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Re terminating ancient cables

Martyn
Hi Folks, 


So I may have a job in the offing where I will need to temporally re terminate these 3 cables, the one on the right is only 1m long so I’ll just replace it. 


The other two are rising mains from the 1940’s each feeding 20 flats, I believe them to be armoured PILC’s though happy to be corrected, the lead is being used as the earth. 


Has anyone re terminated similar and are there any pitfalls that may scupper me? 


The re termination will only be temporary whilst the new building network is being installed.89f8b92115c4d5d4e672a2d7771fc855-huge-a8ae4b2d-f17a-4e4e-a594-4469fa0801a0.jpg



Cheers 


Martyn
  • 0

    mapj1:

    The black box looks in good nick for 1940!  Can you get a pic of what is inside? - The "overbraided" earth suggests to me there maybe  no lead  after all - it may be waxed cotton, or some rubber derivative directly under the strands you can see - which in conjunction with the artful use of builders band, rather look like an addition to provide some  CPC functionality at a later date. Or maybe there is some lead, but what we would now call  Zs was a bit high.




    The three cables coming out of the box on top of the head are all the same and 2 core they are lugged L1,L2,L3 left to right in to the head, the one on the right looks different but is just missing the steel outer, the phase lugs appear to have had 2 cores in each at some point in the pas as these are about 6" long and are taped up behind that 'make do' bit of trunking lid.


    The Neutrals from each cable are in to a terminal block with its screws missing so all a bit loose.


    The overbraid as you call it is actually very similar to that of the steel on modern swa, although, at no point is there any outer sheathing.


     



    edit - your second post arrived as I posted this. The bigger photo changes it a little - perhaps the braid was original after all. It will need unpicking with very great care.


    I'd suggest you may want a back up plan for what if


    The steal is definetely original, it can be seen throughout.


    I may just opt to run a temporary 2c swa to the ground floor 'Ryefield' style boards, bit of a waste though!

    LV Jointing Manual Section 1&2 (big file, lots of pix.)

    LV Jointing Manual Section 3



    These make for very interesting reading! Thanks.



    Sorry taking a while to reply, This new Forum interface seems pretty lousy at the moment


    Cheers


    Martyn
  • 0
    The black box looks in good nick for 1940!  Can you get a pic of what is inside? - The "overbraided" earth suggests to me there maybe  no lead  after all - it may be waxed cotton, or some rubber derivative directly under the strands you can see - which in conjunction with the artful use of builders band, rather look like an addition to provide some  CPC functionality at a later date. Or maybe there is some lead, but what we would now call  Zs was a bit high.


    edit - your second post arrived as I posted this. The bigger photo changes it a little - perhaps the braid was original after all. It will need unpicking with very great care.


    I'd suggest you may want a back up plan for what if - even if it is a roll of swa on "sale or return" that hopefully stays in the van and gets returned, but maybe  gets run out of the landing window and back in again lower down the wall if the worst happens and it all suddenly crumbles before your eyes. (The DNO round here have been known to power a house up temporarily from a neigbouri's cut out using  a roll-end length of ABC across 2 front lawns before coming back for the next couple of days to dig a failed joint out.)

    They also carry tapes, sleeves and rubber 'wizard hats' to form 'site applied insulation' when changing cut outs and so forth. There are certainly techniques worth being ready for


    However, just in case it is not a mistake, for info, the 'how to do' for wavecon and other LV cables too, is illustrated in the UKPN jointer's handbook

    I suggest starting with UKPN jointers manual

     LV Jointing Manual Section 1&2 (big file, lots of pix.)

    LV Jointing Manual Section 3

    for your type of cable and many other situations.
  • 0


    Hi. 


    Cheers for the reply, not sure there will be much option to leave them alone sadly, they are direct on to the Head - which I am hoping the DNO will replace as it and its fuses are physically broken. Looking at Lucy and Ryefield for multi service options at the moment (46 supplies to be re fed)

    1160ed3ca5f3b0e121465eed69b0cf8a-huge-44d147b4-9d80-4c5b-9ea6-5ceccec0eed3.jpg

     

    Cheers


    Martyn

  • 0
    I would not disturb the old cables in any way, far too much risk of failure.

    Leave the existing cables and the metalwork into which they are connected alone. Use the existing switchfuse, or whatever as a joint box. The existing cable cores are presumably terminated onto some form of terminal in the item illustrated.

    Don't disturb these cable ends or the terminals into which they are connected, but connect new conductors thereto, perhaps by soldering.


    The earth continuity looks a bit dodgy, an upfront time delayed 300ma RCD might be prudent.


    If re terminating the old cables is completely unavoidable, then consider subcontracting this work to the DNO or to whatever subcontractor that the DNO use. They are experienced in this old stuff.

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