SCCR of a control panel with no main OCPD

[RNLENI]

Dear All,

I am trying to find out the SCCR of a control cabinet with no main OCPD. below are the features of the cabinet:
a) This control cabinet has a main non-fused disconnect switch with SCCR 5kA by itself. (Combination with upstream fuses is different. But within this cabinet there is no upstream device)
b) Downstream of the disconnect is power distribution block and Three branch circuits,
1) First two branches are each with 35 A, 3 Pole Class CC fuses that is wired to VFDs ( that feeds the 2 separate motors)
2) 3rd branch is with 25 amps current limiting circuit breaker (Rockwell 1489-M...) and is wired to 5kva transformer (480 -120) and the 120 vac circuits downstream of it

My question is can I decide 5kA as the SCCR of this cabinet as the main disconnect is 5kA ?
OR
As the power to this non-fused disconnect is supplied from customer MCC Bucket circuit breaker, Do I need to consider the circuit breaker at the MCC Bucket aswell for calculating SCCR of this cabinet? (The nonfused disconnect manual shows various SCCRs with combination with upstream fuses/breakers. ) But in thiS case as the Breaker is on the customer MCC Bucket (Outside of the panel) , do we need to consider that?

Thanks and Regards

 

[SSDriver]

That cabinet by itself would be 5ka as the disconnect is the lowest sccr of the POWER circuit items. Per UL508 the only way to raise that would be to change out that disconnect or put a transformer before it. Simply putting fuses before it would not raise the sccr rating of the cabinet.

 

[Jraef]

Any use of OCPDs devices to increase the SCCR of a panel is very specific and requires that the devices inside of the panel are specifically listed in a series combination with it. So a breaker in an MCC bucket would have to be the exact breaker series listed with ALL of the components in the panel and unlikely to the point of near impossibility. Fuses are highly more likely to be in the series listing for the disconnect and the power distribution block (which is likely 5-10kA without them as well). The 1489 breaker might be problematic all around. I think they have 10kA by themselves, but I’m not sure they are series listed with anything at any higher levels.