Motor O.C. protection

[thefuse]

NEC Table 430-52 states the maximum O.C. protection values allowed for motor protection.
Recently I received from our mechanical engineer a cut-sheet from a mechanical equipment manufacturer that based their maximum OC protection for fuses on a value using 225% of the largest motor of this multi-motor package. Of course this was not the same value I had calculated at 175%.
How can the manufacturer not comply with the NEC in this manner?

 

[l3city]

Hi there!! well, if that's the case, check NEC 440.22. This section talks about AC equipment (I assume this is AC equipment, since you mention a "mechanical engineer" involved in this issue). The manufacturer might be trying to make sure the motor starting current is sufficient without tripping the breaker.

 

[JJHorak]

Note exception 2(b) under Table 430.52.