Select the Right Portable Generator after a Disaster Select the Right Portable Generator after a Disaster Publication Number 490-303, August 1996 General Power outages can leave a home without power for lighting, cooking, refrigeration and pumping water. Portable generators can be bought to provide substitute power. However, the generator must be properly sized to start the appliances and equipment you want to run. Motor-driven appliances may be listed in horsepower which must be converted to watts.
Motors require four times as much power to start as they do to run.
If the running wattage of a motor is 400, then the starting wattage will be 1,600. The size of the generator you use must be such that it will start and run the necessary appliances. If you get a generator that is too small to run refrigerators and freezers, they will try to start, but the voltage will drop and their motors will overheat and burn out. To select the correct size generator, you decide if both refrigerator and freezer are to start at the same time. You would select the nearest larger wattage generator.