Does this look right?

[JohnW2]

My turn to explain badly. .... You cannot connect a load of more than 3kW to any point on the ring.

I guess that depends on what you mean by 'a point'. I would have thought that a double socket comted as 'a point' and you could connect a load or 26A (some would say 20A) to that, and you could have, say, three of those within a few centimetres of one another (so, almost the same 'point'), to which you could connect loads totally 78A (or 60A).

Kind Regards, John

 

[JohnW2]

In all the explanations, I've forgotten who is saying 20A switches are allowed on ring circuits and who is saying they are not (I'm sure some have changed their minds).

Yes, it's got rather confusing. I have not changed my mind, and the my personal position is, and always has been:

1...I personally can see no electrical reason not to connect 20A switches to a ring final, and so I do it. IF that is non-compliant with the regulations then I am very happy to be "totally irresponsible" and ignore that regulation.

2...My initial view of the regulation was that I could see no conceivable reason why the authors of BS7671 would want to outlaw switches on ring finals (let's face it, the first thing that electrons hit in most BS1363 sockets and many BS1363 FCUs is a switch!) and therefore felt that, although the wording did not seem totally clear to me, I just could not believe that their intention had been to prohibit switches, so I thought that to interpret the (not totally clear - at least not to me) wording per what I thought was their intention seemed very reasonable.

3...However, virtually everyone who has commented on the matter over the years in this forum (and elsewhere) appears to have interpreted the reg as allowing only BS1363 accessories (he4nce not switches) to be connected to a ring final - with some fairly forcefully indicating that one should comply with what the regulation "actually says" (although there is not really agreement about that!) and that it is "irresponsible" to work on the basis of what one assumes was the intention (even if not the word) of the authors.

So, in conclusion, I neither know (for certain) nor care whether the regulation allows switches, since I am going to continue using them (when needed) regardless of the regulation. The fact that groups of intelligent and literate people have, on numerous occasions, discussed this matter and expressed opposing views about interpretation of the regulation is, to my mind, a definite indication that the regulation in question is inadequately clear.

There is, of course, another issue which sometimes arises. Some people (presumably those who do not believe that OPDs exist only to protect cables) are unhappy with (and some claim it non-complaint) connecting a switch rated at 20A to a 30/32A circuit.

Kind Regards, John

 

[stillp]

1...I personally can see no electrical reason not to connect 20A switches to a ring final, and so I do it. IF that is non-compliant with the regulations then I am very happy to be "totally irresponsible" and ignore that regulation.

Long ago, on about page 2 of this thread, you posted:

However, as I've just written, for those who wish (or are forced to) worry about such things, it is, strictly speaking, not compliant with BS7671.

It was that definite statement that it was not compliant that led to this discussion.

 

[EFLImpudence]

3...However, virtually everyone who has commented on the matter over the years in this forum (and elsewhere) appears to have interpreted the reg as allowing only BS1363 accessories (he4nce not switches) to be connected to a ring final - with some fairly forcefully indicating that one should comply with what the regulation "actually says" (although there is not really agreement about that!) and that it is "irresponsible" to work on the basis of what one assumes was the intention (even if not the word) of the authors.

That's a bit confusing.

Are you saying that some state that one should comply with what the regulation actually says by quoting what it specifically does not say?

What it actually does say is, as my post above, virtually meaningless.

You may (are allowed to) have a cup of tea in the morning.



The switch is rated to switch 20A. There will not be 32A through its terminals.
What about on a 32A radial?


I agree with the rest of your post.

 

[JohnW2]

Long ago, on about page 2 of this thread, you posted:

However, as I've just written, for those who wish (or are forced to) worry about such things, it is, strictly speaking, not compliant with BS7671.

It was that definite statement that it was not compliant that led to this discussion.

I know that's what caused you to start this discussion but, as I wrote to you at the time, I was merely reflecting the almost unanimous views on the matter ('interpretations' of the regulation) expressed on many occasions in this forum, in a good few cases from people more qualified than me to comment on electrical matters.

Kind Regards, John

 

[JohnW2]

That's a bit confusing. Are you saying that some state that one should comply with what the regulation actually says by quoting what it specifically does not say? .... What it actually does say is, as my post above, virtually meaningless.

I think that the short answer is "sort-of yes".

As you say, what the regulation actually says" is essentially meaningless, hence stupid, and presumably not was actually 'intended' - hence all the uncertainties about what was intended. It makes no sense to say "Accessories to BS1363 (and, by the way, anything else you fancy, since we are stating no prohibitions) may be supplied ...".

