Any DIY tricks for locating underground wires?

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scuwp

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#265468 22-Jan-2020 21:09

In our house a provision was made for future outdoor lighting. "Somewhere" in our back yard there is a simple domestic wire running from the house out to the boundary fence where it was terminated. I only assume it is in conduit and at least the minimum legal depth. I would like to find where the end of the wire is without digging up half the yard and landscaped gardens so I can install some lighting along the fence.

I know where the switch is, I know where in theory it exits the house (underground cable warning), but the exact path from there or where it terminates is unknown.

Other than getting a person in with the proper tool, was curious if anyone has any DIY or MacGyver tricks I could try?

Divining? (I have done this before with water and was shocked with the accuracy - and I am a skeptic, does this work for electrical?)
App using NFC on a mobile phone?
Needle floating in a glass of water?
Look for where the cats always take a leak?

Open to any ideas, surely there are some good scientific (or not so scientific) based methods?

Lazy is such an ugly word, I prefer to call it selective participation

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#2405024 22-Jan-2020 21:10

Metal detector?

Ge0rge

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#2405025 22-Jan-2020 21:17

I have found that digging exactly where you would like to put a fence post / clothes line pole / anything else that needs foundations is a sure-fire way to locate any cable or water line. The ability to dig the post in somewhere else inversely affects the chances of finding something.

JeremyNzl

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#2405035 22-Jan-2020 21:37

If you have one end of it ,

Most sizable Electrical companys have the gear to do this.

They can even give you the depth.

Which is the same gear the before you dig contractors use.

The basic wall trace gear is not going to work at the depth your cable should have been installed at.

If the cable is not rated for direct burial it should be in conduit.

Delphinus

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#2405036 22-Jan-2020 21:46

I can relate to the fencepost "locator tool" effect. I was doing a proper fencing job and got the guy in with the tool to mark out the main power cable that came into the property. Turns out it ran EXACTLY under where my temporary warratah was placed. At a depth of 0.55m. I would estimate the warratah was 0.52m into the ground.....

Cable locating wasn't expensive, maybe $80+gst from memory.

neb

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#2405071 23-Jan-2020 00:41

Delphinus:
I can relate to the fencepost "locator tool" effect.

My parent's place used to be out in the sticks, nowhere near a sewer main, so the facilities consisted of a long drop out the back. When the hole it was over filled up, it was moved over a bit and the original hole capped with clay soil.

Many years later when the area was less out in the sticks, they put in sewer mains. My dad dug a trench from the house down to where the sewer main was. The guy putting in the piping walked down the trench to check it, and put his foot onto the thin layer of clay that was all that was left of the cap on the long drop contents... and went straight through.

He looked down and said "S**t". Never seen that term used more appropriately.

So just be glad you're only locating buried cables by digging...

MadEngineer

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#2405097 23-Jan-2020 06:59

I have it on good word that if water divining works for you, you'll also be able to divine for cables.

You're not on Atlantis anymore, Duncan Idaho.

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Bung

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#2405138 23-Jan-2020 08:58

JeremyNzl:
If the cable is not rated for direct burial it should be in conduit.

If the cable was taken anywhere near a fence an old style marker used to be a short piece of the conduit screwed to the fence.

geoffwnz

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#2405144 23-Jan-2020 09:07

Similar to the fencepost method, just digging a trench with a pick usually finds any wayward cables. Especially those not buried to the correct depth. Not 100% sure if phone cables were required to be buried down to 600mm as well, but the phone company at the time made short work of burying them properly and without charging me for "finding" them buried at the same depth as the height of the kerb I was replacing.

MotorDrive Rallying

tdgeek

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#2405146 23-Jan-2020 09:10

Im surprised that it exits the house underground and is buried. I have two such wires, one exits the foundation in one place, exits the path in another and are tied up.

Are there any builders plans available?

Sounddude

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#2405151 23-Jan-2020 09:21

Ge0rge: I have found that digging exactly where you would like to put a fence post / clothes line pole / anything else that needs foundations is a sure-fire way to locate any cable or water line. The ability to dig the post in somewhere else inversely affects the chances of finding something.

I found the incoming gas main that way. Unfortunately a bit too late, managed to put a hole in it. The pressurized gas was quite powerful.

Next Minute, 2 cop cars and 2 fire trunks.

Fun times!

MrMistofeles

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#2405157 23-Jan-2020 09:44

MadEngineer: I have it on good word that if water divining works for you, you'll also be able to divine for cables.

Yes the science is equally suited for locating cables.

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geoffwnz

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#2405159 23-Jan-2020 09:51

MrMistofeles:
MadEngineer: I have it on good word that if water divining works for you, you'll also be able to divine for cables.

Yes the science is equally suited for locating cables.

I genuinely can't tell if you are being serious or not.

Is there actual science behind divining?

*goes off to google*

Edit update: Yup, the statements that I quoted are accurate. Nice work guys. :-)

MotorDrive Rallying

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#2405173 23-Jan-2020 10:46

If you lived in Dunedin i'd do it for you..so you could move?

Matthew

skewt

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#2405192 23-Jan-2020 11:19

Probably wont include that cable but will show any council services..

you can request a free report for your property from beforeudig

https://www.beforeudig.co.nz/nz/home

scuwp

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#2405253 23-Jan-2020 13:32

MadEngineer: I have it on good word that if water divining works for you, you'll also be able to divine for cables.

Thanks I did wonder about that, will give it a shot. I was offered a chance to try divining a couple of years ago to find a water bore. I knew where it was and laughingly gave a it a shot after some basic instructions being a total skeptic. I honestly couldn't believe it when the wires crossed when I got to the exact location of the underground stream the bore was drilled to, repeatedly.

Lazy is such an ugly word, I prefer to call it selective participation

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