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Patch cord/cables go bad over time causing system to act erratically

Patch cord/cables go bad over time causing system to act erratically

Here is the setup:

NBX 100
3Com 4300 Switch
3Com Ethernet Power Source
Just voice going to the phones, data is on a separate network.

The NBX 100 is connected to the 3Com 4300 with a single patch cord. The 4300 is then connected to the Ethernet Power Source via a patch cord per port. The Ethernet Power Source then has a patch cord per port going to the patch panel. Then those lines go to each connector in the wall and we use a long patch cord to each phone.

Here is the problem:
We had the whole setup working fine for years before the first instance. You would be on a call and the voice would be dropping in and out. You would try to ping the NBX and you would see packet loss. Going over to the 4300 instead of seeing a solid combo of lights, they would be flashing on and off erratically. Once you look closer you would see that one port was flashing or not flashing quite like the others. If you then unplug the patch cable going into the 4300, the system would stabilize and everything be back to normal. I narrowed down the problem to the long patch cable that was coming from the wall to the phone. If you would replace that patch cord with a new cord, the problem would stop. We would go a month or two and the problem would happen again and we would have to track it down to the next phone. Almost every single time it was the ethernet cable that came with the phone that would be the culprit. I think on a couple rare occasions it turned out to be a patch cable connected between the 4300 and the Ethernet Power Source or the Ethernet Power Source and the patch panel.

About two years ago, after another instance or two of this happening again, I replaced all the cables that went from the wall to the phone with Cat6 cables. Everything has been running fine and not erratic behavior. Until today. Phones started dropping voice, couldn't ping or login to the NBX. Went and watched the lights on the 4300 and soon found the port that had the problem. Unplugged the cable from the phone and everything is back to normal now.

Anyone else ever run into these problems? What is going on with the cords that is causing them to go "bad" and cause the issues? What else can I do to prevent this or just replace all the cables to the phones every two years?

RE: Patch cord/cables go bad over time causing system to act erratically

Based upon your finding I would say your 4300 is going bad. I suspect that it's supplying more power than it's supposed to be and burning your cables up. Do you have another unit to swap it with?

One way to confirm that is what is going on is to cut open a patch cable and inspect the pairs from one end to the other. You'll probably find a bare spot or burn. If you do take that 4300 out of service immediately because it's a building fire waiting to happen.

RE: Patch cord/cables go bad over time causing system to act erratically

I suspect your 4300 is going bad and burning your cables up. Open up those bad patch cables and look for a bare spot or a burn mark, sure it's only suppose to low voltage going down the line but if the transformer is gone it's no longer regulating what is being produced. If you find a burn spot take it out of service immediately because it's a fire hazard.

RE: Patch cord/cables go bad over time causing system to act erratically

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RE: Patch cord/cables go bad over time causing system to act erratically

kwtaylor I took the patch cable and a multimeter and checked each line for continuity. Each strand checked out fine and also there was no reading on any other line.

RE: Patch cord/cables go bad over time causing system to act erratically

Tore apart the cable and inspected each strand and saw nothing physically wrong with any of them.

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