Call it foresight or whatever, but something told me to buy one of these when we were building our house back in 2003. It's powered by a 2.5 liter Ford engine that runs on natural gas piped directly from the Piedmont Natural Gas meter. We had this thing wired to both circuit breaker boxes and have an Eaton Cutler automatic transfer switch that handles the switching from Duke to generator when the power goes out and back to Duke when it comes back on. Although I'm capable of performing the maintenance on the engine portion of the unit, I let Clarke Power come to the house twice a year to do the PM's on it.
Only trouble we have ever had with it was a stuck thermostat one year and the starter went out on it last summer. The computer will shut the unit off automatically if it detects a problem with the engine. That time the thermostat got stuck, it was running it's weekly exercise program and the computer detected an increase in coolant temp and shut it down before the unit overheated.
I paid around $9K for it back in 2003. Of course that doesn't include installation and I'm not sure what that was since the installation, wiring and gas line install, was all integrated with the cost of building the house. But it's definitely a lot less expensive to plan for and install one of these while the house is being constructed vs. doing so after the fact.
This unit has paid for itself many times over the years. The longest it ran non-stop was when we had a two week power outage sometime shortly after we moved into the house back in the mid - 2000's. Purred like a kitten and the Piedmont gas bill only went up about $100.00 that month.
This is an internet picture but mine looks just like this one:
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