Home Generator Sizing

Determining Your Home Generator Needs

In order to power all the needs of your home, proper home generator sizing is essential in determining the size of generator that you need.

This is not a matter of "one size fits all."

Each appliance you want to operate has its own needs in terms of running and starting energy use. Before you buy a generator that is too small for what you want it to do, take the time to learn about generator sizing.

Under Sizing Symptoms

There are many symptoms that will let you know your generator cannot keep up with your energy needs, such as:

• Unreliable or sporadic performance
• Frequent unexplained shutdowns
• Complete system failure
• Shutdowns when additional appliances turn on
• Maintenance problems
• Shortened lifespan for your system
• Risks to you and your property

Figuring Load Demands

To figure out your load demands, list all the appliances you need to have running. This may include a refrigerator, a freezer, a well pump, washer and dryer, lamps, heater, stove, television, computers or any other electrical device.

If your generator is only for emergencies when your normal power source is out, think about the appliances that you absolutely must have running.

Make a list of the wattage needed for each device. Some appliances will have their wattage listed, others list their amperage.

If you see a number like 2.2 A or 2.2 amps, that is the amperage level. To calculate the amperage into watts, use the formula:

Volts x Amps = Watts.

For example, if your appliance uses 2.2 amps c 120 volts = 264 watts.

Remember that some large appliances like your stove, your washer and dryer, and so on, use 240 volts instead of 120 volts like lamps, radios and televisions. In order to accommodate this, look for a generator with a dual 120 and 240 output so all your needs can be met.

Starting Load Demands

Some appliances and other devices need more power when they first start than they use when they are running. This is known as the starting load demand. This is most common with pumps and motors.

The power use drops once the unit is operating normally. When you are figuring your home generator sizing, always count the starting watts, not the running watts or you will be under-sizing your generator needs.

Running Load Demands

This is the amount of watts needed if every item you want to run are running simultaneously. An AC digital meter will let you easily figure out your load demands. You could also use a generator sizing worksheet to figure out your generator needs. If you aren't sure that you can figure this out on your own, you can always hire a licensed electrician to give you an accurate measure of your energy needs.

Once you know your needs, you'll be able to make a better choice when you purchase a generator. In general, the larger a generator is, the more expensive it is. The larger it is, the more fuel it needs. Plan accordingly. You may find you are served better by using two smaller generators or some other combination.