To avoid these ads, REGISTER NOW!

Trouble with electrical conduit

Jaguar Fan

Well-known member
Joined
Mar 13, 2008
Messages
5,511
Location
Park City for Ski Season; Las Vegas for Poker Seas
Hi guys.

This is technically not garage related, but I'm hoping someone might have some advice. We need to clear an electrical conduit that has some concrete inside it.

See the following picture:

screenshot-521.png


I have a courtyard water feature, and in that feature are 3 LED lights at the bottom of the water. These wiring for these LED lights, of course, goes inside plastic conduits that go underneath the slab foundation of the house, coming up on the side of the house where the wires then go into a Pentair system that controls the pool lights, water feature lights, pumps, etc.

So far, this isn't a matter of money out of my own pocket - my home builder and pool builder have to fix this. The house is less than 5 years old.

A light failed. They've tried for days to get the light cable out of the conduit, breaking the light cable at the end where the failed LED light was. They've tried a metal fishtape from both directions but it comes up against a blockage. They've brought out an electrician that is involved with swimming pool light installation, and he's spent a couple days on it. He's managed to get some chunks of plaster or mortar or concrete out of the conduit.

He's tried a can of Coca-Cola. He's said he's tried some Muriatic Acid, although I don't know how much.

From the equipment side, the electrical cable to the LED light is still there. They haven't tried to yank too hard as they don't want it to snap inside the conduit.

I'm wondering if maybe a stronger acid than Muriatic (not sure what) to eat through the mortar/concrete inside that conduit. Or maybe a higher concentration of acid. We presume the old electrical cable is embedded in some concrete inside the conduit.

Or, I'm wondering about maybe having a Roto-Rooter type guy try to use a power snake to grab on to something and yank it out.

Any thoughts?
 
Last edited:
To avoid these ads, REGISTER NOW!

LXCam

ALLIANCE MEMBER
Joined
Apr 23, 2013
Messages
19,449
Location
AZ
I’ve used pieces of a cut fishtape and a drill to eat away at it. I bent an offset so the cut edge is forced against the perimeter of the plug and go to town. Granted it take a **** load of time and patience and a few pieces of tape. Problem is it’ll tear up the pvc too but ya gotta pick n choose your poison sometimes.

As for muriatic acid you need the straight stuff, not the watered down pool supply version. However it will only affect the cement and not any of the aggregate.
 

BigGarage

Well-known member
Joined
Jun 5, 2019
Messages
2,347
Location
Just south of Detroit, MI.
Hi guys.

This is technically not garage related, but I'm hoping someone might have some advice. We need to clear an electrical conduit that has some concrete inside it.

A light failed. They've tried for days to get the light cable out of the conduit, breaking the light cable at the end where the failed LED light was. They've tried a metal fishtape from both directions but it comes up against a blockage. They've brought out an electrician that is involved with swimming pool light installation, and he's spent a couple days on it. He's managed to get some chunks of plaster or mortar or concrete out of the conduit.

He's tried a can of Coca-Cola. He's said he's tried some Muriatic Acid, although I don't know how much.

From the equipment side, the electrical cable to the LED light is still there. They haven't tried to yank too hard as they don't want it to snap inside the conduit.

I'm wondering if maybe a stronger acid than Muriatic (not sure what) to eat through the mortar/concrete inside that conduit. Or maybe a higher concentration of acid. We presume the old electrical cable is embedded in some concrete inside the conduit.



Any thoughts?

If your goal is to remove the wire inside the conduit and you think maybe concrete pieces are preventing that maybe you could use an air compressor to blow in one end or the other and maybe blows the pieces out.

If you aren't concerned with ruining the wire inside the conduit then a stronger acid could be used, maybe sulfuric acid. It could also mess up the conduit though if not washed out thoroughly. Other than these two things I am at a loss to help.

Dennis
 

rlitman

Well-known member
Joined
Oct 18, 2010
Messages
24,793
Location
Long Island
...As for muriatic acid you need the straight stuff, not the watered down pool supply version. However it will only affect the cement and not any of the aggregate.

