Ring main.

[JKMRK1]

Question I have is, is it ok to have x2 ring main circuits on one 32amp type B MCB??

If so does this meet the current regs.

TIA.

 

[Pete999]

Question I have is, is it ok to have x2 ring main circuits on one 32amp type B MCB??

If so does this meet the current regs.

TIA.

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.

 

[buzzlightyear]

Two rings of a circuit, got the regs?

 

[JKMRK1]

Two rings of a circuit, got the regs?

Yes I have the regs book, which states final circuits should be connected to a seperate way in the CU. But I've seen so many others argue this is OK??

 

[buzzlightyear]

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.

 

[DPG]

Yes I have the regs book, which states final circuits should be connected to a seperate way in the CU. But I've seen so many others argue this is OK??

I've never seen many people argue that two ring finals one one MCB is a good idea.

 

[JKMRK1]

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.

I've come across this in the house I've just purchased. There's a spare way in the board I'll add another MCB and seperate them.

 

[Pete999]

Yes I have the regs book, which states final circuits should be connected to a seperate way in the CU. But I've seen so many others argue this is OK??

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.

 

[buzzlightyear]

I've never seen many people argue that two lring finals one one MCB is a good idea.

the chuckle brothers electrical. Lol

 

[JKMRK1]

I've never seen many people argue that two ring finals one one MCB is a good idea.

I'm not saying it's correct just saying what I've seen. That's why I've asked the question to make sure its correct.
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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.

Thanks for the advice it is much appreciated?

 

[Pete999]

I'm not saying it's correct just saying what I've seen. That's why I've asked the question to make sure its correct.

Well no then it isn't
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I'm not saying it's correct just saying what I've seen. That's why I've asked the question to make sure its correct.
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Thanks for the advice it is much appreciated?

You are more than welcome Mate
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I'm not saying it's correct just saying what I've seen. That's why I've asked the question to make sure its correct.
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Thanks for the advice it is much appreciated?

See description of a circuit in OSG or BS 7671

 

[Mark Wright]

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?

 

[DPG]

If there is a spare way in the CU then I would question why someone has decided to combine the two circuits. I recommend doing full set of dead tests before connecting up.

 

[JKMRK1]

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?

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

 

[Mark Wright]

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.

 

[James]

it could even be that originally it was 2 circuits.

failed mcb was removed and temporary supply taken from the one next to it.
late night tempory fix that never got finished off?

 

[DPG]

I suppose you could argue it's just extending the Ring??? - 2 large rings would surely cause constant tripping.
[/QUOTE]

It's not the same as extending the ring.

 

[SparkyChick]

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.

 

[westward10]

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.

 

[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.

 

[James]

@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.

 

[Pete999]

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.

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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@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.

Don't think you need a reg number SC look up the description of a circuit.

 

[Mark Wright]

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.

 

[davesparks]

It may not disagree with any regulations, but SC you surely can see the apparent dangers of applying such a circuit.

Don't think you need a reg number SC look up the description of a circuit.

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 could put more than one radial on a MCB but its not good practice.

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.

 

[DPG]

Bad design does not always have a reg number I guess.

 

[James]

CIRCUIT:
An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s).

I think the arrangement above matches the description

 

[Mark Wright]

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.

 

[radiohead]

The original question asks whether this is a breach of regulations. Nobody disputes it is poor practice, but the opinions of experienced people are not regulations and never have been.

 

[James]

@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.

 

[JKMRK1]

@JKMRK1

@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.

Tell me about it did think it would get so many mixed opinions!

Always tell myself it doesn't hurt to have a second opinion on things and as I wasnt certain about this that's what I done.

Thank you for the positive outlook and advice ?

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.

Tell me about it did think it would get so many mixed opinions! Always tell myself it doesn't hurt to have a second opinion on things and as I wasnt certain about this that's what I done. Thank you for the positive outlook and advice ?