I presume that what some people are doing is trying to make some sense of this 'meaningless' statement, and are guessing/assuming what it is 'trying to say' - even though, as you say, their conclusion necessarily differs from what the words of the reg "actually say".

The switch is rated to switch 20A. There will not be 32A through its terminals.

That's what some people argue about. If the switch is 'on the ring', then 32A could be flowing between the two cables connected to supply side of the switch "in the switches terminal", then some argue that 32A is 'flowing through the terminal'. Like you, I disagree.

What about on a 32A radial?

As far as "they" are concerned, it's exactly the same 'problem' as with a ring final. The same people would presumably express unhappiness about 10A switches or roses being supplied by a 16A lighting circuit!

Kind Regards, John

 

[EFLImpudence]

I didn't think there was any dispute that a 20A switch was allowed on a radial.

 

[JohnW2]

I didn't think there was any dispute that a 20A switch was allowed on a radial.

Your muddling two things. This discussion has primarily been about whether 433.1.204 allows anything other than 'accessopries to BS1363' to be 'supplied by' a ring final.

However, I recently added a different issue. Even if it is decided that (per 433.1.204) double-pole switches may be connected to a ring final, I believe that some would say that a 20A-rated switch should not be connected to any circuit protected by a 30/32A OPD - whether radial or ring.

Kind Regards, John

 

[EFLImpudence]

...but sockets are not rated at 32A.

As I said, I didn't think there was any dispute that a 20A switch was allowed on a radial, so why do you believe that?

 

[ban-all-sheds]

Therefore saying "Accessories to BS1363 may be supplied through a ring final circuit, ... , protected by a 30 A or 32 A protective device ..." is equally non-restrictive. Unless anything is exeplicitly prohibited, then so may they.

Again you are missing the point.

Generically a ring final circuit using 2.5mm² cable and a 30/32A protective device is not allowed by BS 7671. It contravenes the requirements of 433.1.1. Nothing may be supplied by it because you may not have it. Everything is explicitly prohibited from being supplied by it.

There is one exception, and one only, and that says that accessories to BS 1363 may be supplied by such a circuit, subject to a few other conditions, because then (and only then, because 433.1.204 is the only exception) the circuit is deemed to comply with 433.1.1.

 

[ban-all-sheds]

I didn't think there was any dispute that a 20A switch was allowed on a radial.

Surely they are allowed on any radial with an OPD ≤ 20A, and not allowed on any radial with an OPD > 20A.

 

[EFLImpudence]

Surely they are allowed on any radial with an OPD ≤ 20A, and not allowed on any radial with an OPD > 20A.

I don't see why.

The conductors in a ring only have to be rated at 20A.

As I said in another thread, sockets are not rated at 32A.
Sockets and FCUs are allowed on 32A radials therefore it cannot be the OPD rating that limits which accessories may be fitted.

 

[JohnW2]

...but sockets are not rated at 32A.

Are you sure that the terminals of a BS1363 socket are not specified as being able to carry a 'through current' of 32A

As I said, I didn't think there was any dispute that a 20A switch was allowed on a radial, so why do you believe that?

As I said, this is totally different from what we have been discussing in this thread. There are definitely some people who believe that one should not have anything connected to a circuit which has a lower current 'rating' than the In of the OPD of the circuit. I seem to recall that eric often mentions this in relation to 16A (and maybe even 10A) lighting circuits.

... and don't forget, we are taking generically about 'a switch' without considering what is downstream of it. To play Devil's Advocate ... the people to whom I have referred might point out that if the 20A switch were connected to a 32A radial, it's not impossible that there could be several socket outlets downstream of the switch - in which case that "20A switch" might find 32A passing through it.

Kind Regards, John

 

[EFLImpudence]

Apart from the fact that the terminals are likely the same as socket terminals, there is probably not 32A passing through a terminal where two wires are connected together.



Don't play devil's advocate; that happens with spurs from spurs. Do it correctly.

I don't see how doing something wrongly is a reason for not allowing something done correctly.

You could wire a shower in 1mm²; that's not a reason for banning 1mm².

 

[JohnW2]

Apart from the fact that the terminals are likely the same as socket terminals, there is probably not 32A passing through a terminal where two wires are connected together.

You're preaching to the wrong person.

I merely made a comment about 'what some people believe' as an added potential complication in relation to 20A switches.

Kind Regards, John