Voltage drop from underground power line - How to splice?

[Daniel Graves]

I have an old property that has a house and two separate garages that have underground lines direct buried supplying 240v power to them. Two power lines and two common lines (they look aluminum to me) and I'm not good with gauge size but the conductor is about the diameter of a pencil diameter. So, stupid me gets a good sized loader stuck in the mud about a month ago and it sank down far enough to break one of the power wires (I didn't know they were there at the time). I did a little research (not enough apparently) and used an aluminum block splice kit with shrink tubing. Made a good connection and everything worked great until two days ago. I'm now getting 120v on one of the wires and 95v on the other. I checked the breaker and they both leave the house panel at 120v each. I'm going to dig up the connection tonight to make sure that's the problem but I'll be shocked if it's not. LOL, I just reread this, no pun intended.

After that long intro I have a question... What is the best way to repair the break? Once I get it exposed again I'll take some photos but I wanted to ask the question here to get ideas.

Dan

 

[WorthFlorida]

Aluminum wire does not like contact with earth (dirt) material and moisture. It oxidizes very fast as you found out and shrink tubing is not waterproof and most likely not approved for this voltage. Post a picture of any labeling on the cable itself to be sure that it can be buried. What size is the breaker at the main panel? Breaker size is a good indication of the wire gauge but its not conclusive unless you can read the stamping. I'm guessing that it is 6 AWG since you think it is aluminum. Did this wire break only at one point or was it shreded? Was there slack to make the connection?

What you did for a repair is not allowed. You cannot have a buried connection unless it is in an approved box and at ground surface so it can be identified. In the future and you're not there and this connection burns out again, who will know where it is and its a hazard. Buried wire should be 24 inches below the surface, 18 inches if it is in conduit but this can vary with local codes (probably deeper).

 

[Sponsor]

 

[Stuff]

The underground splice kits are allowed in most places but, as you found out, they have a high failure rate.

http://www.gardnerbender.com/en/hsb-28

 

[Daniel Graves]

Thanks guys. There are several things pointing toward redoing the whole thing. Baaah. First is, it's not 2' deep, which is why I broke it in the first place, although where it's buried should've had a very low chance of problems and hadn't been a problem for probably 50 years. I'm guessing, I don't have much history on the place for that kind of thing.

An update: I dug up the connection last night (was a clean break in one place BTW), didn't open it up but moved it around to see if it would make the voltage move at all. Nothing. Voltage didn't budge. I also found a few "nicks" in the protective cover on a couple of the other wires, probably from a shovel. I did figure out which wire has the low voltage at each end but not sure which one in the ground, I don't know how to test them. I'm not assuming it's the broken wire now. 90A breaker with two wires coming off, going underground for about 100ft, then to a sub panel where one of the wires reads around 95v. I've done the simple stuff that I can do so I'm going to get some professional help with the rest. I'm coming to terms with having to replace everything, and if I plan on owning this property for a long time it's a lot easier to justify.

I'll probably be back here asking the best plan for replacing it. Conduit, wire, etc...

 

[Daniel Graves]

Okay, another update. We've decided to abandon the existing underground wires and pull power from the building next to the garage. As it turns out, there are two meters on the building that feed two halves, done a long time ago. We only rent to one tenant so they have to pay both meters separately. As luck would have it, the meters are actually closer to the garages than the house so we've decided to use one of the meters for both garages. Two problems solved.

Now I need to know the correct way to drop power in a trench between three buildings. Should I start another thread?

 

[Daniel Graves]

I had the problem wires looked at by an Electrician and we decided together that replacing the existing lines in the existing route would be best. The wire with the voltage drop was NOT the wire I repaired so I don't want to deal with the old wires. As luck would have it, we were able to buy some second-hand 2awg copper wire from a guy that had to close up shop after only six months in business. It's long enough but in two pieces. The Electrician said it's not a problem, just put a Christy box in where the union will be. That's my next question... where do I find info on how to do the box correctly. I've seen a lot of photos online and see a lot of them with conduit coming out of the ground in the box with wires just spliced together. Is this the correct way to do it?