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Radial Circuit using box installation method...

Former Community Member
Former Community Member
I am curious if anyone has ever done this, and if not any reason?  Is it acceptable? 


So, the scenario is that you install a radial circuit for lighting or sockets for that matter (could apply to either in this instance), and the image I've attached as the example probably isn't the best, but it was the clearest image I could find. 


The example is as follows - you have a circuit coming from the CU on a 16amp radial, rather than just go from one to the other repeatedly could you not use a junction box installation method. As long as the box was accessible.  I know the image shows lighting etc, but I was not thinking of it like that in this instance, it would be either just lighting or just sockets. 

992563266d16340370be4f2ff3f68dde-huge-screenshot-2021-02-15-at-16.28.37.png1f339cb9468d38ac0d0749602b0dec82-huge-screenshot-2021-02-15-at-16.42.16.png


  • Former Community Member
    0 Former Community Member
    Nothing concerned me about the arrangement, just more intrigued about others opinions.
  • 0
    spacey:

    Nothing concerned me about the arrangement, just more intrigued about others opinions. 


    Now that I have viewed your whole installation video I realise that the installation may not have been done with B.S.7671 in mind, as the installer is not from around these parts.


    Z.


  • 0
    "Generally, junction boxes not should be needed or installed" Wise words from Sparkingchip we`d normally avoid any junction box on a new circuit anyway. Well I would.


    " Be aware that if you want to branch at a socket, the terminals of BS 1363 socket-outlets are not required to accept more than 8 mm² of conductor although the better ones will accept 12 mm²"


    .. But yet a 4mm 32A radial with 2.5 spurs is allowed! Yes it depends upon the actual brand used
  • Former Community Member
    0 Former Community Member
    Zoomup:
    spacey:

    Nothing concerned me about the arrangement, just more intrigued about others opinions. 


    Now that I have viewed your whole installation video I realise that the installation may not have been done with B.S.7671 in mind, as the installer is not from around these parts.


    Z.




    That video has nothing to do with what I was asking about, that's some guy installing circuits in Germany for himself in a new workshop.  It was simply because I was able to grab an image from the junction box I was referring to that I used it. 


    I was more interested if you could run a radial circuit in the way the other image I uploaded (ignoring the lighting) again couldn't find an image with just sockets. 


  • 0
    Zoomup:

    Reg. 559.5.1.204 limits certain popular type lamp holders to a 16 Amp maximum protective device. That may restrict lighting circuits being fed from socket circuits.


    Z.


    FCU to BS 1363?


  • Former Community Member
    0 Former Community Member
    ebee:

    "Generally, junction boxes not should be needed or installed" Wise words from Sparkingchip we`d normally avoid any junction box on a new circuit anyway. Well I would.


    " Be aware that if you want to branch at a socket, the terminals of BS 1363 socket-outlets are not required to accept more than 8 mm² of conductor although the better ones will accept 12 mm²"


    .. But yet a 4mm 32A radial with 2.5 spurs is allowed! Yes it depends upon the actual brand used


    Was thinking more 2.5mm with 16A radial 


    The sockets I prefer are Scolmore or Schneider  


  • 0
    Given that UK socket back boxes are much bigger than their continental counterparts, we do not need the joint box, and can tee off at any convenient double socket.

    As others have noted, junction  boxes are not something you normally design in from the outset on socket circuits, but rather are a sign of later additions or changes during building works, Perfectly acceptable though, so long as done properly.


    Unfused spurs from a 32A radial need to be in 4mm (*), and not all sockets will take 3 lots of 4mm cable comfortably - I'd want a deeper box than the minimum 25mm for that.


    (*) though I agree, given that a single twin socket is OK on 2,5mm2 from a 32A ring, then it will be perfectly OK on a 32A  radial too, and then in the  book of perfectly good but confusing circuits there is the lassoo - with a ring of 2.5mm on the end/side of a 4mm feeder.

    No such book exists, but I often think it should.
  • 0
    gkenyon:
    Zoomup:

    Reg. 559.5.1.204 limits certain popular type lamp holders to a 16 Amp maximum protective device. That may restrict lighting circuits being fed from socket circuits.


    Z.


    FCU to BS 1363?




    That's an option.


    Z.


  • 0
    I cannot see the objection to JBs myself. Electricians should be familiar with a variety of installation methods. 


    Might equally well be singles joined in BESA boxes.


    Looping everything may work, but it may also waste a lot of copper (and PVC). It may, potentially, end up with an excessively long circuit.


    If you do loop a radial socket circuit, do you apply a grouping factor for the circuit as it goes up and down the wall?


    What's wrong with a "herringbone"? Anybody who has done some rallying will know what I mean.
  • 0
    Why not a 16 amp radial with 1.5 mm twin and earth?

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