Replacing cover for GPO junction box

Discussion in 'Electricians' Talk' started by Nanook, Oct 14, 2021.

  1. Nanook

    Nanook Active Member



    I have an old but I think it may be still live GPO 52A Junction Box with a broken cover.

    I’ve seen replacement junction boxes for sale on ebay and was hoping to buy one and use the cover only to replace my broken one.

    However, I am aware this box is running some hefty voltage through it if it is live and I am nervous about touching it because of it.

    What is the best course of action please?

  2. MGW

    MGW Screwfix Select

    If it is GPO then it is 50 volt DC, however seen loads around this house seems some previous owner got some cheap, so only option is to test.
  3. adgjl

    adgjl Active Member

    50V dc with 100V on top of it when ringing. With it ringing, it will make you jump, but unlikely to do anything more serious, unless you fall off a pair of steps.
  4. FlyByNight

    FlyByNight Screwfix Select

    To be really pedantic, it is actually a nominal -48v, the exchange end will usually be -52v (originally from a battery bank).
  5. Nanook

    Nanook Active Member

    Thanks MGW.

    I’m just a diyer and broke the cover by accident whilst trying to strip the paint off the wood in the window frame.

    To be honest I don’t know if it is GPO, i’m making an assumption it is.

    I’m aware this is a BT thing and I am not supposed to touch it, however, I only want to replace the broken cover.

    How would I test it please? I know nothing about electrics.
  6. Nanook

    Nanook Active Member

    I would rather not take the risk... I have electrocuted myself before by accidentally making contact via an electrical socket. It was deeply unpleasant.

    Should I just get BT out and swallow their extortionate charges? I absolutely 100% do not know anything about electrics. Everything I have said in this thread is bits I have learned from reading up about these old junction boxes. I’m just a DIYer and accidentally broke the junction box cover whilst stripping the window frame it is mounted on of paint.
  7. Nanook

    Nanook Active Member

    I don’t know why I said I electrocuted myself by accident! As if anyone does it on purpose! :rolleyes:
  8. adgjl

    adgjl Active Member

    If you are worried, take the phone off the hook, without dialling a number. This will drop the incoming voltage down to 20 volts or so, and prevent it from ringing. You then won’t have any risk of an electric shock when taking the cover off.
  9. Tony Goddard

    Tony Goddard Screwfix Select

    Just replace the lid, then you don't have to touch the terminals, but as said above it's just a phone junction box. I can see the two incoming wires, the old black twin stuff used by the GPO at one point, have you looked to see if it goes anywhere the other side of the frame?, remove whats left of the cover and see if those two connect to anything. If there is no ongoing connection and the outside section is cut somewhere, then you can strip it out.

    If it is still connected outside to the network you can either buy another box (a modern one if you wish) and replace the whole box or if you are playing safe just buy another 52A and use only the lid.

    You would only get a tingle, and it is just a tingle off a phone line if someone was to dial the number - and only if you touch the contacts at that time, a kitchen rubber glove or gardening glove would be sufficient to prevent a tingle from a phone ringing current!
    Nanook likes this.
  10. Smokey

    Smokey Active Member

    With care, though not officially allowed, you could transfer wiring into a current Master Socket.
    If OpenReach come out, expect to pay in excess of £150:eek:
    When removing bare cable ends, isolate them with electrical tape or heat shrink, so they don't short out.

    You'll also need a SINGLE GANG surface mounting box, for socket to screw onto.

  11. Nanook

    Nanook Active Member

    Yes there is a wire coming out of the window frame on the other side. It then goes up the side of the pipe to the top of the house and where it goes after that I can’t see.



    The landline phone is broken at the moment but Virgin say everything is good at their end as our phone comes with our Virgin internet package. So another issue.

    Thanks for the help.
  12. Nanook

    Nanook Active Member

    Thank-you for this. I just don’t feel confident enough to take it on. I’m happy to do bits of plumbing and carpentry etc but electrics are not my bag. There is something wrong with our landline phone line anyway so perhaps I will have to end up getting BT out after all this.

    Thanks for the help.
  13. Bazza

    Bazza Screwfix Select

    I think that, as you pay Virgin for your phone line, that you will have to report it through them. Virgin will then have OpenReach investigate and fix the fault.
    They will probably install a master socket as a matter of course, which will resolve your original issue!
  14. MGW

    MGW Screwfix Select

    Squirt some silicon sealant on it and smooth with plastic knife or lollipop stick, easy enough to rip it back off when any phone guy needs to. And it will give you piece of mind that it's safe.

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