When to use Table 430.52?...

[Kganaway001]

When sizing your OCPD for a single motor, when would we use Table 430.52? Example, been told while sizing a Rural pump house consisting of a single shallow well pump at 1/3hp, 115v. If I only use 430.22 for the 125% plus FLC from Table 430.248, OCPD = 15A, however, is Table 430.52 is applied, that’s easily 22.5A then using 240.6, OCPD = 30A. (I used an Inverse Time Breaker for sake of example)..

 

[EC Dan]

430.22 tells you the minimum conductor size at full load current, however you may want the OCPD to be larger to prevent nuisance trips based on starting current. 430.52 tells you the maximum OCPD you can use in that case.

 

[Dennis Alwon]

When sizing your OCPD for a single motor, when would we use Table 430.52? Example, been told while sizing a Rural pump house consisting of a single shallow well pump at 1/3hp, 115v. If I only use 430.22 for the 125% plus FLC from Table 430.248, OCPD = 15A, however, is Table 430.52 is applied, that’s easily 22.5A then using 240.6, OCPD = 30A. (I used an Inverse Time Breaker for sake of example)..

Actually it would be 25 amps but as stated above that would be the max overcurrent protective device allowed however you are not obligated to do so. 430.22 is conductor size at 125% not the overcurrent protective device.