Adding two spur sockets to Ring Final

[sparkwright]

Have seen bungalows with a ring of junction boxes in the loft, and a spur going down to each socket myself. It was a 60s build. Terrible design. If only the 'spur' was 4mm2 or imperial equivalent.

Also seen many houses with concrete floors, the upstairs sockets wired as a ring under wooden floor, with a spur from each of these sockets supplying each ground floor socket. Again, no 4mm2 in sight.

I do know of one occasion where a relative electrician of mine did fit many ground floor sockets as spurs from above, and did use 4mm2 - although he said he chose to use 4mm2 because he was running them in filled cavities!

I have to say, I don't see many instances where rings have been added to with 4mm2, although have seen one only this week. Harmonised 4mm2, so not exactly ancient.

 

[EFLImpudence]

You seem to be missing the point.

I have to say, I don't see many instances where rings have been added to with 4mm2, although have seen one only this week. Harmonised 4mm2, so not exactly ancient.

No, but you have seen many spurs - nearly all - that have been limited unnecessarily by a pesky FCU.

Edit - I did of course mean spurs with more than one socket.

 

[JohnW2]

Have seen bungalows with a ring of junction boxes in the loft, and a spur going down to each socket myself. It was a 60s build. Terrible design.

Why 'terrible'? I see nothing significantly wrong with it 'as installed' - the only possible issues arising if someone subsequently wants to extend the circuit from a socket (rather than, as you suggested, be "perfectly logical and in keeping with the original installation", by running a new drop from the loft ring).

If only the 'spur' was 4mm2 or imperial equivalent.

As above, unless there were a de-rating issue, due to installation method, there would be no point in using 4mm² for the circuit 'as installed' - and if there were such a de-rating issue, 2.5mm² would very probably not be acceptable for the ring, either.

You seem to be suggesting that any unfused spur from a ring final (supplying just one socket) should be wired in 4mm², just in case someone wanted to extend that spur in the future. Is that your view? It certainly does not correspond with the guidance given in App 15 of BS7671.

Also seen many houses with concrete floors, the upstairs sockets wired as a ring under wooden floor, with a spur from each of these sockets supplying each ground floor socket. Again, no 4mm2 in sight.

That's exactly the same, but just on a different floor - so all the above still applies.

I do know of one occasion where a relative electrician of mine did fit many ground floor sockets as spurs from above, and did use 4mm2 - although he said he chose to use 4mm2 because he was running them in filled cavities!

As above, if he needed 4mm² for spurs because of the installation method (of the feeds to the sockets), he would probably also have had to use 4mm² for the entire ring (i.e. replace the entire ring), if he had 'put the sockets on the ring' and some of the cable passed through that same route to the sockets.

I have to say, I don't see many instances where rings have been added to with 4mm2, although have seen one only this week. Harmonised 4mm2, so not exactly ancient.

Again, I have to ask whether it's your view is that all unfused spurs from ring finals should be wired in 4mm² (in case someone wanted to subsequently 'extend the spur')?

As EFLI has said, I think you are missing the point - which is that a 4mm² unfused spur from a ring allows an unlimited number of sockets to be supplied without the need for an FCU and its associated 13A current limitation (i.e. 'fused spur'). If the spur only supplies one socket, there is no need for 4mm² (unless because of de-rating) in terms of the circuit 'as it is'.

Kind Regards, John

 

[333rocky333]

As EFLI has said, I think you are missing the point - which is that a 4mm² unfused spur from a ring allows an unlimited number of sockets to be supplied without the need for an FCU

Not something i have even thought about really.
I assume its acceptable as 4mm can handle 32A and the total plugged in load is limited to the 32A mcb .
Thinking about it, I would have thought this method to have been used more, I presume its not as its not really conventional.

 

[JohnW2]

Not something i have even thought about really. I assume its acceptable as 4mm can handle 32A and the total plugged in load is limited to the 32A mcb .

Quite so. We (particularly EFLI and myself) often discuss it here - and it's certainly something which I have personally done.

... Thinking about it, I would have thought this method to have been used more, I presume its not as its not really conventional.

The reason is probably that people don't bother to think, coupled with the fact that it's not one of the examples shown in the guidance of Appendix 15 of the regs!

Kind Regards, John

 

[sparkwright]

You seem to be missing the point.


No, but you have seen many spurs - nearly all - that have been limited unnecessarily by a pesky FCU.

Edit - I did of course mean spurs with more than one socket.

I don't believe I have missed the point.

I do think the 4mm2 method is a great way of spurring from a ring, particularly as it allows one to spur off again, and even better means no 'pesky' FCU.

