Locate Buried Cable 13

[rnd2]

On my rural property I am trying to map the underground location of an electric sub-main cable. This cable was laid before we purchased. There are no obvious obstructions and no other cables any where near but it apprently does not lie in a straight line between two outlets which I know come from it because I have dug two deep sighter holes to no avail.
I welcome suggestions.

 

[ScottyUK]

Hire a cable locator.

The link below lists some of the models available over here. No doubt there are others in your own locaility.

http://www.surveyexpress.co.uk/cableframe.htm

----------------------------------

If we learn from our mistakes,
I'm getting a great education!

 

[rnd2]

Thanks SkottyUK

 

[rmw]

I have already been laughed off the forum before, so it won't hurt my feelings when it happens here.

What I am about to relate was suggested to me when I was just a young engineering student, and while I was (very very) skeptical, I was also (very) desperate and (after havng dug up a lot of real estate to no avail) said 'what the heck'. I quickly became a believer. I later learned that the chief engineer at a renouned pump company (USA) had done some research on it, and that gave some credence to the technology behind it. It has worked for me, and on numerous occasions. Given your task, I would not hesitate to use it. I have used it on electrical lines, metal gas lines, plastic and copper water lines, and clay sewer pipes.

Take two long metal rods, coat hanger wires, welding rods, (I have seen it done with paper clips) and bend them so that you have a "L" shaped rod, one long side, one short side about 3:1, or 4:1 long to short. Hold the short leg in your hands right out in front of you, such that the two rods' long side are pointing forward. Slowly walk across the area that you thing the cables to be buried in. When you cross the cables, the rods will change direction so as to line up with the buried cables. The alignment will indicate the direction of the cables. That is to say if you are not crossing the cables at right angles, the rods will show the angle at which you are crossing the cables.

The theory (as I remember what I saw later) is that there is a magnetic field associated with the electrical cables which is an anomoly in the magnetic field of the earth around them, and the fields of the rods will tend to align with this anomoly. This is simplistically put, but that is the basics.

When I found out about this technique, I was about to begin my senior year of university, and I brought up the experience in a Senior level seminar class of some type. I was roundly laughed out of the class, but it was good natured, and all in good fun.

The technicians in the ME lab, being blue collar types, knew of the technique and believed in it, and made me a cart with two vertical tubes (pipe nipples) so that the "L" shaped rods could be carried with out human influence, and we used it it find buried lines in the vicinity of the engineering building, but the professors would not come down stairs from their ivory towers to look at our results. (We just surmised that they were afraid of finding out that it worked.)

To my professor's credit, when something was ultimately published on this by the aforementioned pump company engineer some 10-15 years later, he was a "stand up" enough guy to take the trouble to forward (we used mail back in those days) a copy of the article to me.

Good luck with your project.

rmw

 

[rnd2]

OK rmw, even though it is April, it is not April 1. It is going to cost very little time and no money to find out so I'm going to bite. Frustration and exhaustion will preclude anything scientific about this from a proving/disproving aspect , but ONE more hole is not too onerous.
So, to give it the best chance, what are the hardware requirements for this?
Checklist:
Voltage 240V
Wires, 1 active 1 return 1 earth wire
PVC protective conduit conduit.
PVC insulated copper wire rated 20 amp continuous.
Existing current requirement 100 Watt
Current........ need to be on?
Optimum length of short leg
Optimum length of long leg
Optimum diameter of rod
Optimum metal
Best to hold rods in hands or indirectly with insulated [wood] bearing blocks?
What is the best time?
Weather conditions?
What else?
For all of the above WAG quite acceptable.

 

[VEBill]

It's called 'dowsing' and further information can be found all over the

http://WWW on

various paranormal websites (along with crop circles, telepathy, spontaneous human combustion, etc.).

Good luck.

 

[tinfoil]

The bizarre thing about dowsing is that, for some people, it actually seems to work much more often than random chance (but not good enough to use as a real tool).

We had an employee (now retired) in the position of cable locator, and he would often use a single dowsing rod to predict where his fancy expensive locator would find the cables, and he was pretty close on a high percentage of cables. He could even find them when they weren't energized.

I assumed that he was somehow pulling our legs by simply 'guessing' based on what he saw previously on our system maps, until he twice dowsed the proper location of two cables that were mapped incorrectly, and 'located' via dowsing a cable that had been abandoned and wasn't even drawn on the map.

No one was able to replicate his results, and he himself had no idea how he did it!

