I am building a shop about the same size and keep wondering about how to run the DC pipe. My shop is 31 feet wide inside and about 70 feet long. I have a large sliding table saw now and a full shop but in retirement I will add a wide belt sander, and some more industrial grade/size machines. Because I'm not sure on layout I was thinking about putting concrete trenches like 6 feet in from each side wall running the length of the shop. Make them like 12" wide and 24" deep. I would use 1 1/2" plywood decking as a cover and I could then cut holes for DC and power wherever needed. The hope would be the ability to run all under the floor. Thoughts?