Number of spurs from kitchen ring main.

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jocollett

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Hello!

I've tried searching for this but keep getting unhelpful answers.

Is their a maximum number of spurs I can run off an actual ring main circuit cable, using a junction box? I know I can run one spur off each socket, but I'd like to run them direct from the ring main cable as its closer to where I need the plug sockets. I also know I can run one spur from a junction box. But what if I use 2 or 3 junction boxes? All answers I find simply discuss the spurs from sockets (an equal amount) or show a single spur from the main as an example.

I'd like to run two or three off the main if possible.

Thanks in advance.
 
2 or 3 junction boxes ,with one spur from each JB is ok on a ring final circuit, if that's your question ??
Or just extend the ring.
 
terryplumb said:
2 or 3 junction boxes ,with one spur from each JB is ok on a ring final circuit, if that's your question ??
Or just extend the ring.
Click to expand...

Technically there's no limit as to how many spurs from a single junction box, provided the conductors can be terminated appropriately.
 
Thanks for the replies. Terry yes that's my question. What do you mean by 'final' circuit though?

I wasn't going to extend the ring as my understanding is that's not allowed without the part P domestic installer qualification.

Aptsys, by 'terminating conductors', do you mean ensuring they reach a socket?

Many thanks
 
Part P is a building regulation ,there is no such thing as a part P qualification. Ring final circuit is the correct name for what some call a "Ring main".
 
OK thanks for clarifying the 'final' meaning. I'm not certain of definitions etc. By part p qualified I referring to electritions who are domestic installers able to self certify their work. My understanding was that extending a circuit needed BR certification but adding spurs didn't.
 
I remember a ring final install in a refrigerated warehouse to use cleaning equipment, the walls were around 25 foot high, and the main ring was outside the cooled area on the false ceiling, so the ring was using 6 mm² SWA into multi junction boxes with a drop to a socket from each JB, around 100 meters of SWA and drops in 2.5 mm².

As long as the ELI is low enough, and unlikely to over load, and volt drop within limits it is OK.

Where it all goes wrong is when some one tries doing it without the inspection and testing, and the ELI is too high, or volt drop is too high, or there is a real risk of overloading some part of the system.
 
jocollett said:
.... By part p qualified I referring to electritions who are domestic installers able to self certify their work. My understanding was that extending a circuit needed BR certification but adding spurs didn't.
Click to expand...
Not it England. Extension of a sockets circuit, whether by adding spurs or 'extending the ring' is not notifiable in England, unless it is is certain parts of a bathroom (which it never will be). In Wales, most electrical work in kitchens is also notifiable.

So, given that you appear to be in England, you could 'extend the ring' without the need for notification if you so wish, provided only that you can do do 'competently' and safely (which the law {Part P of the Building Regulations} requires).

To put this in perspective, there are some modern bungalows with concrete floors which have a 'ring' (of JBs) in the roof space, with all sockets being on spurs from those JBs.


Kind Regards, John
 
*I am not an electrician*

The way I look at (single socket) spurs is that they are no different to plugging in a device to a socket... but I expect to be corrected.
 
Thanks again for other replies. Im feeling a lot better about tackling this myself without facing building control wrath at some point in the future.
 
opps said:
*I am not an electrician*

The way I look at (single socket) spurs is that they are no different to plugging in a device to a socket... but I expect to be corrected.
Click to expand...
Not quite. When you plug in a device to a socket there is a fuse involved. A spur is wired directly to the circuit, so there is no fuse.
That is why you are only permitted one socket on each spur.

jocollett said:
I also know I can run one spur from a junction box. But what if I use 2 or 3 junction boxes?
Click to expand...
Would like clarification of this. You cannot connect (eg)
RING FINAL > JUNCTION BOX > SOCKET > JUNCTION BOX > SOCKET

also you cannot connect
RING FINAL > JUNCTION BOX > SOCKET
SOCKET
SOCKET
 
But you could have a bunch of junction boxes along the ring final each with a single spur, or a single junction box with a bunch of single spurs from that one point.
 
aptsys said:
or a single junction box with a bunch of single spurs from that one point.
Click to expand...
yes, you COULD, but I really hate that approach. You could connect up say, five separate circuits to that JB. You will probably overload the initial spur, as it will only be capable of less than 30amp. Also it will place one large load at a single point on the ring final. Which is supposed to have loads distributed around it.

I'd like the OP to explain what he has in mind..
 
Taylortwocities said:
yes, you COULD, but I really hate that approach. You could connect up say, five separate circuits to that JB. You will probably overload the initial spur, as it will only be capable of less than 30amp.
Click to expand...
I don't really understand that. What do you mean by 'the initial spur' - I thought we were talking about a JB which was 'part of the ring', in which case all spurs originating from it would be 'equal'.

If the JB were, itself, an (unfused) spur from the ring, then one obviously would not be allowed to feed more than one socket from it.
Taylortwocities said:
Also it will place one large load at a single point on the ring final. Which is supposed to have loads distributed around it. ...
Click to expand...
As I always say, people who get worried about that don't usually seem to be similarly worried about separate spurs taken from several different sockets which are very close to one another on the ring. Yes, one has to be careful to avoid the possibility of a large load being applied near one of the ends of a ring, but provided one is a reasonable distance from the end, there's really no problem with multiple sockets being supplied from one point (or very close points) on a ring, particularly with Method C 2.5mm² (in which case the cable is not far short of being able to carry a 'full 32A). The main issue is the practical one of having socket/JB terminals big enough to accommodate multiple conductors.

Kind Regards, John
 
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