Short in telephone cable


Suddenly, we found that our phone registered as always off-the-hook.
After troubleshooting, I isolated the problem to a run to our kitchen which showed: 10 KOhm between red & green 0 Ohm between yellow and green
Both measurements were made with all equipment & connectors removed from both ends.
Any idea what might have caused such a sudden fault? (all visible parts of the wire are intact but I can't see the portion that snakes up behind the wall)
Is it usual to have 10KOhm (vs either a full open or short) between wires? Why is there also a full short between yellow and green?
It seems odd to me that this would happen out-of-the-blue without any of the wires being played with.
Thanks!
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blueman wrote:

I had a problem similar to this also in the kitchen and fortunately the break was close to the connection box and there was enough slack for repair. I figured that there is always a lot of activity in the kitchen and minor vibration of the kitchen floor after several years was enough to break the wire.
In another situation, with my business phone line in the house, the telephone company installer in stapling the wire around a door etc. had put a staple through the wire but it took a year to fail. Since all bills went the the company I was consulting for, I just had phone company repair and it was repairman that found fault. I think they still charged for their screw up.
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you have one line or two? red and green is one pair, yellow and black for line two.
assuming you have a modular jack on this line? try a differentr phone.
bet a cordless lives on this jack?
they are a major cause of always off hook or tied up line.
please tell us more
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No just a single line (and all phones were disconnected from the line to test it) but I was testing the other pairs too. I ended up rewiring to use two good wires but still a bit mystified about why it failed suddenly.
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This is a common malady on those systems that had the yellow conductor grounded at the protector and connected to the block (jack) to provide dial light operability.
You would do well to measure resistance between each conductor and ground. If any are grounded, remove them from the circuit. You very likely can still create a good pair by testing (and using) two, remaining "clean" conductors.
The cause, presumably, was a hastily inserted plug causing the grounded pin of an RJ11 connector to bend slightly, contacting one or the other side of the talk pair (center, two pins).
Disconnect the yellow conductor from its ground at the protector or, better (to avoid a slight imbalance) disconnect it at the jack.

Well, this shoots-down the above if, in fact, *ALL* conductor ends were cleared.

Although rare, this is something I encountered a few times during my career. Presumably, a nail or staple breeched the outer sheath during construction. X-number of years of garbage trucks shaking the home as they drove by eventually caused the staple to cross between two conductors. This would NOT, however, cause all conductors to become faulty.

Your terminology, or my understanding of it, is falling apart at this point. 10 kOhm is NOT a short in any sense. That's clean (open).
In any case, there should be greater than 10 kOhm between ALL conductors and each conductor and ground. Anything less and the cable is faulted.

Another VERY good possibility is rodents in the attic or crawl space chewing on the cable. BTDT. Good luck.
--
:)
JR

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But the fault occurs with the wire disconnected on both ends...

I ended up doing this to find two good wires.

Not in this case because no connectors on either end now.

Yup
Probably this is the answer.

Well open should be infinite resistance. To me 10KOhm means that there is something bridging across the two conductors even though both ends are clear and free (perhaps a staple as you mentioned or something else pinching through the wires and causing the insulation to wear away)

Hopefully not :(

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On Sun, 17 Aug 2008 18:27:29 -0500, Jim Redelfs

Once I thought I had mice... in fact, I might have had mice... and I thought htey were eating up my electirc wires, Romex. My stove fan didn't work. When I finall got around to fixing it, I figured out that I had disconnected it myself when trying to fix the dining room fixture. I think the problem there was that the rivet in the light socket was no longer contacting the wire, but I didn't find that right away, and waited so long for my next erfort I practically had to start from scratch.

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Are you on dial-up? Disconnect your modem.
Charlie

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Lots of good advice from other posters. A possible cause of these symptoms could be a lightning surge which shorted two of the wires and carbonized the insulation enough to create the 10K ohms between the others. Regardless of the cause, the cable is damaged and needs to be replaced. Fish a new cable if the old one can not be pulled out.
Don Young
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