Ethernet colours for phone extension

I'm using some ethernet cable to run an extension from the master Openreach box. I know there are three cables need connecting, does it matter which colours I use as long as they are the same each end?

Planning on using three colours from three different pairs. Any problem?

YES that will be a problem.

The voice is carried on 2 & 5 so they should be a twisted pair and in keeping with BTs colour code, use Blue/White for 2, White/Blue for 5, then if required - some handsets still require it, Orange/White for 3.

Use blue and blue+white for the pair and orange for the third one.

Thanks
Dan

As said, good practise (for best performance) is to never “split” a pair. It’s a big no, no in LAN data comms and applies equally to broadband.

The twisted pair acts to both cancel the outward emission of “noise” from the circuit as well as helping to reject ingress noise (also known as alien crosstalk) from other services or source of electromagnetic interference.

In a category rated data cable there are four (for the purpose of this thread) fairly much equal twisted pairs in order of pair numbers; blue-blue/white, orange-orange/white, green-green/white and brown-brown/white. It’s up to you which pair you use, but convention and established practise dictates the blue-blue/white pair for the line and solid orange for the bell wire. You really don’t need the bell wire with modern phones and it’s just another possible source of interference for a broadband connection, so usually best left disconnected at the IDC terminal, unless you absolutely need it.

In reply to a post by Pheasant:

In a category rated data cable there are four (for the purpose of this thread) fairly much equal twisted pairs in order of pair numbers; blue-blue/white, orange-orange/white, green-green/white and brown-brown/white.

I would not say fairly much equal - they are quite different. For one manufacturer it is:

Bl 72 turns/m
Gn 65
Or 56
Bn 52

So, Blue is just under 40% greater than Brown. Others will not be exactly the same but not far away.

Thanks, I'll go back and use a pair.

But... would not using a pair just cause interference or total loss of connection? My trouble is there are two ethernet cables at each end and its trial and error to know which is my 'live' extension. So far neither work...

In reply to a post by MHC:

In reply to a post by Pheasant:

In a category rated data cable there are four (for the purpose of this thread) fairly much equal twisted pairs in order of pair numbers; blue-blue/white, orange-orange/white, green-green/white and brown-brown/white.

I would not say fairly much equal - they are quite different. For one manufacturer it is:

Bl 72 turns/m
Gn 65
Or 56
Bn 52

So, Blue is just under 40% greater than Brown. Others will not be exactly the same but not far away.

For the purposes of this thread and running broadband over (with a combined bandwidth well under 100 MHz, more like 20 MHz) - the twists per metres of the various pair colours make no odds in reality.

Do you know why the twist ratios vary?

Edited by Pheasant (Tue 25-May-21 11:42:41)

No, using a pair reduces interference, both received and transmitted.

You can still get basic continuity /connectivity if you just match the wire colours at either end - but the broadband performance as said won’t be ideal.

Ethernet at 10 or 100Mbps will use just 2 pairs in a cable: orange-orange/white and green-green/white. The blue and brown pairs are unused. 1000Mbps Ethernet will use all 4 pairs though, so you may need to do some testing to see what’s what.

Well using the 'correct' colours isn't helping! Dead extension using either of my cable options. I know at least one of these ethernet cables is good as it was in use a few months ago.

I'm reasonable sure the cables are connected at the Openreach Master in the funny wee connector next to the 'test' socket. I'm not meant to strip the wires for that, am I? It looks as if it does that for me. Maybe...

In reply to a post by Pheasant:

… the twists per metres of the various pair colours make no odds in reality.

Do you know why the twist ratios vary?

To reduce crosstalk between different pairs within the same cable, but I think you almost answered your own question in an earlier post.

Edited by prlzx (Tue 25-May-21 12:01:52)

Where on the master socket are you connecting the wires? You should only be connecting to the front face plate and there should be a set that is for phone (filtered) and a set for broadband (unfiltered). If you are connecting to the wrong set of connectors then it will be filtering out the broadband signal. Obviously for this to work the front section of the face plate needs to be plugged in to the master. If you only have one set of connectors on the front face plate then I think you will find they are for phone extensions only and therefore filtered.

EDIT : Just thinking, have I got the filtering the wrong way around again??? Is it the phone line that is unfiltered?

