I'm aware the highest-rated motor is determined solely by rated-load current, regardless of being 1? L-N, 1? L-L, or 3?. The requirement is written regarding determination of disconnect, ocp, controller, ampacity, etc. ratings... in the circuit pathway. However, how should this be applied when doing 220.14(C) load calculations?
For example, say we have the following motors on a service:
Because we calculate in VA, should we include only 120V ? 24A = 2,880 VA ...or... 120V ? 24A ? √3 = 4,988 VA (...? 125% for highest-rated motor) in the calculation?
Now before answering that question, consider that if these were the only two loads on the service, there would be no way to balance the system out. Additionally, Article 430 makes no provision for balancing out the conductor current with other non-motor loads. Furthermore, when determining service and feeder ocpd and conductor size, a typical 3? load calculation simply divides the total VA equally on each conductor.
Opinions?
For example, say we have the following motors on a service:
HP | Volts & ? | FLA |
2 | 120V 1? | 24 |
5 | 208V 3? | 16.7 |
Because we calculate in VA, should we include only 120V ? 24A = 2,880 VA ...or... 120V ? 24A ? √3 = 4,988 VA (...? 125% for highest-rated motor) in the calculation?
Now before answering that question, consider that if these were the only two loads on the service, there would be no way to balance the system out. Additionally, Article 430 makes no provision for balancing out the conductor current with other non-motor loads. Furthermore, when determining service and feeder ocpd and conductor size, a typical 3? load calculation simply divides the total VA equally on each conductor.
Opinions?