Here's the deal per the Bussman rep. The contractor could install a 800a. or 1200a. Safety Switch with conductors that were only adequate for 600a. Now if the customer decides to expands his capacity to 800 or 1200 amps all he needs to do is change the conductors and the fuse and not have to change the switch. This is apparently is a significant cost saving measure. From what Bussman is telling me, it's the only "Listed" way of doing this sort of thing. Works for me.
