Expansion fittings on pvc

[crtemp]

I received a tag for not having an expansion fitting installed on 1" pvc that I installed through an attic for a hot tub circuit. I would assume pvc is free to expand and contract freely in an attic without one. Am I wrong?

 

[Cow]

I would assume pvc is free to expand and contract freely in an attic without one. Am I wrong?

I'd say that would depend on how it was installed, since I don't know how you installed it and you didn't post a pic, I have no idea if you're wrong or not.

 

[crtemp]

I'd say that would depend on how it was installed, since I don't know how you installed it and you didn't post a pic, I have no idea if you're wrong or not.

It's about 60' through an attic going through vaults and it makes several big sweeping bends to get from point a to b. Even with the strapping to the trusses I see no reason it couldn't expand and contract.

 

[tom baker]

Look in Table 352.44 and determine how much the PVC will expand.
Lets say the attic has a temp swing of 20 deg F to 120 deg F. Thats 4 inches per 100 or 2.4 inches. The temp swing could be more, depending on location.
If your conduit expands that much will it buckle or damage a fitting. Is your PVC secured every 3 ft, per 352.30?
An expansion fitting is pretty simple to install, you clamp the barrel so the pvc can expand, and with PVC straps they will let it move.
The inspector may be correct..

 

[JFletcher]

I received a tag for not having an expansion fitting installed on 1" pvc that I installed through an attic for a hot tub circuit. I would assume pvc is free to expand and contract freely in an attic without one. Am I wrong?

Sweeps and bends arent expansion joints. The inspector is likely correct.

A residential attic here can see 100*+ temp swing from winter to summer, which as mentioned above is 4"/100' or 2.4" for 60'. If it was cold the day you installed the conduit, you'd also want to set your coupler nearly fully extended so when the RPVC heats up it can compress/slide in the expansion joint.

https://www.lowes.com/pd/CARLON-1-in-Schedule-40-PVC-Coupling/3817941

With the extra strapping required by RPVC and the need for expansion couplings, EMT is usually a better choice in at attic imho. If the roof trusses are 24" OC you have to strap to every single one with 1" RPVC. 1 1/4" would get you to 5' between supports and every 3rd truss/rafter with 16" OC framing.

Note that with a 60' run, even a 15* change in temps would require an expansion coupling (.61 x .6 =.37", >.25" per 352.44). You cannot leave out supports or float the boxes (by slotting the mounting holes) to compliantly allow for expansion.

 

[kwired]

An elbow is not an expansion fitting, but if it is not secured right at the elbow it may allow for enough movement that could negate the need for an expansion fitting. Mostly depends on how much movement is necessary for the temp change encountered. If only a 1/2 inch of movement is required you might be able to get that out of two "back to back" elbows that are not too secured, but if you need 4 inches of movement you are likely going to need additional expansion fittings.