Choosing the right generator for your home isn’t as simple as picking one off the hardware store floor. Master electrician Evan Jones of Merrimack (pictured), who’s also an Eversource customer, says, “As a residential electrical contractor for more than 15 years, I have seen some frightening DIY generator projects that expose the homeowners, their families, and the fine lineworkers at Eversource and other companies to significant danger.”

So how do you know what type of generator to buy and how to make sure it’s installed safely? Evan says there are four key questions to consider:

Why is connecting a generator an important part of my purchasing decision?

Before you go shopping for a generator, it’s important that you consider how you will connect it to your home safely. I can’t emphasize enough that wiring for a home generator of any type is serious business and requires professional installation. The risk of backfeeding (reversing the flow of electricity) and hurting a neighbor or lineman, or accidentally double-feeding your electrical panel, is simply too much liability.

Eversource Safety Senior Advisor Luke Bowley concurs: “If a generator backfeeds the line due to improper installation, that generator will effectively energize the main line at its primary voltage. This can be especially dangerous when wires are down, impacting not just our lineworkers but your neighbors and first responders as well. Unlike lineworkers, they don’t have the training or equipment to recognize energized wires before it’s too late.”

What are my options for safely connecting a generator?

You have two choices—an interlock or a transfer switch—and both are better and safer than making do with extension cords. Both are safe ways to accomplish the same thing, which is to choose what circuits, equipment or appliances you want your generator to power safely.

• An interlock connection gives you the freedom to switch your entire electrical panel over to the generator power. In the event of a power outage, the interlock physically forces you to turn off your main breaker first in order to activate the one or more switches dedicated to your generator. Once your home’s electrical power is back, you’ll need to shut off your generator and physically move the interlock back to its normal position to return to utility power. It’s a manual process but it can be hundreds of dollars less than a transfer switch, and you don’t have to choose in advance which of your home’s circuits can run on generator power.
• The main benefit of a transfer switch is that it will do the work for you. There are multiple brands and styles, but the principle is that instead of transferring the entire electrical panel to your generator, only selected critical circuits are transferred to be run by your generator. A transfer switch looks like a small electrical panel and automatically provides power to the appliances and rooms of your choice—either by the electrical power supplied to your home during a normal day or by switching to your generator during an outage. No matter which option you choose, it’s good to know that both a professionally installed mechanical interlock and transfer switch are intended to prevent backfeed and keep lineworkers and others safe.

What should I look for when shopping for a generator?

Home generators fall into two basic categories: portable and standby.

• A portable generator is perfect for homeowners who may lose power up to a couple of times a year, and who are likely to be home or nearby when it happens. A portable generator is about as easy to use as an average lawn mower, and setting it up for home use (once the connection system to your panel has been safely installed) is very simple. Be prepared to fill the generator with clean gas several times a day, depending upon usage. Some generators are dual fuel and can also run on the same style propane tanks that gas grills use. Consider purchasing a portable generator with a remote battery-powered electric start—it’s money well spent.
• A standby generator, also known as an automatic generator, is permanently installed and connected to the electrical panel and a fuel source—typically, propane or natural gas. Standby generators are perfect for the elderly, the handicapped, those who travel a lot, or those who can’t afford to have any downtime (for example, someone in the home is on life support, or there is a server in the home that will shut down an entire business). Standby generators, while much more expensive than portables, will add resale value to your home.

How do I know what size generator to get for my home?

This is very important to know before you walk into your favorite store. Your electrical contractor can help you make the decision that is best for you and your household, but the two key factors to consider are:

• What do I absolutely have to use? (Refrigerator, water pump, microwave and furnace come immediately to mind, and, of course, your coffee pot!)
• What do I want to be able to use? (for example, TV, lights, internet, kitchen appliances, air conditioner, laundry).

These are the main factors that will determine the size of your generator, as well as the size and style of your transfer switch. Don’t guess and wind up making the wrong purchase. Ask an electrical contractor or generator supplier to walk you through your options first.

Finally, for your safety, if you choose a portable generator, remember to locate it well away from your home to make sure exhaust cannot easily enter through windows or doorways. Generator exhaust contains carbon monoxide, a deadly poison you cannot see or smell. In addition, consider purchasing a generator tent or building a three-sided shelter to protect your generator from the elements and help keep it running smoothly, and to protect you from possible shock when standing on wet ground.