Sizing a Generator
To figure out how big your generator's output needs to be, make a list of all the appliances you'll need during an outage and add up their surge watts—the amount of electricity a motor needs to start (see image 3). Add to this total the run watts for electrical items without motors, such as lightbulbs, water heaters, and television sets. To this sum add a 10 to 20 percent safety margin, then divide by 1,000 for the kilowatt rating you should look for in a generator.

According to Ron Ford, a sales manager at Kohler, this calculation ensures that a generator will be big enough to cope with emergency power demand while running at ½ to ¾ of its maximum load, which reduces fuel consumption and wear and tear on the engine (see image 2).

Generator Maintenance
A permanently installed generator is a bit like owning an extra car, although it should last considerably longer. The engines can run for 1,500 to 3,000 hours, which, considering the short length of most outages, amounts to a life span of about 15 to 20 years. To make sure the engine works when you need it, most installers offer annual service contracts ($200-$250) for changing the oil and air filter, checking the starter battery, and testing the system. Unlike cars, some generators automatically "exercise" themselves for a few minutes once a week to circulate oil and recharge the battery. (No power is fed to the house at those times.)

Other than size and price, some features to look for include:
•Electronic voltage regulator, to stop the fluctuations that can harm electronics.
•Ease of accessibility for maintenance.
•Weatherproof, insulated housing to dampen engine noise. "The smaller, 8.5- to 11-kw units are pretty quiet," Ford says. Bigger generators, he admits, are much noisier.

The noise and occasional oil change are only minor inconveniences to the Wymans. "We should have done this a long time ago," says Jasper. "Now, I'd be very uneasy without my generator."

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