Is it ok for bare wire to touch wood?

I am wiring a light fixture composed of four 2x4 posts that are each 4 feet long. They will be lined in a square shape. For the sockets, I have 8 ceiling mount light sockets that are going to be wired with 16 gauge wire that runs to a wall outlet for easy transportation. My only question is if it will be ok for the wire that connects all of the sockets to touch the wood frame? From what I can tell now, the wire will be sandwiched between the sockets and the wood, and I am worried about temperature or combustion.