NEC says I need to secure 1" nonmetallic rigid conduit (Schedule 40 PVC to be precise) every 3 feet, which makes perfect sense when it is hanging between supports horizontally, across joists, or on a vertical surface.
However, I am looking to run a length of conduit over my porte cochere. The plan is to have it go up into one soffit, cross over attic space (inaccessible, no stairs or opening) feeding it in via the soffit, and come down out the other. Its about 14' across and there is no real way for me to get in there to attach straps. It would lay on 1/2" to 3/4" plywood which constitutes the ceiling of the porte cochere. Can I leave this long of a run without a strap? It is 'supported' by the flooring.
My only concern is its not protected - outside the fact that you would have to drill through the plywood to hit it. There is a run of romex to four recessed lights in this space as well.
If it has to be supported, can I use something like a rooftop pipe support and feed them in to the space?
Any advice or pointing to somewhere in the code that hits this would be very helpful.