How To Shop For A Standby Generator

by Michelle Ullman | Jan 4, 2013

If you live in an area plagued by frequent power outages due to natural disasters, nearby construction or a remote location, a standby generator can keep your electricity humming even when the power company cannot. Unlike a portable generator, a standby generator is permanently installed outside your house and is hooked into the natural gas or propane line.

Before setting out to purchase a standby generator, check with your local codes and ordinances department. Many cities have regulations regarding the installation, size and placement of standby generators, and you may need to apply for a permit.

Be aware that the installation of a standby generator normally requires the services of a plumber to connect the gas line and an electrician to connect the generator to your house’s electrical circuit. Additionally, the generator needs to sit on a level concrete pad, so if there is not a pad or patio in place already, that will be an additional expense.

How Much Power Do You Need?

Your number one question is how powerful of a generator you need. Standby generators come in a wide range of sizes, typically from 8kW to 20kW for residential use. Keep in mind that unless you live in a small house with little electrical demand, most standby generators will not power the entire home. In particular, you will need to decide whether you want a generator powerful enough to run your central air conditioning system, one of the most electricity-guzzling appliances in the average home.

Generators have two wattage ratings: the running wattage, which is how much energy the generator provides for continuous use, and a surge rating, which indicates how much excess demand the generator can handle when starting up an electrical appliance like a refrigerator or air conditioner. Make sure to choose a generator based on its running wattage. You can get an estimate of your wattage needs with an online wattage calculator. Check off the appliances you consider critical, such as lights, heater, refrigerator and sump pump, and you’ll get a rough estimate of how much wattage it will take to run those devices. Then look for a generator that can handle that load.

The higher the wattage of the generator, the more it will cost to purchase and to run. In an extended power outage, such as after a hurricane or other natural disaster, you might be without electricity for days or even weeks, so conserving your fuel supply is important. Run only the necessities while on generator power.

How Many Circuits Do You Want To Run?

Another way to size your generator is by determining the maximum amount of power your home can consume. You will see this on your main circuit breaker. The main breaker will be 100-amp, 150-amp or 200-amp. Large homes might even have a 400-amp main breaker. This is your home’s electrical limit. Depending on the wattage of the generator you choose, you will be able to run:

Generator Size	100-Amp Circuit	200-Amp Circuit
8kW generator	33% of the limit	Not recommended
10kW generator	42% of the limit	21% of the limit
15kW generator	58% of the limit	29% of the limit
17kW generator	71% of the limit	35% of the limit
20kW generator	83% of the limit	41% of the limit

Decide which appliances are critical to run, how many circuit breakers those appliances are on and then size your generator accordingly.

What About A Transfer Switch?

The transfer switch is the “brain” of your generator. It monitors the power coming into the house, and if the flow is interrupted for more than a few seconds, the transfer switch turns the home’s electrical circuit over to the generator.

An automatic transfer switch will do this on its own, as well as switch the electricity back to the home’s panel when energy is restored. A manual switch requires you to make the switchover. Automatic transfer switches are very common now, and most residential home standby generators come bundled with the appropriate size switch. Typically, the transfer switch matches the amps of the home’s main circuit breaker.

A generator without a transfer switch is very dangerous and illegal in many areas because without the switchover, electrical flow can back feed from your home into the public utility transformer, potentially injuring or electrocuting a power company worker.

How Much Does A Standby Generator Cost?

As a general rule, the more powerful the generator, the more it will cost. Expect to pay between $2,000 and $5,000 for a standby generator, and remember that you will probably need to pay both a plumber and an electrician for installation.

Home improvement centers like The Home Depot and Lowe’s carry a wide range of standby generators, and by taking your time to shop, you might be able to take advantage of a sale. However, be prepared with a vehicle that can transport it home safely. You can also buy standby generators online. Delivery charges may be high, as these generators weigh hundreds of pounds, but the convenience factor may be worth it.

Like most emergency equipment, a generator is something you don’t give a second thought until the lights go out. A standby generator can bring the lights back on in less than 15 seconds, a great comfort in a stressful situation. If you run a business from home, have a family member reliant on crucial medical devices, live in a remote area or one subject to hurricanes, a standby generator will keep your home humming even when the neighborhood is in the dark.