Can You Plug a Portable Generator Into Your House During an Outage?

Why the dryer outlet trick is dangerous

The idea sounds clever the first time you hear it. Buy a cord with a plug on each end, run it from the generator to the dryer outlet, and the whole panel comes alive. The outlet is wired to the panel, so power can flow in as easily as out.

That is the problem. The panel is also still connected to the meter and the wires leading away from the house. Idaho Power's Customer Requirements for Electric Service say a transfer switch prevents the generator from feeding back into its system and exposing workers to hazards they cannot foresee. A line crew in a February storm is working on wire it expects to be dead. Your generator can make that assumption wrong without you ever knowing.

It also leaves live metal in the open. A cord with a plug on each end has exposed prongs carrying full voltage as soon as one end is connected and the generator is running. And the generator can be damaged if utility power returns while it is still feeding the house, which is one more thing Idaho Power's requirements point out.

Turning off the main breaker is not the fix

The common wrong assumption is that shutting off the main breaker makes the dryer outlet method safe. It does separate the house from the utility, as long as somebody remembers to do it, does it first, and never turns it back on while the generator is running. Nothing in that arrangement stops a mistake. A family member resets the main because the lights came back next door, or someone checking the panel in the dark flips the wrong handle.

A transfer switch exists so that the separation does not depend on anyone's memory. Idaho Power requires a break-before-make switch for generators that provide backup power, meaning the house is disconnected from the utility before the generator is connected to it. It is built so both sources cannot feed the house at once. The main breaker and a note on the panel door are not the same thing.

What you can safely do with cords

Without a transfer switch, Idaho Power's outage FAQ says you may temporarily power an appliance by plugging it directly into the generator, as long as the total load stays under the generator's rating. That covers a refrigerator, a freezer, a few lamps, a phone charger and a space heater if the generator can carry it.

Add up the watts before you plug anything in, and use heavy-duty extension cords that are rated for the load and in good shape. Coiled, undersized cord gets hot. So does one pinched in a door or buried in snow.

Here is what cords will not do in a valley house. A furnace or boiler is usually hard-wired, so there is nothing to plug in. A well pump is typically on its own 240-volt circuit. Heat tape may be on a dedicated circuit too. Those are the loads that matter most in a January outage, and they are the reason people get tempted by the dryer outlet in the first place. Our guide to what to do when the power goes out covers the rest of the first hour.

What a transfer switch changes

A manual transfer switch is mounted next to the panel and feeds a set of circuits you choose ahead of time: furnace, well pump, refrigerator, heat tape, a few lights. An inlet box on the outside wall gives the generator a proper place to plug in. During an outage you start the generator outdoors, plug in one cord, and move the switch. The house is off the utility before the generator is on it.

Some electricians use an interlock on the main panel for the same purpose: a mechanical slide that makes it impossible to have the main breaker and the generator breaker on at the same time. Whether that is the right choice depends on your panel, so ask about it during the estimate.

One thing you should not buy is a device that goes in or behind the meter. Idaho Power does not allow customer-owned equipment between its meter and the meter base, and its requirements limit transfer devices at the meter base to specific sealed arrangements on the customer side. Anything sold as a plug-in meter adapter is not something to install on a house here.

Adding a transfer switch and an inlet is new wiring. Our guide to which jobs need a permit explains how electrical permits work with the state, and DOPL can answer for your specific job. Sizing the generator for the circuits you pick is part of the same conversation, and our generator installation page covers what we do.

Where the generator goes in a valley winter

Outdoors, always. Ready.gov says generators and fuel should be used at least 20 feet from windows, doors and attached garages. Idaho Power's outage guide warns that gasoline generators produce carbon monoxide that can be deadly, and says to run them in open areas, away from windows, doors and vents, protected from the weather.

Winter makes that harder. The temptation is to pull it into the garage or under the deck to get it out of the snow, and an open garage door is not enough. Pick the spot before the storm: a place 20 feet out, on packed ground, not under a roofline that sheds snow, with the exhaust pointed away from the house. In Ketchum and Sun Valley, where roofs dump heavy loads, look up before you set it down. Keep the exhaust clear of drifts, and shovel out around it as snow builds.

Make sure the carbon monoxide alarms inside have working batteries before you ever pull the starter cord. They are the backup for a mistake you do not see.

A portable generator will not protect an empty house

A portable generator needs somebody on site to carry it out, fuel it, start it and keep it running. That works for a family that lives in Hailey or Bellevue year round. It does nothing for a second home in Sun Valley when the owner is in another state and the caretaker is an hour away in a snowstorm.

If the point is to keep an unoccupied house from freezing, the answer is usually a permanently installed system that starts by itself. Our standby generator guide covers how those are sized and installed, and a solar and battery system is the other option if you already have panels or are considering them. Whichever way you go, someone local should get the outage alert.