Extension cords are so useful and common that many people forget they can be dangerous.
In fact, some local electrical codes forbid their use. If the cord is wrong for the job or is improperly used, it can cause fire. The Consumer Product Safety Commission estimates that improperly used extension cords cause nearly 5,000 house fires each year.
Here are some do's and don'ts for choosing and using extension cords:
Consider an extension cord a temporary connection. Unplug it and store it after each use.
If several devices are attached to one extension cord and used at the same time, there is a good chance the cord is overloaded.
Most extension cords are marked with a rating in amperes (also called amps or simply abbreviated "A"). The appliance should not exceed the cord's ampere rating.
To obtain an electrical device's amperage, divide its wattage by 110. Then choose an extension cord with appropriate ampere rating. Generally, appliances that produce heat or cold--space heaters, air conditioners, refrigerators, clothes dryers--have higher amperage than appliances that do mechanical tasks--food processors, clothes washers and vacuum cleaners.
The wiring in electrical cords is also rated to help you when choosing extension cords. The lower the number, the larger the wire and the greater the amount of current it can safely carry.
A lamp-type cord usually contains No. 18 wire. Don't use it for any device which draws more than seven amps. Heavier-duty No. 16, No. 14, or even No. 12 should be used for devices that draw higher amounts of current.
An extension cord's length is also important. A longer cord wastes current. If it is too long, the drop in current can reduce an appliance's efficiency. A No. 18 lamp-type cord, for example, should never be more than 25 feet long.
If you must use an extension cord for a refrigerator, air conditioner or some other electrical unit that draws substantial amounts of current, it should be a heavy-duty, three-wire cord.
When working with any power tool--whether large or small, stationary or portable--use only a heavy duty, grounded, three-wire cord that is No. 14 or heavier.
Extension cords should not cross traffic lanes or be used near water. If you must temporarily use an extension cord where there will be traffic, tape it to the floor to avoid tripping over it.
Remove extension cords from an outlet by grasping the plug. If you pull it out by yanking on the cord, the wires may eventually tear loose, resulting in a shock or short circuit.
You can tell if an extension cord is defective by examining it for frayed or cracked insulation or a damaged plug or receptacle. If the cord is damaged, it's better to replace it. If the plug is damaged, you can replace it with a new plug with the same or greater current-carrying capacity.
Make a permanent hanger for an extension cord by tying rawhide or heavy twine behind the plug. After rolling up the cord, wrap the rawhide or twine around it, tie a bow, and use one of the bow loops to hang up the cord.
Distributed by AP Newsfeatures.