I just cut open a CAT5e cable since I wanted it for a project which required several twisted shielded pair cables. To my surprise there were 9 wires with isolation? I was under the impression that there were 4 twisted pairs, shield and possibly a drain wire (which I believe is not isolated). The last wire is of course not part of a twisted pair, what purpose does this wire fill?
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2Is the plug still connected to the cable? If so, why don't you check for continuity between the 9th wire and the plug's shielding? – Jonathan S. Dec 21 '21 at 14:20
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5A photo of the cable with isolation stripped and wires spread would be great. – fraxinus Dec 21 '21 at 14:33
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Interesting. Maybe they put the drain as a discrete wire ?(why?) – Lorenzo Marcantonio Dec 21 '21 at 14:54
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1That's surely the marketing wire: "We have put a spare wire in, in case one breaks, you have one already in place!" – Arsenal Dec 21 '21 at 14:58
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1Does it read anything about the make and model of the CAT5e cable on it? – Justme Dec 21 '21 at 15:07
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It could be 4.5 pair where the extra 0.5 is for making up an explicit signal ground connection between transmitter and receiver separate from the chassis ground. – vir Dec 21 '21 at 16:59
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It’s my understanding that CAT5 is unshielded by definition, this must be CAT6 or above. – Frog Jan 24 '22 at 18:52
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I stripped the wire and measured, seems like it is indeed a drain/ground wire. It has continuity to the shield.
LukasL
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1Hi, Lukas. It is not clear if you have posted this as an answer or if it is additional information for your question. If it is additional information then it should be added into your question, not posted as an answer. Your photo doesn't make it clear what wire you are talking about. Is it the outer braid or the red "wire"? – Transistor Jan 24 '22 at 18:51
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