Underground RMC Repair

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The contractor says he can't remove the conductors. As desribed the original intallation had rigid metal conduit with set screw connectors underground below a building slab. They opened up the conrete slab for improvements to the bathrooms and the couplings disinergrated. They also shorted out one set of conductors and refed them over head since they could not repull through the existing conduit. There are two other remaining conduits that they repaired with split pvc, plastic tie, epoxy and bonded around the fittings. I came across this repair and said it wasn't compliant. I have since found on line some fittings that are rated for concrete but none for direct burial.
 
If the conductors can’t be removed, I would question the integrity of the rest of the conduit and the conductors.
 
RICK NAPIER said:
I have since found on line some fittings that are rated for concrete but none for direct burial.
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How about using the concrete-rated fittings, encasing them in a little concrete, and then backfilling? Or if they are not too deep, stick a sonotube around them, backfill, and pour concrete around them monolithic with the slab repair?

Cheers, Wayne
 
RICK NAPIER said:
They wouldn't work since they cannot remove the conductors. This is what I found from 2 different manufacturors.
http://www.cooperindustries.com/con...mbinationcouplingsforrigidimcconduitfitt.html
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I was under the impression the conduit is damaged from your initial post? Or is it just a damaged or broken coupling?

I can't see what the fittings you linked are going to do for you if you need to replace a damaged section of conduit with wires still in it?

We use "split repair kits" for pvc, I assumed you were looking for something similar.
 
There are pipe repair clamps that have a steel band that can be opened far enough to slip over the middle of the pipe without damage. Similar connectors are also available from muffler shops, but probably not in a 3/4 RMC size.
http://www.jakiflow.com/product.asp?id=76 (an example, not an endorsement)
Stainless_Steel_Repair_Clamp_Ductile_Iron_Lugs7055-130914.jpg

You might get two saddle taps, and use the two backshells (without the taps) as a bolt-on replacement connector.
http://www.jakiflow.com/product.asp?id=57
Saddle_Clamp_for_PVC_Pipe7055-130914.jpg
 
RICK NAPIER said:
It's just the fittings that disenegrated.
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As in basically gone? Something needs to be installed to replace the two couplings.

Just a suggestion, (and yes it would void the Listing), is to take 2 heavy wall 3/4" rigid couplings and cut them in half lengthwise.

Wire brush the threads of the ends of the RMC conduits to clean as much rust as possible from the threaded ends of conduits. (I assume there is not any cut unthreaded bald ends.

Sandwich the two halves of the cut coupling over the threads of the two ends of the conduit. Temporarily clamp the two halves of the coupling tightly together in place.

Use a small 120V Mig welder to tack weld the couplings in place. A good welder will alternate his spot welds around as to keep the heat to the two couplings low enough as to not heat the conductors inside the conduit. He can spot weld the cut sides of the couplings completely closed if you want.

Because the welder will grind away the galvanizing somewhat where he will be spot welding the haves of the couplings back together, use a cold galvanized coating spray paint product to recoat the couplings.

Example Of

The welder will clean the spot welded areas good before spraying the cold galvanizing coating.

To finish the repair, (depends on how far you want to go), to make the repairs somewhat water tight, just one option might to be use an approved epoxy product. Just a guess taping the couplings and conduit would be a waste of time because of the shape/condition of the outer surface of the RMC.

Overkill?
 
Jamesco said:
As in basically gone? Something needs to be installed to replace the two couplings.

Just a suggestion, (and yes it would void the Listing), is to take 2 heavy wall 3/4" rigid couplings and cut them in half lengthwise.

Wire brush the threads of the ends of the RMC conduits to clean as much rust as possible from the threaded ends of conduits. (I assume there is not any cut unthreaded bald ends.

Sandwich the two halves of the cut coupling over the threads of the two ends of the conduit. Temporarily clamp the two halves of the coupling tightly together in place.

Use a small 120V Mig welder to tack weld the couplings in place. A good welder will alternate his spot welds around as to keep the heat to the two couplings low enough as to not heat the conductors inside the conduit. He can spot weld the cut sides of the couplings completely closed if you want.

Because the welder will grind away the galvanizing somewhat where he will be spot welding the haves of the couplings back together, use a cold galvanized coating spray paint product to recoat the couplings.

Example Of

The welder will clean the spot welded areas good before spraying the cold galvanizing coating.

To finish the repair, (depends on how far you want to go), to make the repairs somewhat water tight, just one option might to be use an approved epoxy product. Just a guess taping the couplings and conduit would be a waste of time because of the shape/condition of the outer surface of the RMC.

Overkill?
Click to expand...
I will just say yes it would work, but still would not be a NEC compliant install, plus the risk of overheating conductor insulation during the welding process. If not going to be NEC compliant anyway I'd stay away from welding it, some kind of saddle clamp would be better IMO.
 
I can't help but think, eventually you have to stand back and ask how far are you willing to go just to scab it back together?

At some point, it just makes sense to pull the wire out and redo it properly.
 
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