Backup generator equipment

The generator. Portables and inverter units are gasoline or propane and typically run 6 to 16 hours per fill. Inverter models produce cleaner power that's easier on electronics and run quieter. Standby units are permanently installed and run on natural gas, propane or diesel with no refueling if they're on a service line.

The automatic transfer switch. It detects the outage, disconnects your house from the utility, starts the generator, and reverses all of that when the grid comes back. It comes in different amperages, and matching it to the generator and your service is part of the design work. Bob Vila's guidance is that only a licensed electrician should install it.

Distribution hardware. Many installs add a subpanel ($530–$2,000) so the backed-up circuits are grouped together, or a dedicated circuit ($500–$1,000) for a specific load. Ask which circuits land on the generator side and get that list in the contract.

Siting hardware. Most standby units sit on a concrete pad — roughly $50–$75 per square foot — and Bob Vila's installation guidance notes the generator must be at least 5 feet from windows, doors and soffit vents. Manufacturer clearances vary by model, so the installer should be working from the specific unit's manual, not a rule of thumb.

How to choose

Match the switch amperage to the design, not the price sheet

An undersized or wrongly configured transfer switch is the most common source of "the generator runs but nothing works."

Ask to see the manufacturer clearance page

Bob Vila cites a minimum 5 feet from windows, doors and soffit vents for standby units, but each model's manual sets its own required clearances. Your installer should show you the page.

Decide the backed-up circuit list yourself

This is the one design decision homeowners can meaningfully own. Walk the panel with the installer and mark them.

Buy CO alarms as part of the project

Ready.gov recommends working CO detectors with battery backup on every level of the home. They belong in the budget line, not the someday list.

Inverter for electronics, standard for tools

If a portable's main job is running a computer, a medical device or a modern fridge, the cleaner output of an inverter model is worth the premium.