Advice on PVC conduit expansion couplings.

[Bubbasquid]

I'm currently in the throws of running power to my new pole barn. The pole barn is situated about 30 feet from the south side of my house. Unfortunately, my electrical panel is on the north end of my home, so I intend to go up the north face of my house, across the attic, out and down the south side, and trench the 30 feet across the yard and then back up into my shop on the outside of the building. The entire length of the run will be made with 1-1/2" PVC conduit. My question is in regards to expansion joints on the vertical runs of conduit emerging from the ground - am I required to place an expansion joint on any vertical length of conduit coming from the ground? I've read mixed things; some saying only one end of the run is required to have an expansion coupling, while other advice says the 90-degree elbows underground offer enough flex and no couplings are required. Note, that I am in climate with -20 F winters all the way to +100F summers.

I was probably just going to be conservative, and place one on each end, but wanted to know if it really mattered.

Thanks!

 

[alfredeneuman]

You may also need an expansion joint in the attic as well. Anyplace you have a temperature difference (such as winter to summer) where the conduit expands 1/4" or more requires an expansion joint.

 

[dcg9381]

I've never used expansion fittings, it might be location / soil specific. And I've never seen them used on residential electrical here. I sometimes use flex conduit (which comes in 1-1/2) which might work for these same function.

In terms of code, the answer seems to be here.