Calculating the Running Wattage
To find the running wattage, you will multiply the nameplate amperage x 120 (most household appliances run on 120 volts).
For instance: if the nameplate amperage is 4 amps, you will multiply it by 120 which will give you 480 running watts.
What Is A Duty Cycle?
A refrigerator compressor does not run all the time. Instead, it cycles on and off. The percentage of time the compressor is running, is called the duty cycle. The running wattage is the amount of watts the appliance uses when the refrigerator’s compressor is running, but due to the duty cycle, the average wattage will be much lower than the running wattage.
Calculating the Average Wattage
Each refrigerator has different efficiency levels, which will vary with the insulation value in the refrigerator. Typically a refrigerator runs on 35% duty cycle, (65% for a freezer). This means that if you take the running watts and multiply it by 35%, you can get an idea as to how much power the average running amps will be.
For instance: if the running wattage is 480 watts, and the duty cycle is 35%, the average wattage will be 168 watts.