British Telephone Sockets - Cabling Arrangements

Cabling Arrangements

Shown below are the cabling arrangements for both 4-wire and 6-wire cable. Initially 4 wire was used and many older installations still use it, until recent months however the 6-wire was the new standard, but the 4-wire, has now been reissued to all Openreach engineers as part of cost savings. The modern 4 wire is however the same diameter as 6 wire to allow engineers to use existing tacking guns and cable clips. Note that the wires in the 6-wire cable are coloured with two colours in a ratio of four to one in length, with the first colour mentioned being the predominant colour, e.g. if the colour of the wire is W-B then the wire will be coloured White for 12mm, then Blue for 3mm and so on. In other words it looks like a white wire with blue patches on it.

• Four wire cabling

• Six wire cabling

• Phone Socket - The principle of Bells in Parallel and Opt Out of Service

Strictly speaking, a textbook installation will only actually use pins 2, 5 (for the voice) and 3 (for the ringer). Having said this, most modern telephones contain their own ringing capacitor, to cater for the Irish telephone system which does not have a capacitor built into the socket, and 2-wire extensions, which means you can usually run your extension wiring with only pins 2 and 5. Often where multi-core cable is used, the remaining cables are used for wiring extensions on additional incoming telephone lines.