Ring main.

[7029 dave]

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So its had a name given to it now, bow tie circuit . ha ha
Cant wait to see that in any text book.

 

[David Prosser]

But the hind wings are much smaller and not considered a lifting wing, they are there to counter balance the movement of the front wings hence the erratic flight, but a Dragonfly can hover.

Post automatically merged: May 1, 2020

The Work of the Devil is Clingfilm or is that the Devil spawn.

The rear set of butterfly wings are not always smaller the orange sulphur for example have slightly larger rear wings.

 

[Risteard]

Well I called it a butterfly circuit, anybody can call it what they want, no problem. Just like the age old cooker circuit, modified cos cooker not needed so a ring produced from that point, some call that a "lolipop" circuit or a "lassoo" circuit (not implying a cowboy job I hope!). The butterfly or whatever you call it just like the lolipop can be a decent circuit designed using sound engineering judgement and be ok. The fact that they are not easily recognised as standard circuits does nothing to detract from that. It might confuse the unwary a little but you could ask "should they really be adding/modifying these circuits if they do not fully understand what they are doing?". Answer No, they could ask someone who does know though and there is no shame in that. There is no person who knows everything about everything.
I disagree about calling them crap circuits though.
Another example to consider is a radial circuit, be it lighting or power points. You might branch out at some point for instance 1 begats 2 begats 4 begats 8 etc etc, it is still a radial circuit, again with different topology but nonetheless sound (some call them "trees"), in fact you could start it off with two conductors (or more) at the CU and it`s still ok - might be a beggar to test though! - you`d have several ends for Zs. It is up to the designer if they want to create one circuit,

In my example No 2/ is actually better in terms of volt drop and R1 + R2 than example No1 is.

I wasn't referring to all non-standard circuits as crap. I'm not hygely in favour of four conductors in a circuit breaker etc. though. So it was this particular arrangement which I was suggesting that many might consider to be crap.

A ring supplied by a suitably sized radial feeder is something which I have absolutely no difficulty with, even though it is non-standard.

 

[ebee]

I wasn't referring to all non-standard circuits as crap. I'm not hygely in favour of four conductors in a circuit breaker etc. though. So it was this particular arrangement which I was suggesting that many might consider to be crap.

A ring supplied by a suitably sized radial feeder is something which I have absolutely no difficulty with, even though it is non-standard.

Whatever you label them does not really matter, they are not crap circuits, they may be decent reliable circuits if undertaken properly. The only problem is they are not commonly listed. BS 7671 tells you what to comply with it does not tell you how to comply. So long as you use sound electrical design it complies and is safe. No less so than if you use a bog standard ring or radial.

I can give one example of a circuit that probably does not comply but is nonetheless safe :-
a bog standard ring final circuit B32A MCB with a spur of one twin socket at the origin of the ring i.e from the fuseway. Compliant Yes. Now disconnect the ring but leave the spur in place, so now its a twin socket on a 32a mcb. we would not like the look of it but removal of the ring has not rendered it unsafe has it?

 

[Vortigern]

So like a dog with a bone I have been thinking about this. I can't quite get my head around EFLI test what route would the current take on such a circuit? If I took it at ring A say, would it go around ring B or just ring A and the substation?

 

[ebee]

So like a dog with a bone I have been thinking about this. I can't quite get my head around EFLI test what route would the current take on such a circuit? If I took it at ring A say, would it go around ring B or just ring A and the substation?

Easy, just the ring of that particular fault. Same as any circuit connected in your consumer unit.

Post automatically merged: May 2, 2020

Easy, just the ring of that particular fault. Same as any circuit connected in your consumer unit.

The test would give the most onerous as the answer which should be the 65m ring part of the circuit

 

[Risteard]

Whatever you label them does not really matter, they are not crap circuits, they may be decent reliable circuits if undertaken properly. The only problem is they are not commonly listed. BS 7671 tells you what to comply with it does not tell you how to comply. So long as you use sound electrical design it complies and is safe. No less so than if you use a bog standard ring or radial.

