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There is a (~80m) Cat5e cable that stopped working a few days ago. I tested it with two different cable testers, and with both of them the result was: "short". Usually I get this result if there is a device connected on the other end of the cable, but this time I get "short" even if the other end is disconnected.) If the cable is plugged to switches on both sides, the lights on the switches remain off. I tried re-crimping it on both sides, but that didn't solve the problem.

What could be causing the "short" ? What does "short" could mean in practical terms in this case?

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Where was the cable installed? Is it likely to have sustained damage? – Andrew Oct 24 '13 at 6:07
@Andrew it's on a shaft that runs for a few floors. I guess it might have sustained damage somehow... – xirtyllo Oct 24 '13 at 8:21
up vote 10 down vote accepted

Short in electrical terms is an abbreviation for short circuit. This generally means that there is an unintended connection between two points allowing current to flow where it should not.

In your particular case it means that your cable is damaged and that two or more of the conductors are connected together.

And it's one single cable, there's nothing in the middle

A single cat5 cable consists of 8 conductors.

enter image description here

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It bears mentioning that usually this is the result of damaged interconductor insulation somewhere in the middle of the span. – Falcon Momot Oct 24 '13 at 7:02
@Iain "And it's one single cable, there's nothing in the middle" what I meant is that i'm sure that there is no switch nor patch panel in between the two ends that i'm testing.. – xirtyllo Oct 24 '13 at 8:16
@xirtyllo but is there a crimp or cut? – mpez0 Oct 28 '13 at 20:34

It means the cable has a short circuit. Test from each end and check the distance result. The cable is probably damaged in the middle somewhere. Maybe mice, maybe damaged when pulled. If it's not in a wall it's probably been pinched in a door or by furniture... or it's been stepped on one too many times.

John S

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What is the difference between the accepted answer and yours? – Deer Hunter Jul 15 '15 at 20:07

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