Move BT Master Socket ADSL Filter

How to Move Your BT Master Socket (Without Actually Moving It) – Advice from a Telephone Engineer

In an earlier blog (that people seemed to like!), I explained in no uncertain terms that moving your BT Master socket was A Bad Idea.

But That’s Not The Full Story…

There is a way of translating exactly what your BT Master Socket does to wherever you’d prefer to have your broadband modem plugged in at your house.

Totally legally, easily done, and without compromising your broadband quality by mixing it up with other stuff (which might interfere and slow it down). Please read on!

What Does A Master Socket Do, Anyway?

There’s nothing mysterious in it. It simply serves as the border between you wiring and that of Openreach (former BT). It’s an electronic boundary post, first and foremost. It’s a physical break for testing Openreach’s supply to your house.

BT Openreach’s Bit

Two terminals/pins marked A and B are behind that socket front, and your broadband and telephone traffic arrives on these. I’m frequently amazed that 18mb can arrive via two 0.5mm wires. But it does.

So, what if you wanted to move those two wires that arrive in your house to somewhere else?

The choices are:-

a/ Move the master socket. (We can’t really (officially) do that.)

b/ Make an exact copy of it and run some wires between the two. Yes, we can do that!

So, it’s fairly easy:-

A New Socket

A new complete master socket with a filtered faceplate needs to be bought for where you want the new one to be located. There are plenty on Amazon or eBay. .

A Socket With Filtered Faceplates, That Is.

Buy two filtered faceplates from the same source, one for your new master socket, one for the old one. (Don’t worry – all will be explained.). You’ll need one with pins 2,3, 4 and another A and B in the same area on the socket.   A “filtered faceplate” can be identified by having two sockets on the front, one for your router lead (small plug), and one for a phone plug.

Oh, and a wire insertion tool. A jolly good thing to have, and with useful life beyond this project.

Quality Cable

Buy some professional-quality telephone cable. This will have solid cores (not braided, that is, made up of tiny strands crushed together). It will also have a “twist” in the pairs of cable, a bit like a hair plait. This feature means you lose less of the signal as it travels down the cable. This is more important than it seems, trust me. I’ve blogged about it here

Run Your Cable!

Now run the cable between the two sockets, away from anything significantly electrical, such as TV, monitor, central heating pump, power supplies, transformers, nuclear power stations, GCHQ listening stations, fluorescent tube lighting, or consistently parallel to mains cables, etc., etc. You won’t manage to dodge all of it, but do your best! Outside the house is often good, provided external cable is used.

Terminate (Punch Down) Your Cable

Then feed the cable into both master sockets, and onto the connectors on the both filtered faceplates marked “A”and “B” (the ones next to 2, 3, and 4).  Connect these “A” and “B”pins at the original socket end, with the pins “A” and “B” on the back of the socket at the new end. This is effectively transferring your unfiltered broadband signal straight off the incoming line, and to you “new” master socket.

Check For Signs of Life

Check for a dialling tone at the new socket (with the front on). If found (which means you’ve connected the socket successfully), plug in your broadband hub into the smaller socket, and off you go!

That’s It!

You’ve just “moved” your master socket.  Your old “A” and “B” have been translated to the new “A” and “B”. Your broadband signal should be free of interference.

One More Time…

Your broadband arrives via the “A” and “B” pins on the back of the original master socket.  These are duplicated on the front of the detachable filter plate on the original master socket.   Connected is then made to the rear “A and B” on the newly-installed master socket.  And again:- the outgoing A and B on the original connect to the incoming on the new socket.

Any Questions? Well I suspect you might ask…
Speed Loss

“Don’t you lose some of the broadband signal via the cable run to the new master socket”

Well, provided that you are keeping the new cable fairly clear of any source of interference, you won’t lose much at all, probably about as much as you would if your house was a few yards down the street, and further away from the exchange.

Why Not Cat 5 / Cat 6?

“Shouldn’t you be using high-specification Ethernet/network “Cat 5” data network cable to connect the two sockets?

