Shorted Cat6E Cable

Hi all, happy to be here!
my first post so hope someone can help.

I have wired up flat with cat 6E cables. I have bought a network cable tester and found that there is a short between pins 4 &5 (blue cable and Blue with white bands) I confirmed with my multimeter that there is continuity between these two cables.

I am so annoyed with myself that I didn't test this earlier as now I have a wood floor down and not possible to take it up

My question is: do I need all 8 cables for an Ethernet connection, i.e. to connect my PC to a SKY modem for example

Running a new cable means surface mounting which really will look awful

Many thanks all

A fault in one of the conductors usually manifests as a break, it can take pretty hefty damage to cause a short circuit.

On the other hand, a fault in the termination at one end can easily result in a short circuit... I'm assuming you can get at the ends without major upheaval, give them a good examination.

Someone else will have to comment on how many pairs you need...

2 pairs for 10/100 , 4 for gigE

Hello Bill, perhaps I am using the wrong terminology. I cut the RJ45 off both ends and tested one end with a multimeter with the continuity setting. When I place the 2 probes on the Blue & Blue /White cable it signals continuity so I guess there is a screw or the insulation is damaged under the floor

I attached 2 new RJ45 modular inserts and used the network tester. It shows that the pins 4&5 light at the same time, I assume this means the same thing. Further when I use the main part of the network tester (i.e. without the remote end attached) pin 5 lights intermittently

Thanks for your response by the way

Hello huwwatkins,
forgive my ignorance of this subjects but does that mean I only use 4 wires (2 pair) for up to 100mps data type. Would that include sky boxes, PC, live streaming of movies etc across the web?

If so, which pins should I use or does the device (such as a wireless network card) detect that automatically?

For 100 meg working you only use 2 off the 4 pairs, these are the orange and green pairs (pins 1, 2, 3 and 6). For Gig you use all 4 pairs.
Your network card will sort out the connection, however having a short across 4&5 may upset the kit, might be worth removing these wires at the terminals on the socket.

In reply to a post by DIY_Johnny:

Hi all, happy to be here!
my first post so hope someone can help.

I have wired up flat with cat 6E cables. I have bought a network cable tester and found that there is a short between pins 4 &5 (blue cable and Blue with white bands) I confirmed with my multimeter that there is continuity between these two cables.

I am so annoyed with myself that I didn't test this earlier as now I have a wood floor down and not possible to take it up

My question is: do I need all 8 cables for an Ethernet connection, i.e. to connect my PC to a SKY modem for example

Running a new cable means surface mounting which really will look awful

Many thanks all

Hi, it sounds complicated connecting up different colour wires�

http://www.duxcw.com/digest/Howto/network/cable/cabl...

Take Note
The importance of the word "twist" in making network cables which will work. You cannot use an flat-untwisted telephone cable for a network cable. Furthermore, you must use a pair of twisted wires to connect a set of transmitter pins to their corresponding receiver pins. You cannot use a wire from one pair and another wire from a different pair.

Note that pins 4, 5, 7, and 8 and the blue and brown pairs are not used. Quite contrary to what you may read elsewhere, these pins and wires are not used or required to implement 100BASE-TX duplexing--they are just plain wasted.

Hi E7er,

I guess its somewhat lucky in a way that I damaged one pair only, although I assume the colouring is for standardisation and you could have one pair going to one corresponding set of pins (e.g. 1&2 swapped with 3&6 at both ends)

I have a look at running a new cable and its really not possible without a lot of work trying to find a new route so I guess I will stick to the 100BASE-TX duplexing as you note.

Perhaps I may need it in the future, not sure, but I guess its still find for streaming blue ray movies and the like

Thanks for the link, very useful

Many thanks thanks Rockh

You don't need all 4 pairs but you do need the blues so swap the blues for browns at both ends weather it's rj45 or rj jacks and you'll be golden.

No such cable as cat 6e lol, if you have continuity within the pair but showing a short the pair maybe touching if your using modals check the cuts sometime they touch, also look at the pins on what ever your patching into if they are damaged they could be touching its easy to do. Also if you made off your own ends and your a newbie it's probable just you, buy a bag full at maplins and keep trying

In reply to a post by Anonymous:

No such cable as cat 6e lol,

Category 6e

Category 6 Enhanced (6e) is an augmented specification designed to double transmission frequency to 500 MHz. By wrapping Category 6e in grounded foil shielding, full 10-Gigabit Ethernet speeds can be reached without sacrificing the max cable length of 100 meters.

That's cat6a.

No it says quite clearly Cat6e.

If it says 6e that is a typo or maybe a mistranslation (on an imported product). The standard that allows 10G ethernet for the full 90 metres of solid cable is 6a standing for "augmented" rather than "enhanced" (it is always possible a future iteration yet to be announced could be called "enhanced").

Whereas Cat 6 can run this speed for only 35 - 50 metres depending on the environment.

(in both cases I am allowing a bit for the possible patch cables at each end)

As usual for longer runs and/or electrical isolation one could use fibre.

Edited by prlzx (Sat 15-Sep-12 12:21:09)

You can buy some here http://www.cablingplus.com/t/cables/bulk-cable/cat-6...

or maybe some of this http://www.cablingplus.com/t/cables/bulk-cable/cat6a...

As others have noted, you only need two pairs for 100Mb/s, so you could go down that route, just clip the shorted pair at each end to avoid damaging your equipment and use one of the two spare pairs instead, that would be fine for a 100Mb/s link .

