Discuss Ring main. in the UK Electrical Forum area at ElectriciansForums.net
All I can say is... subjectively it's wrong. Objectively it complies with the regulations, if you disagree and would like to convince me otherwise, please explain (a) how it violates the figure 8 test (the purpose of which is to look for interconnections between the legs of the ring at a point other than the origin, interconnections that could if ill-informed alterations were made result in a situation with the potential to overload a cable) and (b) which regulations it violates and why.
It's wrong, we all know it's wrong... explaining why with actual regulations is a little trickier. Please don't cite Appendix 15 (Informative)... it is not a regulation. Without wanting to offend, it's the regulations equivalent of 'The dummies guide to the ring final circuit as defined by regulation 433.1.204'. It provides a lot of compliant examples, but listing all possibilities would be an impossibility which is why it's informative, it's a quick start guide if you will. As best as I can tell the only actual regulation specifically about 32A ring circuits is 433.1.204, it's entirely possible I've missed some but I've looked hard whilst writing some of my replies to this thread because I wanted to be certain I was objectively correct, but I'm all ears if I've missed some.
Maybe we should look at this another way... how would you code this arrangement if you came across it on an EICR? Which regulations would you cite as those it breaks and why?
Remember... I'm really just playing devil's advocate but I am getting a little tired of late of the blind following of rules. The regulations are the bare minimum, we need to be able to think for ourselves, so if you feel like telling me which code Codebreakers applies to this situation, go right ahead and explain what justifies such a code, backing your explanation up with actual regulations and how the arrangement breaks them.
And for another fun exercise in analysing the twisted mind of this old bint... lets suppose I have a ring circuit and I ran out of 2.5mm on the job, only got an off cut left that's about 18 inches long, only had two more double sockets to sort out... kitchen job, all the cables clipped direct or in the void of a dot and dab wall, so I run a length of 6mm from a convenient place (before anyone asks how I managed to squeeze 2 x 2.5mm and 1 x 6mm in accessory terminals.. I love the new 3 way slimline Wago connectors that take 0.5mm to 6mm cable.. awesome for this kind of thinking... nice maintenance free Wagobox tucked out the way, great it was) to the first of the doubles and as they are next to each other, I use the off cut of 2.5mm to supply the other. Does that comply with the design criteria for a ring circuit supplied by a 32A OCPD? If not, why not? And if this complies... how does the situation described in the OP not?
Oddly enough @JBW175 post #330 from today is shown as older than @SparkyChick post #331 from 25 Aug!
Is it wrong or dangerous? Not really.
Is it worth coding? Probably C3 as it was most likely a separate circuit added to an existing OCPD due to some other factor, so it could be improved by separating it and having another OCPD (ideally RCBOs, but that is another discussion point).
Oddly enough @JBW175 post #330 from today is shown as older than @SparkyChick post #331 from 25 Aug!
Is it wrong or dangerous? Not really.
Is it worth coding? Probably C3 as it was most likely a separate circuit added to an existing OCPD due to some other factor, so it could be improved by separating it and having another OCPD (ideally RCBOs, but that is another discussion point).
Oddly enough @JBW175 post #330 from today is shown as older than @SparkyChick post #331 from 25 Aug!
Is it wrong or dangerous? Not really.
Is it worth coding? Probably C3 as it was most likely a separate circuit added to an existing OCPD due to some other factor, so it could be improved by separating it and having another OCPD (ideally RCBOs, but that is another discussion point).
Yep. C3 just mean improvement recommended.I cant be a C3 because it complies though
C3 means a reg defect. If it`s not a C1 or a C2 then its a C3, but if not a defect it must NOT be coded at all.Yep. C3 just mean improvement recommended.
you could take one leg from each rfc and joint them in the board, leaving you one big rfc.
Well, if they're old colours, sleeve one 'ring' brown and blue.......there's your C3. ?C3 means a reg defect. If it`s not a C1 or a C2 then its a C3, but if not a defect it must NOT be coded at all.
Incorrect colour coding of conductors is one example of a C3
If each one is safe if on 2 devices, what makes them become unsafe when put on 1?Absolutely no chance should there be 2 RFC in a 32A MCB.
There aren't.Neither should there be a 2.5mm2 radial let alone 2,3 or 4.
It isn'tIt is covered in the regs and is further legislated against in test and inspection.
But why, other than testing aggro?Firstly assuming it is 2 RFC then it is in-fact an interconnected ring main which is the whole purpose of the ring final test to avoid.
By exactly the same logic we should not have any ring finals, because if the ring is broken then the circuit becomes 2 radials.The reason for avoiding is simple should either of the two rings of an interconnection become open circuit then the circuit becomes two or even four radials.
A figure-of-8 actually decreases the chances of a break leading to an overload potential.Which also answers all other scenarios the 2.5mm2 Cables of a radial circuit on 32amp supply will become over loaded and be a potential fire hazard.
My dad had his tv and video recorder into same plug. I think it would be safer than one of those cube adaptors hanging out the wall.I've come across 2 table lamps in one plug before now, though personally I wouldn't do it a few people seem to think it's ok.
My dad had his tv and video recorder into same plug. I think it would be safer than one of those cube adaptors hanging out the wall.
Afigure of 8 (meaning a bridge somewhere in the ring) means we can not be sure to which extent the current will flow in every scenario of current draw at any particular times .If each one is safe if on 2 devices, what makes them become unsafe when put on 1?
There aren't.
It isn't
But why, other than testing aggro?
By exactly the same logic we should not have any ring finals, because if the ring is broken then the circuit becomes 2 radials.
A figure-of-8 actually decreases the chances of a break leading to an overload potential.
Diagram 3 and 4 are the same, just one extra socket, what are you trying to prove? or diss-prove come to that?
Didn't Marbo (?) used to make a plug designed to take more than one flex?I've done the same in the past I must admit. In my own home. Not ideal, but as long as it is 2 small flexes and the cord grip secures them properly then not too bad.
Didn't Marbo (?) used to make a plug designed to take more than one flex?
Not really other than it's not called a ring main a ring main is a distribution circuit it's ring final circuit if you get your terms correct you may get some better responsesIt's testing which is the problem, I think. Without the predictability/consistency of readings from a proper, single, ring it's harder to spot problems such as multiple socket spurs.
But as for loading and balance - I won't mind if I prove myself wrong with some worked examples, (or if someone else does to save me the effort ?), but my initial feeling is that any cross-connections which make a figure of 8 or anything else just add current paths and thus lower the current flowing in them, not increase it.
I can sort of envisage a scenario where a section near the origin of the ring could become unbalanced, but I'm not sure how improbable it is. Need to do some sketches.
Anyone out there with circuit design software which could be used to analyse different scenarios?
youneed to get out more. don't the pubs open soon?If I start with this:
View attachment 84116
and add a loop like this:
View attachment 84117
or if I start with this:
View attachment 84118
and add a link across the middle to end up with the same figure of 8, which cable(s) become at risk of being overloaded that would not if I'd done this:
View attachment 84122
?
The more paths there are for current to flow to each point of loading the less flows in any given one, not more.
Ignoring the practical realities of actually wiring it, a "full mesh" topology of interconnections
View attachment 84124
would minimise the current flowing in every single cable (apart, obv, from the ones from the OPD to the "first" and "last" sockets, but those cables are never affected by any interconnection topology anyway).
And the more connections you have the harder it becomes to turn the circuit into radials, or to create multi-socket branches, by cutting connections.
If you are referring to me Tel, then nothing gets up my snout more than Wannbee's quoting something they know little or nothing about post ban waiting, still no one likes the truth these days do they?youneed to get out more. don't the pubs open soon?
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