430.62(a) and 430.72(b)

[Steve Lococo]

I am having trouble understanding code art.430.62(a) and 430.72(b)table which refers to note 1 can anyone give me an example and a soloution

 

[RUWired]

I am having trouble understanding code art.430.62(a) and 430.72(b)table which refers to note 1 can anyone give me an example and a soloution

Article 430.62(A) is saying the feeder breaker for a group of motors cannot be any higher than the total amperage of the highest rated in the group plus the total of all the others.So by using table 430.52, You added 250% the one of the motors, that gets added to the running amps of the other motors.The total of all that needs to be less than the feeder breaker.

430.72(B) is saying motor control circuits need to be protected at their amperage and not the feeder or branch circuit breaker unless it is of the same size as the control circuit.
Rick

 

[Karl H]

Theres a big difference between "Feeder" for a group of motors and the Branch-circuit short-circuit and ground fault protection device of the individual motors of the Feeder.Ie. the individual motor OCPD can be rounded UP but, the feeder OCPD must be rounded down this is calculated by taking the largest OCPD of the group of motors plus the sum of all of the other motors on the same phase.