Quite right, radials are not needed.
Single to double socket off fused spur
- Thread starter Soong
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Yes I do say so, they both have advantages and disadvatagesDid you mean "not still needed" and "imply".
Yes they were needed when they were devised until MCBs were introduced.
As I'm sure you know, they allowed 15A radial circuits to be extended into a ring with a 30A fuse using the same sized cable that would not be adequate for a 30A radial.
Bear in mind a radial circuit with 30A BS3036 fuse today would require 6mm² cable.
Yes, with MCBs without the derating factor of BS3036 fuses.
Obviously.
That is not what outdated means.
If you say so. Only one of them is not needed.
I like that tongue in cheeck commentQuite right, radials are not needed.
Which is actually completely accurate.I like that tongue in cheeck comment
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I would hate to be restricted to cumbersome and expensive 4 or 6mm² radials in single backboxes.
Why not??
and both meanings (Assuming my understanding of these words hasn't changed since being at school) are an acceptable use in the question.
Every single circuit can be implemented using a ring final. If you are aware of circuit design requirements you wouldn't need an explanation.
Oh dear. Are you serious?
Put simply: Imply is what someone else suggests to you and infer is what you deduce from that suggestion.
Given that the question regarding ring circuits - "If they are still needed, does that infer the were ever needed?" - does not actually make sense but should read "If they are not still needed, does that imply they were never needed?".
Are you saying a ring final with 1mm² T&E with a 25A MCB would be compliant with the regulation and if so, why would you bother to do it?
Edit - just added the 'y' - another mistake I missed.
Because as you said they mean different things.
Put simply: Imply is what someone else suggests to you and infer is what you deduce from that suggestion.
How can they be?
Given that the question regarding ring circuits - "If they are still needed, does that infer the were ever needed?" - does not actually make sense but should read "If they are not still needed, does that imply they were never needed?".
You know perfectly well that we are talking about the UK ring circuit according to 433.1.204.
Are you saying a ring final with 1mm² T&E with a 25A MCB would be compliant with the regulation and if so, why would you bother to do it?
Edit - just added the 'y' - another mistake I missed.
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I would personally not regard 4mm² as particularly 'cumbersome' and, in fact, generally find it nicer to work with than 2.5mm².
... and is 4mm² really more expensive than what is likely to be roughly twice the length of 2.5mm²?
Kind Regards, John
I apologise for believing Mister Amos, my English teacher for getting it wrong.
As I understood his tuition;
Imply is to do with the results of suggestion, whereas
Infer is to do with the results of proof.
I have deliberately not looked up current deffinitions
Therefore: If someone is citing the regs as proof that the current rules for our 'standard' ring final is outdated and incorrect (I apologise in advance if my conclusion in this matter is incorrect), on that basis I'd expect the correct word to be infer.
Whereas if someone one suggests to you ring finals circuits are not still needed, can you question ever needed? On that basis I would suggest the word is imply.
The question as written could easily have been interpreted either way.
However it is only a suggestion, by a few, that ring circuits are no longer needed and there are many on this site who dispute their obsolescence. So this whole conversation is not needed as in itself it has no relevance. Our 'standard' ring final circuit remains in the book and I see no sign of it being withdrawn.
Everyone is entitled to their opinion but the regs are the regs and if push came to shove any disputes can be referenced to the regs to demonstrate best practice.
As already stated
Equally you know perfectly well ring finals are permitted to any design and were in place for at least 50 years before some idiot designed our horrible 13A plug. Nowhere in the thread does it mention a specific design of ring circuit, it is of course easy to make assumptions.
The whole of my working life has been based in commercial environments, the last new ring circuits I've installed being 1ph 80A using 6mm² singles in 3 pop-up just eat style kitchens during lockdown and the one prior to those about 2005 started by installing a 3ph 500A fused switch (to the LV bussbar fed by a 1MW 11KV transformer), 200A fuses and I think 95mm² SWA. Actually that one started by digging the pit in the reinforced concrete floor between the position for transformer and main distribution panel, installing the panel, assisting DNO positioning transformer etc.
