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[door_bell]

Folk,

Does anyone have pictures of the BT wiring side of the newer faceplates?

I don't want to ruin my 22 day uptime to get one.... 

Do they still wire the ringing cable (3, I believe) or is that not connected anymore?

I've looked at the wiring guides, but it's usually in reference to extensions, not masters.

I've got memory of an old faceplate having screw A+B - where does 3 go?

Does it affect DSL if it's not connected at master?

Cheers

[roseway]

The BT wiring only has two wires, A and B, connected to the back of the master socket. The wires connected to the faceplate are the user's responsibility. The ring signal is generated in the master socket, it's not part of the incoming connection to the property.

The input to the modem is also only two wires, terminals 2 and 5 in the faceplate, which are connected to the incoming A and B wires via the test socket. The only effect which the ring wire has on DSL is as a possible source of interference.

[door_bell]

Thanks Eric.

I hoped I wasn't going mad.

Someone was arguing with me that all phones need the 3 wire to ring - I thought that was only the real old bell style ringing phones and analogue stuff, which is hardly likely these days.

D_B

[Black Sheep]

To be pedantic, and just to add to the debate, only extension wiring officially requires the 3rd wire (bell shunt) to be connected in order to make the phone ring. The Master Socket only uses 2 wires, as it has a ringing capacitor in-situ.
In practice, most modern phones don't require this 3rd wire, and as Eric has pointed out, if it is connected it only serves to act as an aerial for 'noise interference', as it is in effect a single wire being introduced into the circuit, rather than being a 'twisted pair of wires', which as we know acts as a barrier against 'noise'.

Also, even the older style phones that used to rely upon the 3rd wire being connected, can utilise the dongle micro-filter as they have an in-built ringing capacitor. This allows them full usage of the landline phone, and the chance to maximise DSL speeds by the removal of the 3rd wire.

Hope this makes sense.   

[door_bell]

Hope this makes sense. 

Clear as a bell, connected by a 2 wire system using a filter! 

Excellent - cheers!

[Black Sheep]

Ha ha ………. that's the one. 

[BernardUK]

The input to the modem is also only two wires, terminals 2 and 5 in the faceplate, which are connected to the incoming A and B wires via the test socket. The only effect which the ring wire has on DSL is as a possible source of interference.

I know this is no concern of the customer, but I'd like to know anyway whether A and B connect to 2 and 5 respectively or the other way about. http://www.kitz.co.uk/adsl/socket.htm has a table in which A is 5 and B is 2, whereas your advice appears to be A is 2 and B is 5. Also http://www.clarity.it/telecoms/nte5.htm has a diagram and text saying the latter.

In my attic there's an ancient (GPO?) junction box in which I can see the incoming lines are coloured respectively White and Orange.

[Black Sheep]

It really doesn't matter anymore (apart from the rare answering machine/caller display). But as you ask ............

A (Positive Earth) goes to T5 (This would be the Orange incoming wire)
B (Negative 50v Battery) goes to T2 (This would be the White incoming wire)

Even if it is connected correctly at the Exchange, by the time it works it's way through a multitude of 'Joints' and gets to the top of the telegraph pole, it really is a 50-50 as to which way round the batt and earth are ?? Ergo, the Orange/White incoming wires could also carry either 'Potential' ??.

[BernardUK]

It really doesn't matter anymore (apart from the rare answering machine/caller display). But as you ask ............

A (Positive Earth) goes to T5 (This would be the Orange incoming wire)
B (Negative 50v Battery) goes to T2 (This would be the White incoming wire)

Even if it is connected correctly at the Exchange, by the time it works it's way through a multitude of 'Joints' and gets to the top of the telegraph pole, it really is a 50-50 as to which way round the batt and earth are ?? Ergo, the Orange/White incoming wires could also carry either 'Potential' ??.

Thank you, and it's interesting that it no longer matters in ordinary use. I just tested the incoming wires' potential difference, and sure enough the White is 48.6V below the Orange.

[burakkucat]

Connect the positive terminal of a DMM or DVM to a good earth and then connect each wire of the pair, in turn, to the negative. The wire that registers the largest potential with respect to earth is the B-wire and, thus, the other is the A-wire. 

[BernardUK]

Connect the positive terminal of a DMM or DVM to a good earth and then connect each wire of the pair, in turn, to the negative. The wire that registers the largest potential with respect to earth is the B-wire and, thus, the other is the A-wire. 

Yup. I didn't have a local earth nearby, otherwise I'd have done exactly that! And actually I didn't really need further confirmation. Still, your advice will be useful to others too, I expect.

[BernardUK]

A (Positive Earth) goes to T5 (This would be the Orange incoming wire)
B (Negative 50v Battery) goes to T2 (This would be the White incoming wire)

Just to complete the potential(!) for confusion (should it actually matter, which it doesn't seem to), the Wikipedia article on BS 6312 was updated only last month (15-Jan-2014) to add that the A/T5 and B/T2 voltages are the opposite of Black Sheep's spec:

The two wires from the exchange are denoted the A leg at -48 V relative to ground when the line is not in use and the B leg which is near ground potential when the line is not in use. The A leg goes to pin 5 and the B leg to pin 2 in the master socket. (although all equipment will work with a reversed line, so a reverse wired socket is not strictly a fault.)

The link is https://en.wikipedia.org/wiki/BS_6312#Master_socket_and_NTE5_Line_Box
I'll drink to anything that works.

[burakkucat]

A (Positive Earth) goes to T5 (This would be the Orange incoming wire)
B (Negative 50v Battery) goes to T2 (This would be the White incoming wire)

Just to complete the potential(!) for confusion (should it actually matter, which it doesn't seem to), the Wikipedia article on BS 6312 was updated only last month (15-Jan-2014) to add that the A/T5 and B/T2 voltages are the opposite of Black Sheep's spec:

The two wires from the exchange are denoted the A leg at -48 V relative to ground when the line is not in use and the B leg which is near ground potential when the line is not in use. The A leg goes to pin 5 and the B leg to pin 2 in the master socket. (although all equipment will work with a reversed line, so a reverse wired socket is not strictly a fault.)

The link is https://en.wikipedia.org/wiki/BS_6312#Master_socket_and_NTE5_Line_Box

Simple question: Which entity is the definitive source for correct information? (1) GPO / PO Tel / BT / Openreach or (2) Wikipedia? 

[Black Sheep]

Ha ha …….. Wales and Sanger were perhaps once on BT's books, B*Cat ?? 

[Black Sheep]

I thought I'd check our 'Bible' (ISIS Library) for proof positive, and it was as I said in the post above.
For any other engineers looking on who have access rights, and feel the need to waste 10mins of their life  ........ it is ....... ISIS directive : EPT/ANS/A016.