3 AC OUTPUTS for 3 Phase AC COMBINER CALCS?

[Pressure]

I am combining 3 SMA 5.0-US Inverter outputs onto a 100A 240 Delta 3phase Combiner Panel. All inverters output 21A. I will have Inverter 1 output on phase A and B, Inverter 2 output on phase B and C, and Inverter 3 output on phase A and C. All inverters will have a 30A OCPD.
I am in need of assistance with the calcs for the combined output for my Fused disconnect and Tap size.
Not sure how I got to this, but I think I will use #4 THWN-2 CU with a #8 EGC. A 60A Fusible NEMA 3R 240V 3phase disconnect with 60A Fuses. There will be a production meter, but I will carry on with the #4 CU for my current carrying conductors #8 EGC and from the disconnect have a #6 GEC Bonded directly to the Existing Grounding Electrode.
I want to show the calcs for this in my PS. How did I do this for the disconnect, fuse and wire size?

 

[Pressure]

Ok. Here is my limited understanding of 3 phase and coming to my sizing answer, and someone please correct me because I am sure I am wrong.
3 x 5000W = 15000. (15000/(240V x 1.732)) = 36.09A x 1.25 = 45.1 A = 50A OCPD. Oops should have 50A fuses? And lets see... 36.09A/.91 for temp corrections = 39.66A. So, #8 THWN-2 for my wire size? Except I will need to transition to a min of #6 for the Taps

 

[jaggedben]

You basically have it, or at least good enough.

Strictly speaking you need to use the datasheet continuous output rating (21A) not 5000W/240V. Since your currents are balanced (same on each phase) you can simply do 21Ax1.73 x1.25 which doesn't change your answer of a 50A OCPD.

(If your currents were not balanced, the calculation would be much more complicated.)

That said, this method isn't explicitly permitted in the code, and the time spent on calcs and educating your AHJ why it's correct, if you have to do so at all, is not worth the savings in wire. So maybe just stick with 60A fuses and at least 52.5A rated wire (21Ax2x1.25).

(I don't know how you calculated #4 instead of #6 in your first post unless you have a very severe temperature derating.)