This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

I`ve been thinking

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.
Parents

  • mapj1:

    No, I think the intention is always that the spurs are wired in the same stuff as the ring, namely 2.5mm. IF you had 4mm radials the 2 socket limit would make no sense.


    In any case the rating of 2.5mmsq is 27A for surface wired or in plaster - which would have been the options when it was being dreamt up. Dont forget that part L and all this thermal stuff ony go t going after the 1984 revisions to the building regs - because until you have central heating the indoor and outdoor temps in all rooms without a fireplace are not so different.




    The 14th Edition updated to 1976 rates 2.5 T&E is rated at 21 Amps in Table 3M. Copper conductors P.V.C. twin and multicore cables, one twin cable with or without earth continuity conductor, single phase a.c. or d.c. Clipped direct to a surface  or on a cable tray and unenclosed.


     A couple of 3kW appliances run from a spur could warm that up a bit.


    Z.


     

Reply

  • mapj1:

    No, I think the intention is always that the spurs are wired in the same stuff as the ring, namely 2.5mm. IF you had 4mm radials the 2 socket limit would make no sense.


    In any case the rating of 2.5mmsq is 27A for surface wired or in plaster - which would have been the options when it was being dreamt up. Dont forget that part L and all this thermal stuff ony go t going after the 1984 revisions to the building regs - because until you have central heating the indoor and outdoor temps in all rooms without a fireplace are not so different.




    The 14th Edition updated to 1976 rates 2.5 T&E is rated at 21 Amps in Table 3M. Copper conductors P.V.C. twin and multicore cables, one twin cable with or without earth continuity conductor, single phase a.c. or d.c. Clipped direct to a surface  or on a cable tray and unenclosed.


     A couple of 3kW appliances run from a spur could warm that up a bit.


    Z.


     

Children
No Data