automatically — typically within 10–20 seconds of an outage — without any action from you.

The generators we install run on natural gas or propane. Most O'Fallon homes on Laclede Gas/Spire have natural gas, which provides an unlimited fuel supply with no refueling required.

Yes. Generator installation requires both an electrical permit (for the transfer switch) and sometimes a gas permit. We pull all required permits and schedule inspections as part of every installation.