Quick Answer
Running watts refer to the continuous power output of a generator, while starting watts are the initial surge power required to start the device being powered, which is usually higher due to inrush current.
Understanding Running Watts
Running watts are the steady-state power output of a generator, measured in watts (W). When sizing a portable generator, consider the running watts required by the devices it will power, typically appliances and tools. For example, a refrigerator might require 150-200 running watts, while a window air conditioner might require 500-700 running watts. To size a generator, calculate the total running watts of all devices to be powered and add a 10-20% margin for safety.
Accounting for Starting Watts
Starting watts are the initial surge power required to start a device, which can be 2-5 times the running watts. This is due to the inrush current, a brief but high-energy surge that occurs when a device is first powered. For instance, a refrigerator’s starting watts might be 300-500 W, while a window air conditioner’s starting watts might be 1,000-1,500 W. When sizing a generator, it’s essential to account for the starting watts of all devices to ensure the generator can handle the initial surge. A common rule of thumb is to size the generator for the highest starting watts of all devices to be powered.
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