Cat 6 cabling issues

Gary Merchant · 31 Oct 2020 at 08:36

Hi. I’m in a new build house and the builders have run cat 6 cable from a number of different rooms to where the master line comes in. They connected the cables to wall plates but didn’t terminate the other ends. I have terminated them myself with RJ45 connectors. When I connected the tester to it I found a short on each cable. A particular (and different pin) is shorted on each cable. One cable has multiple shorts. I cut and re-terminated the ends 3 or 4 times and it’s always the same pins that are shorted.

Does this mean the problem is with the wall plates that the builders connected? Is it unusual for them to have not connected each plate properly?
Any help most appreciated. Thank you.

neil_g · 31 Oct 2020 at 09:46

Best to pull a wall plate off and take some photos.

Builders and regular electricians often don't know the first thing about data cabling.

Gary Merchant · 31 Oct 2020 at 10:22

Thanks I’ll have a look. Is there a particular standard of cable you would expect in a build like this? It doesn’t seem as heavy duty as my patch cables. Just wondered if damaged cables could also cause this problem?

bremen1874 · 31 Oct 2020 at 12:09

You've just got to hope they didn't cheap out too much on the cable.

Without any reference, there's no way to say whether it's suitably 'heavy duty' or not. It should be 23AWG and preferably copper rather than CCA (copper clad aluminium).

It's actually quite difficult to create a short when terminating cables. It's usually no connection or swapped wires. They may have managed to punch down two wires into a single IDC which will be obvious from a visual inspection.

Post some pictures and consider buying a cheap cable tester. Also, using a patch panel or another set of faceplates instead of crimping plugs on would be a better option.

Gary Merchant · 31 Oct 2020 at 12:31

Thanks I’ll get some picture sorted.

When I used my cable tester both the master and the remote were cycling through the numbers and both missing out one particular pin. I read somewhere that indicates a short? Is that right? For example on one cable both the master and remote had 2-8 lighting up but missing 1.

bremen1874 · 31 Oct 2020 at 12:32

It's almost certainly telling you that the wires aren't connected. They probably just need repunching.

pp111 · 31 Oct 2020 at 13:29

I would suspect this is something to do with the tester and in fact what's happening here is that they have wired the socket incorrectly. Thing is with some sockets they are not wired in sequential order. I mean I can't really see how they have shorts.

JohnStewart · 31 Oct 2020 at 21:07

If they have used Cat 6a tool-less keystone jacks, then these are made of metal and it is possible to get a short if the wire hasn't been trimmed enough and it's touching the metal casing.

bremen1874 · 31 Oct 2020 at 21:56

Wow, that's some imagination you've got there!

Flake87 · 1 Nov 2020 at 15:25

The stuff which runs around the home should be solid core and needs terminated with a patch panel. The RJ45 connectors should be cat 6 themselves and are slightly different because they are in a 'double decker' arrangement. Crimping the solid cores I found next to impossible, which is why there is such a thing as a patch panel!

bremen1874 · 1 Nov 2020 at 15:34

Flake87 said:
they are in a 'double decker' arrangement

Some are, some aren't. The biggest practical difference compared to a Cat5e plug is that they're designed to accept 23AWG cable rather than 24AWG.

Flake87 said:
Crimping the solid cores I found next to impossible

Easy enough if the plugs are designed to accept solid core cable. Again, some are, some aren't. Check the specs.

Crimping plugs onto Cat6 shouldn't be encouraged, but not because it's difficult.

Flake87 · 1 Nov 2020 at 15:37

Flake87 said:
The stuff which runs around the home should be solid core and needs terminated with a patch panel. The RJ45 connectors should be cat 6 themselves and are slightly different because they are in a 'double decker' arrangement. Crimping the solid cores I found next to impossible, which is why there is such a thing as a patch panel!

BTW as an aside, how have you terminated the RJ45 connectors? Which colour code standard have you used and how do you this to be the right one if you haven't checked the boxes on the wall ?

edGfaCTor · 1 Nov 2020 at 17:32

I had experienced something like this before and it was because of electricians using stable gun to tack the cable.

They always cheap out on the cable these people are all about as cheap as possible they don't care about quality which is why they are the ones doing a partial job.

Gary Merchant · 4 Nov 2020 at 20:13

This is what one of the panels looked like. One wire had been cut when they scored the cable and another was hanging off. I cut the cable and re-did. The other panels were like this too. So I cut the cables and punched again on them all.

Cable itself is AWG23 solid core.

One of the cables still has no connection on pin 1 (568B). I did both ends multiple times and the tester has no light for that pin. Any ideas? Thanks again for everyone’s help.

Gary Merchant · 4 Nov 2020 at 20:14

(Just trying to figure out posting images!!)

bremen1874 · 4 Nov 2020 at 20:31

That wiring is/was awful. What you often see when electricians have a go without any knowledge (not all electricians, some are excellent and do cabling on a regular basis).

For your NC wire. It could be broken somewhere along the length or could be the faceplate. The IDC terminals aren't designed for repeated use. They can spread and not cut into the wire properly, especially on cheaper faceplates.

If you disconnect both wires in the pair at both ends you can test the continuity with a DVM. Strip the insulation back and twist them together at one end so you have a loop.

kosymodo · 5 Nov 2020 at 17:14

Wow, that looks shocking! Makes me glad the electrician on our new build terminated the cables neatly, and without untwisting all the pairs like yours did!