Things You'll Need
Very basic understanding of AWG (American Wire Gauge numbering system)
How to Use Extension Cords Safely. Everybody's got at least one and some of us have a garage full of them-and probably none of us think of them as dangerous. However, according to the U.S. Product Safety Commission, extension cords are among the most dangerous electrical appliances in our homes. In fact, in the last year, accidents from extension cords reportedly killed 50 people, resulted in injuries requiring hospital treatment to 4,000 others and also caused over 3,300 residential fires. With these kinds of numbers-maybe we should all learn a little more about using extension cords safely.
Consider how you plan to use your extension cord. Outside or indoors? Will it be carrying a small load (i.e. trouble light) or a heavy load (i.e. electric handsaw)? Where are you going to use the tool-relatively close to an electrical outlet or a long distance away?
Recognize that not all extension cords are safe to use outside. Extension cords that are safe to use outside are specifically marked "Suitable For Use with Outdoor Appliances." Don't use a cord that's not marked this way for any outside jobs.
Understand the basics of the American Wire Gauge (AWG) system. The smaller the wire gauge number, the more current the cord can safely handle. For example, an extension cord made from 12-gauge wire can safely handle more current that an extension cord made from 16-gauge wire.
Know how much current (wattage) your appliance or tool will need when operating. The more current the appliance requires, the lower the extension's wire gauge number should be. All electric appliances indicate how much wattage they consume on their packaging and often in the care and use manual that comes with them as well. Some appliances and tools indicate their requirements in amps rather than watts. To calculate the watt requirement of a tool that for example says it draws 6 amps at 125 volts, multiply the amps times the volts (in this case 6 x 125) so it draws 750 watts.
Consider that length matters as well as size. Current carrying capacity drops as the length of an extension cord grows, due to resistance in the wire itself. Plugging extension cords together will also decrease the current delivered to the far end, since each time the electricity passes through a plug it drops a little. If the current (wattage) delivered is less than the tool or appliance needs, it may not work. Or if it does work it will wear out more quickly. The safety aspect of this is long cords have more resistance to current flow and a longer cord will tend to heat up more than a shorter cord. Use the shortest length of extension cord possible to minimize current loss and heat build-up in the cord.
Don't store extension cords in areas where they will be exposed to the elements. Constant weathering will age them quickly. Always look for the UL (Underwriter's Laboratory) mark on any cord you buy. Don't leave an extension cord plugged in when it's not being used. Don't plug extension cords into each other to extend their length. Get the right length cord.
Never use an extension cord with cut or damaged insulation. Never file or cut off the third prong on the male end of the cord so you can plug into an old outlet. Don't run extension cords under carpets or across wet ground.