Replacing an old GPO jack plug

[Timbrook99]

I have an old GPO jack plug fitted onto a standard wall box. I want to replace it with an up-to-date socket so that I can use it. I haven't been able to find its details online so if anyone can help, I'd be grateful.

It was installed when the house was built, about 1970. It has five terminals:

1 - brown wires (2) 2 - orange wires (2) 3 - blue wires (2) 4 - green (1) 4A - brown which is looped back to 1.

There are two cream-insulated wires coming into the box, since this extension oulet is one of several in the house and the wiring goes on to the next room.

The fitting is flush to the wall with a standard metal box behind it, set into the wall exactly as a light switch would be.

The cream plastic face of the jack has "GPO" on it.

What is its model number and what which wires would I use when I replace it with a standard extension socket? Ta,

[Andy Burns]

You do realise that *you* shouldn't be touching that don't you?

Perhaps if your modem/fax/phone started "having intermittent problems" and BT had to send an engineer out, and you offered him/her nice tea & biscuits the "fault" would require a new faceplate to be fitted ;-)

[Steve P]

Do you mean like this?

so it will be part of a plan 4 or similar and you can't just replace 1 socket

[Andrew Gabriel]

You can't simply swap them. The jack plugs run the phone bells in series, and you'll need to change the circuitry for parallel phone operation, which will require rewiring the separate bell box you should have too (or disconnecting it). Probably best to consider it as starting fresh with a master socket where your two wires enter the house, and then wiring extensions where you want them. You could reuse the existing wire to avoid wrecking decorations. It also requires re-jumpering the phones if you want to continue using them. Obviously, you aren't really allowed to do this yourself though.

This change will probably also affect your line rental. People without modern phone sockets get a discount on the line rental (but pay rental for the phones). The jack plug scheme you have was also an extra rental charge option. It might be that your line rentral will drop if you get BT to do this officially for you. Don't know what they charge for doing it though.

[Stuart]

Thats what happened to me yeras ago .I had an engineer out to fix a line fault,he noticed I sytill had the old style socket and "suggested " I might like it modernised so he changed it and gave me a new style phone .i passed a few shekels his way and offf he went . Stuart

[Dave Plowman (News)]

The strange thing is they don't. On that plan the bells were in parallel - otherwise you'd have needed some form of switch when one was unplugged.

I've got the original wiring diagram of both the installation and phone strapping if you'd like a copy.

[Mike]

Order broadband and they'll replace it for free.

[Peter Crosland]

BT will replace it free of charge if asked. They will not be at all happy if you try to do so yourself!

[Steve P]

The bells are in series. There is a set of contacts in the jack that form a switch when the plug is unplugged.

[Andrew Mawson]

Sounds like a "jack 420" socket to me

[Frank Erskine]

It's actually a "Jacks 95A" and the corresponding plug is a "Plugs

420"...

As has already been said, this is a "Plan 4" installation, where bell/s in the phone/s and a fixed bell are all in series, with a break contact between terminals 4 and 4A in the jack/s.

If the line had been on "shared service" there would have been a "Jacks 96A", with six terminals.

[Timbrook99]

Perhaps I didn't explain properly. The jack socket in question is an extension socket not the primary one that was sorted by BT years ago. Thus I don't think BT will be very interested in it.

So, given the layout described and assuming it's a 95A, which of the wires do I connect to a modern socket? TB

[Stuart]

Would you not be better getting a length of the wire currently in use and replace what is there already. Stuart

[Frank Erskine]

It sounds a bit of a non-standard installation if you have a mixture of a modern "primary" socket and a 95A.

From your master socket you need three wires (a "pair" and a single) to go to the corresponding terminals of your new "secondary" socket. The colour scheme you mentioned indicates a "quad" so it doesn't really matter which actual colours you use, but you need to interconnect terminals 2,3 and 5 of the "new-style" socket.

[Dave Plowman (News)]

The BT diagram I have shows this recommendation when converting :-

Blue to 2 Brown to 3 Green to 4 Orange to 5

Green isn't normally used.

[Mike]

I thought they already owned it ;-)

[Toolmaker]

"Timbrook99" wrote

Have a look here

of useful info

[robertmlaws]

The jack plug is what you push into the socket, the socket is just called a "jack".

pedantic,

Cambridge

[Dave Plowman (News)]

Snag is in the good ol' manual exchanges etc, a lead with jack plugs on either end was known as simply a jack lead...

[Stefek Zaba]

At an IETF a few years ago, the rather flash Stockholm hotel - the one they do the Nobel Prizes in, ISTR - didn't have too many elevators, and were frequently clogged with a stream of IETF types trying to get in and out. I was *most* impressed by the speed with which one of the wags advised the assembled multitude to 'beware of geeks barring lifts'...