Generators: Motor Starting Sizing Questions

“Our dealers, as a routine matter, ask the type of questions [shown] to ensure the generator meets the application requirements,” says John Garcia, Doosan Portable Power. “The supplier’s goal is to provide a generator that precisely meets the applications, so the questions they ask and the information shared by the contractor will ultimately achieve this goal.”

1. What is the phase required — single or three phase?

2. What is the voltage (e.g., 120, 240, etc.)?

3. What are the amps (starting)?

4. What is the motor horsepower?

5. What is the ambient temp?

6. What is the altitude?

7. What is the motor code — letter designation? (usually “G”)

8. Do the motors have softstart or reduced voltage starting?

9. Is there more than one motor to start? Can the motors be started sequentially, or do they all have to start at the same time? If sequentially, is there a desired starting order?

10. List each motor, including horsepower, phase, volts, starting amps and code.

To learn more about sizing generators to the application, turn to the article "Don’t Let Generator Selection Trip You Up" or visit the Fleet Management section of