two ring mains joined

[JohnW2]

[I have attempted so unentangle your in-line responses within a quote of my post]

If an electrician has been trained to BS7671 they will know what to expect when they find an interconnection in a ring final cicuit.

I'm not really sure what you mean. What does complete knowledge and understanding of BS7671 tell one about "what to expect" when one finds an interconnection in a ring-final circuit?

I was referring to a post were you stated you would prefer a change to Part P to allow registered electricians and atypical diyers to self certify their jobs.

Unless you are omitting some major qualifications in what I wrote, I cannot believe that I ever wrote that - since it is nonsense. How on earth could one define the "atypcal diyers" who were allowed to self-certify??

As I said, this is not some amazing design by a super electrician - it's a ring with an interconnection. As such it doesn't require a phd in physics to undersstand the readings on the test meter.

Indeed it doesn't, but, as below, it does require knowledge of, or the ability to work out, what additional tests are required if a cross-connection in a ring final circuit is detected - something I've never noticed being described in any of the main reference materials/guidances (and which I suspect is usually not taught).

You frequently tell us about the electricians you come into contact with and how little they understand about the principles of electrical theory.

A few of them, yes - and I'm certainly not the only one here, and elsewhere, who makes similar comments. Given that some have only been 'trained' for a few days, it's hardly surprising.

I have never seen you post that you have met one who has demonstrated this understanding.

I often acknowledge that there are excellent electricians, including in my post that you have just quoted.. In any event, how often do you hear on the 6 o'clock News about all the aircraft that have not crashed on a particular day?

I didn't think I needed to specify that this only applies when the tests are all passed.

Yes, but what tests? As I said, you won't find the additional tests required (after a cross-connection has been detected) mentioned or described in BS7671 or guidances such as GN3, and I very much doubt that they are taught in many courses.

As I said, this whole discussion started because a significant proportion of electricians appear to believe that a cross-connection in a ring is non-compliant - and therefore should, in itself, be 'coded'.

Did it? Reading back, it was you who decided that thius is beyond the wit of most (or at least a large majority of) electricians.

That's not how I see it. Had there not been suggestions that the arrangement, per se, was non-compliant, I would probably not have bothered to get involved.

Your position seems a little complicated, in that you would not 'code' it, presumably indicating that you regard it as compliant and do not think it is appropriate to even 'recommend improvement', but you wouldn't work on the circuit without first removing the interconnection.

Kind Regards, John

 

[securespark]

As I said before:

My guess is that the downstairs was intended to be an extension of the first floor ring final but it went horribly wrong when they did not know how to break into the circuit.

Instead of taking each leg of the extension circuit and connecting it as an extension of the upstairs ring final, they connected each end to two different sockets, ending up with a spur feeding lots of sockets, fed from both ends.

 

[JohnW2]

Instead of taking each leg of the extension circuit and connecting it as an extension of the upstairs ring final, they connected each end to two different sockets, ending up with a spur feeding lots of sockets, fed from both ends.

Indeed, as I've been discussing with EFLI, my interpretation is the same as yours.

However, that does not necessarily mean that there is anything (electrically) 'wrong' with the circuit. It results in lower EFLI and VD, better current sharing and more CPC redundancy than would be the case had the 'extension circuit' been inserted into the existing ring in the conventional manner. The description of ".. a spur feeding lots of sockets, fed from both ends" might make some people's eyebrows rise, but it should be remembered that a bog-standard ring final could be described as a "radial feeding lots of sockets, fed from both ends"!

Kind Regards, John

 

[EFLImpudence]

Instead of taking each leg of the extension circuit and connecting it as an extension of the upstairs ring final, they connected each end to two different sockets, ending up with a spur feeding lots of sockets, fed from both ends.

But then you wouldn't end up with two sockets upstairs AND two sockets downstairs all with three cables.

 

[JohnW2]

Instead of taking each leg of the extension circuit and connecting it as an extension of the upstairs ring final, they connected each end to two different sockets, ending up with a spur feeding lots of sockets, fed from both ends.

But then you wouldn't end up with two sockets upstairs AND two sockets downstairs all with three cables.

Fair enough - I take your point. However, unless the circuits have been traced, some of those 3-cable sockets could be supplying spurs, rather that representing interconnections between two rings. Nevertheless, I suppose it means that your interpretation of the topology may be correct - but, even though that is an even more complicated arrangements than I was considering, I don't think it alters anything I've been saying about the circuit.

Indeed, the arrangement you are considering is quite interesting, since the 'inner ring' is actually comprises parts of two additional rings (as far as supply is concerned), 'in parallel'. Most of the cross-connection in the primary ('outer') ring is therefore effectively 5mm², hence offering even more theoretical 'advantages' over a conventional single ring. It would certainly be 'interesting' to fully test such a circuit!

Kind Regards, John

 

[EFLImpudence]

If it is not as I am thinking (which is what the description states, although, obviously, the OP may be mistaken) and one of the downstairs three-cable positions is a spur (then consequently one of the upstairs three-cable connections must also be a spur) then it definitely IS non-compliant because there would be two rings (only one of which is from the MCB) one of which is connected and supplied by a single cable.

 

[JohnW2]

If it is not as I am thinking (which is what the description states, although, obviously, the OP may be mistaken) and one of the downstairs three-cable positions is a spur (then consequently one of the upstairs three-cable connections must also be a spur) then it definitely IS non-compliant because there would be two rings (only one of which is from the MCB) one of which is connected and supplied by a single cable.

It's only speculation, but what I was suggesting was:

Kind Regards, John

 

[visionset]

If I have understood correctly, this is the configuration:

View attachment 85949

Yes that is what I am deducing is the case.

 

[securespark]

Lemon entry, my dear EFLI?

 

[EFLImpudence]

 

[JohnW2]

Yes that is what I am deducing is the case.

Thanks for clarifying. Are you basing that deduction on the fact that there are two 3-cable sockets upstairs, and the same downstairs, or do you have any additional evidence that the arrangement is probably as you have suggested?

As I have been saying, although it is a very unusual arrangement, IF it is as you believe, I cannot personally see anything electrically wrong with it (no 'worse' than a conventional ring) - although I am sure there will be continuing debates as to whether it is strictly compliant with regulations.

Kind Regards, John

 

[ban-all-sheds]

[amidst another serious abomination of quoting ]

I never used to get it wrong as often as I have done recently. There must be something in the way the new forum behaves which results in mistakes being easier to make, harder to spot, or harder to put right. With the latter I know that I have sometimes nearly lost the will to live when trying to fix mismatched [QU0TE] [/QU0TE] pairs given the way the forum actually appends missing ones to the end of the post rather than assumes their presence when displaying it.

If I have understood correctly, this is the configuration:

View attachment 85949

Yes that is what I am deducing is the case.

No - neither of us said those things.

 

[ban-all-sheds]

I am sure there will be continuing debates as to whether it is strictly compliant with regulations.

There may be debates on whether it is valid to say "strictly compliant". People might point out that compliance is dichotomous. Just as one is either pregnant or not, something either complies or it does not.