When running branch conduit on exposed slab ceiling what determines if you run the conduits on strut surface mounted to the slab or have to suspend them on racks etc.?
Often running on racks allows you to keep the conduits at a single elevation. With structural beams every X number of feet running on the slab would require you to go around every beam obstruction. For most conduits that up and down would need to be avoided to lower the cost of running the conduit, the amount of conduit, adding bends which adds pull points, etc.