Best way to seal sch 80 pipe underground w/ old direct burial cable?

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newservice

Senior Member
Farmer friend of mine we patched a fault in the old direct burial 100a 3 wire feeder to his garage. Put it in a section of pipe where it crosses over the cast sewer pipe so it doesn't fail again there. The direct burial cable is old, kind of a composite rubber casing, ( it does say 'Direct Burial' ) so an old electrician I know said to just pump 100% silicone in there and call it a day. I'm with him. Anyone done something similar?
 
kwired

kwired

Electron manager
Location
NE Nebraska
newservice said:
Farmer friend of mine we patched a fault in the old direct burial 100a 3 wire feeder to his garage. Put it in a section of pipe where it crosses over the cast sewer pipe so it doesn't fail again there. The direct burial cable is old, kind of a composite rubber casing, ( it does say 'Direct Burial' ) so an old electrician I know said to just pump 100% silicone in there and call it a day. I'm with him. Anyone done something similar?
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If you waterproofed your repair I don't really see why you need such a seal.
 
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newservice

Senior Member
kwired said:
If you waterproofed your repair I don't really see why you need such a seal.
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did not have a good way to waterproof each conductor as the insulation on the individual old conductors was quite deformed due to age and the rope just inside being stuck on them, the usual splicers and shrink tubes wouldn't have worked. so just taped the butt splicers with rubber and vinyl and slid the pipe over them.
 
Smart $

Smart $

Esteemed Member
Location
Ohio
I agree with your old electrician friend. The conduit is just a sleeve, so there are no sealing requirements.
 
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newservice

Senior Member
Smart $ said:
I agree with your old electrician friend. The conduit is just a sleeve, so there are no sealing requirements.
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Right. Once the old cable jacket is opened up and the individual wires broken out, there is no way to seal the whole thing back to the cable jacket without it, so stuffing it in pipe made sense. Then the only thing to seal is where the jacket breaks out of the pipe.
The old electrician friend was a former Navy electrician and spent the rest of his time in his own electronics company. Am sure he has buried his fair share.
 
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big john

Senior Member
Location
Portland, ME
Don't use silicone caulk. It emits acetic acid that will attack the conductors and cause serious corrosion.

You could try potting compound or Scotchkote. Latex caulk may be fine, but I can't guarantee that.
 
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newservice

Senior Member
big john said:
Don't use silicone caulk. It emits acetic acid that will attack the conductors and cause serious corrosion.

You could try potting compound or Scotchkote. Latex caulk may be fine, but I can't guarantee that.
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The silicone was only used to plug the ends of the pipe.
Too late now we went ahead with the silicone. Oddly enough he had made other splices in it about 3 years back, no inhibiting grease, only butt connectors, and vinyl tape and buried it. They were largely just fine. lol
 
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
A Scotchcast kit will work. I'm surprised they still make them. They were a messy PIA 30 years ago with warnings a mile long even then.

We would have crimp butt spliced (staggered) each conductor with individual heat shrinks then topped it off with another heat shrink over the whole thing. A PVC sleeve doesn't hurt but IDK if it helps much either.
 
kwired

kwired

Electron manager
Location
NE Nebraska
ptonsparky said:
A Scotchcast kit will work. I'm surprised they still make them. They were a messy PIA 30 years ago with warnings a mile long even then.

We would have crimp butt spliced (staggered) each conductor with individual heat shrinks then topped it off with another heat shrink over the whole thing. A PVC sleeve doesn't hurt but IDK if it helps much either.
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Probably would do about the same you mentioned. Have done that in a pinch when I didn't have a UF splice kit handy. Do they make such kits for larger then 10 AWG?
 
Smart $

Smart $

Esteemed Member
Location
Ohio
kwired said:
Probably would do about the same you mentioned. Have done that in a pinch when I didn't have a UF splice kit handy. Do they make such kits for larger then 10 AWG?
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Haven't looked lately, but I believe so.

If I recall correctly, the splice is required to be done with a listed direct burial cable splice kit. Otherwise, you'd have to use a junction box rated for direct burial with the appropriate cable connectors, backfilled with premium-grade, easily excavated aggregate... or use a handhole enclosure.
 
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kwired

kwired

Electron manager
Location
NE Nebraska
ptonsparky said:
IDK. Never looked. If it isn't on the shelf at the suppliers, we go to plan B. Nobody ever calls to have a fault repaired 2 to 3 weeks before they need it. At least not in my neighbor hood.
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Same here, but they will call you because they need it now even though they knew there was a problem 3 weeks ago:roll:
 
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