Since we don't have any framed walls on the 2nd floor, we ran the ceiling fan wires down 3/4" plastic conduit and painted them black to match the black iron floor joinst brackets. After exiting the conduit, the wires run along the top of the girder...

...to a junction box where they connect to the single power feed from a switch.

The building inspector wanted to see a smoke/CO detector up around the 2nd floor area, so Jeff ran another piece of conduit up one of the middle RPSL's and mounted a box well above the floor level.