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I`ve been thinking

ebee
OK the title might startle some who know me.

Ring Final rules.

What is the intention behind the rule "no more spurs than points on the ring".

I think most of us who have run rings would almost exclusively put every point on a ring and no spurs at all.

Spurs are then usually just additions.

One spur max per point.

One spur allowed at origin.

If I saw a ring with say 12 points on ring and one ring per point and say 1 point at origin that would be 12 on ring and 13 spurs that would not worry me.

In fact if I saw say 5 points at origin it would not worry me either.

If I saw 12 on ring each with one spur then 5 spurs at origin then 11 spurs on joints between points woul I worry?

No I would not although this "golden rule" would have been well and truly broken.

I think the rule intention was purely good housekeeping to keep us all on the straight and narrow.

In fact some on here have mentionded a ring in a loft with junction boxes dropped dow to spurs. Therefore all spurs and not on ring.

Note I did not pick the number of 12 points on ring for any reason, I could have picked 5 or 50 or 5000.
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    Sparkingchip:




    Chris Pearson:




    Sparkingchip:

    Any circuit with junction boxes is a nightmare if fault finding has to be undertaken, there is rarely a reason why a domestic socket circuit should be wired through junction boxes from new.




    So how do you make a branch in a radial?


     




     

    Ideally from the back of a socket.


    Irrespective of the direction of arrival (or departure) how do you join the cables?


    3 into 2 won't go.

  • 0
    "3 into 2 won't go."

    Chris, what are you trying to say here? you lost me there
  • 0
    For the cost of a junction box including installation you can replace three to four metres of 2.5 mm twin and earth through a floor void, cable is relatively cheap.


    So pick up a connection a bit further back and omit the junction box.


    Andy Betteridge
  • 0

    "3 into 2 won't go."

    Chris, what are you trying to say here? you lost me there



    I think this is about BS 1363 accessories not necessarily being able to take 3off 4mm² conductors. My answer to that is either to use brands that can take 12mm² (in practice many do) or shove some extra terminals into the back of the box (not the neatest solution but being accessible, still preferble to a hidden JB somewhere, IMO).


      - Andy.
  • 0

    AJJewsbury:




    "3 into 2 won't go."

    Chris, what are you trying to say here? you lost me there



    My answer to that is either to use brands that can take 12mm² (in practice many do) or shove some extra terminals into the back of the box 


      - Andy.

     





  • 0

    AJJewsbury:




    "3 into 2 won't go."

    Chris, what are you trying to say here? you lost me there



    I think this is about BS 1363 accessories not necessarily being able to take 3off 4mm² conductors. My answer to that is either to use brands that can take 12mm² (in practice many do) or shove some extra terminals into the back of the box (not the neatest solution but being accessible, still preferble to a hidden JB somewhere, IMO).


    That's it - as I said a few posts ago.

  • 0
    Repost after having posted this on the wrong thread.....


    With simple rules for ring final circuits we know where we are. If a non fused spur can only supply a single OR a double socket then any socket with just a L and N is supplied by a spur. A non fused spur supplying two separate and distanced single sockets may appear to be on the ring at the first socket, but is not. So that is not allowed. Is it that simple? All other sockets with 2 or 3 Ls and Ns are on the ring.


    Z.
    •  

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    All other sockets with 2 or 3 Ls and Ns are on the ring.





    But not a safe assumption when dealing with existing as earlier rules permitted two (single) sockets on the same spur - so two cables at one socket could still legitimately be a spur (never mind later instances with less legitimacy but just as much actuality).

      - Andy.
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    AJJewsbury:




    All other sockets with 2 or 3 Ls and Ns are on the ring.





    But not a safe assumption when dealing with existing as earlier rules 

     




    We professionals make no assumptions do we Andy? We would test for ring continuity.


    Z.

  • 0

    Zoomup:




    AJJewsbury:




    All other sockets with 2 or 3 Ls and Ns are on the ring.



    But not a safe assumption when dealing with existing as earlier rules 


    We professionals make no assumptions do we Andy? We would test for ring continuity.



    I agree that during inspection, a single T&E cable means that it must be a spur, but the presence of two cables does not prove things either way.


    As far as testing is concerned, the presence of a spur wouldn't affect stage 1. You might notice a rise in resistance in stages 2 and 3, but if the spur is very short the increase, say up to 0.03 Ω would be within the limits of accuracy of the test. And of course if you are sampling, you might miss it altogether.


    So now let's consider a double spur. The first is attached to the nearest bit of the ring and goes unnoticed. The second is further away and is revealed by a higher resistance. Is there any reason why you would deduce that the second spur came off the first one as opposed to somewhere in the ring? I think not.


    I also think that the only way that the situation would be found would be if you decided to split the ring at the first spur rather than at the CU. The choice of that rogue socket would be something of an accident. So you get no ring continuity at all and spend the rest of the day wondering where the hell the break is to be found.

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