How Whole-Home Generators Work

By David Fish, Owner & Lead Technician, TX Lic. TACLB99535E · Last updated July 2026

A whole-home generator is a permanently installed standby power plant that watches your utility feed, and when Oncor's grid power drops, an automatic transfer switch disconnects your home from the grid and starts the generator — typically restoring power in ten to thirty seconds without you touching anything. It runs on your home's natural gas line or a propane tank, so there are no extension cords, no gasoline runs, and no going outside in an ice storm.

What are the parts of a whole-home generator system?

Three components do the work. The generator itself — an engine spinning an alternator inside a weatherproof enclosure on a pad beside the house — produces the electricity. The automatic transfer switch (ATS), mounted at your electrical panel, is the brain: it senses the outage, commands the start, and switches your home's circuits from grid to generator. The switch also does the safety-critical job of isolating your home from the utility lines so your generator never backfeeds the grid and endangers line crews. The fuel supply — natural gas in most of our service area, propane where gas is not run — feeds the engine for as long as the outage lasts.

What happens during an actual outage?

The sequence is fully automatic. The ATS detects loss of utility voltage and waits a few seconds to ignore momentary flickers. It signals the generator to start; the engine cranks, comes up to speed, and stabilizes its output. The ATS then transfers your circuits to generator power — lights, refrigerators, and critically in Texas, the HVAC system come back on. When utility power returns and holds steady, the ATS transfers you back, and the generator runs a brief cool-down before shutting off. The generator also starts itself weekly for a short self-test, so problems surface on a calm Tuesday instead of during the storm.

Why do North Texas homes increasingly install them?

Because our outages come in both seasons and both are dangerous. Summer brings severe thunderstorms, straight-line winds, and grid strain during 100°F-plus stretches — and a house here without air conditioning in August becomes unsafe for kids, elderly family, and pets within hours. Winter brings the ice storms and generational events like the 2021 freeze, where homes lost power and heat for days and pipes burst across the metroplex. A standby generator sized to carry the HVAC turns both scenarios into a non-event. For estate properties in Westlake and Southlake, it has become a standard line item alongside the mechanical systems rather than an exotic add-on.

What are the failure modes of a neglected generator?

A generator is an engine, and engines that sit need care. The classic failures are a dead starting battery (the most common no-start cause), stale maintenance — oil, filters, and spark plugs that never get changed because the unit "never runs" — and gas supply problems, where an undersized gas line or low delivery pressure lets the engine start but stall under load. Placement matters too: clearances from windows and property lines are code requirements, and in HOA-governed neighborhoods the enclosure location needs approval before concrete is poured. All of these are preventable with correct installation and a maintenance schedule. Placement planning also includes sound: modern standby units are far quieter than portable generators, but they are not silent, and the weekly self-test should be scheduled for a weekday hour when it will not wake anyone — a detail worth deciding at installation rather than discovering the first Monday at 2 a.m.

What does a real installation involve?

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What should you do next?

Start with sizing — the single decision that determines cost, capability, and whether your AC actually runs during an outage. Our guide to what size whole-home generator you need walks through the load math in plain English. When you are ready for a site assessment, our Whole-Home Generators team handles the full scope — pad, gas, electrical, permits — including whole-home generators in Westlake, TX and whole-home generators in Colleyville, TX. Some efficiency-linked upgrades may also qualify for federal incentives — see federal tax credits for AC and heat pump upgrades for how those mechanics work.