Split pairs at that level is terrible news. It's bad enough within the house.

The two wires of a pair are twisted round each other and that helps cancel out interference - I forget my school-day physics to explain why, but wires carrying a current create a magnetic field around themselves.

A split pair is when a circuit is made with a wire from one pair and the other from a different pair. Electrical chaos ensues. You may have seen blue or blue/white used with a white/blue, or orange/white with white/orange. If you see a blue/white with anything other than a white/blue it needs fixing. On home phone wiring this refers to terminals 2 and 5, that carry the signal. You may see a third wire on terminal 3, which should be irrelevant for this purpose but can cost broadband speed. See this easy page!

Yeah I did know what a split pair is and why its bad.
Cable must be bad if they have had to resort to split pairs
It just shows you how BT/Openreach will stitch you up rather than replace cable!


I wonder will happen when they just run out of any wires that work let alone pairs.

I suppose it would be better for us when they do as they would have to replace the cable surely?

I believe the OP is talking about split pairs in the Openreach network cable, not on the internal stuff Bob, so your description of the internal colour codes, whilst helpful, is not correct in this scenario. If punters are looking over an engineers shoulders whilst they dive into the world of UG cables, the colour codes are different, so don't be alarmed if what one sees bears no relevance to your description.

Yes, I agree. I know they are different. I described the colour codes he may have seen, or possibly easily can, in order to explain a split pair. That's why I specified that this was internal wiring.

That makes it also useful if anyone finds the post when looking for split pairs are in relation to their own property, or even fining burglar alarm wire there.

As for why a twisted pair is a good thing my understanding is that is has to do with the way interference is picked up on the two wires.

By twisting the wires the interference picked up on one is exactly mirrored by the interference on the other and they cancel each other out. At least that was the theory I was taught. If you use an untwisted pair you could be doubling the interference rather than cancelling it so it is not just a bad idea but a really bad idea.

This is the reason I avoid those flat extension cables.

In reply to a post by andyhurley:

By twisting the wires the interference picked up on one is exactly mirrored by the interference on the other and they cancel each other out. At least that was the theory I was taught. If you use an untwisted pair you could be doubling the interference rather than cancelling it so it is not just a bad idea but a really bad idea.

Not quicte exactly, but very very close in phase and amplitude!

Earlier this morning there was a Quinn's employee with a chamber open and a water proof junction open. It sounded as though he was not having a good time. In a short conversation he mentioned trying to find a suitable pair in fully loaded cables to get a customer back and working. He had a choice - Aluminium from there to cabinet which is around 500m or to use a split pair in full copper - although it may have needed to be one leg in one 50 pair and the second leg in another cable. He said there was absolutely nothing else available!

He had a choice - Aluminium from there to cabinet which is around 500m or to use a split pair in full copper - although it may have needed to be one leg in one 50 pair and the second leg in another cable. He said there was absolutely nothing else available!

What a doughnut ! And you wonder why us guys hate them ????

He would rather bodge to get the 'comp' on the task, when what he has done is create a bigger issue for others. Excessive management pressure is what I blame. [censored].

He did say he would be reporting what he had done and that at least the customer would have a basic service!

What other choice would he have?

well its not as if he could do the proper fix is it?

order some new working copper pairs