sizing sbj for transformer

[Mejourneyman39]

Planning a job with a 150kva transformer that will feed two separate panels on either side of the transformer, each panel will have 3/0 copper supplying them. Not understanding how to size the SBJ from XO to the transformer case. The feeders on the primary side are the larger of the conductor sizes do I use in table 250.102 (c) (1)? Which would equate to a # 2 copper, just as a 3/0 would require a # 2?

 

[infinity]

You use the secondary conductors to size the SBJ based on the sum of the ungrounded conductors according to T250.102(C)(1) Note #3.