What point do you feel I am missing??

 

[EFLImpudence]

I don't believe I have missed the point.

Ok.

I do think the 4mm2 method is a great way of spurring from a ring, particularly as it allows one to spur off again, and even better means no 'pesky' FCU.

Good.

What point do you feel I am missing??

I thought you were arguing against the method by proposing extending the ring with both legs in the same place.

It must have been I who missed your point.

I Apologise.

 

[sparkwright]

Why 'terrible'? I see nothing significantly wrong with it 'as installed' - the only possible issues arising if someone subsequently wants to extend the circuit from a socket (rather than, as you suggested, be "perfectly logical and in keeping with the original installation", by running a new drop from the loft ring).
As above, unless there were a de-rating issue, due to installation method, there would be no point in using 4mm² for the circuit 'as installed' - and if there were such a de-rating issue, 2.5mm² would very probably not be acceptable for the ring, either.

You seem to be suggesting that any unfused spur from a ring final (supplying just one socket) should be wired in 4mm², just in case someone wanted to extend that spur in the future. Is that your view? It certainly does not correspond with the guidance given in App 15 of BS7671.
That's exactly the same, but just on a different floor - so all the above still applies.
As above, if he needed 4mm² for spurs because of the installation method (of the feeds to the sockets), he would probably also have had to use 4mm² for the entire ring (i.e. replace the entire ring), if he had 'put the sockets on the ring' and some of the cable passed through that same route to the sockets.
Again, I have to ask whether it's your view is that all unfused spurs from ring finals should be wired in 4mm² (in case someone wanted to subsequently 'extend the spur')?

As EFLI has said, I think you are missing the point - which is that a 4mm² unfused spur from a ring allows an unlimited number of sockets to be supplied without the need for an FCU and its associated 13A current limitation (i.e. 'fused spur'). If the spur only supplies one socket, there is no need for 4mm² (unless because of de-rating) in terms of the circuit 'as it is'.

Kind Regards, John

As regards to your query on why I think it is a terrible idea to have a ring of junction boxes supplying spurs to each socket:
1) Terrible in the sense that there are unnecessary junction boxes in hard to access easily places.
2) Terrible in the sense that you cannot easily add to these 'spurs'., assuming they are in 2.5mm2, as you have basically already pointed out.
3) Possibly terrible in the sense that the number of spurs exceeds the number of sockets wired directly to the ring.

As you say, no point doing the spurs in 4mm2 unless there is a de-rating issue as you've said...

I'm suggesting it could be a good idea to do spurs in 4mm2 if it may help someone in the future. Why wouldn't I? It may be me who wants to add to it in the future.

No, my relative was never going to replace the whole ring. He was not rewiring the place. He was not concerned with the existing installation. He wanted his additions to be the best he could do without too much work. He put some thought into it, more than most would I like to think.

No it is not my view that all spurs should be done in 4mm2, but may be an idea when adding a spur to somewhere that doesn't have any sockets anywhere near it. Although my personal choice is often to extend the ring in 2.5mm2. Any of the three methods would generally do, wouldn't you say?

You have remarked that I am missing the point that EFLI - to which I would say, NO, I don't believe I have missed any point - I am all in favour of avoiding the FCU if possible, particularly in kitchens where demand is high.

 

[sparkwright]

Ok.


Good.


I thought you were arguing against the method by proposing extending the ring with both legs in the same place.

It must have been I who missed your point.

I Apologise.

Thank you.

(No apology needed.)

 

[sparkwright]

.

 

[JohnW2]

1) Terrible in the sense that there are unnecessary junction boxes in hard to access easily places.

We (at least I) was talking about JB's in roof spaces of bungalows, so probably pretty 'accessible', but I agree that it would be more of an issue in the situation you introduced of sockets being spurred from JBs in the space under floorboards above. In any event, if you believe in such things, there are always 'MF' JBs.

2) Terrible in the sense that you cannot easily add to these 'spurs'., assuning they are in 2.5mm2, as you have basically already pointed out.

Indeed I have - but I'm not sure to what extent initial design of a circuits needs to, or should, take into account what changes/additions may be required in the (quite possibly distant) future. One could take such 'future-proofing' to silly extremes.

3) Possibly terrible in the sense that the number of spurs exceeds the number of sockets wired directly to the ring.

What's "terrible about that (electrically), particularly given that I was talking about a situation in which there are zero sockets "wired directly to the ring"?