 

[resqcapt19]

I've seen utility company locators find underground utilites with their dowsing sticks, where their expensive electronic equipment couldn't. I have no idea how it works because I have seen empty PVC conduits located by this method.
Don

 

[rmw]

rnd2, I have the following observations:

Being a basic magpie, I know that I still have that article that my college professor sent me, but I wouldn't have a clue where to begin to look for it among my engineering "stuff". I can't picture that I would have tossed that, based on the abuse I have taken over this topic over the years, and yes, even here. Anyone should feel free to pile on. I have big shoulders. Should I ever come across it, I will try to scan it, and post it to this thresd.

Second, the place I learned about this concept was at a summer youth camp, with hundreds of people in attendance, and the word spread fast, and soon everyone was doing it (males mostly-girls didn't seem to care), hence the comment I made about having seen it done even using paper clips.

Kids, campers and staff, were driving me nuts showing me places where they had gotten indications, most of which I already knew about since I worked in the camp maintenance section and was basically familiar with the layout of the camp's utilities.

We did make one observation, though, and it was that people who tended toward red hair, very fair skin, and/or freckles couldn't do it. I had some people almost in tears since most everyone else could do it, and they couldn't. Don't ask me to explain that, I am just giving imperical results.

Once, while walking through a parking lot at a major paper mill in the south of our country, I encountered a workman looking (unsuccessfully) for a water line buried under the asphalt. I went back to my car, dug out a pair of coat hanger wire rods that I used to carry with me back then (about 20 years ago-and I was still associated with the youth camp as an adult adviser) and got them out and went to searching, much to his astonishment and incredulity. I got an indication, and when you work with it enough, you learn how to do some triangulation and determine depth as well, so I said dig here and it will be "X" feet deep. I walked back to the car put the rods up, and went on into the mill to a meeting with the power sup't. Upon my return a couple of hours later, they were digging right where I had said, and had found the line at about the depth I had indicated. I asked him why he chose that location to dig, and he said he had no choice, since his instrument had produced no useful results, and he had to dig somewhere or get fired. He still had an incredulous look on his face.

As to your questions, I already gave the 3:1 to 4:1 leg length ratio, although all that is really needed for the short leg is just enough to get a grip on in your hands.

I have used 1/8" welding rods as well. So the range I have seen it done with ranges from paper clips to welding rods.

If I am going to seriously do this, I usually use a metal coat hanger wire, cutting away only the portion up at the top near the hook.

Since my Mamma taught me to get in out of the rain, I mostly have done this in fair weather, but wouldn't hesitate to try it in any season of the year.

It is not the current you are detecting, but the magnetic anomoly of the wire, conduit, and yes, even the trench in the overall magnetic field of the earth around them. I have detected both active and inactive electrical circuits.

I generally hold the rods in my hands, and only use wooden handles when a non believer is accusing me of using my hands somehow to infleunce the rods. (if it works for you, you will know when they move that you are having no influence on them. I just hold the rods out in front of me waist to chest high, elbows resting on my tummy. I give the rods a slight (very slight) downward tilt in order to keep them to the front. Get them too level, and your momemtum change will cause them to veer to the side. A little gravity assist by tilting them (only a couple of degrees off of horizontal) will keep the positioned. When they indicate, they will climb back up that slight inclination easily.

I hope you are not red headed. Good luck.

rmw

Oh, and PS to resqcapt19, I, too have found empty PVC lines with the method. And to everyone else, I have found this is an area where there is no grey. You either believe in it or you are a scoffer. No in-between.

 

[rnd2]

Thank you rmw. That is useful information. I am going to do a dry run before the weekend to get a feel of how it may work. I don't have red hair. What you say about the wires moving by themselves once they "locate" an anomaly seems amazing to me but when I first saw light defract and didn't understand how and why was pretty amazing as well. Still is really.
One more thing.
While there are no other cables I am certain there are any number of tree roots. Will these cause problems in regard to accuracy?

 

[rmw]

Most of what I did regarding this was in a heavily wooded area (the camp was located in the piney woods) but I don't remember looking for such a line that close to a tree where roots were much of a problem. When we did dig up lines, however, roots were always a problem, and sometimes were the culprit that caused the need to dig up a line to repair it.