I've worked on 1200A OCPD rings, I'm guessing 300 or 400mm² where the individual cores need to be formed into place with levers, ratchet straps and jacks.
Just about as far from DIY as it could be but still ring circuits.
Hey, folks, Friday is quite a long way off
............................ To be fair, I think your exchange with EFLI is probably somewhat 'at cross-purposes, be that deliberately on the part of one (or both!) of you, or 'accidental' ...
You are, of course correct in saying that there is nothing, either in terms of electrical principles or BS7671, which prevents any circuit (for any purpose, with any CSA of cable and with any appropriate OPD rating) being wired as a ring - and, although it's unlikley to arise in domestic installations, there may well sometimes be good reasons (presumably usually in relation to Zs and/or VD) for wiring a ring other than that permitted by 433.1.204.
However, given context and the nature of this forum (and its readers), I would expect us all to understand that when EFLI writes (here) about 'ring finals', he is really only talking about those specifically 'allowed' by 433.1.204 - which specifically permits a ring with a 30/32A circuits to be wired with a cable with a CCC which may be as low as 20A.
If,as in your commercial examples, the OPD has an In anything other than 30/32A, then 433.1.204 does not apply, so a straightforward application of BS7671 would require that the CCC of the cable be at least equal to the In of the OPD (i.e. the same as if it were a radial circuit).
I suppose you could 'abandon' that 'straightforward application of BS7671' and, instead present a 'from first principles' argument that each point on your ring had (unequal) 'parallel conductors' back to the OPD, but you would then presumably still have to size the cable such that the short leg of the ring would not be overloaded even if the circuit's full design current were applied at the closest possible point to an end of the ring - and, depending on circumstances, that may not make much difference.
Hence, the point about 'ring finals as permitted by 433.1.204' (the only type of ring finals relevant to this forum) is that they are specifically allowed to be wired with cable with a CCC of only about 63-67% of the In of the OPD, but only IF that OPD is 30/32A, whereas the required CCC becomes 100% of the OPD's In, or something approaching that, if the OPD is anything other than 30/32A.
One might, logically, expect that BS7671 would also allow, for example, 20A rings to be wired with 1mm² cable, 25A rings to be wired with 1.5mm² cable or 45A rings to be wired with 4mm² cable - but it doesn't, since 433.1.204 relates only to 30/32A circuits
Kind Regards, John
Blimey!
Dare I mention that there might well be a distinction between "ring finals" often found in domestic wiring and "ring mains" often found in the street outside or at power/distribution and transmittion systems.
Dare I mention that there might well be a distinction between "ring finals" often found in domestic wiring and "ring mains" often found in the street outside or at power/distribution and transmittion systems.
Thank you John.
I am puzzled why SUNRAY 'liked' the post.
It was obvious what 'rings' we were talking about because it was all in response to Taylortwocities' post #9.
I am puzzled why SUNRAY 'liked' the post.
It was obvious what 'rings' we were talking about because it was all in response to Taylortwocities' post #9.
Then Ebee's post #10.
Yes of course there is but I've also worked on a few 40A domesic ring finals, a local developement listed as a feature in their 'luxury' houses and took me by surprise when I first encountered one.
Equally I've worked on 50/60/63A ring finals for 13A sockets in commercial properties, particularly IT situations and in nightclubs it was (my knowledge based in mid 90's) normal to have a lollipop final running 50+ KW sound systems.
Edited to make more sense.
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Quite so
Indeed. but (despite misuse of the technical term by many people) "ring mains" are obviously a totally different kettle of fish, other than, of course, that they physically exist as a cable wired as a ring.
Hence even the ("non-433.1.204") ring circuits mentioned by SUNRAY are "ring final circuits" - although, as I said, only the "433.1.204 ones" are likely to be of any interest to people in this forum ... which, in turns, means that if someone writes in this forum about "ring final circuits", it is (or should be) pretty obvious what they are talking about.
Of course,if (as is very commonly the case) they write about "RFCs", that is theoretically very ambiguous - but that's a different story
Kind Regards, John
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