True, but with the cement destroyed, what's left behind will crumble. At that point, once I can poke a snake through, I'd try to wash out what's in there with a hose. Just be careful not to end up packing the aggregate into a sweep and forming a new clog.

If your goal is to remove the wire inside the conduit and you think maybe concrete pieces are preventing that maybe you could use an air compressor to blow in one end or the other and maybe blows the pieces out.

If you aren't concerned with ruining the wire inside the conduit then a stronger acid could be used, maybe sulfuric acid. It could also mess up the conduit though if not washed out thoroughly. Other than these two things I am at a loss to help.

Dennis

No to all of this. First off, I'll shout a big NO to blowing compressed air in a conduit that's already got acid in it. Second, muriatic is no worse at etching through concrete than sulfuric acid.

And when you're done, pour baking soda in the hole, chased with a little water.
 

BigGarage

Well-known member
Joined
Jun 5, 2019
Messages
2,347
Location
Just south of Detroit, MI.
If your goal is to remove the wire inside the conduit and you think maybe concrete pieces are preventing that maybe you could use an air compressor to blow in one end or the other and maybe blows the pieces out.

If you aren't concerned with ruining the wire inside the conduit then a stronger acid could be used, maybe sulfuric acid. It could also mess up the conduit though if not washed out thoroughly. Other than these two things I am at a loss to help.

Dennis

No to all of this. First off, I'll shout a big NO to blowing compressed air in a conduit that's already got acid in it. Second, muriatic is no worse at etching through concrete than sulfuric acid.

And when you're done, pour baking soda in the hole, chased with a little water.

You give sound advice but as long as a person was intelligent enough to wear safety glasses and/or a face shield and not stand above the open end and look into it while blowing air into the other end he would be mostly safe.

I figured anyone would obviously take safety precautions.

Dennis
 

alfredeneuman

Well-known member
Joined
Mar 3, 2011
Messages
4,596
Location
Fullerton, CA
So far, this isn't a matter of money out of my own pocket - my home builder and pool builder have to fix this. The house is less than 5 years old.

Hercules/Oatey makes a liquid product for plumbers called "Clobber" that possibly could be used to clear the conduit. Its made for blockages like this but it's for professional use only, so it's not available to the general public.
Short of that, the way to fix it properly is to jackhammer to slab, replace the blocked conduit, and patch the slab.
(I've had to do this before to remove a rock that had fallen into a piece of 2-1/2" PVC) :mad:
 
Last edited:
OP
J

Jaguar Fan

Well-known member
Joined
Mar 13, 2008
Messages
5,511
Location
Park City for Ski Season; Las Vegas for Poker Seas
Many thanks for the ideas. First step, it seems to me, is the plumber with a video snake so we can see what's really down there.

I like the idea of a more concentrated acid -- standard muriatic acid for a swimming pool bought at Home Depot is something like 15% or so. https://www.homedepot.com/p/HDX-2-x-1-Gal-Swimming-Pool-Muriatic-Acid-2-Pack-10014HDX/202254527

I believe I can get it at 30% strength which might be more effective.

And that Clobber(tm) stuff looks good - very high concentration sulfuric acid.
 
Last edited:
To avoid these ads, REGISTER NOW!

alfredeneuman

Well-known member
Joined
Mar 3, 2011
Messages
4,596
Location
Fullerton, CA
As others have suggested, I would try a camera in the conduit. If the conduit is to small for a plumber's camera, you could try something like this:
BlueFire Semi-Rigid Flexible Wireless Endoscope IP67 Waterproof WiFi Borescope

Any camera is unlikely to work well with wire in the conduit.
 

k1rodeoboater

Well-known member
Joined
Feb 1, 2011
Messages
357
Location
NC

Higgins

Well-known member
Joined
Dec 25, 2009
Messages
1,959
Location
Shepheardsville, KY
There are USB cameras that are about the diameter of a #2 pencil that could be snaked down the conduit, and be able to see what he is up against!

AL
 
To avoid these ads, REGISTER NOW!
Top Bottom