Generally, however, the lines had been run in lanes (usually along roads or trails) where the trenching equipment used to bury the lines could operate, so we weren't that close to roots.

rmw

 

[rnd2]

rmw,
Practice run No.1
Apparatus. 2 galvanized steel wire coathangers cut, straightened and bent at rt angles with leg ratios 4:1.
Degree of difficulty walking and keeping the rods ~ 5 deg below the horizontal and pointing forwards ? About the same as negotiating a long corridor with a too full mug of coffee but skill improves after about 30 mins.
After 30 minutes of praticing how to hold the rods steady I went to where I know exactly a cable exists and crossed over it very slowly at right angles to the buried cable.
The left hand rod swung to the right, the right hand cable swung to the left and after a few seconds they pointed 180 degrees in the opposite direction. I was very close over the cable but not dead over it.
Is this typical?

 

[Higgler]

Just a Radio thought.
AM radio gets pretty darn noisy when you drive under power lines. Maybe it gets loud when you walk above them too.
Take an AM radio out to your underground wire location and see if it picks up the interference. An external long wire antenna on the radio may help.

kch

 

[efp]

This is one of things you have to actually see to believe. When I was much younger my father and I were digging a trench in our yard and wanted to avoid a buried water pipe. I puzzled over how to find it while my dad went back into the house. He emerged with 2 coat hangers which he bent into the previously described L's. The hangers separated and my dad marked the spot. We dug down and, of course, the pipe was there.

I didn't believe it. I accused him of guessing or trying to trick me but he swore that it worked. He said that they used it at his job (power construction for a major electrical supplier) to find buried pipes and cables.

I finally got him to put on a blindfold and let me watch as he walked across the property in a new location. I marked the spot where the L's spread and then dug a small test hole. Sure enough, the pipe was within 6 inches of my marker and about 2 feet deep.

I'm still skeptical about a lot of things but I have to lean toward belief in this case.

EFP

 

[rbulsara]

For what it is worth, I second rmw. I tried this with #8 copper wires and it worked. Only thing is the "L" rods will " align" indicating anything under ground such as a water pipe, metal or plastic, copper condcutor or a cable.

So if there is too many things in the same area, its not good, but if you are reasonably sure only a few things are in the area..this gizmo does work.

You can imagine, the looks on the bystanders on a all "women" collge campus, while my client's electrical supervisor, who insisted on demonstarting this to me ,and I were walking around with these in hands..

I have not tried this for offical purposes.

 

[rmw]

rnd2

This method takes some practice to get the 'feel' for the turning of the rods. Sometimes they cross and sometimes they turn outward. It is random.

I usually walk over the search area, and let the rods cross, and keep going past the indication point and then let them uncross, and try to find the mid point of where that occurs.

Combining the momentum effects, all the while trying to maintain constant velocity in order to minimize them, with the movement of the rods from a straight ahead position and back will come with practice.

I will tell you now that I did find my buried plastic water line the first time I used this method, and my worker, a large teenage camp worder cut the water line on about the third or fourth stab with a sharp-shooter type shovel, so I had that kind of accuracy on the first try.

A man who was the son of a plumber had noticed us digging up half of the real estate in front of the boys bath house at the camp, and had made the rods, (borrowing my Kleins to do it) and did a brief search, but in what ultimately turned out to be the wrong area. I was still in the skeptical mode, not giving him much credence, so in disgust, he just set the rods on my truck, and walked off. Hours later, and much digging later, in desperation, I picked up the rods and said 'what the heck.' The rest is history.

I like your analogy to carrying two full cups of coffee down a long corridor.

Keep practicing, and it will come, and you will get good at it.

rmw

 

[RalphChristie]

rmw

Certainly worth a try and also worth a red star.


(or what did you said about red heads? - can I edit the stars? Hehehe No, just joking - I am not a red head, and this info is really worth a star)

 

[rnd2]

rmw. Thanks again for the advice. I was late home tonight (dark) and so have postponed practice run No. 2 til Friday. The problem with P run No 1 is 30 mins trying to learn how to hold the rods out straight and true is hard work. As rwm says, I'm confident P. run 2 will be less onerous. Come Saturday P run 3 and then I'm going try it for sure.

 

[VEBill]

Don't forget to set your dowsing rods to 'electrical cable' for this search. As you know, the default setting is 'water'.



After you're done, adjust the rods to 'Dowsing Challenge' and you can score a quick US$110,000.

;-)

 

[resqcapt19]

I have also found that if you are not crossing perpendicular to the under ground line, that only one of the indicating rods will move and it will align itself parallel to the underground line. The rods will also respond to overhead lines.
Don