The NEC allows for the supply breaker to be sized large enough to withstand the inrush current with the assumption that the motor overloads in the motor starter are protecting the motor and supply wires from damage due to overcurrent.
In motor circuits, the breaker needs to be large enough to avoid tripping on startup. That works out to about 57 amps, so the bare minimum is a 60 amp breaker in those cases. In typical, non-motor, applications, a breaker needs to be sized such that it is not loaded to more than 80% of the full load amps of the load being served. (I am assuming that a 480 volt supply is not being considered here.) The supply breaker needs to handle the inrush current to the motor which will be quite severe. An entry to this post stated the following: 'If you go with the 10 hp motor, it will require a 50 amp breaker.' According to my Grainger catalog, a 10 HP, 230 volt, single phase, motor will draw 46 amps.