Yes, instructions found in some new sockets supplied by Openreach stress this. It’s a source of much debate among professionals, including some that I network with on-line. I don’t think it makes any difference – it has arrived at your house along non-Ethernet cable so far, often a couple of miles from the exchange. There are even those who say that broadband was actually designed to run on traditional telephone cable.There’s casual evidence from a former BT senior engineer “insider” that this is correct.  So, providing that you use solid-core, twisted-pair cable (that is, professional-grade stuff, not cheap and nasty, often used by burglar alarm companies), losses should be minimal.

Why Can’t I Joint Straight Onto The Line?

“Can’t I just connect to the A and B on the back of the original master, the ones that have BT/Openreach’s incoming line connected?”

No. That original master needs to remain as the boundary between your premises cabling and their network, via the detachable frontplate. If you’ve ever had to deal with a persistent line noise problem (and dispute), believe me, it’s vital to have that demarcation point. Remove the front plate and you can prove that the problem is on Openreach’s side in seconds.

Won’t A Joint Do?

“Why can’t I just put a joint in where the old master socket is, and do away with the master socket?”

Because an old, grubby cable mysteriously jointed to a shiny new one is evidence enough to an Openreach engineer that fiddling and relocation have taken place. Therefore, they may sting you for a £200 reinstallation fee , especially if you’ve put a short circuit on their network. And most non-engineers don’t know how to joint in-line cables in the same way that engineers do. So it’s very hard to hide the evidence.  I’ve seen it done…

I’ve blogged about the do’s and don’t of jointing cables here

Most master sockets were located in ground floor areas near the point of cable entry, typically the hall or front room. Rarely were they put elsewhere. £20.00 on materials, or a potential £200.00 fee?

Oops This blog has got quite long!

There’s much more on-line on this topic. Thanks for your patience!

I might be able to help I cover Middlesbrough, Darlington, North Yorkshire and beyond, as I’m a telephone engineer based in Stockton on Tees, So, if you need me to come and sort anything out, please get in touch!

  1. Michael Kenward04-18-2016

    The first sane explanation I have seen of what I want to do: turn an extension socket into a modem friendly socket for VDSL. Let’s hope it works!

    • BriW02-06-2017

      So the front on the BT master stays. & Theses Faceplates plug in????, So its Better Quality extension lead with built in filters rather than the plug Micro filters. & cheap splitters???. & you don’t feed the wire into the old master socket, & just into the faceplate????

      • Rob Govier02-06-2017


        Thanks for the comment.

        Connect “A” and “B” on the first (master) socket filtered plate to “A” amd “B” on a second socket of the same type. Those “A” and “B” are the “in” or “out” straight to the line.

        I hope that this is clear.

        The photos shows a superceded faceplate – Openreach have introduced two newer types since I wrote this blog, but all more recent ones have the “A” and “B” pins, as well as the usual voice-side “2”, “3”, and “5” for filtered voice extensions. A filtered face plate is more effective and reliable than the plug-in dangle-out types.

        I hope this helps!


        • Mike Howard12-17-2017

          Why 2 identical face plates? I’ve followed this successfully for ADSL but am now upgrading to fibre. Do I need to buy 2 VDSL2 faceplates



          • Rob Govier12-17-2017

            Thanks for the visit.
            By “upgrading to fibre”, do you mean that you will have fibre to your premises (which involves specialised termination equipment), or fibre to a local cabinet, with your service delivered on a copper pair to your premises?

            Two face plates. One becomes the slave to the other master, giving the advantages of the high-performance filtered face plate, and a supply straight from our incoming line, but on the customer side of the master socket, so still legitimate in terms of network testing.

  2. Michael Kenward04-18-2016

    A question you might want to cover:

    If I have an existing extension socket, can I convert that into a new second master?

    From your instructions, it looks like a case of just moving the wires around inside the old master plug. Or is that against BT’s rules?

