[Al Skierkiewicz]

T,
I am recommending that teams assemble the blocks just as shown. The additional grey (thin) spacers give an extra added buffer between sections in a system that moves around. Just insurance I admit. They are needed when the blocks are used at rated voltages (110-240) for insulation. The grey locking blocks are the same kind of thing. Just extra insurance that the whole assembly doesn't slip and slide around on the rail.