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Thread: Locating fiber by chainlink fence near ATC electric tower

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    Default Locating fiber by chainlink fence near ATC electric tower

    Hello forum,

    Yesterday, a fellow locator and I were trying to locate a couple of fiber cables that ran along highway parallel with a fence(Runs the entire length of my the scope).

    I hooked up in a handhole(DC to sheath-just an "in and out" fiber) and followed the signal(Decent depth and current)-which was pretty clear, until it started getting to the fence-line.

    Then, the fence started to pick up the signal and was lost about 20' into the locate, I believe due to a water main and an ATC tower(Large metallic electric transmission structure) right next to the friggin fence. Each of us were on either side of the fence trying to pick up the signal.

    We tried 256hz-200khz, low and high power outputs, induction clamp, fish tape.. Same results, We couldn't get anything past a certain point.

    Just about giving up, I daydreamed of a device that could hook to metallic objects that automatically neutralizes foreign current...

    I gave the contractor a call and let him know the situation. But, I'm probably going to have to spend some time with them on site to find this sucker.

    Does anyone have any suggestions? similar experiences?

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    Default Re: Locating fiber by chainlink fence near ATC electric tower

    I have never had any luck around fences . A few of my damages thru the years have been around fences. Now , when I get around fences , marks go on both sides of the fence and I call the contractor and explain to him what you explained in your post posing the question. If there is a way to separate that signal from the fence , I have not figured it out to this day.
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    wise men talk because they have something to say and fools because they have to say something....plato

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    Mke
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    Default Re: Locating fiber by chainlink fence near ATC electric tower

    I've never tried it, because most of the time real world conditions prevent the application in a situation like this, but if you use a jumper between hook up points you are supposed to be able to help isolate the current on the intended lines and be able to negate the effect the fence has on it. Like I said though, Never when I needed to try it was it something I could practically do. Either too much distance for a jumper... don't have a spare 200'+ of wire in the work truck or the jumper would have to be ground across active roadways and the like.

    You mentioned a fishtape. If you tried pushing a fishtape in the conduit or spare conduit. I would just toss a sonde on a rodder and push it through, that should help you isolate the signal from the fence. You would just have to stop every 10-15 feet to locate, but if you have a second body they could push and you can mark. That will quicken things up.

    good luck

    mke
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    Default Re: Locating fiber by chainlink fence near ATC electric tower

    Have you tried locating from the other end of your target line? Might make a difference.
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    Default Re: Locating fiber by chainlink fence near ATC electric tower

    Quote Originally Posted by Tom Edward View Post
    Have you tried locating from the other end of your target line? Might make a difference.
    Unfortunately, the other Handhole the fiber runs to is still next to the fence. I don't trust it

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    Default Re: Locating fiber by chainlink fence near ATC electric tower

    Try getting a long length of insulated wire and snake it up the duct . Then un-bond both ends of tracer wire and at one end connected to un-bonded tracer wire, nothing grounded. Then at the other end connect to the tracer wire with one lead and the other lead to your wire. Now you have a closed circuit and if your transmitter allows set to a lower power output to reduce / prevent the fence from acting as an antenna picking up radiated signal.

    I have thought this would work best connected to the signal wire (not the sheath ground) CATV coaxial shielded cable for my inserted wire so the signal would perhaps be received, and marked, from the tracer wire.
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    Default Re: Locating fiber by chainlink fence near ATC electric tower

    I'm with MKE on this one. We had a fiber paralleling a guard rail and the only way we could locate it was with a sonde. We gps it after we got done so we only did it once.
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    Default Locating fiber by chainlink fence near ATC electric tower

    Quote Originally Posted by benjitsu View Post
    Yesterday, a fellow locator and I were trying to locate a couple of fiber cables that ran along highway parallel with a fence(Runs the entire length of my the scope).

    I hooked up in a handhole(DC to sheath-just an "in and out" fiber) and followed the signal(Decent depth and current)-which was pretty clear, until it started getting to the fence-line.

    Then, the fence started to pick up the signal and was lost about 20' into the locate, I believe due to a water main and an ATC tower(Large metallic electric transmission structure) right next to the friggin fence. Each of us were on either side of the fence trying to pick up the signal.

    We tried 256hz-200khz, low and high power outputs, induction clamp, fish tape.. Same results, We couldn't get anything past a certain point.

    Just about giving up, I daydreamed of a device that could hook to metallic objects that automatically neutralizes foreign current...

    I gave the contractor a call and let him know the situation. But, I'm probably going to have to spend some time with them on site to find this sucker.

    Does anyone have any suggestions? similar experiences?
    Greetings benjitsu! Last Thursday I had a Renewal ticket for an electric pole replacement along the north side of a busy street that lays east to west. Upon my arrival, there was old paint and flags visible on my three utilities in conflict for which I am responsible. I trust no one's paint but my own and this was the work of a my 16 month tenured locator/trainee.

    I used my RD8000 with f8 on the fiber using low gain, f33 on the gas main using low gain and I used my McLaughlin Verifier G2 utility locator with f38 on the water main.

    The pole being replaced is 8" south of a chain link fence. I found my 6" diameter cathodically-protected steel gas main laying parallel to the fence less than a foot south of the pole. I found my 8" diameter ductile iron water main laying parallel to the fence 2 feet south of the pole. I found my intrastate fiber laying parallel to the fence 2 feet north of the chain link fence.

    Everything my trainee painted was marked ass-backwards. My trainee marked the gas in blue, water in yellow and the fiber was mis-marked as 4" SOUTH of the chain link fence.

    When I quizzed my trainee, f33 was the only frequency used, the gain was too high and no sweep (attempt) was made on either side of the fence to find the fiber. The chain link fence was "messing" with the signal response and the assumption made was the fiber "must be" under the fence.

    My recommendations to my trainee:

    1.) Start out using a lower frequency. Work your way up to higher frequencies, if needed.

    2.) Make a complete sweep on each individual utility hook-up. Do your sweep on both sides of the fence.

    3.) Don't swing your receiver. Keep your receiver sweeps parallel to mother earth.

    4.) Once the utility is found, keep the gain low enough to get a signal response width the same as the diameter of the utility being sought after.

    5.) Don't lay down paint relying on "shitty tones." Double accessing the target utility works wonders.

    6.) If you can't find it within a few reasonable minutes, call for help.

    I hope this helps. Good Luck benjitsu! Luv Ya Man!


    -----------------------------------------------------------------------------------------
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    Default Re: Locating fiber by chainlink fence near ATC electric tower

    If you leave the splice case grounded, or ground it if it's not already, and use a ring clamp, you can isolate the legs of fiber. Strange but true.

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