As you say, no point doing the spurs in 4mm2 unless there is a de-rating issue as you've said... .... I'm suggesting it could be a good idea to do spurs in 4mm2 if it may help someone in the future. Why wouldn't I? It may be me who wants to add to it in the future.

You seem to be contradicting yourself - is there "no point", or is it "a good idea"? As above, I accept that it may facilitate future extensions to the circuit in the future, but wonder to what extent one needs to, or should, consider that in the initial design?

No it is not my view that all spurs should be done in 4mm2, but may be an idea when adding a spur to somewhere that doesn't have any sockets anywhere near it.

Similar to above, you're almost contradicting yourself again. If you believe in considering (unknown) extensions to the circuit that may be required in the future, I would have expected you to advocate always using 4mm².

Although my personal choice is often to extend the ring in 2.5mm2. Any of the three methods would generally do, wouldn't you say?

Sure (provided that all design considerations are satisfied), at the present time - the differences relate to what people might want to do in the (possibly distant, if ever) future.

You have remarked that I am missing the point that EFLI - to which I would say, NO, I don't believe I have missed any point - I am all in favour of avoiding the FCU if possible, particularly in kitchens where demand is high.

Fair enough. Anyone who supplied multiple sockets in a kitchen (or some other areas) from a ("13A") fused spur would be being a little silly. However, as has been discussed, the rather surprising thing is that very few seem to consider the alternative of feeding them with a (4mm²) unfused spur from a ring.

Kind Regards, John

 

[sparkwright]

We (at least I) was talking about JB's in roof spaces of bungalows, so probably pretty 'accessible', but I agree that it would be more of an issue in the situation you introduced of sockets being spurred from JBs in the space under floorboards above. In any event, if you believe in such things, there are always 'MF' JBs.
Indeed I have - but I'm not sure to what extent initial design of a circuits needs to, or should, take into account what changes/additions may be required in the (quite possibly distant) future. One could take such 'future-proofing' to silly extremes.
What's "terrible about that (electrically), particularly given that I was talking about a situation in which there are zero sockets "wired directly to the ring"?
You seem to be contradicting yourself - is there "no point", or is it "a good idea"? As above, I accept that it may facilitate future extensions to the circuit in the future, but wonder to what extent one needs to, or should, consider that in the initial design?
Similar to above, you're almost contradicting yourself again. If you believe in considering (unknown) extensions to the circuit that may be required in the future, I would have expected you to advocate always using 4mm².
Sure (provided that all design considerations are satisfied), at the present time - the differences relate to what people might want to do in the (possibly distant, if ever) future.
Fair enough. Anyone who supplied multiple sockets in a kitchen (or some other areas) from a ("13A") fused spur would be being a little silly. However, as has been discussed, the rather surprising thing is that very few seem to consider the alternative of feeding them with a (4mm²) unfused spur from a ring.

Kind Regards, John

Yes, I was thinking along the lines of all the JBs being in the loft. Accessible, but still a pain to get to.

Fault finding could be impossible from the ground floor.

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Future proofing isn't a requirement as such, but imagine what a faff it would be trying to add an extra socket, anywhere, when every existing socket is a spur.

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The ring would consist solely of JBs and spurs, although it could also be a mixture of both, as many houses are. There was a rule about the number of spurs (many in this case) not exceeding the number of points wired directly to the ring (could be zero in this case). An outdated rule, which could have been enforced when said bungalow may have been wired.
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The electrician or designer will naturally decide if there is no point, or it's a good idea, to allow for future extensions and alterations - if he chooses to. Experience may be helpful here.

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As far as adding one spur goes, no way am I going to use 4mm2 everytime. If I think there is a good chance it may help me or someone in the future, I may use 4mm2, particularly if the new cable run is going to be awkward to install.

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Always think about the future, particularly if it makes life easier for you.

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I don't like spurring multiple sockets from an FCU in a kitchen - when you have a washing machine and a kettle on the end of an FCU, you anticipate trouble. Many people do not consider using a 4mm2 spur to do multiple sockets because you don't see it in text books.

 

[JohnW2]

Yes, I was thinking along the lines of all the JBs being in the loft. Accessible, but still a pain to get to.

I suppose that's a matter of opinion, but such access would only be required very rarely.

Future proofing isn't a requirement as such, but imagine what a faff it would be trying to add an extra socket, anywhere, when every existing socket is a spur. ... The ring would consist solely of JBs and spurs, although it could also be a mixture of both, as many houses are. There was a rule about the number of spurs (many in this case) not exceeding the number of points wired directly to the ring (could be zero in this case). An outdated rule, which could have been enforced when said bungalow may have been wired.

