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Electric Motor Service Factor Caution

Don't set your motors up so they run continually in the service factor.

The motor service factor is the cushion the motor manufacturer builds into the motor to prevent damage from occasional surges, spikes and short-term heavy loading.

The motor service factor is not some sort of secret code for certain chosen people. The maximum amperage is plainly stated on the motor nameplate and the installer should make certain that the motor does not draw more than the nameplate maximum amperage.

I used to knew a guy who thought he was one of those chosen people who knew the service factor secret code. If George bought a motor that said it would draw 10 amps and had a service factor of 1.25 , you could be sure that George would set the sheaves so that the motor would run well into the service factor. George would set the motor to pull 12.5 amps (10 x 1.25 = 12.5).

George would also spend a lot of time replacing burned out motors. Most of them were the motors less than a year old that he had just installed. George will never admit his practice of setting motors up to run in excess of the rated max amperage was burning the motors up. George would always complain that motors just don't last long anymore.

Do yourself a favor and don't be like George. Don't set your motors up so they operate continually in the service factor.