I can give one example of a circuit that probably does not comply but is nonetheless safe :-
a bog standard ring final circuit B32A MCB with a spur of one twin socket at the origin of the ring i.e from the fuseway. Compliant Yes. Now disconnect the ring but leave the spur in place, so now its a twin socket on a 32a mcb. we would not like the look of it but removal of the ring has not rendered it unsafe has it?

I never suggested that any of them were unsafe. In fact I specifically stated that the circuit in question was not unsafe unless there was an issue with the connections to the four conductors at the origin.

 

[littlespark]

Going round in circles indeed... or going round in rings...

earlier in the thread.... much much earlier... it has been established by the OP that there is two rings from one OCPD. Tested, and not found to be one ring and two radials.
It has also been established that there is a spare way in the board, and a suspect damaged breaker, possibly removed from the board.

it is highly likely, Your Honour, that these two rings have been put together as a stop gap, Friday afternoon, temporary fix until Monday.... and was never returned to.

Discussing whether it is safe or not is a mute subject... because the OP, I believe has mentioned previously that he (or his electrical representative) will seperate the two rings into seperate ocpd’s as soon as he can.

I surmise from this that the case is now closed, and no further discussion is required.

 

[westward10]

Can you expand on that please your closing evidence is not clear

 

[scootknew]

what is the 2 ring mains supplying? 1 bedroom , 2 bedrooms, /// livingroom + kitchen etc?

 

[Pete999]

what is the 2 ring mains supplying? 1 bedroom , 2 bedrooms, /// livingroom + kitchen etc?

Most likely the whole dwelling.

 

[Mike Johnson]

Just an aside, does anyone else have page lengths of 100 posts? Seems excessively long to scroll down to the last post.

 

[ebee]

Hi,
the point I was making is that if we wish to comply with BS7671 then we do not need to stick to the standard circuits, there are other alternatives.

Most of us, including me, if we see a non standard circuit then we initially think "hey that`s wrong!" because of familararity. But, if we consider further then we realise those circuits are indeed ok and often compliant with BS7671 too. We all fall into the trap of thinking something uncommon must automatically be wrong.

You often get things cropping up due to Part P.
Part P is part of the Building Regs in England and Wales and as such is the law (unlike BS7671).
Then they created the approved doc P, that is just guidance, nothing else, not law.
Originally the approved doc stated following BS 7671 or an Equiv European standard should satisfy the requirements. Nothing in Part P or the approved doc forbad following the rules of any civilised country. Later years the app doc only mentions BS 7671.
That does not make BS 7671 a legal requirement by statute.
The only time it becomes a legal requirement is you are a scheme member and that means you have a contract with that scheme to follow BS7671 in your workings. It is contract law, that`s all.
All Part P says is that reasonable provision must be made for safety and not much else really.

Things tend to become legends.
Having said all that, the most sensible option to cover yourself is to always comply with BS 7671 and my point is that the lassoo and the two ringed one circuit, and radial trees all comply, no matter how odd they look at first glance.

 

[G1ZQC_David]

Unless you have tested it a visual assessment that four conductors equate to two ring final circuits may or may not be correct. It could be four radials, one ring final and two spurs or just all four interconnecting with themselves.

If it were four radials on a 32 a MCB, its wrong anyway, as a radial curcuit requires a 20a MCB, 2.5 mm wire is only 26 amp rating.!!

 

[ebee]

If it were four radials on a 32 a MCB, its wrong anyway, as a radial curcuit requires a 20a MCB, 2.5 mm wire is only 26 amp rating.!!

Agreed, it would be wrong (probably) it would not be any more hazardous than a spur on a 32A ring though. So 4 or more radials of not exceeding one twin socket of good length (not excessive length so it compromises volt drop and Zs though) would also be OK ref overload, Two singles would but the reason why 2 single per spur was dropped was because at least one of them was likely to be converted to a twin at a future point in time.

Of course any of us seeing it would think "Oh No" including me, even though it usually would be quite safe

 

[John clark]

I'm not saying I would do this because I wouldn't install like this, but I am going to play devils advocate.

