Do I Need Expansion Fitting?

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TeddyAdkins

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Industrial Electrician
Gonna run pvc as a riser about 18ish feet. Do I legally need an expansion fitting?

If so where do I put it, right at the socket or between the 2 conduits?
 
oldsparky52 said:
If it's straight and the straps allow for movement and one end is not secured then I don't see why you would need one.
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What do you meant 1 end not secure? Because yhe bottom will be fastened to the base. Like leave some play for the weather head?
 
No. I was agreeing with OldSparky, if the conduit is free to move and strapped in a manner that allows movement, there is no need for an expansion joint.
 
augie47 said:
No. I was agreeing with OldSparky, if the conduit is free to move and strapped in a manner that allows movement, there is no need for an expansion joint.
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Cool. Now do you think an inspector would see it the same way or a little convincing would be in order
 
For an 80 degree temp change 18ft will expand just under one inch. If one end if fixed, say to a meter socket and the other end is a weather head, you should be ok. If your run goes between two fixed enclosures, that is over the 1/4" allowed in 352.44. Expansion joints have instructions, just follow those to set the length in the barrel
 
For a straight run where frost heaving is not a concern, using PVC conduit straps or clamps with PVC conduit should allow the conduit and clamps/straps to expand and contract at a similar rate and avoid bowing of the conduit.
 
TeddyAdkins said:
What do you meant 1 end not secure? Because yhe bottom will be fastened to the base. Like leave some play for the weather head?
Click to expand...

"Not secure" is a little misleading. What OldSparky meant was not securely fastened against axial movement.

PVC conduit straps used on PVC conduit will allow for axial movement, while constraining against lateral movement. Unlike using metal straps, that secure against both. Terminating on a fixed box also secures against axial movement, while a weatherhead termination is free to rise and fall with thermal change in length.
 
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