No not really, a circuit originate from 1 OCPD, secondly it's not a "Ring Main" it's a Ring Final Circuit RFC, pedantic but correct terminology counts these days.
No is the answer, you will overload the mcb
Are you adjusting a circuit or putting another one in and have no room in CU.
Are you adjusting a circuit or putting another one in and have no room in CU.
I've never seen many people argue that two ring finals one one MCB is a good idea.
I'll reiterate, a circuit originates from an individual OCPD if some dipstick has decided to combine 2 RFCs into 1 circuit incorrectly then He / She needs to hang up their screwdrivers, and take up another Trade.
Well no then it isn't
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You are more than welcome Mate
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See description of a circuit in OSG or BS 7671
You could put more than one radial on a MCB but its not good practice.
2 Rings on 32mcb is dangerous are you sure it's not 2 radials?
2 rings would have four wires goinging into a MCB
Some people spur off a MCB maybe it was that - 3 wires?
2 Rings on 32mcb is dangerous are you sure it's not 2 radials?
2 rings would have four wires goinging into a MCB
Some people spur off a MCB maybe it was that - 3 wires?
Looking at this thread there is argument that it is safe but not common
_theiet.org/forums/forum/messageview.cfm?catid=205&threadid=32208
I suppose you could argue it's just extending the Ring??? - 2 large rings would surely cause constant tripping.
_theiet.org/forums/forum/messageview.cfm?catid=205&threadid=32208
I suppose you could argue it's just extending the Ring??? - 2 large rings would surely cause constant tripping.
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.
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.
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.
R
radiohead
In all honesty I cannot see anything in Bs7671 that this would contravene other than good workmanship. If it originates from one MCB it is a single circuit. Despite what has been said about it overloading there is no reason to assume it would be. A single ring with 10 double sockets could have 20 3kw heaters plugged into it.
Very poor practice though and it needs altering on that basis.
edit. Post crossed with Sparkychick who has reached the same conclusion.
Very poor practice though and it needs altering on that basis.
edit. Post crossed with Sparkychick who has reached the same conclusion.
@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.
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.
It may not disagree with any regulations, but SC you surely can see the apparent dangers of applying such a circuit.
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Don't think you need a reg number SC look up the description of a circuit.
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Yeah fairly interesting and I'm not saying I would do but considering Table H2.1 unlimited Sockets in 100m2 - probably could be considered as extending the ring without extra danger.
D
davesparks
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.
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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.
I did wonder because the Design project limits you to circuits of 30m so I had several lighting circuit only rated about 2Amps I wondered in real life if I could in theory just put three of these say in to a single 6Amps MCB or maybe even more into a 10Amp MCB.
I think I'd be pushing my luck but couldn't find anything dangerous about it.
I think I'd be pushing my luck but couldn't find anything dangerous about it.
@JKMRK1
wow, look what you have started here!!
I like the conversation thread,
you are listed as a trainee, when you get your qualifications you will be a qualified electrician. just look at the different ways the regs have been interpreted and peoples opinions on what is good, bad and indifferent practice.
as your time and experience in the trade expands, you will start to build an idea of what is a good installation and will also be more opinionated about what is not ok.
bottom line for me when I consider things that are not accurately defined, would I be happy if this was installed at my daughters house?
it normally guides my mind in the right direction.
wow, look what you have started here!!
I like the conversation thread,
you are listed as a trainee, when you get your qualifications you will be a qualified electrician. just look at the different ways the regs have been interpreted and peoples opinions on what is good, bad and indifferent practice.
as your time and experience in the trade expands, you will start to build an idea of what is a good installation and will also be more opinionated about what is not ok.
bottom line for me when I consider things that are not accurately defined, would I be happy if this was installed at my daughters house?
it normally guides my mind in the right direction.
Going the other way round and this is from a European web site
"The rules for ring wiring say that the rated current of the cable must be at least two-thirds of the rating of the protective device. This means that the risk of prolonged cable overload can be considered minimal. However, in practice it is very rare to find a ring with a different protective device than a 30 A fuse, a 30 A circuit breaker or a 32 A circuit breaker and a cable with a cross-section different from the one mentioned above."
right or wrong what's the common response to finding a Ring on a 20A MCB or wired in 4mm??
"The rules for ring wiring say that the rated current of the cable must be at least two-thirds of the rating of the protective device. This means that the risk of prolonged cable overload can be considered minimal. However, in practice it is very rare to find a ring with a different protective device than a 30 A fuse, a 30 A circuit breaker or a 32 A circuit breaker and a cable with a cross-section different from the one mentioned above."
right or wrong what's the common response to finding a Ring on a 20A MCB or wired in 4mm??
But there's a spare way in this particular CU.
R
radiohead
I dont think you have got mixed opinions, nobody has said this is anything other than bad practice. But the question concerns regulations, and as yet nobody has given an actual regulation that this breaches, and throwing hands up in horror does not count as a regulation.
For all we know it could only be two double socket outlets in the circuit.
I propose we call these bow-tie final circuits from now on!
I propose we call these bow-tie final circuits from now on!
You couldn't, because by definition it would be one radial.
How is it dangerous, apart from the potential issue with the four conductors in the terminals/cage clamp (which although crap is unlikely to be an issue in real terms)?
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