The IET is carrying out some important updates between 17-30 April and all of our websites will be view only. For more information, read this Announcement

Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 12 replies
  • Subscribers 31 subscribers
  • Views 1403 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Which is best, long ring final with 2 spurs or short ring final with more spurs?

Former Community Member
Former Community Member
Good afternoon, hope you are all well. I have been re-evaluating the number and position of sockets in my bungalow, and considering having a few more added for convenience. Currently I seem to have a relatively short ring with 2 long spurs. If I measure the new route for cables incorporating the existing spurs and new sockets, I anticipate a total cable run of about 100m. From what I gather on this forum this is the limit for a ring final per 100m square of floor. Question is, is this a good idea, or should the ring final be made to run a shorter route and add more spurs, not exceeding the number of sockets on the ring, in order to keep volt drop to within acceptable limits. Not being an electrician I have used online cable size calculators to see if my idea is anywhere close to being ok and they come back with a huge 25mm squared cable. I am clearly out of my depth here hence the question. As always, many thanks in advance. Kind regards, Simon   
  • 0

    Which is best, long ring final with 2 spurs or short ring final with more spurs?



    In may ways it's swings and roundabouts. In terms of voltage drop you're trading a reduced load (on a spur) against having two cables rather than one (ring) - so it's down to the particular individual circumstances (which will probably vary over time anyway). In terms of other design factors, such as Zs, then a ring probably wins, usually.


    In terms of flexibility and future-proofing (e.g. adding an extra socket or two in the future) - an extended ring almost certainly wins over a spur - since you can add as many sockets as you like to a ring, but you can't (other than changing a single to a double) on a spur.


    If you prefer spurs then you might be better not having a ring at all and just have a simple radial circuit (with as many branches as you want).


      - Andy.

  • Former Community Member
    0 Former Community Member
    Hi Everybody, thanks for all of your replies, as usual, so much appreciated. sounds like the ring should be better for z's even if it does look like an antler, and volt drop should be acceptable even with a couple of spurs. hopefully when i get it installed and tested the ratings will pass. Kind regards Simon

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines