My shop space had cinder block walls up to about knee height open 2/4 walls from there up (waaaaay up <g>). I ran conduit along the block walls at a height that allowed it to run right into my electrical outlet boxes. I ran 3 conductor (+ ground) cable and cut the tabs on all my outlets so that I could have seperate circuits top and bottom on each outlet. That way I don't have to worry about the dust collector/shop vacuum being on the same circuit as the power tool and kicking a breaker. I also added ceiling drops over the "island" where my big dust collector, table saw, planer, and jointer will live. tTat way I don't have wires running across the floor.