Which regulations does such an arrangement breach?

And how would two ring final circuits installed in accordance with the regulations connected to the same 32A MCB be dangerous?

As I say I wouldn't do it, except as a temporary measure to restore supply, so I'm just curious about the thought process behind the statements.

common sense prevails in this case

 

[ebee]

common sense prevails in this case

Agreed, Common sense says it is not dangerous. Common sense say it does not breach the regs. But common sense tells us that it is not the most elegant of solutions and that it may well allow those who go there after us to confuse themselves. Therefore most of us would probably avoid it.
I did actually use this scenario (once) because quite a few new circuits got added as the job was ongoing so my planned spare ways got used up .

I made diagrams and notes next to consumer unit and appended to EIC to clarify to the unwary, plus labels on conductors too. 6 months later he got rid of another circuit to the remainder so I took the opportunity to normalise the situation

 

[davesparks]

It just gets peoples backs up IMO, and adds nothing to the debate. I know he disagrees without the red cross because I've read his previous posts!

By that logic none of the little pictures add anything to the debate.

 

[radiohead]

By that logic none of the little pictures add anything to the debate.

They don't, and neither do all of the posts on any debate.

 

[ebee]

So its had a name given to it now, bow tie circuit . ha ha
Cant wait to see that in any text book.

I doubt it will get into any text book. Any name might be equally as good (or bad) as another. I personally have never seen in any textbook or article the name Lassoo circuit (6.00 T & E radial feeding a 2.5 T & E ring final) , not at all uncommon in a kitchen where an old redundant cooker circuit was disconnected and used to form a new kitchen ring. The name lassoo is quite common for it. I`ve never noticed it in the OSG or the like. I`ve never noticed tree circuits mentioned for radials either but they are just as valid too.
We all (me included) tend to look at non standard circuits and think "Hey that`s wrong" then we look again and relalise "no it complies" or sometimes "no it does not comply, but is safe" (the later for example is an umpteen radial 2.5 T & E each feeding 1 max twin or 2 max single sockets on a 32A MCB - providing that the terminals in the CU can accomodate it both mechanically and electrically of course).

 

[markythesparky]

Definitely two rings there are 4 cables in the MCB. I'm going to add another way and seperate them.

How do you know they are both rings? Have you tested them?

Post automatically merged: Jun 19, 2020

@SparkyChick

I have been having similar thoughts,
I don't think its right, and its not something I would install as new.

however I have just been browsing the book, and nothing is jumping out to say I couldn't do it if I wanted to.

I think we can mostly all agree that it is certainly not best practice but if someone could point me to a reg number it would make me feel better.

Appendix 15, page 505.

Post automatically merged: Jun 19, 2020

I fully agree that this is incorrect and should not have been done.

But having said that what are the apparent dangers? I don't see any particular danger attributable to this.

The definition of a circuit is based around everything that is connected to a single way in a distribution board, so this would still count as one circuit, although it is nom-standard.

Post automatically merged: Apr 28, 2020

You can have two legs of a radial cir uit connected to an MCB, but that is not two circuits. Also it is not bad practice.

Beg to differ; appendix 15, page 506.

 

[Pretty Mouth]

How do you know they are both rings? Have you tested them?

Post automatically merged: Jun 19, 2020

Appendix 15, page 505.

Post automatically merged: Jun 19, 2020

Beg to differ; appendix 15, page 506.

Appendix 15, contrary to popular belief, is not regulation. It shows options for for the design of ring and radial final circuits.

I can't see anything in app 15 that prohibits 2 radials in one MCB, or even 2 rings.

 

[ebee]

Right, so we all in agreement then. Two/three/four/ umpteen rings in one fuseway32A is one circuit is compliant and is safe.
4,5,6,umpteen radials in one fuseway 20A with one twin skt max in each radial is no compliant but still perfectly safe.
both 2.5 T & E and both including all other considerations that would normally apply with rings and radials (including floor area served)

 

[markythesparky]

Appendix 15, contrary to popular belief, is not regulation. It shows options for for the design of ring and radial final circuits.

