Spurring off a ring

dook · Mar 6, 2011

Quick question,

Can you spur off a ring twice in the same place? e.g. 30A JB with 4 x 2.5mm cables in. One ring supply in, one ring supply out and 2 spurs? Hope this makes sense.
I've looked in the BRB but I can find no reference to this example.
Thanks Guys and Gals.

hopkins85 · Mar 6, 2011

No it would over load the connection.

Why don't you put 2 junction boxs in and have a spur off each, with ring in each.

Sent from my HTC Desire using Tapatalk

nick611 · Mar 6, 2011

there is no regulation to stop this. you must have no more than 1 spur for each socket on a ring but this is not the same as 1 spur from each socket. i have disscused this with n.i.c man and it is not against regs. but like last post said why not use 2 jb if it makes you feel better

dook · Mar 6, 2011

Why would it overload the connection?

ThreePhased · Mar 9, 2011

Dook,
The fewer jointing points in any circuit the better, the JB will accept 4 cables, and it won't be overloaded imho. I can't think of any reason for two separate JBs, unless you were creating long cable runs and would save on cable. As long as the number of spurs does not exceed the number of ringed sockets, and each unfused spur is a max of one twin socket I can't see any problems. Interestingly, the standard circuit in appendix 16 page 362 only shows 2.5 to a single socket off a JB, but I'm sure you can do twin sockets OK.

ThreePhased

hopkins85 · Mar 9, 2011

The man from Hereford he say NAY.

So your telling me you would take two spur cables off one socket.

Sent from my HTC Desire using Tapatalk

telectrix · Mar 9, 2011

yes, you can spur a double socket off a ring. max. load without diversity is 26A, but that would be very unlikely on one double socket. i personally would not take 2 spurs off one point on a ring. unless it's a long run, i would run 2 cables to the new sockets and maintain the ring throughout. even though 2.5 T/E requires a mortgage these days.

you could do it like the eastern europeans though, use 3 core & E, brown for 1 socket and black for the other. common up the blue for neutral and cut the bare one off . ( don't try this at home , kids )

ThreePhased · Mar 9, 2011

Telectrix,
Is that not brown to black and blue to .........

ThreePhased · Mar 9, 2011

No not at a socket, three is enough, one more would be too many.
I see where you're coming from re two spurs through one JB, because if two spurred twin sockets were each loaded with the max possible load thats 12kW/52A thru the JB terminals. At that current a 32A type B MCB would trip on thermals after about 15 mins, and the JB is the weakest link. Two separate JBs would only carry 26A, as would each of the ring conductors, hence the standard ring circuit diagram shows only one spur per JB.
It is unlikely but not impossible, so the man from Hereford is right.

Startinez · Nov 29, 2016

Sorry to dig up a very old thread, but how is best to spur from a double twin socket outlet?

Let's say that the previous work was done correctly, that would mean wiring into the further outlet first to keep the ring intact rather than wiring into the socket which takes the cable and then spurring off this (if this description makes sense)

So I am assuming that with this method you could in fact wire from either outlet depending on which looks neatest, as both are in the ring. But what about if it was in fact the other method, would the only option be to rectify the socket arrangement so that both outlets are in the ring before tackling this problem? Otherwise you're either spurring off a spur, or creating one outlet which has two spurs branching off it.

Midwest · Nov 29, 2016

Don't quite follow. Appendix 15 page 453 (BS7671) should answer your questions.

Wilko · Nov 29, 2016

Are you overthinking this?
Here's a nice diagram of some Wago stuff being used to spur off a ring

[ElectriciansForums.net] Spurring off a ring

Wilko · Nov 29, 2016

Re-reading your post - the ring is the cable, not the fitting. The 2nd double outlet may already be a spur (pic would be nice). So a new spur starting at the cable entry into the first fitting - if I've understood

Startinez · Nov 29, 2016

Wilko said:
Are you overthinking this?
Here's a nice diagram of some Wago stuff being used to spur off a ring
View attachment 34650

Maybe I am. I've attempted to attach an image showing the arrangement I'm trying to explain.

So if this arrangement is currently fed into S1 first, then it's a full ring and spurring from either makes sense. If it's fed into S2 & then this feeds S1, this would in essence be a spur?

Edit: as it's SWA the cable feed in and out are both coming into S2 but this may not necessarily be the order of the wiring, hence my question.

Pat H · Nov 29, 2016

Yes in the diagram S1 is a spur. You do end up with 3 cables into the S2 back box that can be tight. Hence the choice to use a wago box externally.

Spurring off a ring

dook

hopkins85

nick611

dook

ThreePhased

hopkins85

telectrix

-

ThreePhased

ThreePhased

Startinez

-

Midwest

-

Wilko

-

Wilko

-

Startinez

-

Pat H

-

News and Offers from Sponsors

Similar threads

OFFICIAL SPONSORS

YOUR Unread Posts