Edited by ian72 (Tue 25-May-21 12:20:44)

There’s really only two ways depending on the age of the plates to connect, either IDC (no coloured insulation stripping required) which is ‘punched down’ onto the block and the blades in the connector cut the insulation (and theoretically) make a gas tight seal from the blade edge onto the copper. You should be able to stack three conductors into a single IDC on a BT plate.

The second type is screw terminals which need the insulation stripping back.

Sound to me like you have a broken conductor somewhere or an imperfect connection.

Apologies it was a rhetorical question. 😀

Yes indeed and it’s really only a concern as I’m sure you’re well aware of when all four pairs are being used for high speed data transmission. With broadband it’s neither high speed (well not reallly!) and there’s only a single pair in use. So it’s a moot point to bring up twist pair ratios - which is why is said what I did earlier on the thread - that here it doesn’t matter from a performance perspective which pair carries the service. Pair colour choice is down to convention and “administration” - e.g. blue was always the ‘voice’ pair in structured cabling.

Edited by Pheasant (Tue 25-May-21 12:08:55)

I did wonder but it was a 50/50
and I've always assumed it is no coincidence that the pair with the highest twist ratio was the preferred/central voice pair given some telephony-only cable runs in old buildings go way beyond the 100m.

Edited by prlzx (Tue 25-May-21 12:13:17)

You can blame AT&T / Bell Labs for that 😎

Worked it out! No line because I hadn't put the faceplate back onto the Master socket. If TBB did emojis I'd use the facepalm.

Yes, I'm connecting to the single extension connector I see when removing the faceplate on the master to reveal the test socket. There's only one on this and its unfiltered. I could hear noise on the extension until I used a filter there.

👍 Happy Days. It will all be a “lost art” before too long (if the seemingly increasingly millions of premises passed by 2025 rollout plans are to be taken seriously)

Folks will be asking how to extend their fibre connections etc etc. What’s an SC/APC guv? 😂

Those ‘funny wee connectors next to the test socket’ are a royal PITA. Fiddly to use, not ‘craft sensitive’

The wires do NOT need stripping, the act of closing the ‘catch’ if the wires are set up right, will make the metal part act act as an IDC as the wires get pushed home.

Without wishing to sound rude … you are setting it up correctly aren’t you ?

Use a single twisted pair .. blue/white and white/blue for instance … untwist the pair apart for a few centimetres, and pull the wires to makes as straight as possible. (Don’t bother with a bell wire unless the phone the other end is archaic)
Lift the clear ‘cam’ part (it comes out to about 40 degrees) hold both wires some way back from the end and guide the wires into their correct holes in the cam .. blue to 2 white to 5 is the usual way. They should pass through the holes, through the 3mm gap after, and into the locating holes after that ….. whilst still holding the wires in position, use your other hand to to close the cam and wires therein onto the IDC. It should click shut quite happily, if it doesn’t … you’ve done something wrong.

If you have done it wrong, remove ALL wires, trim a couple of mm off and try again.

If you are anywhere near as decrepit as me, plenty of bright light, your glasses, and a swear box are essential.

Give me a Krone termination every time. These ones are cheap and [censored].

Since you often have to do the above faff whilst head down, [censored] up, preying to the great God telephony, I find it simpler to correct a few inches of wire into position before attaching the NTE to the back box … you can then gel crimp these wires onto those of the extension wiring going away, thus avoiding a lot of the heartache these poxy things cause ….. but this depends on you having crimps, crimpers etc readily to hand.

Worked it out! No line because I hadn't put the faceplate back onto the Master socket. If TBB did emojis I'd use the facepalm.

They do ……. 🤦‍♂️

In reply to a post by Zarjaz:

Without wishing to sound rude … you are setting it up correctly aren’t you ?

Feel free to sound rude! Sorted now anyway. I now understand how the test socket works by disconnecting the extensions. I already knew that...

In reply to a post by Pheasant:

👍 Happy Days. It will all be a “lost art” before too long (if the seemingly increasingly millions of premises passed by 2025 rollout plans are to be taken seriously)

Don't get me started. I'm in a Fibre First exchange. Every street has been fibre'd up and is live or will be in a week or three. Except me and a couple of streets nearby. No plans, not happening now or anytime soon. Meanwhile, two miles away, choice of 500Mb Virgin fibre, Gigabit Openreach and in a couple of weeks asynchronous Gigabit via CityFibre.