This topic

5C master linebox extension

Duke500 — Wed, 03 Sep 2025 09:52:19 GMT

Hi, I have a BT 5C master linebox with single socket on the front and with no extensions using Virgin broadband with voice over internet calls- only ever used for incoming calls by relatives.

I want to add an extension using discreet cat6 wiring to a new flush cat6 RJ45 outlet a few metres away, thus relocating the router to a better, more central location.

1: can I fit a flush metal wall box where the incoming line is and put the relevant parts of the (currently poorly-fixed) 5C box onto this, running the new cat6 cable away discreetly?

2: if I am only running data to the extension, should I just be connecting to terminals 2 & 5 on the rear of the 5C master faceplate?

3: I am using cat6 components everywhere and will connect using T568B colour code

Thanks in advance for your expert comments

Re: 5C master linebox extension

WSH — Wed, 03 Sep 2025 10:29:08 GMT

Very unclear what you are trying to do here. Is this a telephone extension or a network cable? (The two are very different). Also, Virgin used to use co-axial cable and were very touchy about DIY extensions, as the power levels had to be rebalanced if the line length changed.

You talk about connecting wires 2 and 5. That suggests a phone extension. While you could make cat 6 work, it is way over the top specification-wise and you would only use 2 of the 8 wires.

To give an answer we really need to be clearer about what you are doing and why. I take it the NTE 5C is a BT 431 socket (i.e. phone socket)? Sorry.

Re: 5C master linebox extension

Duke500 — Wed, 03 Sep 2025 11:01:20 GMT

Hi WSH, thanks for your reply. So sorry I am not clear in my description, I'll try again:

I have a BT incoming copper line (only option in my area), terminating in their linebox marked "OpenReach Master Socket 5C"

I have a router plugged straight into the only socket on the linebox but wish to move the router to a new location.

I am separately running cat6 (little extra cost but to future-proof) around my property (a bungalow, so relatively easy to run to the chosen destinations) from a switch in the roof space, connected to the router via the cat6 wiring.

My goal is to make a short (4m) dedicated run of cat6 cable direct from the BT linebox to an RJ45 faceplate outlet at the new router location, plugging the router into this with a very short lead.

I was going to use cat6 everywhere since I have loads of it and can't see an advantage in a downgrade for just this part of the system?

Thanks for any thoughts

Re: 5C master linebox extension

iniltous — Wed, 03 Sep 2025 12:11:15 GMT

You said you have Virgin broadband , so unless you have two completely separate services , one with Virgin and another with BT , then what has the Openreach master socket got to do with your Virgin service , it’s completely unrelated to your Virgin broadband.
If you only have Virgin (I suspect that’s the case ) anything you want to add to their IP phone service such as adding a wired extension socket has nothing to do with BT , Openreach or the OR master socket .

Re: 5C master linebox extension

Duke500 — Wed, 03 Sep 2025 12:43:11 GMT

Hi iniltous, thanks for your reply.

So sorry, we are now on Sky broadband with line through BT.

Hope that addresses the confusion.

Re: 5C master linebox extension

licquorice — Wed, 03 Sep 2025 15:09:54 GMT

@Duke500wrote:
So sorry, we are now on Sky broadband with line through BT.

No you are not. Sky broadband has nothing to do with BT. You are confusing Openreach with BT, they are separate companies.

Re: 5C master linebox extension

iniltous — Wed, 03 Sep 2025 15:25:58 GMT

As stated Cat6 cabling is unnecessary over engineered but will work , AFAIK an NTE5c won’t fit into a standard electrical patress box , but apart from that all you are doing is extending the incoming pair when the master socket is assembled , you still need this wiring to be detachable from the master socket for fault location reasons, so not the rear of the master socket but the extension connections (blue IDC socket AFAIK ) your Sky telephony will be IP from the router so no separate filter should be required.

Re: 5C master linebox extension

Duke500 — Wed, 03 Sep 2025 18:36:13 GMT

Thanks iniltous, I was going to use the linebox's 'extension' idc connector (clear plastic on mine since it is later than the blue version apparently) for my cat6 but it has only 3 terminals and these are marked "2, 3 & 5" respectively while the cat6 has 4 pairs.

