Locate buried electric line?

[mbohuntr]

Rent a TDR (Time domain reflectometer)

 

[YLee Kioti]

I like your thinking, but I wonder how they work with a break in the wire. I'd have to identify which wire is broken (hopefully, not all of them).

The systems use a transmitter.
On edit:
Lift hot, neutral and ground. Use Ohmmeter to make sure that none of the conductors are coming in contact with each other. Possible wear of insulation and two conductors could be touching. Of course if this was the case then the breaker would be tripping. But does not hurt to check.

Lift the hot (black) wire, Neutral (lift from the panel buss), and also same process for the ground wire. Should get a clean read all the way through for conductor that is intact. However, the conductor with the open then the signal will fade from the receiver. Then you will accomplish location of the cable and identify which leg of the circuit is open.
So it would be a two step process.
Transmitter to the breaker side (of course make sure breaker is in the off position) that feeds the cable and then trace it out and when signal is lost, the break is located.
Repeat process at the user end of the cable, outlet, smaller panel etc. Follow signal path again until signal is lost.
Should be able to ascertain direction of cable run and get a good approximate location of a cable break.

Then break out the sharp shooter and dig!
Regards

Sure hope it makes sense. if not let me know I can ramble confusion with the best....j/k

 

[Mendonsy]

I like your thinking, but I wonder how they work with a break in the wire. I'd have to identify which wire is broken (hopefully, not all of them).

My Amprobe AT-4000 will find open circuits so I'm sure the AT-3500 will, and you can also identify which wire is broken. Mine only works down to about 36" but the AT-3500 should go deeper.
There is a small transmitter that you connect to one wire and a ground then follow the signal. If the wire you are connected to is broken the signal will stop there. If it is not broken it will follow all the way. Then you go back to the start and connect to a different wire to check it.

 

[Stimw]

I was trenching power to my new shop and I knew I had to go past the underground service to my house.
I borrowed one of the locators from a friend and it worked great!
You put the transmitter loop on the wires on either end (no connection) then you scan with the receiver and it tells you where the wire is buried.
I hand dug the area, located my service then dug the rest with my backhoe.
You probably need to just replace the whole wire though.

 

[/pine]

If it's just a light...(safety police stop reading now)...and you want to save some effort...
And it was typical UF or standard romex etc... hot, common and ground conductors...do a continuity test between all three conductors...if there are still two intact just use them even if one is the original (uninsulated) ground just use it for the common...
...to be on the more prudent side replace the breaker with a ground fault breaker...

 

[quicksandfarmer]

I've had good luck with this cheap locator I got on Amazon:
Noyafa NF-816-C Underground Cable Wire Locator Locate Pet Fence Wires, Metal Pipes, Electrical Wires, Telephone Wire, Coax Cable with Earphone: Computer Ethernet Cables: Amazon.com: Industrial & Scientific

I once traced a wire that was 42" down. If the wire is cut, the locator will stop sounding at the break. You could trace it from both ends and they should both put you in the same spot.

If your plan when you find the break is to dig it up and splice it, this should help. But I would consider just running a new wire.

 

[CalG]

Bring in a back hoe or excavator

Start with a shallow dig where you are sure there are no wires or pipes.

You will hit the wires first, then the pipes. IT'S A LAW! Murphy's law. ;-)

 

[Tractor Seabee]

The witching system works. I use 1/8" bronze welding rod bent into a U shape. It is more sensitive. I have found lines dead and alive down to around 4'. It also works on plastic pipes with water in them.

I have tested it against electronic detectors and proves almost 100%. Just like water dowsing, it doesn't work for everybody. Learned from an old Navy Chief at Utilitiesman school.The onl foolproof method is digging with a backhoe till you pull it up. Have some proof in bucket tooth gouges. Works every time for those the detectors don't find.

Ron

 

[100 td]

I have had success in locating underground power cables with a battery operated AM radio tuned to lowest frequency and it buzzes as you pass over the energised cable at ground level. Depends on ground and cable depth though. Make sure you don't have any radio frequency dog fences turned on as they cause interference. Turn radio up flat out. If it is your hot(active) conductor that is down, start near source and sweep across ground, keep following for cable location. Now, whether you detect the break will depend on a couple of things.
One, whether this works for you at the source and your cable isn't too deep.
Two, that the break in in the active conductor.
Three, that induction doesn't create enough continued signal in the neutral conductor.(It shouldn't, if it does, you may be able to turn the radio down and note a decrease in noise.)
Four, if the break is in the neutral, you may have to transpose the conductors at the source for testing.
With all this it's probably easier to get a proper detector in to do the job.

 

[Cord]

Dug into this a bit deeper last night and it appears my assumption was wrong. Initially, I tried to reset a GFCI outlet that was before the post light. The GFCI refused to reset. I tried checking for power and it was dead so I assumed the line had a break because the breaker was still on. I pulled the gfci last night and found that it had 120v to it. The device was bad. I had another GFCI on the shelf so I replaced it, but it wouldn't hold. You press the reset and it would immediately trip. There must be a little voltage leak somewhere down stream. I finally just twisted the wires together bypassing the GFCI and light worked. I think I'll just put an outlet in and not bother with the hassle of a GFCI.

I'm thinking about getting one of those wire tracers for some future use. I'm somewhat hesitant because they have such mixed reviews. Sure would love to hear more about peoples experiences with them.