    • Rob Govier04-19-2016

      Of course, we’d never advocate interfering with Openreach’s equipment… As per this and earlier blogs, providing you connect the “A and B” pins (corresponding to numbers 2 and 5 on a slave socket or on the main master’s face plate), then you can replicate the unfiltered output of “A and B” (or “2 and 5” providing nothing else is connected to it) on the main master socket to somewhere elsewhere in your premises, connecting it (ideally) to another socket with a filtered face plate (which are much more effective than a “plug-in and dangle” filter). The key issue in respect of Openreach’s equipment is being able to disconnect all your premises wiring from their network at the main master socket where their cable enters your premises in order to allow a test straight onto their network. Thanks for your interest and comments!

  3. chris09-06-2016

    Hello, many thanks for this insightful piece. I would like to do this in our new house, but we will get a BT Fibre installation. Will it still work as you describe, or do I need to watch out for something (e.g. what faceplate to use, etc.)?

    • Rob Govier09-07-2016

      Hello. Thanks for your kind words. Have you seen one of my othger blogs on this?

      Also, there’s loads of advice available via Google on this topic, as I used it to research the blog.

      My first thought is that you should run an ethernet (Cat 5 / Cat 6) cable from the hub to wherever you need the service to be, and terminate it on an RJ45 socket. Data in commercial premises runs like this. All the various bits to allow you to do this are available on-line.

      I hope that this helps.


  4. Dave Matthews10-22-2016

    Hi there, very informative post and I’m looking to undertake the work soon for some friends that have just moved into a new house. You mentioned in the above post…

    ‘Buy two filtered faceplates from the same source, one for your new master socket, one for the old one. (Don’t worry – all will be explained.)’

    You didn’t explain and I’m just wondering why you’ll need one for the old socket?

    Thanks, Dave.

    • Rob Govier10-22-2016

      Thanks for the comment. Maybe I didn’t put it that well. Further down is point 5/ which should explain it. You are effectively connecting the incoming “A and B” between each identical socket, and benefiting from the centralised filter facility on the new socket.

      I hope this explains it. Otherwise, please come back to me!

  5. Darren11-04-2016


    Thanks for the well described post, I have one question though.

    Can I still plug my telephone into the New master socket as well as my broadband router or is this only for broadband?

    Many Thanks


    • Rob Govier11-04-2016

      Thanks for the kind words.

      The answer is “yes” – both broadband and voice services travel over the same single pair of wires, so providing the pair are present, then you will be able to receive both. All I’m advocating in the blog is replicating the original master socket at another point in the house. Rob.

      • Darren11-07-2016

        Fantastic, thanks Rob, I’ll be tackling this at the weekend.

        Best regards


  6. Dan11-21-2016

    Thanks for this information. Pretty much exactly what I was looking for but there is one small detail that I wanted to clarify and I wanted to see if I had you right in principle…

    When installing a faceplate on the original master socket I am basically presented with the unfiltered A and B terminals without having to tamper on the BT side of things. This is basically the same as the two connections coming into the house but are simply transmitted to the terminals on the faceplate through the test socket, correct?

    I then run cable from the terminals A and B on the faceplate on the original master socket into a new master socket. Do I terminate this pair of cables directly into terminals A and B in the new master socket or do I connect them to the suggested facplate on the new master socket.

    The way I understand it I should wire them directly to the new master socket. Although I accept the filtering to be better with the faceplate, a dangly box filter should work the same for testing purposes, correct?

    Many thanks again for your help on this.

    • Rob Govier11-22-2016

      Thanks for your kind comments.

      When installing a faceplate on the original master socket I am basically presented with the unfiltered A and B terminals without having to tamper on the BT side of things. This is basically the same as the two connections coming into the house but are simply transmitted to the terminals on the faceplate through the test socket, correct?


      I then run cable from the terminals A and B on the faceplate on the original master socket into a new master socket. Do I terminate this pair of cables directly into terminals A and B in the new master socket or do I connect them to the suggested faceplate on the new master socket.

