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Thread: Clamp question

  1. #1
    Administrator TheCableVine's Avatar
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    Default Clamp question

    A few days ago I'm trying to locate a cable tv line. Basic setup: cable comes into ped, connects to the tap, and then goes back out the ped. The ped had been run over. I clamped on to a cable and can't locate anything. I clamp onto the other cable and it locates fine. I clamp on first cable and get nothing. I then notice on first cable that one of the green lights on the clamp isn't on. I put it on the second cable and both lights are on. I do this 3-4 times and it happens every time. So, I try to figure out why and I notice that the first cable was damaged when it was run over and a bolt from the tap mount is actually penetrating the plastic and touching the aluminum sheath. I pull everything upright and the bolt is now free of the cable. the sheath is no longer grounded by the bolt. I clamp back on to the first cable and both lights are now working. the cable locates fine.

    Why/how does a clamp detect that the sheath was grounded?

    Also, my colleague said that for the past two weeks only one of her green lights is operating on the clamp but everything still locates fine. I told her the light may be burned out. Who knows.

    Any thoughts on this?
    "Change does not always equal progress."

  2. #2
    Senior Member yahoo's Avatar
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    Default Re: Clamp question

    your clamp has lights???? WOW ! That is a good question.
    wise men talk because they have something to say and fools because they have to say something....plato

  3. #3
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    Default Re: Clamp question

    Quote Originally Posted by TheCableVine View Post
    Why/how does a clamp detect that the sheath was grounded? Also, my colleague said that for the past two weeks only one of her green lights is operating on the clamp but everything still locates fine. I told her the light may be burned out. Who knows. Any thoughts on this?
    One of the LEDs indicates "signal received" from the transmitter.

    The other LED indicates "signal transmitting", which tells you that the clamp is fully closed and the jaws are making good contact.

    Although the clamp was not specifically designed to indicate a dead short like the one that you encountered, that's essentially what it did. When clamped onto a dead short, so much current is transferred from the clamp's core that there's not enough left to activate the "signal transmitting" LED.

    It sounds like your colleague's clamp has a burned out LED. It will still transmit just fine but you will obviously lose some of the visual feedback that the clamp provides.

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