Jun 26, 2020
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Milton Keynes
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I have installed a new Cat5e cable (about 10m) between my network hub and a new office outlet. The cable does not light up with my cable tester (with new battery). I made a test lead with all pairs shorted out to plug into the wall socket and a second socket (to accept the new RJ45) wired to a choc-bloc. I get 0 ohms on my multimeter for each pair of wires, but still no lights on the tester and no signal detectable on a laptop. Any suggestions how to work out whats going wrong?
Thanks.
 
What sort of "Cable Tester" do you have ? Can you prove that it works on a known good cable... (you should'nt need to short anything out... ) ?
 
What sort of "Cable Tester" do you have ? Can you prove that it works on a known good cable... (you should'nt need to short anything out... ) ?
Its a JS-468, a very cheap basic unit. It works as expected on 1m patch leads, and indeed on two patch leads linked through a pair of linked socket modules. The shorted test cable was just a way to measure continuity when the cable ends are a long way apart.
 
So... you've proven that the tester is working, it has a new battery installed (I assume that it's a new one that you know is good), the patch leads you have, also test ok and the length of the cabling is <1000ft.... so it must be the cabling between the socket and the router.

The tester, from what I read of the manual, should tell you which connections are not good or if there is an issue with the order of those connections. So what do you see on the tester ?
 
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So... you've proven that the tester is working, it has a new battery installed (I assume that it's a new one that you know is good), the patch leads you have, also test ok and the length of the cabling is <1000ft.... so it must be the cabling between the socket and the router.

The tester, from what I read of the manual, should tell you which connections are not good or if there is an issue with the order of those connections. So what do you see on the tester ?
Nothing on the tester. No lights at all.
 
So.. revalidate that everything is as you think it is... then I'd probably remake one end, retest, then remake the other end. If no lights at all, and you're sure the tester works... from the manual it means that no connections are good !
 
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To clarify - the cable you've installed has a socket on one end, and a plug on the other?

Are you sure each pair is 'the right way round'. Testing by shorting a pair at the far end, and measuring the near end, would show 0 ohms if inadvertently reversed!, but the tester would not register?
 
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what ends are you using ?
 
One end is an RJ45 socket module (the office) and the other end (the hub) is an RJ45 plug. Yes I've checked that the orientation is correct, but I'll sleep on it and check again tomorrow, Its easy to convince yourself that your seeing what you want to see after a while.
 
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I assume you have the correct crimp tool for the plug and correct punch down tool for the socket.
the socket should have colours marked on it. use the colours marked B and the arrangement above for the plug and all should be ok
 
Trust you're connecting wires using a consistent convention pin-to-pin, rather than just following colours marked on the socket etc.
If you have a T568A marked socket, but you're wiring using T568B convention, it won't work (though in that case the continuity tests wouldn't pass!)
James beat me to it 🤪
 
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I have installed a new Cat5e cable (about 10m) between my network hub and a new office outlet.
Hope this doesn't sound rude - did you use infrastructure cat5 cable and crimp the plug, or did you purchase a cable with plugs moulded on, chop off a plug and connect that end to the socket?
 
Hope this doesn't sound rude - did you use infrastructure cat5 cable and crimp the plug, or did you purchase a cable with plugs moulded on, chop off a plug and connect that end to the socket?
Doesn't sound rude at all. This was cable from a drum because made-up cables would not go down the conduit. I then put the plug & socket on with the cable in place. Worked just fine for all the other outlets, just this one giving me grief.
 
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Doesn't sound rude at all. This was cable from a drum because made-up cables would not go down the conduit. I then put the plug & socket on with the cable in place. Worked just fine for all the other outlets, just this one giving me grief.
Thanks. Well it seems you've done all the right things. If it were me I'd try buzzing it out, eg from pin 1 on plug to pin 1 on socket just to make sure + and - aren't transposed somehow. I know that would be a pain.
If you happen to have a 10m RJ45 cable which you trust, you could plug it in the socket and bring the plug back to your fixed one, and do it all there 🤪. Otherwise a bit of wire and your jig re-purposed!
 
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To clarify - the cable you've installed has a socket on one end, and a plug on the other?

Are you sure each pair is 'the right way round'. Testing by shorting a pair at the far end, and measuring the near end, would show 0 ohms if inadvertently reversed!, but the tester would not register?
Sorted now. Turns out Avo Mk8 was on the money. The plugs were upside down (White/Orange on pin 8 not pin 1). I just got to a point where no matter how often I looked, I just saw what I expected to see, not what was really there.

Thank you to everyone whe responded and helped me get my head straight on this.

If you think a thing is foolproof, you haven't imagined a sufficiently creative fool.
 

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If you're a qualified, trainee, or retired electrician - Which country is it that your work will be / is / was aimed at?
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Retired Electrician

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