The "cross section" would be the 4"x4" dimension & would not include the 5' dimension, otherwise, that would be a leangthwise section. Confused? See the second paragraph of 362-5 where it speaks about the cross sectional area of conductors, nothing is said about measuring their areas leangthwise.
If the conductors did a bunch of cross overs, then you could derate them, use as many as you want provided you don't fill up any cross section more than 20%. Derating penalty would be a killer though.
This installation prompted a question that I never received a good answer to. This is labeled as a wireway & I have to use the rules of a wireway. If I had a custom made junction box, I would be able to fit in 426 #12's & no derating. ((4x4x60")/2.25=462)
Is there any differance, other than technical definitions?
Few things are harder to put up with than the annoyance of a good example.