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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??
 

ipf

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Just a point.
Two rings or not, in general, what are FIRST thoughts on four (or more) cables in a circuit breaker terminal, whilst carrying out an EICR?
How long is a piece of string, maybe?
 
Just a point.
Two rings or not, in general, what are FIRST thoughts on four (or more) cables in a circuit breaker terminal, whilst carrying out an EICR?
How long is a piece of string, maybe?
It would depend on an informed engineering judgement as to whether the conductors were securely terminated for me.
 

James

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Just a point.
Two rings or not, in general, what are FIRST thoughts on four (or more) cables in a circuit breaker terminal, whilst carrying out an EICR?
How long is a piece of string, maybe?
It says to me that things have probably been done on a tight budget, i.e. the consumer unit has not got enough ways for what they want to supply.

look out for other things that may have been overlooked!
 

DPG

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It says to me that things have probably been done on a tight budget, i.e. the consumer unit has not got enough ways for what they want to supply.

look out for other things that may have been overlooked!
But there's a spare way in this particular CU.
 
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 👍
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.
 

James

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But there's a spare way in this particular CU.
Still, tight budget could also mean tight on time, not got another breaker in the box?
never mind, its Friday the pub is open, just stick it in the other breaker and we are out of here!!
when you see an obvious short cut like that it makes me look for others.
 

Risteard

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You could put more than one radial on a MCB but its not good practice.
You couldn't, because by definition it would be one radial.

2 Rings on 32mcb is dangerous are you sure it's not 2 radials?
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)?
 

DPG

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Still, tight budget could also mean tight on time, not got another breaker in the box?
never mind, its Friday the pub is open, just stick it in the other breaker and we are out of here!!
when you see an obvious short cut like that it makes me look for others.
Yep, fair point.
 

SparkyChick

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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.
@Pete999 , Dave has summed up my own personal view to a T.

If both of the rings are correctly installed and the cables sized correctly, then I'm struggling to see how this arrangement would be any more dangerous than each of them connected to their own MCB, sure from an isolation point of view it's less than ideal, but from a safety perspective I don't see how it's any less safe than a ring final running from it's own 32A MCB. If you were talking two ring circuits supplied by two MCBs with one leg of each ring in each MCB, that's another matter (have seen this and nearly got bit by it, thankfully my chicky sense started tingling and I did another check at the socket I was working on).

And I'll reiterate what I said... I personally wouldn't do it, except as maybe a temporary solution to restore supply in the event of say an MCB or RCBO failure. But I think it's an interesting thought exercise because I'm not sure what regulations it would be breaching. The closest I can come to is largely dependent on how you define circuit.

Just a point.
Two rings or not, in general, what are FIRST thoughts on four (or more) cables in a circuit breaker terminal, whilst carrying out an EICR?
How long is a piece of string, maybe?
Absolutely, it's not good, and it would be a C3 from me, unless there were clear signs of bad connections (loose cables, heat damage etc.) in which case it would be a C2. My reasoning... does it present a danger now or would it present a danger if something else happened? Potentially it might, but so would any ring final circuit and I'm thinking broken or poor end to end continuity or some other error in installation.

But like I said, I'm just curious about peoples thought processes and reasoning. We can't remember everything and we certainly can't know everything so it's an interesting topic for debate :)
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right or wrong what's the common response to finding a Ring on a 20A MCB or wired in 4mm??
Could be a long cable run, the 20A MCB could be a left over from a broken ring when someone downgraded it to be safe, the 4mm could be there because the Zdb at the source of the circuit was too high for 2.5mm to cut it from a Maximum Zs perspective, or in extreme cases even a maximum NL loop impedence perspective.

But if it was safe and compliant, I'd just be asking myself why?

I did a rewire job last year and ran a ring in 4mm. It was a mistake on my part... I picked up the wrong reel and just cracked on. Was a costly mistake, but hey ho :)
 
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pc1966

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Ugly but not dangerous. This circuit, not me (but close enough)

In terms of overload you can overstress the 32A MCB on a ring with only 4 items plugged in, so unless this was conjoining two rings that had been chosen to separate high-demand loads it is not really any worse than a bigger single ring.

What is curious is why was this done? The OP says there is one slot free so probably this was a temporary fix for a failed MCB that has become permanent.
 

ipf

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It would depend on an informed engineering judgement as to whether the conductors were securely terminated for me.
You could probably make sure on that if reconnecting after testing. Available breaker? Terminal and c/b condition? Circuit condition? General install condition?
Like I say, how long's a piece of string?
Definitely needs improvement though, probably C3, dependant upon what it leads to.
 

DPG

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Ugly but not dangerous. This circuit, not me (but close enough)

In terms of overload you can overstress the 32A MCB on a ring with only 4 items plugged in, so unless this was conjoining two rings that had been chosen to separate high-demand loads it is not really any worse than a bigger single ring.

What is curious is why was this done? The OP says there is one slot free so probably this was a temporary fix for a failed MCB that has become permanent.
Exactly. I would be doing some testing before going any further.
 

ipf

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Ugly but not dangerous.
Hey, be careful! You don't know who's lurking.
 

pc1966

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right or wrong what's the common response to finding a Ring on a 20A MCB or wired in 4mm??
Both are rare but not in any way dangerous.

4mm is needed if the end-to-end length is over about 106m, but on a multi-floor building you could have a fair amount of that used up in the CU-to-floor run up and down so it need not be a ridiculously large area covered.

