I could be wrong but from what I have understood in the past the "service factor" is the percentage the motor can be overloaded for a SHORT DURATION without causing damage to the motor.. So really that motor will put out ( 10 * 1.15)= 11.5 horsepower ( 15% overload) for a short duration with no damage to the motor.. The overload heater being at 125% of nameplate FLA is just a MAXIMUM value of the setting of the overload heaters, not the percentage of how much you can overload the motor..
BTW, some overload heaters allow for the 125% rating.. you just size them to what your motor FLA is and thats it...should say somewhere on the overload or starter somewhere..
A.D