If I am connecting the other end of the extension cable using the T568B colour code, do you know which colours I need to connect to the linebox terminals "2, 3 & 5" to end up with the data connection I want please?

Many thanks

Re: 5C master linebox extension

WSH — Wed, 03 Sep 2025 19:03:46 GMT

Sorry, been out all day.

You are still trying to mix two different standards. A phone line at one end and a network cable at the other end. They are two different things. What you want is something more like CW1308 cable and a secondary phone socket at the other end.

Re: 5C master linebox extension

Anonymous — Wed, 03 Sep 2025 20:12:34 GMT

@Duke500

As well as there being no point whatsoever in using Cat6 cable, there's also no point in terminating with an RJ45 socket. Just means you'll need to buy an RJ45 to RJ11 cable to connect to the router rather than using the existing cable.

Re: 5C master linebox extension

pddco — Wed, 03 Sep 2025 22:41:49 GMT

@Duke500 Thinking that at some point, in the perhaps not too distant future, you may be offered a fibre to the home connection, could you not make the relocation of the router easier for now by buying a long white RJ11 lead. Seen some upto 5m. And neatly routing it along the skirting or whatever to the hub?
Yes you’ll still have the NTE 5C there. But at some point when fibre comes along that’ll disappear. And you may find that the ONT for the fibre connection can be placed near the relocated hub in any case. If you see what I mean..

Re: 5C master linebox extension

Duke500 — Fri, 05 Sep 2025 08:35:57 GMT

@pddco thank you, that sounds like a great suggestion. I will give up on using the cat6 stuff I have- seems it isn't a good idea to use over-spec parts and no one can tell me which terminals go to which in a hybrid system. Back to basics! Thanks again

Re: 5C master linebox extension

WSH — Fri, 05 Sep 2025 08:55:09 GMT

It’s not that no one can tell you, it’s just that what you’ve said so far still isn’t very clear.

So does this NTE 5C have an RJ45 socket then?

You can get faceplates with two sockets, a BT431A phone socket plus an RJ11, (which in some cases is a dual purpose RJ11/RJ45), but a single RJ45 socket on an NTE 5C would be extremely unusual.

The best I can suggest then, if it is an RJ45, is that pins 4 & 5 are likely to be the ones in use, (to mimic pins 3 and 4 in an RJ11 plug). They will connect to pins 2 and 5 in a BT socket resp., although modern equipment is not usually polarity sensitive. (Pin 3 was the old bell wire, to make very old phones ring. A router doesn’t need it and it can act as an aerial and feed interference into a DSL line, so I’d leave it disconnected).

As RBZ5416 said, the Smart Hub 2 uses an RJ11 socket for DSL/FTTC, so an RJ45 will need an adapter to connect it.

I hope that helps but I still say using cat 6 for this is like trying to fit Ferrari tyres to a tractor, (both in terms of performance and fit).

Re: 5C master linebox extension

pddco — Fri, 05 Sep 2025 09:35:43 GMT

@WSH At the end of the day it seems that all that’s needed is a longer version of what @Duke500 has now connecting the hub to the NTE 5C.

Good point about the unterminated ‘aerial’ leads within a cable. Not sure how many wires might be in the longer RJ11cable. But hopefully the longer lead will do the job. Easy to test by simply connecting it up the longer lead before installing it and checking that the speed hasn’t been affected.

Re: 5C master linebox extension

WSH — Fri, 05 Sep 2025 09:39:14 GMT

Which is what people have been saying all along.

Re: 5C master linebox extension

pddco — Fri, 05 Sep 2025 10:32:21 GMT

@Duke500 With the RJ11 cable it can be quite neatly fixed to the top edge of the skirting board with a thin line of clear adhesive - or maybe clear silicon - applied to the top edge and the cable lightly pressed on top. Saves unsightly clips. The downside is that it may lift the paint when you want to remove it. Perhaps less so with silicon. But just a thought.