I have seen 20A BS3036 rewireable fuses used for the ring before so there may be some historic reason for that, and it is quite possible that a CU upgrade just copied the existing fuses with the nearest MCB.
 
Both are rare but not in any way dangerous.

4mm is needed if the end-to-end length is over about 106m, but on a multi-floor building you could have a fair amount of that used up in the CU-to-floor run up and down so it need not be a ridiculously large area covered.

I have seen 20A BS3036 rewireable fuses used for the ring before so there may be some historic reason for that, and it is quite possible that a CU upgrade just copied the existing fuses with the nearest MCB.
Yeah my first Response to OP questions was NO! this is Dangerous but thinking about it can't really find how although A break in 2 rings would be very bad.

But then looking at it the other way round 20A or 4mm that's actually safer but not considered standard - so what response would this cause.
 

pc1966

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But then looking at it the other way round 20A or 4mm that's actually safer but not considered standard - so what response would this cause.
The Best Practice Guide #4 has various things mentioned that are departures or non-compliance with the standard that are not unsafe so don't merit a code.

Probably you would add it as a comment, more so the 20A MCB as it might be prone to nuisance trips if it serves several power hungry things (washing machine, tumble dryer, dishwasher, etc).
 

Pete999

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Are we not going off piste Lads and Lasses? the original scenario was 2 separately wired RFCs connected to a single OCPD, this constitutes a single circuit, no matter how you twist and turn with it which is not only bad practice but in my opinion a dangerous situation, Discuss.
 

ipf

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But then looking at it the other way round 20A or 4mm that's actually safer but not considered standard - so what response would this cause.
None, to my mind. Certainly not the 4mm. The 20amp...only if load problems.
 

SparkyChick

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Are we not going off piste Lads and Lasses? the original scenario was 2 separately wired RFCs connected to a single OCPD, this constitutes a single circuit, no matter how you twist and turn with it which is not only bad practice but in my opinion a dangerous situation, Discuss.
We're not denying it's bad practice, there is seemingly unanimous support for that view, but dangerous... if they are both sized and installed correctly in every other aspect, how are they dangerous?

I'm not being facetious Pete, I'm genuinely trying to understand the thought process behind the statement.
 
Going to Lollipop and other non standard circuit territory.

Could a break in a Ring cause a fire?
Possibly but probably not

Could a break in 2 Rings on a single 32A MCB cause a fire ??? that is the main thing I'm thinking now.
 

ipf

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Are we not going off piste Lads and Lasses? the original scenario was 2 separately wired RFCs connected to a single OCPD, this constitutes a single circuit, no matter how you twist and turn with it which is not only bad practice but in my opinion a dangerous situation, Discuss.
Take one leg out of each ring and link 'em (properly, of course). That'll make it miles safer ;)
 

SparkyChick

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Going to Lollipop and other non standard circuit territory.

Could a break in a Ring cause a fire?
Possibly but probably not

Could a break in 2 Rings on a single 32A MCB cause a fire ??? that is the main thing I'm thinking now.
A break in a ring is definitely a safety issue regardless of other factors such as the supply arrangements for the circuit. And yes, a break in a ring can cause a fire.

If a ring is running on a 32A MCB and it has a break in a live conductor you should look at downgrading the MCB to 16A/20A.
 

Pete999

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We're not denying it's bad practice, there is seemingly unanimous support for that view, but dangerous... if they are both sized and installed correctly in every other aspect, how are they dangerous?

I'm not being facetious Pete, I'm genuinely trying to understand the thought process behind the statement.
SC I have stated my point of view, and although an interesting post I really have nothing more to say on the subject, you questioned the dangerous statement, which is your prerogative, I just think sticking two separate systems on one OCPD forming one circuit out of two systems is inherently dangerous, I have no other arguments to continue, what next a lighting system added to a RFC circuit OCPD? or vice versa?
 
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.
It does not meat the regs BUT. if you exceed the loading I will be surprised but if you do the breaker will trip, ie doing its job.
 

littlespark

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Has it been proven by testing that this is in fact two rfc’s?
It may be 1 rfc, and a spur was added at source.... then another added.

how many sockets does this 1 OCPD protect?

I think it’s right, if it is 2 rings coming out, to move one into the spare way... but end to end continuity must be found to know you’ve got the right legs of each ring into the same breaker.

My other worry is that there has been work done in the house which has somehow linked the 2 ring together. Rather than investigating, they’ve just bundled everything together
 
SC I have stated my point of view, and although an interesting post I really have nothing more to say on the subject, you questioned the dangerous statement, which is your prerogative, I just think sticking two separate systems on one OCPD forming one circuit out of two systems is inherently dangerous, I have no other arguments to continue, what next a lighting system added to a RFC circuit OCPD? or vice versa?
Don't start that one ;) but if the lighting is wired in 2.5 it's not actually dangerous is it :p

I'll get my coat.....
 
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SparkyChick

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SC I have stated my point of view, and although an interesting post I really have nothing more to say on the subject, you questioned the dangerous statement, which is your prerogative, I just think sticking two separate systems on one OCPD forming one circuit out of two systems is inherently dangerous, I have no other arguments to continue, what next a lighting system added to a RFC circuit OCPD? or vice versa?
So in essence, it's a 'I just don't like it' kind of situation and that's fair enough Pete thanks :)

I feel the same way about it, I don't like it, I'm not sure I can qualify why I don't like it other than 'it feels wrong'.
 
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