Specialty · Franklin County & St. Louis, MO
When Ameren goes down — ice storms, summer thunderstorms, or a car in a pole — a standby generator kicks on automatically within seconds and keeps your HVAC, sump pump, fridge, and lights running until utility power is back. CAS Electric installs and wires whole-home standby generators across Franklin County and the Greater St. Louis area — Pacific, Washington, Union, Sullivan, St. Clair, Eureka, Wildwood, Villa Ridge, and Marthasville.
A standby generator is a permanent, hardwired backup power system. It sits on a pad outside your home, runs on natural gas or propane, and is wired through an automatic transfer switch (ATS) to your electrical panel. When utility power fails, the ATS senses the loss, starts the generator, waits about 10 seconds for it to stabilize, and transfers your home's load to generator power. When utility power returns, it transfers back and shuts the generator down. You don't have to do anything.
The most common sizes for homes in the St. Louis area are 14kW (essentials only — furnace, fridge, sump, some lights), 20–22kW (whole home with reasonable A/C management), and 24–26kW (whole home including large A/C without load management). We do a real on-site load calc to size the unit rather than guess.
We handle the electrical scope end-to-end: pad placement and prep, generator set, ATS install, panel tie-in, permit, and Ameren coordination. Gas line work is done by a licensed plumber (we can recommend one) and permitted separately.
Whole-home standby generator pricing depends on generator size, transfer switch type, and distance from the panel and gas meter. We provide a free written estimate. Gas line work is quoted separately by a licensed plumber.
We walk your home, look at your panel, and calculate the actual load. You get a flat quote for whole-home coverage or an essentials-only setup.
We recommend the right unit (typically 14kW–26kW for a home) based on your HVAC, well pump, and what you need running during an outage.
We pull the permit, set the pad, mount the generator, install the automatic transfer switch, and tie everything into your panel. Gas line coordinated with a licensed plumber.
We simulate an outage, verify transfer timing, walk you through the monitoring app, and get the final inspection signed off.
Cost depends on generator size, transfer switch type, and distance from the panel and gas meter. We provide a free written all-in estimate covering the generator, automatic transfer switch, pad, wiring, and permit. Gas line work is quoted separately by a licensed plumber.
For most St. Louis-area homes with central A/C, a well pump, and standard appliances, a 20–22kW unit covers the whole house comfortably. A 14–17kW unit is fine if you only need to run the essentials (fridge, sump, furnace, some lights). We do an actual load calc on-site.
Natural gas is usually the easier choice if your home is already on the Spire line — no tank to refill, unlimited runtime. Propane is the answer for rural Franklin County homes without gas service; a 500-gallon tank will typically run a generator for a week or more of outages.
Yes — every Franklin County and St. Louis-area jurisdiction requires an electrical permit for the transfer switch and panel tie-in, plus a mechanical/gas permit for the fuel line. We pull the electrical permit; the gas plumber pulls the gas permit.
Most residential installs are a 1–2 day electrical job plus a separate day for the gas plumber. Total elapsed time from contract to running is usually 3–6 weeks depending on generator availability and inspection scheduling.
Licensed, insured, owner-operated. We respond to all estimates within 1 business day.