Single to double socket off fused spur

[JohnW2]

Thank you John.

You're welcome, but I only 'spoke the truth'!

I am puzzled why SUNRAY 'liked' the post.

It did seem a little odd. I can but presume that he used the "liked" to really mean "agree" - since I imagine that even he would not be able to disagree with anything I wrote.

It was obvious what 'rings' we were talking about ...

As I said, I would have thought so, particularly given the nature and readership of this forum. We've been through this before, and I think that all of us involved know that there are (usually non-domestic) situations in which "non-433.1.204 ring finals" are installed - BUT we also know that such are not what people are talking about when they refer to "ring finals" in this forum.

Kind Regards, John

 

[ebee]

Of course,if (as is very commonly the case) they write about "RFCs", that is theoretically very ambiguous - but that's a different story

I will not ask what you think those letters might well stand for John ) but I have seen some installations in my time that could come under that interpretion too.

 

[JohnW2]

I will not ask what you think those letters might well stand for John ) but I have seen some installations in my time that could come under that interpretion too.

Not all the sockets circuits in my house have the same wiring topology,but all would qualify as "RFCs"

Kind Regards, John

 

[SUNRAY]

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.

I don't know how prevalent it was or even if correct but when I were a nipper I remember the terms light or lighting fuse and mains fuse and if fuse boxes were labelled would be so labelled. Typically there might be a lighting fusebox and a mains fusebox.

I don't know when I first heard the term 'final' being used but it certainly wasn't anywhere near the early part of my life. I only have a 2004 copy of 16th so can't look at deffinitions prior to that. I did have a little book called 'Modern Wiring Practice' from 20's or 30's which described installing ring mains using bare wire and ceramic insulators. It has been suggested to me the red copies of 16th used the term 'ring main' I'd love to know if that's correct and when the definition changed.

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.

Except 40A ring circuits seem to be creeping in to new builds and I'd expect questions to start appearing on here.

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

And IIRC strangely RFC used to be used by some of the 'better posers' on here and initially fell ino the trap myself because back then no-one said 'radial final circuit' and strangely even now during conversation it seems to be 'radial' or 'ring final'.

 

[JohnW2]

I don't know how prevalent it was or even if correct but when I were a nipper I remember the terms light or lighting fuse and mains fuse and if fuse boxes were labelled would be so labelled. Typically there might be a lighting fusebox and a mains fusebox.

That wouldn't surprise me. Terminology, even 'correct' terminology, changes over time, and that's quite apart from those who 'misuse' terminology at any point in time.

I think that a significant proportion of the general population still use 'ring' to refer to any circuit - hence we quite often see people talking about, say, 'lighting rings'; in domestic properties (which, in reality, must be incredibly rare, if they exist at all). However, I don't know whether this is just a 'terminology issue' or whether they believe that such circuits are wired as rings.

I don't know when I first heard the term 'final' being used but it certainly wasn't anywhere near the early part of my life.

Same here. For me it ws probably when I first saw a copy of gthe "Wiring Regs" - which, like you, was probably 16th. Maybe someone can tell us when the term first appeared (secure??)

Except 40A ring circuits seem to be creeping in to new builds and I'd expect questions to start appearing on here.

I wasn't aware of that. What OPD, and what cable, do they use?

Kind Regards, John

 

[SUNRAY]

Thank you John.

I am puzzled why SUNRAY 'liked' the post.

It did seem a little odd. I can but presume that he used the "liked" to really mean "agree" - since I imagine that even he would not be able to disagree with anything I wrote.


Kind Regards, John

Why is it puzzling when I like a perfectly acceptable post?

I wholly agreed with most of it and didn't disagree with the remainder.

I wasn't aware of that. (40A ring final) What OPD, and what cable, do they use?

Kind Regards, John

4mm² & B40
I think what's happened is 20 RFC's are causing overload tripping problems and the developers solution is to go one better for the luxury properties.

 

[JohnW2]

4mm² & B40

As I recently wrote, that would not be compliant with 'a straightforward application of BS7671' (since even Method C 4mm does not have a CCC of 40A) in which case I would have thought that many an EICR inspector would give it a C2.

I agree that such an arrangement is 'no worse' than a 32A circuit using cable with a CCC of 20A, hence almost certainly would be 'fine' but, as I said, is not explicitly allowed by BS7671. Whilst, as I said, one could produce a 'from first principles' argument to justify it, an EICR inspector will not usually be aware that you have done that - and, even if he/she is aware of the argument (e.g. because one has told them) that still would not necessarily stop them ('at their discretion') giving a C2 (and citing 433..1.1).

Kind Regards, John

 

[ebee]

I think we all are in danger of falling into the auto thought of certain things (not just in electrics but in all walks of life too and everyday life itself. "We have always done this thing that way so it is correct to do so" and "We never do this other thing in that way, therefore it must be incorrect to do such!" without, quite often, due regard to the actual rights and wrongs of the situation.

Sometimes these things can actually rank as silly as the "It`s a WELL KNOWN FACT!" so to speak.

 

[JohnW2]

I think we all are in danger of falling into the auto thought of certain things (not just in electrics but in all walks of life too and everyday life itself. "We have always done this thing that way so it is correct to do so" and "We never do this other thing in that way, therefore it must be incorrect to do such!" without, quite often, due regard to the actual rights and wrongs of the situation.

That's very true, and we know of a good few examples (e.g. 1,5mm² lighting wiring, 6mm² (Method C) 32A cooker circuits etc. etc.). Some are leftovers of old (e.g. pre-MCB and/or pre-metric cables) days, but in other cases it is less clear why 'it started' (before everyone else 'followed').

However,in terms of what I most recently wrote (which I presume is what you are responding to), it's a bit different - since it's not a case of 'what we have always done' but, rather, what a 'straightforward application of BS7671 allows'. I'm feel sure that, in the eyes of many an EICR inspector, a circuit (of any configuration) wired in 4mm cable protected by a 40A OPD "is a C2", wouldn't it be?

Kind Regards, John