Windows air conditioners come in a couple of variations, either 120-volt or 240-volt models for home applications. Most receptacles in a home are of the 120-volt variety, but in the case of 240-volt window air conditioners, they need their own special 240-volt receptacle. When installing an outlet for such an installation, it is helpful to know which side of the air conditioner the cord is on. If you know the location before installing an outlet in the wall, the connection point will be beneficial for an easy connection. Also, this will eliminate the need for an extension cord.
Unlike 120-volt connections that use one leg of the service power, the 240-volt connections takes advantage of both of the legs of power. Because you are using the same amount of power from each leg rather than only one, the power used on one leg is half of what it would be on one leg alone. This creates a balanced load and reduces your electric bill, or at least saves you energy.
The window air conditioner receptacle is a single receptacle that provides high voltage power (240 volts) to the air conditioner. Because of its configuration, a 120-volt plug cannot be plugged into this receptacle. That's a good thing for all of your 120-volt appliances and equipment. Having specific plugs and outlets for equipment makes good sense and adds a nice electrical safety aspect to installations. Learn more about 240-volt Window Air Conditioner Receptacles.