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How much power do you really need? How to figure out which portable generator is right for you

Calculate the wattage you need to power what is most important to you.

GREENSBORO, N.C. — Whether it’s a hurricane, an ice storm, or even a wildfire, power outages seem to be happening more often and in more places. Maybe you’re thinking about buying a generator to keep the juice flowing. While a whole-house model can be very expensive, Consumer Reports says there’s a less pricey option to power just the essentials.

A transfer switch is like a mini circuit breaker panel that allows you to draw electricity from your generator instead of from the power company. An electrician can easily install it next to your breaker panel, and you pick which circuits you want to run through it.

On its own, a generator powers units that use a standard plug. But the transfer switch can power anything that’s hardwired into the circuit panel, such as a well pump, and anything requiring a 220- or 240-volt plug, like a dryer or an electric range.

Consumer Reports says to keep in mind that the generator must be at least 5,000 watts to easily connect to a transfer switch and to handle the load of several appliances. 

"And you want to make sure to get a generator that’s large enough to power all your essentials, but still the smallest model you can get away with because you’ll save a lot on gas," said Paul Hope of Consumer Reports.

2WTK looked to the Home Depot for guidance on how to choose a portable generator. This is from their page on how to calculate what wattage you need to cover:

Written out formulaically it's: 

(Running wattage x 3) + running wattage = Total wattage needed. 

Example: You want a generator that will run a small refrigerator.

Running Wattage = 350 watts

Starting Wattage: 350 x 3 = 1,050 watts

Total Wattage: 1,050 + 350 = 1400 watts

The total wattage you need to run a small refrigerator would be 1400 watts, so you would need a generator that provided at least that many watts. 

Tip: For best results, always use a generator that can comfortably handle all your power needs while using no more than 90 percent of its capacity. 

Plan to spend between $200 and $400 for an electrician to install the switch, plus upwards of $300 for parts. You’ll lose some of the convenience of a transfer switch but save hundreds on parts using an interlock device, installed directly on your circuit panel.

When the power goes out, you flip off the main switch with power from the street, slide the little interlock device up, and flip on the circuit breaker, which allows the generator to power any of the circuits on the main panel.

And Consumer Reports reminds us that to avoid exposure to deadly carbon monoxide, you should never run a generator in an enclosed space. Always place the generator at least 20 feet from the house, with the exhaust pointed away from the house.