First thing to try though would be to check for a bad connection at one of the sockets, so you could try snipping the ends, re-terminating the connection and checking again (you did leave some slack cable, right?). If that doesn't fix the problem then you are looking at damage along the cable run, probably either a really bad kink or you've scraped it against something and stripped the cable to the metal. If that's the case, you might want to try and replace the cable - would it be possible to attach a new length of cable to the old one with some duct tape, then carefully pull the old one out from the other end, bringing the replacement cable through the same route with it?

As other posters have stated, you only need two pairs (4 cores) for a 100Mb/s link.

I have been running CAT6a since June 2009 and have never managed to have a short in a cable. I have even mistakenly drilled through one of the cables (In one side and out the other), and haven't managed to damage the cores or short them out. It still works at Gigabit speeds with no problems.

I would check the terminations on each end of the 'faulty' cable and re-terminate them just to make sure it wasn't a faulty connection.

Also have a look at the RJ-45 plug you are testing with and ensure the gold contacts are completely straight and not bent. Also make sure they are all at the same height when looking at it from the front.

My old RJ-45 crimp tool for some reason suddenly stopped pushing all 8 pins down correctly and only partially pushed down a few and pushed them sideways. Check whether your crimp tool may not be working properly .

For future reference, it's always recommended to test the cable immediately after installation .

As I indicated, that is mislabelled unless someone can quote the official document explaining what it stands for.

May even be the factory printing onto the cable had heard of 5e and assumed 6a was a typo, and "corrected" it. Stuff like that happens too. Don't be surprised if you see some 9e or e9 cable too (hint rotate a printed 'a')

Just because a vendor stamps a label on something, does not make it an official standard. But I will stand corrected if there is some new standard I have not yet seen!

Mislabelling and "made up standards" happened with earlier types of ethernet cable too, with claims to be suitable run longer cables that the guidelines state.
(the limit being not just about impedance and as much to do with maintaining reliable signal timings even in an unfriendly environment, rather than it just stopping working at 1 metre longer in all use cases).

Edited by prlzx (Sat 15-Sep-12 19:40:57)

There's plenty available. Why don't you buy some and compare it to Cat6a? http://www.icc.com/p/71/cat-6e-utp-solid-cable-600-m...

You could just cut off the current RJ45 ends and switch to using a different unused pair in-place of the damaged pair (since 100mbps Ethernet only needs 2 pairs).

Just make sure that the colours match up at both ends when you come to crimp on new RJ45 connectors ( :

I almost had a similar type of dilemma when installing Ethernet outlets in the loft room when it was being built, one end of the cat5e run got buried under the floorboards and sealed up.

Took us a good few hours locating it and fishing it back out.

http://www.ampnetconnect.eu/neptun/neptun.php/oktopu...
bored now

http://www.ampnetconnect.com/product_cut_sheet.asp?p...

Edited by deleted (Sat 15-Sep-12 22:46:23)

http://xkcd.com/386/

http://xkcd.com/927/

CAT6A is the TIA (ie- the people who helped make the cat 5/5e standard) standard and is the one that should be used.

The latest standard from the TIA for enhanced performance standards for twisted pair cable systems was defined in February 2008 in ANSI/TIA/EIA-568-B.2-10. Category 6a (or Augmented Category 6) is defined at frequencies up to 500 MHz�twice that of Cat. 6.

I think cat6e is a bit of a misnomer - even though its called cat6e it probably adheres to 6A standard (or at least you'd hope so)

Edited by deleted (Sun 16-Sep-12 00:02:40)

Whilst agreeing fully about testing immediately after installation and also any subsequent work in the vicinity of the cable, I would recommend if practical, crimping the plugs on the appropriate length of cable and testing BEFORE installation, from the experience of installing probably several hundred cables, ranging from current-loop, co-ax, Cat 5 etc.

For co-ax cable particularly, a TDR Tester is more appropriate. (TDR = Time Domain Reflectometer ~ "Pocket Radar Set".

But it's good to know it's available to buy, if the OP wants to get some more Cat6E.

In reply to a post by chris6273:

I have been running CAT6a since June 2009 and have never managed to have a short in a cable.

I have. Caused by over tightened cable ties and kinks in the cable that exceed the minimum bend radius of the cable. They are rare, but very irritating when it happens.

In reply to a post by chris6273:

I would check the terminations on each end of the 'faulty' cable and re-terminate them just to make sure it wasn't a faulty connection.

Also have a look at the RJ-45 plug you are testing with and ensure the gold contacts are completely straight and not bent. Also make sure they are all at the same height when looking at it from the front.

My old RJ-45 crimp tool for some reason suddenly stopped pushing all 8 pins down correctly and only partially pushed down a few and pushed them sideways. Check whether your crimp tool may not be working properly .

For future reference, it's always recommended to test the cable immediately after installation .

Agree with all this, by far the most likely cause is a faulty crimp, either the plugs or the crimp tool. Even with high quality plugs and a good, well maintained, crimp tool you will get a few faulty crimps every now and then. (Also very annoying)

In reply to a post by pmb00cs:

I have. Caused by over tightened cable ties and kinks in the cable that exceed the minimum bend radius of the cable. They are rare, but very irritating when it happens

Which is why the standards require the use of velcro ties and not PVC ones.

Which is why you should never let a muppet lose on cat6a cables with nylon cable ties and a cable tie tightening gun.