      You could do either, but I’d be inclined to put them onto the “exchange-side” A and B, that is, on the non-detatchable bit. Then they are out of sight, and out of “harm’s way”

      The way I understand it I should wire them directly to the new master socket. Although I accept the filtering to be better with the faceplate, a dangly box filter should work the same for testing purposes, correct

      Yes. But the “faceplate” filters tend to be of a higher spec.and are more reliable than the dangle ones. I have replaced some dangle ones and seen a marked increase in speed.

      Many thanks again for your help on this.

      You’re welcome!


  7. Harry12-18-2016


    Visibly all the phone sockets in my property look identical.

    Please can you tell me, is there away inside the face plates to identify which is the master?

    This question is because I understand that routers need to be plugged into the master socket or is this incorrect?

    Thank you

    • Rob Govier12-18-2016

      It’s quite possible that you don’t have one! Older locations don’t. And occasionally they are removed by a previous owner. The master is usually at the first point of entry of the Openreach cable to the building. You could possibly connect the router at any of the sockets. However, I would always recommend disconnecting any sockets you don’t use, as they can attract interference. I hope that this helps. Rob

  8. Tommy01-06-2017

    Hi, just following up on your instructions re moving the master socket, can you advise me exactly what I need to buy?
    I already have fibre Broadband, with a BT mk3 master socket downstairs that gets about a third of the speed it should be getting due to running an extension upstairs to PC.
    It’s not possible to plug the router in direct as it needs to be near the computer upstairs.
    The other problem is the master socket has connections to my sky box downstairs living room and downstairs telephone, so how would those be affected?
    Let me know everything I need and I’ll do a search on Amazon or eBay.
    Cheers n regards.

    • Rob Govier01-06-2017


      Buy an identical Mk3 Master socket from eBay or elsewhere, and connect the A and B terminals to the same A and B on the upstairs “master socket”, as per the description in the blog. Your Sky box connections will remain on the filtered side of the downstairs socket, so should not be affected.

      The speed loss you mention sounds serious – you shouldn’t be losing that much. Have you tried plugging your router straight into the downstairs master and see if there is a speed increase? A new cabled connection to the duplicate master should improve matters.

      I hope that this helps. There’s much more available via Google.

      Thanks for visiting.


  9. Tommy01-08-2017

    Hi Rob, I did plug the router into the downstairs master, but the speed went down rather than up, Two BT engineers have checked the wiring in my house and can find no faults, I’m under 2 miles from the exchange, my ISP say I should be getting around 32 to 36 Kbps down speed, but I have never got more than 12.
    Not sure where I go from here but will keep you updated.

    • Rob Govier01-08-2017


      This is where the master socket really does become your friend. If you are testing from there back to the exchange, and not getting the required speed, then it’s time to persist with your ISP to get it sorted. You are paying for the service. What speed do they predict?

      • Tommy01-09-2017

        Around 36 Kbps Rob,
        I’ve had a laptop connected downstairs all day today with Ethernet and RJ11 going to the master and never got higher than 8 Kbps.
        That was me also taking out the telephone and sky connection, but no change either, and I’m not using a filter.
        The ISP say to keep it connected so they can check it from their side, but I’ve heard nothing from them.
        I also have a spare router I was wondering if I could bring into play, weather not great today, but don’t reckon it’s a factor in this case.
        Will keep you updated.

  10. Rob Govier01-09-2017

    Definitely an ISP-side issue, be that due to modem or line quality.. I really does need to be pursued with them, be that through an Openreach visit/investigation, emplacement proven modem, or both.

    • Tommy01-12-2017

      Just a wee update Rob, a third engineer on the way Tomorrow, and to top it all off, our phone system is down tonight, you have to laugh , will keep you updated
      PS Router is connected to master test socket via filter and we are getting speeds of about 12 mbps down and 1.5 mbps up

      • Rob Govier01-13-2017

        12Mb down is respectable. A quick look at will give you some idea of your distance from the exchange and what you should be getting. It’s a reliable, respected site.

