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...