PVC expansion fittings

[electricguy61]

In 40 years in the trade, I've never installed this long a run of PVC. Basically, I'm running along a fence @ 200' of 1" pvc with (3) #6 THHN conductors and (1) #10 ground to provide a 30amp/230v receptacle at the end of the run.

Article 352 requires thermal expansion fittings. This job is in the East Foothills of the Bay Area. I'm going to assume a temperature difference of 20-110 degree F (90 degrees), which translates to 3.65 inches of expansion per 100'. So it appears I'll need (2) expansion joints on this run of pipe.

My question is, if the pipe expands that much, how do you allow for the extra wire length required? Loops in j boxes? How do you assure the wire will travel properly and in the correct direction upon detraction?

Thanks for the help.

 

[jaylectricity]

You don't. The PVC expands, but since it's fixed on either end, it expands inward. The expansion joint takes care of that. Basically the joint will open and close and move along the conductors. The conductors will basically stay in the same place.

 

[jaylectricity]

Now if you were NOT to put expansion joints, the pipe would bend out of shape and that would create a longer raceway that would pull on the conductors.

 

[Coppersmith]

How does one determine how much to pull open (expand) the expansion joint upon installation? Do we just set in the middle? Do we determine how hot it is that day and calculate?

 

[electricguy61]

http://www.primeconduit.com/TechDocs/Sch40Sch80/Expansion_Contraction.pdf

 

[Coppersmith]

Thank you for a very definitive answer.

 

[electricguy61]

After further mastication, I think I get it.