Wiring BT Extension - Good Job I'm Analytical

[Stratmangler]

You have wired it back to front.
You need 2 to 2, 5 to 5, and 3 to 3.
2 & 5 are the speech circuit, and 3 extends the bell circuit.
It's probably easier to move things around at the socket end.

4 is there for historical reasons, and no longer needed, so you can leave it off in the socket.

[Stratmangler]

Is the socket screw terminal, or IDC?
IDC is insulation displacement connection.
IDC means that you do not strip the insulation back - it's push to make, and it's a gas tight connection. It requires a specialised tool.

[Ninanina]

Is the socket screw terminal, or IDC?
IDC is insulation displacement connection.
IDC means that you do not strip the insulation back - it's push to make, and it's a gas tight connection. It requires a specialised tool.

Hi Chris
Thanks for your reply. The socket is IDC and I have the tool for it

Are you able to give exact socket terminal colours I should have and then the same for the 431A plug? Very much appreciated

My OCD won't allow me to have the colours the wrong way round even though I know it'd make no difference as long as they matched both ends

[Stratmangler]

You have the wires paired out correctly, which is good.
It doesn't matter which way around they go, as long as you get pin 2 on the plug going to pin2 of the socket, etcetera .....

At the socket end you need to connect orange to 2, blue to 5, and green to 3, according to what you posted earlier.

I have wired the extension slave box as follows:

Blue Wire: Terminal 2
Brown Wire: Terminal 3
Green Wire: Terminal 4
Orange Wire: Terminal 5

I have wired the 431A Plug as follows:

Blue Wire: Pin 5
Brown Wire: Pin 4
Green Wire: Pin 3
Orange Wire: Pin 2

[Ninanina]

You have the wires paired out correctly, which is good.
It doesn't matter which way around they go, as long as you get pin 2 on the plug going to pin2 of the socket, etcetera .....

At the socket end you need to connect orange to 2, blue to 5, and green to 3, according to what you posted earlier.

Thank you so much Chris I really appreciate it

I did think it a bit strange that my plug pin number didn't match my socket pin number

So the brown wire and also pin 4 are not used

[Ninanina]

All re-done now and thanks again Chris

In the plug I did connect the Brown wire into pin 4 as it was easier to use it so all 4 lined up properly as you slide them in but didn't connect it at the socket end

Super service Chris

[Stratmangler]

A long time ago it used to be used on business PABXs to make the R button work, and permit users to transfer calls. It was known as ER, or earth recall.
The telephone cabling was all connected to a reference ground point via the leg on pin 4.
Most non BT PABXs used TBR (timed break recall), and didn't require the reference ground point.
Over time TBR has been universally adopted.

To answer your question, no, you don't need pin 4 to be connected.
Just leaving it disconnected at the socket will be good enough.
You can connect it if you want, but it'll not be doing anything. It's inconsequential.

[Ninanina]

Thanks Chris

I'll connect it just to tidy it up I think

Well it's all working

[Stratmangler]

Thanks Chris

I'll connect it just to tidy it up I think

Well it's all working

That's OCD for you - I wouldn't bother.
As for the rest, you're more than welcome