Feeder and equipment sizing for several split system air conditioners

[SteamDonkey]

I'm working on a project that has a transformer and panelboard serving several split system A/C units (similar to typical residential systems). Since they're hermetic refrigerant motor-compressor type units, I am under the impression that 440.3(B) will not allow me to use 430.24 to size everything for 125% of largest + 100% of remainder. I'm assuming A/C loads must be considered continuous and as such, I must size the conductors and overcurrent devices for 125% of connected A/C load. Does this sound correct?

Thanks.

 

[Gregg Harris]

I'm working on a project that has a transformer and panelboard serving several split system A/C units (similar to typical residential systems). Since they're hermetic refrigerant motor-compressor type units, I am under the impression that 440.3(B) will not allow me to use 430.24 to size everything for 125% of largest + 100% of remainder. I'm assuming A/C loads must be considered continuous and as such, I must size the conductors and overcurrent devices for 125% of connected A/C load. Does this sound correct?

Thanks.

The information needed is on the equipment label.
440.3(B) is for refrigeration compressors driven by an external shaft and motor

 

[augie47]

I don't see that 440 specifically addresses "feeders" so you have to fall back to Art 430, however,440.33 seems to set out the scenario for multiple loads. Of course with the transformer involved, you will need to take Art 240.21(C) and Art 450 into consideration.
If any of the compressors are sizable, I would also consult the transformer manufacturer.

 

[SteamDonkey]

I don't see that 440 specifically addresses "feeders" so you have to fall back to Art 430, however,440.33 seems to set out the scenario for multiple loads. Of course with the transformer involved, you will need to take Art 240.21(C) and Art 450 into consideration.
If any of the compressors are sizable, I would also consult the transformer manufacturer.

Per 440.3(B): "The rules of Articles 422, 424, or 430, as applicable, shall apply to air-conditioning and refrigerating equipment that does not incorporate a hermetic refrigerant motor-compressor." All the A/C units are the hermetic type so I don't think I can fall back to Article 430. 440.33 seems to be applicable. There are no large compressors, just lots of small ones. Thanks.