Maximum Spacing between supports of Schedule 80 on flat roof

[cybersurge]

I have 2" schedule 80 running #3 wire. What would be the spacing distance between Uni to Uni on a flat roof. I am in southern CA where the flat roof gets very hot in the summer and I don't want the conduit to sag. Also, does anyone know the code I would reference for that distane?

 

[tom baker]

Find your spacing requirement in Art 352 Rigid PVC
Pay attention to the expansion and need for expansion couplings
But PVC on a roof will never look good, no matter how often it’s supported
Is EMT not an option?

 

[ptonsparky]

Laying it in cable tray might work to keep it pretty.

 

[don_resqcapt19]

You could support it ever foot and it will still sag between supports.
Expansion couplings were mentioned in post #2, but in addition to the expansion couplings the fasteners must be designed to permit the PCV to slide so it can expand and contract with temperature changes.

 

[augie47]

I've never seen a horizontal rub of PVC outside that didn't look like crap after 1 summer regardless of straps, exp joints, etc

 

[wwhitney]

In the plumbing world, you can readily get a "pipe support track" that is like a metal quarter cylinder. E.g.

https://www.zurn.com/product-bucket/a-p/qmst_x

Is anything like that available for PVC conduit? I guess it would need to let the pipe slide along its length to handle differential contraction/expansion.

Cheers, Wayne

 

[infinity]

Not saying it won't sag a little but 2" Sch80 is pretty rigid. The code.maximum is 5'. I would think that a support every 2-3' would keep the sagging to a minimum. If you need anymore supports than that and I would choose a metal raceway.

 

[tom baker]

The challenge is to find straps that allow the PVC to move.
And do this: based on the temperature difference, and exposed length, what is the max expansion expected?