BT Openreach Master as an extension?

[LanciaSteve]

Hi,

First time poster with no telco experience just knowledge gleened from posts on this site, so apologies for all ignorance displayed

I believe I have 2 BT Openreach branded master sockets in the house, assuming a master socket is one with A/B terminals.

Both are connected by 5 multi-coloured wire cable to a junction box where the outside (4 core) BT cable comes in.

In the junction box 2 of the 4 BT cable wires are joined to 2 (of 5) wires of the cable leading to a master socket with a phone/ADSL face, these are connected the the A/B terminates. This works fine.

The other master socket has a single phone socket face and the A/B terminals are connected to 2 (of 5) wires of a cable but none of the 5 wires are connected at the junction box end. Obviously this socket doesn't work.

Could I turn this redundant master into a working extension by...

- disconnecting the A/B terminals wires
- wiring the 2 and 5 extension terminals to the 2 and 5 extension terminals in the working master

Even if the wiring is okay I've noticed from diagrams there is a link shown between terminals 1/4 called "C1" so not sure if I need to replace with an proper extension socket.

To avoid running a new cable between the sockets I am planning to use 2 redundant wires in the existing 5 wire cables, joined in junction box, to do this. Is this an acceptable frig or complete no no?

Any advice gratefully received. Thanks in advance

Steve

 

[cajar]

Hi,



Could I turn this redundant master into a working extension by...

- disconnecting the A/B terminals wires
- wiring the 2 and 5 extension terminals to the 2 and 5 extension terminals in the working master

No. if you do that the line will hum on both sockets. -50v in should only be connected to the A/B terminals, never the faceplate. From faceplate of the first to the A/B of the second is fine.

To avoid running a new cable between the sockets I am planning to use 2 redundant wires in the existing 5 wire cables, joined in junction box, to do this. Is this an acceptable frig or complete no no?

It's a no no, although not a complete one, known as backwiring. Better to run a cable between them, or use the existing cable to supply socket 2 with its feed from socket 1 and run a new separate feed cable to socket 1. Backwiring does get done though, by lazy bt engineers, and often works fine, so maybe worth trying and checking you're happy with the speed etc and if not, you can always run the new cable.

Also if your junction box is outside consider how you're going to connect the wires. Any exposed metal will corrode ie screw terminals. BT use scotchlock connectors.

 

[LanciaSteve]

Thanks for feedback. Will give it a go. Cheers.

 

[trowelhead]

Just out of interest, why is 'back wiring' a no-no?

 

[AlanE]

Think BT did some tests at their Martlesham Heath research centre which found it could degrade the signal because the same signal would be travelling in opposite directions in close proximity. Could be wrong though.