PVC supports

[nathan1]

I am working on a project concerning exposed PVC. After reading up on the installation codes I found that the code allows for a strap to be no more than 3ft away from an Lb that is not supported. So if i am reading this right if you are three foot away from the entrance and exit of your lb you would be within code. The installation seems flimsy to me and it seems that this would violate the 3ft strap rule because now your straps would be at 6ft away. Any clarification would be appreciated before I install 4million miles of this stuff.

 

[peter]

Re: PVC supports

From your description, it seems that the sequence is: strap, 3 feet, LB, 3 feet and then another strap. This seems legit. You do not add 3 + 3 = 6 and then conclude that you are six feet from a support, if I read you right.
However, LBs are usually used as pulling points and having them hanging in the air like that does sound flimsy. Is there any easy way to add an additional solid support [even though not technically required]?
~Peter

 

[iwire]

Re: PVC supports

Don't forget that PVC has much closer support spacing requirements then metal raceway.

6' between supports regardless of the LB is a violation unless the PVC is 2.5" or larger.


Table 352.30(B) Support of Rigid Nonmetallic Conduit (RNC)

352.44 Expansion Fittings.
Expansion fittings for RNC shall be provided to compensate for thermal expansion and contraction where the length change, in accordance with Table 352.44(A) or (B), is expected to be 6 mm (1/4 in.) or greater in a straight run between securely mounted items such as boxes, cabinets, elbows, or other conduit terminations.

And

352.6 Listing Requirements.
RNC, factory elbows, and associated fittings shall be listed.

Do not use supports that are not listed for PVC, the supports must let the PVC slide from expansion and contraction.