Well the reason the term ring main persists is because it has been in use for over a century when ring mains were (and for that matter still are) very common and in sizes well over the tiny 32A we know.
As you will be aware, I'm much more 'neutral' than you, but agree with most of your specific points.
It's not really all that massive a deal if the cable in Method C 2.5mm² - 32A is not much more than 27A and, anyway, it's probably very usual for a domestic ring final to be loaded even to 27A for an appreciable period of time.
You don't have to 'say' anything. You simply sign to confirm that, to the best of your knowledge, the work is compliant with BS7671 - which a ring final is - and nor do you have to 'say' anything to explain your approach to splitting the installation into circuits etc.
Unfortunately or maybe fortunately BS 7671 only gives the ground rules, so it may say volt drop shall not exceed 5% but it does not say how to achieve that.
Ring mains have been in service for a century or more. Sadly I threw out a load of books etc handed down to me by an elderly friend a few years back, one of which was akin to our current OSG which clearly showed how to install a ring main in a house using porcelain or glass insulators (Think old telephone poles style) and bare wire, the format was a complete ring of bare wire with ceramic tubes or beads where it went through any obstructions and insulated singles spurs on similar porcelain/glass insulators to the sockets. There were also training notebooks (foolscap graph paper books) from his fathers apprentice days showing ring mains and their variations for different applications.
As before it is the name they had always been known as prior to being adopted into wiring regs.
And happy new year back to you.
As I've said, I'm personally pretty neutral in relation to the radial/ring debate. As I see it, the only real significant 'benefit' of a ring final is the 'CPC redundancy', which you mention above - but, as you also say, there is 'con' to balance that 'pro' ....
... and, of course, if an L or N of a ring final is broken somewhere, there is no 'indication', so users remain oblivious to the existence of the problem which, as you say, could theoretically result in (minor) overloading of cables
I'm not quite sure what you mean, and it depends upon what you're comparing with. A 4mm² 32A radial has the same total power supplying capacity as a 2,5mm² 32A ring final, but without any restrictions about apply all of the total load near an end of the circuit.
I'm not sure what you mean by 'saved'. If you're referring to 'saved from death due to electrocution in domestic situations', there are so few such deaths in the UK (a couple of dozen or so per year) that there is very little scope for improvement, and at least some of those deaths will probably be those which no RCD could have been prevented. As I often say, if the amount spent on buying and installing RCDs over recent decades ('billions') had been spent on something else (like road safety), I suspect that far more lives could have bee saved.
That's pretty speculative. The CPC of a sockets circuit is not necessary involved in electric shocks (even if the L involved is of such a circuit), so it's presence (or absence) may not make any difference in a particular situation.
True, in a sense. It's probably more correct to say that they just did not ever see an need/point in introducing them (and would not have been happy with them, anyway)
Indeed so. Just in the same way that if tobacco, alcohol, aspirin, paracetamol or whatever (all of which result in far more deaths than electricity) were to first appear today, they would almost certainly be outlawed/'not allowed'.
As I said, the only real advantage of a ring I can think of is the 'CPC redundancy' (although, as above, that comes with a corresponding 'disadvantage'. 'Saving copper' (allegedly the main reason ring finals were invented) is either trivial or non-existent (particular after the move from BS3036 fuses to MCBs). Indeed, depending on the layout of sockets and cable routes, a 4mm² radial may use less copper than a 2.5mm² ring.
Agreed. As I've said, I'm personally pretty 'neutral'!
As I've said before, I've seen fairly similar done (with the ring of JBs in the roof space) in modern bungalows with solid floors.
My understanding is a ring main is designed so sections can be isolated for work to be done, and the cable used can take the current permitted by the protection device.
is of a reasonable quality, many are rather poor to put it mildly, without the 4 stages shown by the one I use. So we need to keep domestic wiring to what the ordinary person will expect to find, and not expect them to know the difference by looking at a cable between 4 mm² and 2.5 mm² even in commercial premises I have found a 4 mm² radial split and extra sockets added as if it was a ring final with 2.5 mm².As before, when one signs an EIC (or EICR) one does not have to 'say' anything about VD. To comply with BS7671 (which is all one is ';signing for') all that is required is that one is satisfied that VD does not result in supply voltages to connected equipment falling to a level which "impairs the safe functioning" of the equipment - and I struggle to think of a situation in which one would not be satisfied about that!
Possibly, but it depends very much on the layout of the circuit. You often talk about 106 metres being the maximum length of a ring final (if one utilises the 'guidance' figures for maximum VD), but that's rather misleading, since it relates to both legs of the ring. Even if the sockets are all' in a straight line' that still means that the farthest socket can only be 53 metres from the CU. That is not dramatically different from the 42 metres maximum which you calculate (again, using 'guideline' max VD) for a 20A radial.
In a sense, one can understand that -i.e. they favour 'a devil they know', and have selected themselves. However, that issue only arises if one wants to undertake everything (including the testing) oneself. LAs undoubted vary, but the fee mine charge for notification includes the cost of whatever supervision and testing they deem it necessary to organise themselves.
That may be how things work out in practice, but I'm not sure that it is necessarily the case, particularly with LAs like mine. The person appointed by the LA could certainly (on an EIC) 'sign for' the design (if he/she had approved the design) and also for the I&T (if they had undertaken it). That just leaves 'construction', and that declaration on an EIC has to be signed for the person 'responsible for' the construction. That does not mean that the person signing has to have actually undertaken the construction and if (as with my LA) the person has been contracted to undertake whatever degree of supervision the LA deem necessary, then I would think that such a person could be reasonably regarded as 'having been responsible for' the construction.
As you imply, a lot is down to individual BCOs, but it's worth noting that the OSG (and also the Approved Documents) are even less 'authoritative' (let alone 'mandatory') than are the Appendices of BS7671, so cannot be used as a determinent of whether something is, or is not, compliant with BS7671 (which is meant to be what matters!).
Is that a 'royal you' (perhaps "one)? I personally am not "trying to DIY home re-wire using LABC", so won't be able to tell you how I get on. I have, in my time, undertaken complete re-wires, but that was prior to the appearance of Part P (hence notification).
So have I, but would think that approach is problematical and potentially dangerous, and I'm far from convinced that it would be compliant with regs (unless, perhaps, the two MCBs were mechanically linked). It would also have practical problems since, although theoretically a "32A circuit", one of the MCBs may well operate if anything approaching 32A were connected close to one end of the ring.
I don't really understand that. As I often say, I'm not all that comfortable with 20A radials, but am very happy with (and use) 32A ones.
I did point that out. As to 32 amp radial, the question is as with all domestic installation will it cause a danger when in the control of an ordinary person.
The same applies to a ring final where some one has not checked if still a ring. Or swapping from splitting side to side to up/down, side to side was the norm before the RCD, it gave a better loop impedance and would not temp people to run leads up/down stairs in an emergency when a circuit failed, but we don't put red, yellow and blue dots on the sockets to show where fed from, may do that with commercial to show which phase, but what ever house some one has been raised in, that person will go to the next house and expect it to be the same.
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