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One of the most commonly used items in our homes is the extension cord. We use them to put lights in areas where no lights exist, to put our computer desk in front of the window so we have that window view, to put holiday decorations throughout the interior and exterior of the home, and many other tasks too numerous to mention. Unfortunately, the extension cord, from the short 3-footer to the long 100 footer, is so common that when we need electricity in a place where there is none, we’ll pick up just about any extension cord and use it. Our only requirement seems to be that it has to be long enough to go where we want it to go. However, before using just any old extension cord, we need to think about whether it is the right extension cord to do the job adequately and safely. In addition to choosing the right extension cord, check it for damage before using it. Extension cords with loose prongs or damaged insulation should not be used.
Determine the cord’s suitability
In determining whether or not an extension cord is the right one for the job, the first thing to do is decide whether it will be used indoors or outdoors. Once that’s decided, check the tag on the extension cord for its rating. If it is rated for use outdoors, the tag will say something similar to “suitable for use with outdoor appliances.” Extension cords rated for use outdoors can also be used indoors, but indoor extension cords should not be used outdoors, even temporarily. They are for indoor use only.
“What’s the difference?” you ask. There is a much greater chance of damage to the extension cord when used outdoors, such as when it catches on the side of the stucco wall, a brick planter, or a fence. Consequently, if you compare an extension cord rated for use outdoors with one rated only for use indoors, you might notice that the wire is much heavier and with more insulation. That’s to provide it with additional protection needed for use outdoors.
After you’ve decided on where the extension cord is going to be used, determine if it is compatible with that use. All extension cords (and other wiring) are rated by wire size, known as its “gauge.” The gauge of the wire is standardized, and if you look at the wire itself, you’ll typically see a number preceded by the letters “AWG,” such as AWG 14. That means the wire is 14-gauge. The thicker the wire, the lower the wire gauge. For example, AWG 10 is thicker than AWG 16, and the thicker the wire, the more electricity that wire can safely carry.
The amount of electricity that a wire can carry is its amperage and is directly related to its gauge. Large power tools can use a significant amount of amperage, thereby needing a higher gauge or thicker wire. For example, it’s not unusual to find a circular saw with an amperage of 50. Because it needs a lot of electricity to run, it needs a thicker wire, so if you have to use an extension cord to power that circular saw, make sure that the extension cord is the same gauge as the power cord for the saw. Undersized extension cords can get extremely hot, possibly melting the insulation on the extension cord and causing a fire. Oversized extension cords could result in not enough electricity getting to the tool or appliance. If you are using a multi-receptacle extension cord to power multiple tools simultaneously, make sure the amperage rating of the extension cord meets the combined amperage of the tools to be used.
Another factor to consider is the length of the extension cord. The longer the wire, the less electricity it can carry, so a larger wire gauge will be required in order to power the appliance. In many cases, the instructions that come with the tool or appliance provides a chart that shows the recommended wire gauge for different extension cord lengths.
Safety and maintenance
The three most common ways to misuse an extension cord are (1) using multiple extension cords plugged into each other, such as shown in the picture at left, (2) using extension cords as permanent wiring, and (3) modifying the extension cord by splicing it or filing the prongs.
Plugging several extension cords into each other to get greater length can cause a loose connection, overheating, arcing, and fires. If you find yourself using multiple extension cords, it is far safer to simply buy a longer extension cord. If you find yourself using multiple extension cords as permanent wiring, it is far safer simply to have an electrician install an additional electric outlet in the areas where you need electricity. Extension cords should never be used as permanent wiring; they are for temporary use only.
If the tool or appliance has a grounded plug, that is, two flat prongs and a round prong, as shown in the picture at right, it must be used with a grounded extension cord. Cutting off the ground prong (the round one) or filing the prongs defeats the grounding capabilities of both the tool and the extension cord. Such modifications can result in property damage, personal injury, and possibly even death. Never remove the grounding prong from any extension cord or otherwise modify it to try to defeat its design features.
Routine extension cord maintenance should include periodically checking the cord to be sure the ground prong is in place and examining the entire length of the extension cord to ensure that there is no damage that penetrates the insulation. If there is, the extension cord should be discarded.
Occasionally, extension cords go bad. You can use a plug-in electrical tester to check the extension cord. Electrical testers are inexpensive and are available at home improvement stores, grocery stores, and discount stores. Electrical testers can tell you whether or not the cord is grounded and other defects that could prevent the extension cord from working effectively and safely.
- Keep extension cords out of doorways and any other areas where there are lots of people around, especially children.
- Maintain some slack in the cord to prevent pulling the cord apart or damaging the prongs.
- Never nail or staple extension cords. If you have to place one in a certain location, use an appropriate cord clamp or temporarily tie the cord in place with non-metallic cable ties or heavy string.