DEAR TIM: Last year, we lost electric power to our home 3 times. One of the episodes cost us approximately $400 in spoiled food. Will a portable generator solve this problem? How do you size a generator? Can they be safely connected to the electric panel or do you have to use extension cords to power separate items? Will these generators supply sufficient power to run sensitive electronic equipment such as my computer? Doug Turner, Oregon

DEAR DOUG: Two years ago, the exact same thing happened to me. Last year, a summer storm left my family and I without power for 36 hours. Five years ago, a freak fall snow storm knocked off my power for three days. A portable electric generator would have allowed me to run my refrigerator and freezer just enough to save my food. I could have also powered my furnace for 10 minutes an hour to keep the pipes, my wife and kids from freezing.

Portable electric generators come in all sizes and levels of quality. They can provide you with emergency power to run virtually any electric appliance in your home. They can also provide electric power for picnics, camping and construction needs. However, if you plan to power a whole house air conditioner or heat pump, you are dreaming. These large electrical devices will overwhelm an average or large size portable generator.

Portable electrical generators are sized by the amount of watts they will produce when operating. A 2,500 watt generator will supply enough electricity to power twenty-five 100 watt light bulbs for 30 minutes. After that, you should reduce the load by 10 percent to avoid overheating the generator. The total capacity of a generator cannot always be delivered to a single appliance. The power you can deliver to any one appliance is determined by the size of the outlets on the side of the generator.

Sizing a generator for your household emergency needs can be a bit complicated. You need to calculate the total amount of watts (electrical load) you might have connected to the generator at any one time. Appliances and motors have labels that tell you how many watts the appliance requires while operating. In addition, certain appliances require significantly more power at start-up than while actually running. Refrigerators, furnace blower motors, freezers, washing machines, etc. are examples of these appliances. If you have ever seen your lights temporarily dim while your refrigerator starts up you know what I am talking about.

Connecting a portable generator to your household appliances can best be accomplished using a transfer switch. These switches completely take your house off line while the generator is operating. If you do not use a transfer switch and simply feed power to the electric panel, you could kill a utility company linesman who is attempting to restore power to your neighborhood. These switches also protect the generator when power is restored by the utility company. Make sure a qualified electrician installs your transfer switch. It must be inspected by your local electrical inspectors and/or the utility company.

Avoid the use of extension cords if possible. If you choose to use them, be sure they are sized adequately to handle the flow of electricity. An undersized cord can overheat, short out and cause a fire.

To power sensitive electronic equipment, you need to purchase the highest quality portable generator you can afford. The quality of electricity produced by different generators can vary. The gasoline engine and the generator must provide consistent, smooth power. Inexpensive motor or generator components can adversely affect electrical power production. Consider purchasing an engine that has an automatic shut off that can detect low engine oil levels. This simple feature will protect your engine from failure. Remember, higher quality usually means higher initial cost. The most economical generator may not be the best long term investment.