I can't see anything in app 15 that prohibits 2 radials in one MCB, or even 2 rings.

That doesn’t answer my question as to whether the OP had made sure that they are both rings.

In answer to your statement, whether it’s a Reg or not, the options it gives do not include bunching two rings into an OCPD (which by the way would be a figure of 8, which you test for when doing an EICR). If you decide to make up your own options then where will this end? The same applies for the next page (506) which is about radials.

BS7671 is ‘Requirements for Electrical Installation’ and as such should be adhered to as close as possible.

 

[ebee]

That doesn’t answer my question as to whether the OP had made sure that they are both rings.

In answer to your statement, whether it’s a Reg or not, the options it gives do not include bunching two rings into an OCPD (which by the way would be a figure of 8, which you test for when doing an EICR). If you decide to make up your own options then where will this end? The same applies for the next page (506) which is about radials.

BS7671 is ‘Requirements for Electrical Installation’ and as such should be adhered to as close as possible.

No, two rings one circuit is not what is meant by "figure of 8".

The figure of eight test is a test of ring conductors that allows R1 + R2 readings to be taken (fairly consistantly but not 100% exactly) from any point on the ring

 

[dodger421]

That doesn’t answer my question as to whether the OP had made sure that they are both rings.

Post 69 on page 3 mate:

I've carried out Continuity tests on all four conductors this evening to find it is 2 RFCs, both sets of circuit conductors have now been marked so they can be identified correctly. Also on closer inspection I've found an sorry looking 32amp breaker in amongst a load of other rubble which could of potentially been from the spare way in the Consumer? Orignally it looks as if these RFCs were both on there own MCB. Going forward I'll purchase a new breaker and seperate these two circuits to there own supply.

 

[Pete999]

Appendix 15, contrary to popular belief, is not regulation. It shows options for for the design of ring and radial final circuits.

I can't see anything in app 15 that prohibits 2 radials in one MCB, or even 2 rings.

That doesn’t answer my question as to whether the OP had made sure that they are both rings.

In answer to your statement, whether it’s a Reg or not, the options it gives do not include bunching two rings into an OCPD (which by the way would be a figure of 8, which you test for when doing an EICR). If you decide to make up your own options then where will this end? The same applies for the next page (506) which is about radials.

BS7671 is ‘Requirements for Electrical Installation’ and as such should be adhered to as close as possible.

Agree, and what are the Regs
They are a non statutory document to aid installers/designers design and install Electrical installations in compliance with the Electricity at Work Act, a statutory document.
If people are installing circuits, that have already been described as not being discussed in BS 7671, are we not complying with the [email protected]?
It's all well and good when people say this and that circuit is safe, that's their assessment doesn't make it right, we should be complying with BS7671 to comply with the [email protected], these are my apinions,

 

[markythesparky]

Absolutely spot on. What on earth is the point in producing a book on how electrical installations should be carried out if an installer then makes up his or her own guildines? We go back to college every three to four years at substantial cost, to ‘learn how to use‘ this British Standard so why then ignore it?
Another thought, if some thing bad were to happen, and the circuit is of a design that isn’t in BS7671, the installer wouldn’t or have a leg to stand on. If something bad were to happen and the circuit was designed along the guidelines of BS7671 then the installer would be totally in the clear. Slam dunk! Ain’t worth the risk!

 

[DPG]

Absolutely spot on. What on earth is the point in producing a book on how electrical installations should be carried out if an installer then makes up his or her own guildines? We go back to college every three to four years at substantial cost, to ‘learn how to use‘ this British Standard so why then ignore it?
Another thought, if some thing bad were to happen, and the circuit is of a design that isn’t in BS7671, the installer wouldn’t or have a leg to stand on. If something bad were to happen and the circuit was designed along the guidelines of BS7671 then the installer would be totally in the clear. Slam dunk! Ain’t worth the risk!

The regs aren't supposed to be an A to Z of allowable circuits though. It's not painting by numbers, and a degree of experience may be used to tweak things.