Cut underground electrical line question

   / Cut underground electrical line question #1  
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gmason

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About 8 years ago I cut the in ground power line(120v 20A) to my septic tank high water alarm with a tiller. Needless to say it was a mess. I spliced it the best i could do back then, I had to add about a 4ft piece of in ground rated electrical line. I soldered the wires and use shrink tubing and some die-electric paste. Still recently, the alarm failed and I tested the voltage on the wires coming into the box and found that the voltage getting to the box was only in the 10v range.

I dug up the line where the splices were made and found that the voltage at the splice was a little better at 24v max, still nowhere near 120v.

Now when I cut the line to test the voltage i found that there was some moisture inside the wire insulation and the copper had the green corrosion on the surface. I dug up another 2ft back on the line and cut it there too and got 35v max and the copper was still green.

I've got about 75ft left to the get to the house and just wondering if there are any ideas of what I should do. I'm very much just considering trenching a whole new line, a little deeper this time.

Can anyone tell me what might have happened, my guess is that the water found it's way up the line and found a place to short out the wire, but without digging the whole thing up, I don't know how I'd find it. I know coming out of the house it's 120v.

thanks
gary
 
   / Cut underground electrical line question #2  
gmason said:
About 8 years ago I cut the in ground power line(120v 20A) to my septic tank high water alarm with a tiller. Needless to say it was a mess. I spliced it the best i could do back then, I had to add about a 4ft piece of in ground rated electrical line. I soldered the wires and use shrink tubing and some die-electric paste. Still recently, the alarm failed and I tested the voltage on the wires coming into the box and found that the voltage getting to the box was only in the 10v range.

I dug up the line where the splices were made and found that the voltage at the splice was a little better at 24v max, still nowhere near 120v.

Now when I cut the line to test the voltage i found that there was some moisture inside the wire insulation and the copper had the green corrosion on the surface. I dug up another 2ft back on the line and cut it there too and got 35v max and the copper was still green.

I've got about 75ft left to the get to the house and just wondering if there are any ideas of what I should do. I'm very much just considering trenching a whole new line, a little deeper this time.

Can anyone tell me what might have happened, my guess is that the water found it's way up the line and found a place to short out the wire, but without digging the whole thing up, I don't know how I'd find it. I know coming out of the house it's 120v.

thanks
gary
Click to expand...

I can't recall if it is voltage that drops or amperage that drops when corssion comes in. Example- A battery cable that is corroded inside that goes from battery to starter. Battery could be 100% new and charged and sometimes there is enough resistance and breakdown of the copper that the current will not get to the starter- acts like battery is low or starter is bad. It's happened to me. I thought the cable was clean and then I looked under the insulation....OPPPS. Put a brand new one on.... thing turned over like it was a stuck pig.

Just for kicks, check it at the panel......

My suggestion, replace ALL of the line with new stuff rated for being burried. If you damanged it w/ a tiller (don't know what kind), but that seems really shallow. Even a 3pt tiller might get 8-11" down. I suggest trenching at least 18"-24" if you plan to to be gardening above the line.... if not deeper.
 
   / Cut underground electrical line question #3  
Well a cable trace probe could probably locate the bad spot within a few feet, but with that much past damage and the water intrusion you have noted, it is probably just better to lay in a new line. I mean you could dig and sweat and fix the problem on the old line(and seal every place you test) only to have the water weep a few more feet along and short it out again in a few weeks or a year. A new cable will be more work and cost, but you will only have to do it once... And running it deeper is a very good idea:)
 
   / Cut underground electrical line question #4  
The wire has either corroded open or shorted. Sounds like it could be open. You should be certain to use UF rated wire for direct burial. As stated earlier, you really should replace the entire run. Per code, direct burial cable needs to be at least 24" deep, so dig down. If you do need to do any buried splices, which I would recommend against, use the splice kits that are made for submersed wells. It is a crimp connector that uses a heat shrink rubber sleeve that is filled with a heat melt glue. When you heat the sleeve, it melts the glue and makes a solid water proof joint.

paul
 
   / Cut underground electrical line question #5  
The way I read it the line has been there for a long time 10 12 yrs. Far better and easier to just lay a new line.
 
   / Cut underground electrical line question #6  
Jimbrown said:
The way I read it the line has been there for a long time 10 12 yrs. Far better and easier to just lay a new line.
Click to expand...
Yeah, I wouldn't be surprized if the corrosion extends through practically the whole line. The corrosion will drop both the voltage and current through the line. By the way, did you use acid core solder on the wires? That's a big no-no, and maybe part of the problem. You should only use rosin core solder on wire. Save the acid for copper tubing.

Mike
 
   / Cut underground electrical line question #7  
I would replace the whole run also. It doesn't take much moisture in a wire to destroy the whole thing. The wire acts just like a candle wick drawing moisture along it's length.
 
   / Cut underground electrical line question
  • Thread Starter
#8  
techman said:
The wire has either corroded open or shorted. Sounds like it could be open. You should be certain to use UF rated wire for direct burial. As stated earlier, you really should replace the entire run. Per code, direct burial cable needs to be at least 24" deep, so dig down. If you do need to do any buried splices, which I would recommend against, use the splice kits that are made for submersed wells. It is a crimp connector that uses a heat shrink rubber sleeve that is filled with a heat melt glue. When you heat the sleeve, it melts the glue and makes a solid water proof joint.

paul
Click to expand...

Paul,thanks for the info, do you have a web link to these splice kits or what they are called? I've used that black dielectric glue/sealer with some great results. stays wet for a while, but does a great job of sealing up the exposed copper. any comments on that stuff?
gary
 
   / Cut underground electrical line question #9  
gmason said:
Paul,thanks for the info, do you have a web link to these splice kits or what they are called? I've used that black dielectric glue/sealer with some great results. stays wet for a while, but does a great job of sealing up the exposed copper. any comments on that stuff?
gary
Click to expand...

I've seen them at Home Depot in the plumbing area.

You can also look here:

well splice kit - - SHOP.COM

paul
 
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