I'm not sure when there was last such a regulation in BS7671 itself, but the current OSG still thinks that there is ..

H2.4 Spurs
The total number of fused spurs is unlimited but the number of non-fused spurs should not exceed the total number of socket-outlets and items of stationary equipment connected directly in the circuit.

However, whether a regulation or not, that has never made any (electrical) sense to me - can you think of an (electrical) justification for it? Mind you, the OSG has been known to come up with some pretty bizarre ideas of its own!

The electrician or designer will naturally decide if there is no point, or it's a good idea, to allow for future extensions and alterations - if he chooses to. Experience may be helpful here. ... As far as adding one spur goes, no way am I going to use 4mm2 everytime. If I think there is a good chance it may help me or someone in the future, I may use 4mm2, particularly if the new cable run is going to be awkward to install. Always think about the future, particularly if it makes life easier for you.

The real-world problem is that one doesn't only need 'experience' but also a crystal ball in order to anticipate what changes/additions someone may want to implement in the (possibly distant) future.

I don't like spurring multiple sockets from an FCU in a kitchen - when you have a washing machine and a kettle on the end of an FCU, you anticipate trouble.

As I said, it's essentially daft, and indicating a lack of thought/ common sense on the part of the designer.

Many people do not consider using a 4mm2 spur to do multiple sockets because you don't see it in text books.

That's essentially what I said. They can't be bothered to (and/or are unable to) think for themselves, and don't find 4mm² spurs in 'books' (e.g. , as I said, in the examples shown in the guidance of App 15 of BS7671).

Kind Regards, John

 

[SUNRAY]

Personally I try to extend the ring, that's not to say I get pedantic about it.

When I moved into the current Sunray Villa the ring final in 7/0.029" appeared to have 3 or 4 sockets and the remaining 20 or so points being spurs (with several points on each spur) in a selection of 7/0.029" and 2.5mm².
The first requirement being to remove the cables clipped to most skirting boards (mains, telephone and TV and in places all 3) and fit enough sockets but more importantly in the right places. Most of it was fairly simple to add on to the end of the line of spurred sockets to incorporate into the ring. It wasn't until a number of years later when I wanted to add a SFCU in the master bedroom for TV etc (to power down the standby lights when not in use) that I truly realised on that wall were a total of seven points on 2 spurs from the SSSO on the ring - as opposed to the 6 points on the ring and 2 spurs I thought (goes to prove my initial inspection wasn't accurate else I'd have altered it much earlier) however much to my shame I'd added one of those points believing it to be on the ring.

Quite often including a new point in the ring is no more work than a spur and is often neater.

In 50's and 60's many amateur electricians didn't really understand the protocols of ring mains (as were always called then) and spur drops to or from sockets to a JB was a very common method, I always imagined it started where existing split conduit will only accept one T&E so a JB and spur fitted. I've certainly done that as a solution. Equally when loads of sound radials are converted to a ring JB's in the floor/ceiling voids reduces the need to chase the walls.

 

[JohnW2]

Personally I try to extend the ring, that's not to say I get pedantic about it.

I suspect that such is the first inclination of the great majority of us (whether 'doing' or advising), on the basis that it sounds like the 'correct'/'decent' way of doing it - but, as I've also said, I'm not at all sure that it's a view that can really be supported if we actually engage in some ('electrical') thought.

The old reg (and a concept still persisting in the current OSG) that the number of spurs should be limited to the number of sockets/loads "on the ring" seems particularly (electrically) ridiculous, since it is (at least for me) hard to think on an (electrical) justification.

In 50's and 60's many amateur electricians didn't really understand the protocols of ring mains (as were always called then) and spur drops to or from sockets to a JB was a very common method ...

I'm sure that's true, and I doubt restricted to only "amateur electricians", nor probably only in the 50s and 60s. Speaking for myself (as an 'amateur'), I'm sure that some of my earliest efforts at 'extending sockets circuits' (in latter part of 60s, and the 70s) took place with no real understanding of the significance of the differences between spurs and 'the ring' - so if I wanted 'additional socket(s)', I would probably have simply wired it/them from the nearest socket, without any regard to whether it was 'a socket on the ring' or already an unfused spur from the ring....

... and, of course, needless to say, there were never any 'consequences' of that! In fact, in the real world, rather than the world of theory and 'cautiousness', I would imagine that it would be incredibly rare for any serious problems to arise because umpteen sockets had been supplied by a single unfused (2.5mm²) spur from a ring - let's face it, with Method C we're only talking about the difference between 27A and 32A.

Kind Regards, John