        • Tommy01-23-2017

          Hi again Rob, finally an engineer who seems to have gotten to the bottom of it all.
          Seems there was some BT wiring fault at the junction at the beginning of my street, a new connection and cable have been installed, I’ve run a speed test with the excellent down speed of almost 33 Mbps and up speed of just over 2.5 Mbps.
          Hopefully it should now be stable, but we are still seeking some sort of compensation from our ISP for the previous reduction in service.

          • Rob Govier01-23-2017

            Good news! Sometimes you just have to persist with an engineering company which often seems under-resourced and under-skilled. Meanwhile, if my comments have been useful, could you please leave some feedback on our Facebook and/or Google Plus page, please? Cheers

  11. David Williamson01-10-2017

    Hi Rob, excellent blogs, thanks for all the info. However, one thing has always troubled me in relation to who owns what, etc. and I hope you can help. I realise that the provider owns the MS (in my case a NTE5a) and I mustn’t tamper with it or face financial penalty, etc BUT does that apply to the lower removable face-plate itself? There are all sorts of I-plate, ADSL, VDSL faceplates for sale to do the kind of projects you see written about here and elsewhere, so I presume I’m at complete liberty to screw any one of them to the MS? And rewiring/replacing the ENTIRE NTE5a MS if it is faulty is a no-no I guess?
    Thanks again, David

    • Rob Govier01-11-2017

      Thanks for the kind words. The lower part of an NTE5 is the customer’s side of things, so you can add anything that it designed to fit, then cable from there to wherever you need to.

      Openreach don’t seem to care much about folks moving master sockets these days, but of course I have to give the official line.

      I’ve not heard of anyone being penalised, but I do know that Openreach will charge if a fault is created due to incorrect wiring on (technically) their side of the master socket, and they have to send someone to site.

      Master sockets and other Openreach-standard cabling equipment is far more readily available now than it was when I first started blogging on this topic some years ago. And it’s not massively complex to cable a new one if you need to.

      I hope that this helps.

  12. Jeff Hopton02-07-2017

    Hi Rob

    Looks just the answer to moving the master socket near to an electric socket however when I checked the master socket it looked nothing like one pictured above a lot smaller socket about 65mm square with an old fashioned Telecom symbol on it. Is it possible to move this ?

    • Rob Govier02-07-2017

      Thanks for visiting!

      Very old installations may not have a master (NTE5) socket. I’ve worked at a few places recently just like this. The old-style “T” logo dates it to pre-’85 or earlier! It’s quite important to have one with the detachable front panel to allow testing in case there are disputes with your provider over line noise, faults, etc. And most call centre operatives won’t believe you if you say you haven’t got one (because it’s not on their script…)

      My recommendation is to add “78A” junction box where the current socket is, buy a new master (the latest is the NTE5C with a built-in filter), cable to where you want to it be (near where your router needs to be and close to a power socket), and the job’s done. All items are available on eBay.

      If this has been helpful, would you be able to leave some feedback, please at the following?:-



  13. Jonathan crouch02-26-2017

    Hi -trying to move master skt from windowsill to inner wall with power skts. Bought phone and modem skt components etc (have some cat5 cable already) but when i took off the master skt adsl plate expecting to find extension terminals, theres none. Plus one BT cable goes to terminals A & B and a 2nd cable from BT goes into the phone plate. Whats that all about and can i still extend phone and adsl from a&b terminals or can ibuy the adsl faceplate with the extension terminals separately? Many thanks jonathan.

    • Rob Govier02-27-2017


      The ADSL front plate typically has “2”, “3”, and “5”, then “A” and “B” on the front, next to them. The mainstream suppliers all seem to be like this. You may have a strange make that doesn’t have them.

      As to the other cable, this could be an extension within the house if it’s been done properly. Have you been in the house long, and do you know if the previous owner cabled some extensions from the master socket? Alternatively, someone may have fiddled with BT’s incoming cable for purposes unknown. It happens.

      I hope that this helps. It’s hard to diagnose without seeing it!


  14. de08-30-2017

    Thanks for your article.

