The basic sequence

A standby generator sits outside, permanently connected to a fuel source and wired into your home's electrical system through an automatic transfer switch. When utility power drops, the transfer switch detects the outage, signals the generator to start, and — once the generator is up and stable, usually within about 10–30 seconds — switches your home's circuits over to run on generator power.

Why the transfer switch matters

The transfer switch does more than just connect the generator. It physically disconnects your home from the utility grid before connecting the generator, which prevents backfeeding power into utility lines — a serious safety hazard for utility repair crews working on what they assume is a de-energized line.

Coming back to utility power

Once utility power is stable again, the transfer switch reverses the process: it disconnects the generator, reconnects the grid, and signals the generator to shut down after a short cool-down run. Most standby units also run a brief weekly self-test automatically, so problems tend to surface before an actual outage rather than during one.

Load management on smaller units

On a generator sized for essentials rather than whole-home coverage, some systems include load management modules that automatically shed lower-priority circuits (like an electric dryer) if a higher-priority appliance (like central air) needs to start, keeping total draw within the generator's capacity without you manually flipping breakers.

This is a useful feature to ask about specifically if you're sizing toward the smaller end of a coverage tier rather than a full whole-home system.