Get the right-sized generator for your needs.
Selecting the proper wattage of an electric generator involves more than simply adding up the wattage of the lights and appliances you want to power. Electric motors require extra power to start up. A sump pump, for example, may need more than 1,200 watts of power to start up, but only 800 or so to run afterwards. A furnace fan may need over 2,000 watts to start running, then drop to half that level. (Light bulbs, water heaters, radios and other motorless end uses have the same wattage requirements to start as to run.)

Some generators provide a few hundred watts of power, which severely limits what you can operate with them. Planning to run just a few large appliances or tools and some lights may require from 4,000 to 12,000 watts' total power from your generator, or more. Smaller generators cost less to buy, but may cost you a lot if you don't respect their limits. For example, if you have computers or other sensitive electronic equipment on-line when a device (a well pump or furnace fan, for example) needing extra start-up power kicks in, a generator without adequate reserve power may cause a drop in line voltage that can damage or destroy that other equipment.

Careful practice involves making sure that electrical devices are turned off before you connect them to a generator or generator-powered circuit. Once the generator is running, switch devices on one by one. Shut them down again before switching back to your utility service.

Read manufacturer's technical information carefully to ensure your generator won't be overwhelmed by start-up power needs or the total running load of the appliances or other uses you attach to it. In addition, if you plan to hook up larger appliances like ranges, well pumps, or dryers be sure your generator is rated for 240-volt as well as 120-volt loads.