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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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    I agree the "no more spurs than points on the ring" rule was more about good practice than any electrical issue. Some of the original diagrams for rings seemed to be attempting to run a cable next to every wall you might ever want to have a socket on - even to the point of having a figure-8 arrangement with a 'bridge' cable along the interior wall between the front and back rooms (one ring for the whole house in those days) - the emphasis seemed to be on being able to have sockets anywhere (initially or as future additions) with the least overall cable used. Probably not surprising given the post war copper shortages.


      - Andy.
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    You can think up all sorts of hybrids. I see no problem with a ring in the ceiling void or loft space with spurs dropping down (or rising up) from JBs. One could perfectly legitimately have more than one spur from a particular JB. I see no reason in principle why you should not spur off to multiple sockets using 4mm2 cable (even though it is not shown in Appendix 15).


    However, the more complicated it gets, the less reason I see for a ring - just make it a 4mm2 radial.


    What you don't want is so many alterations and additions that it becomes a snakes' wedding.
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    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.


    Andy Betteridge
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    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?

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    Yep agreed junction boxes have no place in a new install, however for additions/alterations are sometimes not easy avoided, any joints should be made in existing back boxes.

    Effectively in this instance the blanked box would become a junction box in its own right. However if it is plastered over then it must be established that the remaing and/or new additions provide zone indication for all buried cables less than 50mm deep (I do not like the 50mm limit at all personally). To do the job properly and avoid the blank solution then cables must be rerouted if any zone info will be lost
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    "So how do you make a branch in a radial? "


    From an existing point is often possible and worth any extra work usually
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    Sparkingchip:

    I have worked in houses where the ring circuit has been wired through the floor void with the ring supplying the first floor sockets in the bedrooms and every ground floor socket being wired as a spur from a first floor socket above it.


    That absolutely minimises the cable used, but it means there is not a socket in the house you can connect another spur to and the number of spurs equals the number of points on the ring.


    So to add another socket or spur you have to cut and joint the ring to extend it from upstairs, wherever the new point will be located.


    Andy Betteridge 



    Or go to the nearest downstairs DS, put in a FCU next to it , feed the DS from the FCU and add as many sockets as you like all around the room 

     

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    Do able but not at all ideal is it though? but naff really.

    I did something similar once to give a few sockets in a vestible fed from ring, impossible to get extra cable in to extend ring. They were only for table lamps or so I was told.

    What happend after I left, who knows?
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    ebee:

    "So how do you make a branch in a radial? "


    From an existing point is often possible and worth any extra work usually




    BS 1363 accessories need only accept 8 mm2 of conductors although e.g. MK ones accept 12 mm2. Three lots of chunky tails is also a bit tight even in a 35 mm back box.

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    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.


    Andy Betteridge

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