Standby generator or portable generator with a transfer switch: which fits your house

A standby generator is a permanent unit on a pad beside the house, wired through an automatic transfer switch and fed from the gas line. When the grid drops, it starts, waits a few seconds to reach speed, and takes over the house. When power returns, it switches back and shuts down. It exercises itself weekly and needs an annual service.

A portable generator lives in the garage until it is needed. With a proper hookup, an inlet box on the outside wall and an interlock or manual transfer switch at the panel, it can power chosen circuits safely. Without that hookup it is a set of extension cords to a few appliances.

On natural gas, a standby generator runs for as long as the outage lasts, which matters in an ice storm when restoration can take days. On propane it runs as long as the tank allows. There is nothing to refill in the middle of the night.

A portable runs on gasoline, and a tank typically lasts hours, not days. That means refueling trips, stored fuel and someone awake to manage it. For a short summer outage that is fine. For a week-long ice storm, it becomes a real chore, and fuel can be hard to find.

A standby generator is the only option that works when nobody is home, which matters for pets, sump pumps, freezers and anyone who travels. It also removes the most dangerous part of generator use: running an engine near the house. Portables must run outdoors, well away from windows and doors, never in a garage, because of carbon monoxide.

The single most dangerous thing people do with portables is backfeeding the house through a dryer outlet with a double-ended cord. It can energize the utility line and endanger line workers, and it can destroy the generator when power returns. A proper inlet and interlock or transfer switch is the safe way.

A standby generator has manufacturer clearances from windows, doors, vents and the house wall, and local rules can add setbacks from property lines. Those clearances decide where the pad goes, which in turn affects the length of the gas line and the electrical run.

Noise varies by model and load. Standby units exercise briefly each week, usually at a time you choose. Portables are often louder and sit wherever the cord reaches, which is worth thinking about on a quiet street during a long outage.

Choose a standby generator if outages here have cost you before, if someone in the house depends on power for health reasons, if you travel, or if you want central air through a long outage. Choose a portable with a proper hookup if outages are occasional, you already own a generator, and someone will be home to run it. Many families start with a portable hookup and add a standby later; the transfer switch work is not wasted.