Fixing the wiring of a phone socket

[Graham.]

Yes, but the break is so close to the socket, and the socket is not even screwed to the wall, so why not reconnect the cable as before?

[JoeJoe]

A friend's new puppy bit through a telephone cable, and she doesn't have a dialling tone any more, and the house phone doesn't work. She asked me to have a look, so am planning to drop by tomorrow to see what I can do.

She sent me a few (pretty poor quality) photos, see here:

A few questions:

- There seem to be two cables entering the socket, one of them cut off. Can I assume that the one coming from "the outside" is the one that is cut off, and the other goes to an extension? I'll have a closer look tomorrow of course.

- I am familiar with BT sockets, but hers is an NTL (now Virgin Media I believe) one - she is on cable. Are they the same? (in terms of the wiring)

- There seem to be 3 wires connected within the socket. Is this because the only cable left connected is the one going to an extension? (as in

Any tips will be much appreciated.

[Alex James]

I think the third wire is a bell wire, causes phones to ring, which isn't used my modern phones and hence isn't necessary.

Why doesn't she just splice the wire that got chewed through, the blue and white pair.

Caution - I have no idea what I'm talking about. Well not much but I think it is enough.

[Graham.]

You are correct about the purpose of the two cables. The socket is an NTE5 and is (or perhaps was) also used by BT Openreach.

If you remove the two screws you can pull off the lower faceplate complete with the extension wiring. You will then see two more screws, undo these and the rest of the socket can be removed from the back-box. at the rear you will see two screw terminals marked A and B, note the colours of the wires, discard the stump, and rejoin the cut cable.

[Brian Gaff (Sofa)]

Yes indeed that is what they did here when I needed it to be moved. In those days I could see. Even if you don't understand it and you need to do a join, any old cheap terminal block with the right number of connections will do. Just strip the wires and join the same colours together. Phones are very simple things and the highest voltage you can get on them might give you a tingle but often the static shock you get from a car door is far worse in my experience. Might not look so pretty, but until the puppy is over the wire eating stage, its probably cheaper. A word of waning. If the puppy is a chewer of wires, for goodness sake keep it away from mains cables especially live ones!

Brian

[Reentrant]

Good video here that explains everything:

To join wires you ought to use a gel crimp - the video explains these.

[Terry Casey]

Yes, but surely VM didn't install it like that? I know that the contractors they use are past masters at cutting corners but surely not that bad?

I wonder if the puppy was playing with it and just pulled it off the cable?

Also, does this mean that there is another connector upstream somewhere and someone has moved the master socket.

If so, the master socket should be replaced in its original position and a new extension socket firtted in the current location - and screwed down!

[Brian Reay]

Good advice.

Plus, chances are each conductor is a solid wire which can be a s*d to connect inline neatly and reliably without the proper tools etc.

Solid wires are intended to be clipped into place and not moved around by people or puppies!

[Max Demian]

Or not. ;->

[John Rumm]

That looks like a normal NTE5 style master socket. The incoming cable is the one wired to two connections, in the back of the socket. These are often labelled A & B. They normally are carried on the blue pair, as appears to be the case here.

The extension wiring is onto the back of the removable face plate (that allows all the extensions to be disconnected for testing simply by unplugging the face plate). Its correct that only three wires should be connected. The connections here are normally numbered 2 - 5, with the blue pair being connected to 2 and 5, and then the orange on 3.

All the terminals on that box are Insulation Displacement Connections - basically you just push the insulated wire into the terminal with the right tool, and it cuts through the insulation at the point of contact.

The best way to fix it, if there is wire spare, is to remove the stub of wire left connected to the box, re-terminate the free end of the incoming wiring. Ideally you need an IDC punch down tool to do this, but you can do it with care using a fine tipped screwdriver to push the wire in from either side of the blades of the terminal. Don't push directly into the blades though - apply force onto the wire just beside them.

If there is not enough spare wire, then you will need to joint the cables. Either with a appropriate comms style junction box, or heatshrink and solder, or possibly IDC "jelly bean"[1] style connectors if you have access to them.

[1] Kind of like the wago terminal of the comms world!

[JoeJoe]

Thanks all for your replies.

Just been to see her and it was a 5 minute job - the incoming cable from the outside was a bit crashed in one spot where the little devil (a gorgeous friendly Samoyed) tried to sharpen its teeth. Luckily there was plenty of slack, so I just cut it off and reconnected. The extension cable in the photos has long been disconnected - just the ends were left inside the socket, so removed those altogether.

PS: the damage was caused on the puppy's 2nd day in the house, and it hasn't gone near anything it shouldn't have since.

Thanks again!

[Terry Casey]

Saliva is conductive, so perhaps it got a brief 50V warning shock when he bit through the cable!

[Andrew]

I thought you only got 50v when someone was phoning your number ?

[Ray]

Nope, its there all the time so the system and work out when you have picked up the phone and are about to dial.

[John Rumm]

You get ~90V AC when ringing, but 48V DC across the A and B wires all the time.

[Dave Liquorice]

I can assure you that a DEL has 50v DC on it all the time and it's enough to be moderately painfull. Not nice when you're up a ladder, in the pouring rain, soaking wet, attaching music, control and 4 wires (which don't have any DC on them) to a BT terminal block forgetting that said block has DELs on it...

[Marland]

Isnt the former the reason that the UK BS6312 phone sockets have a shutter as the ringing voltage takes them above ELV as their is a slim chance a child could poke a finger in just as the phone gets rung.

GH

[John Rumm]

Could well be part of it, although to be fair I have never given it much consideration. It could equally be just to keep crap out of the socket or look neater.

(RJ45s tend to be shuttered when wall mounted as well)