telephone extension

[Monkeh]

The colour is not important as long as you use the same wire at both ends...

Not strictly true. The usual cable construction is twisted pairs, with each wire of a pair sharing the same colours. WHITE/blue and BLUE/white is a pair. WHITE/orange and ORANGE/white is another etc, etc.

Splitting the transmission path A&B wires (terminals 2 & 5) over two pairs can degrade both the speech and ADSL signals.

Point taken but in a short internal cable run it won`t make any difference,if the pair coming from the exchange to the end user is on a split pair it will effect the capacitance balance and when tested will coming back as a unbalanced pair.A few metres of internal will make no difference.

So it's fine to screw up inside because BT might have screwed up outside?

 

[simonpolly]

The colour is not important as long as you use the same wire at both ends...

Not strictly true. The usual cable construction is twisted pairs, with each wire of a pair sharing the same colours. WHITE/blue and BLUE/white is a pair. WHITE/orange and ORANGE/white is another etc, etc.

Splitting the transmission path A&B wires (terminals 2 & 5) over two pairs can degrade both the speech and ADSL signals.

Point taken but in a short internal cable run it won`t make any difference,if the pair coming from the exchange to the end user is on a split pair it will effect the capacitance balance and when tested will coming back as a unbalanced pair.A few metres of internal will make no difference.

So it's fine to screw up inside because BT might have screwed up outside?

Thats not what i said is it ?.If the pair is split(not to be confused with crossed) from the exchange to the end user it will have a major impact on your adsl,if its split for a few metres in the internal cable it will not.

If you have a new line installed now or a fault repaired you will now get a pqt test done using a laptop and a hawk tester this test is FAR superior to the old rat or eclipse test and will pick up any problems.

 

[Monkeh]

Yes, if the pair is split in the drop line it will cause a serious issue. However, a split pair (or unsuitable cable, like flat phone cable) in local wiring will also cause an issue, especially at greater ranges from the exchange.

Split pairs are unacceptable no matter where they are. So is flat cable.

 

[TicklyT]

I have seen a setup for a small business where several poor transmission and overhearing complaints were traced to a DIY move of two telephones. About 10 metres of 8-wire cable had been run from the NTEs to a double socket, with the colours terminated on one socket and the whites on t'other.

Just correcting that eliminated the transmission problems and raised the downstream ADSL speed from 512K to about 2M.

The old B/O/G/Bn 4-wire cable was one twisted quad construction.

Flat flexible cordage is just that - instrument cordage, used in about 2 or 3 metre lengths between phone and socket. It's not designed for fixed wiring, although many DIY extension kits do seem to use it.