    I have a BT openreach mk3 face plate with one socket above the other. If i run a cable from A and B connectors on it to an extension my speed is reduced to abot 20Mbps on both spckets. With the extension disconnected I get about 37Mbps through the master scoket. I assune the signal is being split. How do I get all the signal to go to the extension.


    • Rob Govier08-30-2017

      Thanks for your kind words.

      Your situation is difficult to diagnose without knowing the configuration of the extension cabling.

      If you did not run the cabling yourself, there may be “horrors” hidden away from sight that cause the loss of speed.

      This is where the process of elimination and hard-won experience of an experienced engineer is required. I do have contacts close to youup and down the UK who may be able to help.

  15. Danny09-17-2017


    I’ve followed this blog and replaced my old faceplate with a filtered one, wired a and b on the faceplate to the a and b on the back of a new matching master socket using good quality solid core telephone cable.

    I’ve plugged my new matching filtered faceplate into the master socket I’ve installed and the internet is working but at a crawling pace. It was consistently 2mb/s but it is now about 0.2mb/s and literally unusable (using 4G on my phone for internet at the moment).

    The run from original master socket to new master socket in around 10m. Any idea what could be causing the dramatic speed loss or things I can check/test etc.?

    I’m a trainee electrician so have access to test equipment, just don’t know a lot about telecoms engineering!

    Many thanks,

    • Rob Govier09-18-2017

      This is most strange. I’d check each component in sequence and check continuity of the circuit you have installed. Remarkably, broadband will work on one wire, albeit very slowly. If you have a dial tone, you have a circuit. If not, but you still have service, then check the cabling and termination.

      Most fault-finding is a process of considered and careful elimination of thefaulty item.

  16. John10-10-2017

    Hi – thanks for this really informative post. I was hoping to follow it, but when I opened the faceplate to what I thought was our master socket, it didn’t look like your example. Inside there were only orange, blue & white cables linked to numbered sockets (1 – 6), and no A & B. I traced these cables back and they originate from a small junction box, around 5.5cm x 4cm, next to our front door. Inside the junction box the cables appear to join to the source cable from the outside of the house, however they also seem to join to the upstairs phone wiring (which I was hoping was connected to the master socket and wanted to disconnect it as it is no longer needed).

    So my questions would be – what can I legally touch, and is there any point in installing a filtered faceplate and wiring this to a new socket? My broadband speeds are reasonable but we do have intermittent disconnections (3+ per day) and I was hoping that disconnecting the upstairs wiring and following your instructions would help with this by removing any source of interference.

    • Rob Govier10-11-2017


      Thanks for your comment.

      As there’s no master socket,there’s no clear point of demarcation between you and the network.

      (“Obviously, I would never advise modifying Openreach’s network, but…) “some engineers” might add a master socket at the first point of entry, connect the broadband hub straight onto the line there, and see of the faults continue. If so, the issue is with Openreach’s side of things, and you need to report this to your provider.

      If the problem has gone, then connect only what you need as extensions around the house, one-by-one, in order to determine which one might be causing problems. Once you find the one that is,then leave that disconnected.

      As described in other blogs, you could add a second “master-type” socket, and connect the A and B (consumer-side) from that to A and B (normally-side), elsewhere in the building, and have the benefit of a more-effective filter.

      I hope that this helps!

  17. Farukh10-12-2017

    Great blog! You indeed have helped a lot of people!

    I now have NTE5C master socket with an MK4 faceplate. As the location of the Master Socket is inconvenient, following your guidance, I installed the exact same NTE5C MK4 socket as a Secondary. I connected 2 and 5 from Master (in house wiring) to the back of the NTE5C Secondary. This gave no broadband signal on the Secondary. Then I connected the back A-B from the MK4 faceplate Master to the A-B of the MK4 faceplate Secondary. Now I have broadband and phone available on the MK4 faceplate. I also have a second extension from the MASTER 2 and 5 running to a socket and alarm panel.

