Can Using Extension Cords Ruin an Appliance or Other Electrical Device?

Appliance Damage

• Electricity moving through a wire encounters resistance, analogous to friction. This friction reduces the voltage. An extension cord that is too long or too limited in capacity can cause voltage to drop below the minimum voltage required by your power tool or appliance. This decrease in voltage can cause your tool or appliance to run sluggishly and overheat to the point of burning out or not run at all. The solution is to move the device closer to the outlet or use a higher-capacity cord.

Cord Sizes

• Extension cord capacity depends on the size of the wires that carry the current. Wire size is measured according to gauge. The lower the gauge number, the bigger the wire and the more current it can carry safely. The most common cord wire sizes are 16 gauge, adequate for up to 10 amps at up to 100 feet, 14 gauge, which can handle up to 15 amps at up to 50 feet, and 12 gauge cord, which can handle 15 amps at 100 feet. Extension cords aren’t recommended for loads beyond 15 amps or distances beyond 100 feet.

Finding Loads

• Most electrical devices have nameplates that tell you how much current they draw when running. The current draw usually is expressed in amps, but sometimes it is given in watts. To convert watts to amps, you divide the watts by 120, which is the nominal mains voltage in the United States. The math works out to be 600 watts equaling 5 amps and 1,200 watts equaling 10 amps. Most extension cords have labels telling you how many amps they can carry safely.

Cord Safety

• Safe operation requires that you match your extension cord to the electrical load. You should avoid putting multiple devices on one extension cord. If your cord feels hot to the touch, you are overloading it. Unplug it immediately and remove some of the electrical load. Extension cords that are frayed, cut or otherwise damaged should be discarded. Avoid pinching an extension cord by putting a chair leg or other heavy weight on it. Pinching can damage the insulation and create a shock or fire hazard. Extension cords are meant for temporary use only. If you have lots of devices on extension cords and they have been like that for months, you may want to consider an electrical upgrade to your home.