Written by Fran Donegan
Approaching bad weather always produces a run on certain items. Incoming blizzards empty stores of snow blowers; heat waves have air conditioners flying off of the shelves; the threat of power outages makes it difficult for retailers to keep portable generators in stock.
But many homeowners – especially those in parts of the country that have experienced storm-caused power outages – have started taking a closer look at permanent home generators. That’s with good reason: Power outages are not only inconvenient, but they also can be dangerous and expensive. An outage during cold weather can lead to frozen or burst water pipes. Houses that rely on sump pumps could experience flooding. And don’t forget about the perishable food stored in refrigerators and freezers that are out of commission during an outage.
Permanent generators, or standby generators, can avoid those problems. They provide electrical power to the entire house automatically. The generator package usually includes a generator to produce power that is installed outside of the house, and a transfer switch that is the interface between the generator and the home’s electrical service.
The scenario goes like this: When power is disrupted, the transfer switch disconnects the house from the electric grid and fires up the generator. In a matter of moments, the lights come back on, and all electrical systems are functioning. When power is restored, the generator shuts off, and the house is reconnected to the grid. The transfer switch separates the house from the grid, because any electricity generated by the generator could back feed to the utility lines, possibly harming anyone working on the lines.
Choosing the Right Size
Generators are rated by the number of watts they can produce. You can find small portable generators that produce only 1,000 or so watts, but whole-house standby generators start at about 6,000 watts and go up to about 22,000 watts and higher. Because 1,000 watts is one kilowatt (kW), electricians and generator manufacturers call a 20,000-watt generator a 20kW unit, a 22,000-watt generator a 22kW unit, and so on.
You can tally up your electrical needs to determine what size generator you will need, but most generator manufacturers have size calculators on their websites. The calculator will ask you the square footage of your house and the electrical appliances you have in your home. Homes with major electric appliances, such as electric water heaters, clothes dryers and stove ranges, will need more powerful generators. The generator dealer or installer can also help you pick a size.
You should also consider noise levels. Generators can be noisy, but thanks to the introduction of air-cooled engines, many newer models are quieter than those manufactured in the past.
Work with a Pro
Installing a standby generator is a major project, both in terms of cost and the amount of work required. Expect to pay between $8,000 to $12,000 for the installation of a 20kW or 22 kW model. And in addition to wiring the transfer switch to the service panel, you or your contractor will need to:
- Get a building permit
- Follow all setback laws in your town (Setbacks determine how close to the property line you can place a structure.)
- Be sure the outside generator is placed at least five feet from any house opening, including windows, doors, and even dryer vents
- Run buried cables from the generator to the electrical panel inside the house
- Install the generator on an approved gravel surface or a concrete pad
- Get the whole project inspected
Depending on the model, generators run on gasoline, propane, or natural gas. If you can hook up the generator to a gas line, it is worth the extra expense and effort, because you will never worry about the generator running out of fuel.
Though standby generators may seem like a luxury, they are worth the cost if you experience frequent power outages, or any outage that runs into days rather than hours.
Home-improvement expert Fran Donegan writes on heating systems, including furnaces, and home air quality issues, for Home Depot. Fran is the author of the home DIY books Pools and Spas and Paint Your Home. You can research Home Depot’s forced air furnace selection online.