Many families today are interested in installing backup—or standby—whole-house generators to provide electricity during power outages.
Weather events that cause outages are becoming more frequent and intense. Our modern lifestyles are heavily dependent on electronic appliances, so it is a major inconvenience when they
A true whole-house generator produces enough electric output to operate every appliance in your home just as you would with power from your utility grid. Depending on the size of your house and family, a large standby generator and installation will cost thousands of dollars. It is a major expense for something you will not use often. Think of it like fire insurance. Hopefully you never have to use it.
Many families can get by with a smaller generator that provides enough power to run essential appliances, such as a refrigerator, some lighting, sump pump, etc.
If you use electricity for your primary source of heat and are concerned about
freezing pipes during a winter outage, you need a whole-house generator.
If you heat with gas, oil or propane, a smaller generator provides plenty of power for the blower and controls.
Most whole-house generators start automatically when power from the grid drops or stops. It takes less than a minute for the generator to start and have full electric power again. To ensure the system is ready and functioning properly for a future outage, the generator periodically starts to test itself.
It is important to install a transfer switch with a whole-house generator. This disconnects your house wiring from the utility grid before the generator starts. Most do this automatically. If it is not disconnected, your generator will feed 120-volt electricity back onto the grid, which can be dangerous for those repairing power lines.
The size of standby generator you select depends on how many items you want to operate during a power outage. A 15-kilowatt generator will handle a typical family’s power needs. If you are disciplined and will not run too many appliances simultaneously, a 10-kw model may be adequate.
When comparing generator sizes, the listed rated power output of any generator—from small portable to fixed whole-house—is the amount of wattage it can produce continuously. The maximum rated power is the amount it can produce for a maximum of about 30 minutes. Running at maximum output longer can damage the generator.
The first step to determine proper generator size is to add the wattages of all the electric items you think you need. The wattages of various appliances are listed on each appliance nameplate. Heating appliances usually use the most electricity, but they often cycle on and off from a thermostat. A heat pump or central air conditioner usually uses the most.
Many appliances with motors require greater starting wattages for a short period than the continuous use listed on the nameplate. For example, a refrigerator using 700 watts may require up to 1,500 watts each time the compressor starts.
If you choose a smaller portable gasoline generator and plan to use extension cords, read the manufacturer’s guideline for the proper gauge.
Natural gas, propane and diesel are the main fuels for standby generators. If available, most people select natural gas. Gas is relatively inexpensive, burns cleanly and does not require a storage tank. However, if there is a natural disaster, such as an earthquake, the gas supply may be interrupted.
Propane is another common fuel. It burns cleanly. Since the storage tank is on your property, the supply cannot be interrupted. Propane is more expensive than gas. It also requires an expensive storage tank, which may not look nice next to the generator.
Diesel-powered generators are less common. A major advantage is that diesel fuel is available at a gas station. It does not burn as cleanly as gas or propane, so it requires more maintenance. Diesel fuel has a shelf life of about two years, so you cannot just fill the tank and ignore it.