Window-type air-conditioning units are one way to cool your home if you do not have a central air system or simply wish to cool specific rooms instead of running the central air. If the unit's power cord is not long enough to reach an electrical outlet, it is possible to use an extension cord. Many manufacturers discourage this practice, but the key is purchasing a power cord that can handle the electrical pull of the air conditioner.
Find the label on your air conditioner that lists the electrical information. The label could be on one side of the unit, on the front bottom edge or behind the front filter cover. The label usually contains the voltage, watts and sometimes the amp information for the unit.
Write down the amp information if the amps are listed. If the label lists only voltage and watts, calculate the amperage by dividing the watts by the voltage. If the label says 120 volts and 600 watts, divide 600 by 120 for a general amp draw of 5.
Measure the distance between the air conditioner and the nearest 120-volt wall outlet with a tape measure. It is not necessary to purchase a 20-foot, heavy-duty extension cord if you only require 10 feet of cord.
Go to a home-improvement center and look for a CSA-certified, UL-listed, three-prong extension cord with the ability to pull slightly more amps than your window air conditioner. If your unit draws 5 amps, purchase a cord that handles 10 amps. Always round up, not down. Look for a cord that is long enough to reach the outlet but not so long that it creates a tripping hazard.
Plug the air conditioner power cord into the heavy-duty extension cord. Plug the extension cord into the nearest wall outlet.