? How to insulate/waterproof repaired underground power lines

   / ? How to insulate/waterproof repaired underground power lines #1  

docrocky

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10 or so years ago I ran #6 alum black coated wire from the house to the pole barn about 120 feet. Wire was a gift really being outdoor pole wire not needed on a project. Ran 3 lines so I could have 220 to run welder and air compressor. Lines were buried about 18 to 24 inches using a trencher. Soil is pure yellow sand and drains extremely well. Suddenly, only 110 at the barn and no event such as a dig etc to proceed the loss of half the power. After checking the circuit breakers at either end, suspected one of the lines had a corrosion problem. Turned the power off at the house and started digging by hand and found one of the wires corroded completely. This was right next to water pcp pipe running over top which I had double walled...did this about 8 years ago..and I must have put a small nick in the insulation and the decay process began slowly.

Now I am about to repair the disruption by side to side clamping but the question now is how to re insulate this rejoined wire and how to waterproof it. I am sure electrical tape alone will not totally block the moisture invasion, but what will. Is heat shrink tubing helpful? Or should I wrap it in a covering of J B weld or Devco? The rest of the wires are in mint condition without cracks in the black insulation. Why I didn't conduit it the first time, I frankly don't remember and with the cost of copper wire today, I want to make due with what I have.

thank You
 
   / ? How to insulate/waterproof repaired underground power lines #2  
Heat shrinks are what our company uses to repair URD secondary direct bury cables. In a pin h you can use bishops tape. It's a thick mastic roll that we use to keep water out of things. You have to cut it otherwise it just stretches. If its overhead wire and not direct bury, you may be on borrowed time.
 
   / ? How to insulate/waterproof repaired underground power lines #3  
This is one of those "all bets are off" type of home electrical jobs that make electricians, linesmen, engineers and inspectors cringe. Contrary to popular belief. If the light come on when the switch is flicked, it don't mean it's wired right.
Outdoor pole wire is not direct burial TWU , RWU or the like with thick rubbery insulation.
As stated burial in a conduit is always a good idea .
A short peice of AU wire and No-Ox and AU clamps. Wrap with self amalgamating tape. lots of black electrical tape and friction tape on top for protection.
New wire is recomended. It really isn't that expensive to run four conductors of #6 copper from the house to pole barn.
Major point of contention is the ground at the pole barn end. Some folk still haven't learned that ground is ground and neutral is neutral , they are not the same nor interchangable. Just because years ago when they didn't know any better and electrical outlets only had two slots. There were some mistakes made in design.
The barn had better have two 8 ft ground rods driven at least 10 ft apart,tied together with #6 copper and ran ONLY to the ground bar in the electrical panel. The neutral bar should only have the neutral on it . No bond screw of connection between ground and neutral.
Then a tingle filter tied between the ground and neutral. Or a bar ground burried from the house panel ground lub back to the pole barn's ground lug.
Any livestock in the barn ?
That said I know there is a zero chance that electrical safety will be more important than the bucks you "saved" in your wallet.
 
   / ? How to insulate/waterproof repaired underground power lines #4  
they make a type of heat shrink that has hot glue on the inside. Seals to the wire jacket. And i think i remember splice kits being sold just for underground wires.
 
   / ? How to insulate/waterproof repaired underground power lines #5  
I use Scotchkote 14853(Google it) by 3M to coat the splice.
 
   / ? How to insulate/waterproof repaired underground power lines #6  
a long time ago we needed to splice onto our underground satellite dish wiring to extend it to where our new house would be. rather than rebury all new fresh length of wire a guy at radio shack told me .. splice on the extra length of wire. first though, to slide a 1 1/4" diameter or so, about a foot long length of pvc pipe.
make the splice and then center up the pvc pipe over the splice and then fill with a caulking gun into the pvc , using silicone caulk, and fill that pipe from both ends til the whole pipe is packed full of silicone totally embedding and sealing off the splice.
I do not know what amount of voltages were present with satellite dish wiring, but the underground splice worked well for the 5 or so years that we used it.
my thoughts for an electric wire, would be to use the heat shrink tube with the glue inside it for starters , then envelope it into the pvc pipe with the silicone.
something to think about.
 
   / ? How to insulate/waterproof repaired underground power lines #7  
I have never used it for direct-burial, but Scotch 2228 mastic tape is great for weatherproofing/waterproofing above-ground stuff. I use it on RF connectors. Get a roll of regular old electrical tape. Wrap the connection with a single roll of that. Then wrap it with mastic tape, stretching the mastic tape as you go so that it joins to itself and becomes a single, form-fitting mass around the connection. Make sure to keep wrapping the mastic tape a couple of inches past the end of the splice. Then put another layer of electrical tape on top of the mastic tape. Technically, the second layer of electrical tape is to protect against UV, which isn't an issue underground, but I'd probably do it anyway, just on principle.

EDIT: the first layer of electrical tape is in case you ever have to remove the mastic tape later, which, again, probably won't be an issue in your case. If you don't put a layer of electrical tape down, the mastic tape is impossible to clean off--like scraping off putty. If you put a layer of electrical tape down, then make sure to apply the mastic tape another inch or two past the first layer of electrical tape, you can easily cut down and peel off the first layer of electrical tape if you need to get at the connection again.

Since this is going to be a permanent splice, and since it is not going to be exposed to UV, you can probably just use the mastic tape all by itself.
 
   / ? How to insulate/waterproof repaired underground power lines #8  
My advice: replace it completely. I had a contractor "accidently" cut my underground wires, so I phoned my electrician to come out and fix it. Of course it was a Friday afternoon coming up on a long weekend, but he came out anyways. He took one look at it and said it needed to be replaced, but since it was late Friday, he said he could splice it, BUT there were no guarantees that it would last. Since the equipment was already at my place, I offered everyone if they wanted to store everything here and do a proper repair the following Tuesday, no prob. If it was above ground, more than likely last a few years but especially not underground. He said it has to be perfectly sealed with absolutely no way of moisture being able to penetrate, or it will corrode again. He is also adimant that only dirt be used to backfill, absolutely no gravel at all should touch the conduit. Then he made me take pictures of the trench and take GPS waypoints for future reference. (and fire the hoe operator)
 
   / ? How to insulate/waterproof repaired underground power lines #10  
I think you'll find that the corrosion has wicked it's way along the wire for quite a distance. Whatever splice you do will only be temporary.
 
 
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