    When I plugged in the phone into the socket next to the alarm (without microfilter) incoming calls kept disconnecting the brpadband. I have therefore moved the phone and the router to the Secondary NTE5C/MK4. Broadband Connection now is stable but the issue I now have is that I have lost speed from 39999Kbps to about 30000Kbps.

    My questions are:
    1. Is the wiring between Master and Secondary (Master) correct?
    2. Does the NTE5C/MK4 filter out the broadband from 2 and 5 (extension front of NTE5C – in house)?
    3. Does the NTE5C/MK4 filter out the phone from AB (extension – back of filter plate)?
    4. Any suggestions on cause of speed drop (cable is new and good quality BT)?

    • Farukh10-12-2017

      Connection Speed 32400 kbps 8496 kbps
      Line Attenuation 17.2 dB 0.0 dB
      Noise Margin 15.8 dB 14.14 dB

      • Rob Govier10-13-2017

        Thanks for your kind words. Sadly, I’m committed on other projects at the moment, so don’t currently have time to give a detailed reply today. I hope to be back to you soon, though. Rob.

  18. Rahul Misra11-01-2017

    Hi Rob, thanks for the informative blog. Before I start on this project, I wanted to ask if I can just use a CAT6 cable(about 15m) with RJ11 on both ends to move my router away from the Openreach faceplate. Or will I lose much signal that way? Thanks.

    • Rob Govier11-01-2017


      Thanks for your kind words.

      The loss over Cat 6 will be negligible. Cat 5 can run at good speeds up to 90M between devices if installed correctly, and Cat 6 will better that. You may struggle to get the cable terminated in a RJ11 plug, though! It’s designed to go into an RJ45 plug.

  19. Rod Barrett11-17-2017

    Hello Rob, and thank you for your informative pieces.


    If I understand your instructions correctly, the master socket isn’t moved but duplicated. My original master socket has 3 other outlets daisy-chained to it. You don’t clearly state that existing secondary sockets should be disconnected.

    Thanks for pointing this out. It’s implied (by omission), but not stated. I’ll add it in

    Will the ‘dual’ master sockets be equally and equivalently functional as a single master socket?


    In part answer, I guess that having competing broadband devices is a bad idea but what about additional phones? Is the REN capacity increased?

    The master does nothing to affect REN. Additional phones should be fine until you run out of ringing current from the line supply. REN is not such a critical issue as it used to be, as many folks used cordless base stations with their own power supply to power the ring function.

    What is the effect of having ‘dual’ master sockets on the upstream (copper wires to the local green box/exchange) side?

    Nothing that I know of – they are not drawing any extra current. The A and B pins on the faceplate (customer side of things) are simply allowing access to the line independent of the first filter. They are an unfiltered supply. Connect these two to the “line-side” A and B on the rear of the second socket and you’ve provided another filtered supply, unaffected by any other device connected to the line.

    Again, thanks for your time,

    You’re welcome. Thanks for asking interesting questions!


  20. liam01-06-2018

    so just to confirm (prob me struggling to understand)
    1. Wires into A and B on new filter which then plugs in to original master socket?
    2. Wires from filter run to new location
    3. Wires from filter are then wired into new master socket? or wired into the second filtered face plate which is then plugged into the new master socket?
    4. Same wires into A & B at both ends or are they swapped at each end?

    Sorry for any confusion caused!! (im trying!)

    • Rob Govier01-08-2018


      1. Wires into A and B on new filter which then plugs in to original master socket?
      >Yes – there should be terminals marked “A” and “B” as well as “2,3, 5”.

      2. Wires from filter run to new location
      >Yes, from the A and B to where the other socket is.

      3. Wires from filter are then wired into new master socket? or wired into the second filtered face plate which is then plugged into the new master socket?
      >You will need a complete new master socket including the non-detachable bit that the Openreach cable usually terminates on (also marked “A” and “B”). There are widely available.

      4. Same wires into A & B at both ends or are they swapped at each end?
      >Yes, but this time you are terminating onto the “back” pins on the new socket, not the ones on the front filter plate. The polarity does not matter, although I’d always keep it the same just for the sake of good order!

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