Cable Trays fill calculation

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Florin

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Fairfax, VA
My dilemma is regarding Cable tray fill, specifically regarding equipment grounding conductor which is a lot smaller than the current carrying conductors ( in my case 1200 Amp circuit, 350KCM current carrying and 3/0 ground) NEC 392.22(B)(1)(d) says Where any of the single conductor cables are 1/0 through 4/0 AWG, the sum of the diameters of all single conductor cables shall not exceed the cable tray with.
The current design calls out a 250KCM ground just to avoid the single layer calculation. I believe that the grounding conductor shouldn’t fall under this requirement and trigger a single layer fill requirement since it is not contributing to the heat generated or causing phase reaction problem. But it should be counted in the fill area calculation

I hope that someone ran into this issue in the past and found a reasonable explanation.
 
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