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Can a portable generator run a whole house?

Updated September 18, 2026

It can run the parts of a house that matter in an outage, not the whole house at once. A long list of essentials adds up to about 4,400 running watts in our calculator, which a mid-size portable can cover. To feed house circuits you need a transfer switch or an interlock kit installed by a licensed electrician. Never plug a generator into a wall outlet.

What "the essentials" add up to

Take a refrigerator, a chest freezer, a furnace blower, a 1/2 HP sump pump, a microwave, LED lights, the TV and router, and chargers. Using the typical figures in the wattage calculator, that is 4,400 running watts and 5,900 starting watts. With headroom, look for about 5,500 running watts.

What is not on that list: central air, an electric water heater, an electric range and an electric dryer. These are 240 volt loads that can each use several thousand watts. Check their labels. A portable generator runs a house by taking turns. You run the essentials, and you switch a big load on only when there is room for it.

Which picks fit

• The Westinghouse WGen9500DF has 9,500 running watts on gas and 8,500 on propane, with both a 30 amp and a 50 amp 240 volt outlet. It covers the essentials list with room for one large load. The caveats: it is a 210 pound open-frame machine, and the listing we read did not mention a CO shutoff sensor.
• The Westinghouse WGen5300DFcv has 5,300 running watts on gas. That covers the 4,400 watts above but sits just under the 5,500 watt size tip, so you would manage loads by hand. It lists a CO shutoff. The caveat: on propane it drops to 4,800, and it is recoil start.

One detail to bring to your electrician: a 30 amp, 240 volt outlet can carry at most 30 x 240 = 7,200 watts. To use more of the WGen9500DF's output, the hookup has to use its 50 amp outlet. The other picks are on the roundup page.

How to connect a generator to a house safely

1. Transfer switch. A small panel next to your main panel. The electrician moves chosen circuits to it. Each circuit is fed from the utility or the generator, never both.
2. Interlock kit. A metal slide on your main panel that blocks the main breaker and the generator breaker from being on at the same time. It lets you pick any circuit, up to what the generator can carry. Not every panel or town allows one, so ask first.
3. Either way, the generator plugs into an inlet box on the outside wall with one heavy cord. The generator stays outside, 20 feet away.

The Red Cross says to have an electrician install a transfer switch that meets the National Electrical Code. Expect a permit in many places.

Without a transfer switch

You cannot safely power house wiring. You can still power things. Run outdoor-rated extension cords from the generator to the refrigerator, freezer, sump pump and a lamp. Anything wired in, like a furnace or a well pump, has to wait for the electrician. Plugging the generator into a wall or dryer outlet is called backfeeding. ESFI warns it can electrocute utility workers repairing the line. This page is general information, not electrical advice.

Sources

• Portable Generator Safety - Generate Safety - Electrical Safety Foundation International
• Generator Safety | Generator Safety Tips | Red Cross
• Carbon Monoxide | CPSC.gov