430 Motor Duty Cycle

[tom baker]

Most of the time we use 125 of the motor full load current per 430.22 to determine the size of the motor branch circuit.
Table 430.22(E) has other duty cycle multipliers, for short time, varying duty, and so on, up to 200%.
Under intermittent duty, it lists pumps, and is for a continuous rated motor its 140%.
This is telling me if I take a water pump that runs less than 3 hours I have to size the conductors at 140% of the motor FLC.
How often are motor circuits for pumps sized at 140%?

 

[mivey]

You would have to consider the note with the "under any condition of use" being a key point:

"Any motor application shall be considered as continuous duty
unless the nature of the apparatus it drives is such that the motor will
not operate continuously with load under any condition of use."

You would need to know that the pump will never operate continuously. Even a well pump can run continuously if the sprinklers are on.