I have a set of plans that show a 600a disconnect outside at power company drop. 2 4inch pvc conduits running under slab and stubbed up in space approx. 100 ft away. Drawings show parallel 500 alum. feeders pulled in to a trough above a drop ceiling and tapped to a 400 a mb and a 200a mb panel boards with tapped conductors 250 alum to 200 and parallel 250s to 400. Do these tapped feeders to panel boards have to be a certain length? Thanks in advance for any response. I have never seen a service drawn like this before, is this a unordinary application?