Fix for outdoor conduit separating?

[miketyler]

Hey folks -

I'm in the DFW TX area and weve been enjoying some pretty serious summer drought the last few years (105* here yesterday). Despite soaking the foundation we still see ground shrinkage due to subterranean dehydration. This has brought on a condition where the ground is dropping lower and causing electrical PVC conduit to separate.

Is there a permanent fix for this short of extending the conduit and re-pulling the cable?

 

[Norcal]

The fittings are broken so your going to need to replace them but the only long term fix will be expansion fittings but the conductors are going to need to be able to move along with the fitting to keep it from happening again, not really enough information to add more.

 

[miketyler]

Not what I was hoping to hear. I do get it though, with the cable moving away from the entry point sooner or later the cable will be a concern as well.

 

[Zeke]

Looks like the far one wasn't glued. The near one is destroyed so....

I wasn't going to chime in but I've seen some creative repairs. As @Norcal says, you may have to pull the wires and redo with a slip joint. I suspect the ground is gonna rise back up later this year. Nevertheless, spend some YouTube time.

What's in there? Low voltage or other? LV wouldn't have me too excited unless you run out of slack. I mean with LV I might invest in a roll of tape.

 

[Innovate1]

I have some low voltage conduits that should have had expansion joints but don't. I am thinking that I can take a string saw or something similar and score it all the way around keeping the depth even. The conduits are under tension and about 20 years old so hoping that they will crack on the cut line. tie a line to the cable and pull it back just enough to clear the cuts. Cut out a section long enough to install the expansion joint. Then pull the cable back in position. It looks like your LB is low enough the bottom of the expansion joint (if you add it) may be in the dirt. Not the best but I suppose that's ok. A 3/4 expansion joint is $20! Seems crazy for what it is but I don't see an easy alternative.

 

[miketyler]

Thanks for the advice. Was hoping there was a worthy wrap-around or in-place solution for this. The large one is the main power going in. One of the shorter ones is low voltage, ethernet, coax and security and the second one is 110v that powers the lights in my fence columns. I just noticed the same thing on an adjacent wall where the sprinkler control is. The LV lines are in tension there now. Man, I gotta soak the slab more often.

 

[Fav Onefour]

There has to be a better solution than wetting the ground. We'd never get any sleep if all our solutions were temporary. It also doesn't do anything for the problem you have now.

I'm not real clear on which box is which wire.

The first box looks like they tried a slip expansion connection. Bummer deal on that failure. Pull the wire and do it right.

You have some room to work with the two in the second picture. Pull the lines, install wall mount box (sealed correctly) and flex conduit down to rigid. Use a slight s curve on the flex to leave room for the ground movement cycles. Push the same wire back inside.

You mention the sprinkler control lines are tight? Pull the outside assembly and put in a setup to allow for movement. I'm guessing the inside control box can be dropped down a couple inches. I'd just move the box down to alleviate the slack.

 

[LXCam]

Carlon make expansion couplings. But your issue seems more than a bit extreme. I’d guess the conduits were sitting on fluff before backfill.

 

[Innovate1]

Anyone use the end bell of the conduit as an expansion coupling and just not glue it? The bell is fairly long and enough to take up typical movement I think. Expansion couplings are often used on vertical runs (but not always I suppose) so it would still shed water. And the inside of outside conduit is considered a wet space anyway. So I don't see the need for the rubber oring in the actual expansion couplings in most places they are used, at least for residential. I'm thinking I will do that at least for the low voltage runs and maybe for the line voltage ones also.

 

[eejack]

I am thinking that I can take a string saw or something similar and score it all the way around keeping the depth even.

Try using mason line instead of a string saw. Mason line will cut pvc without generally cutting the conductors inside.

 

[miketyler]

Some good ideas here. I've been soaking the foundation and have seen only marginal closure. I guess until we get some real significant rain I wont know just how much it will close up. I need to buy new covers for those that have broken. I like the idea of a slip coupling that can move with the ground. We're in the 100's this week in Dallas. Want to tackle this in the evenings after it's cooled down