Ring circuit fed/controlled by two MCBs?

doozerie

I'm moving house soon and we've had a new consumer unit fitted to upgrade the existing unit. I was working out today which sockets are connected to which MCB. Simple process of plugging something into a socket and manually tripping each MCB in turn until I found the one that killed power to that socket.

At least, it was simple until I got to the plug sockets in the kitchen. No single MCB would kill power to the sockets, so I tried various combinations. Eventually I found the combination of two MCB's that had to be tripped to kill power. That also set off the house alarm so presumably it is fed from the same circuit(s?).

I'm confused by this, my simple understanding is that radial circuits and ring circuits are fed/controlled from a single MCB. Is it normal (and safe!) to have the same ring circuit (I'm guessing it must be a ring circuit in this case, by design or otherwise) fed by two MCB's? Perhaps the house alarm wiring is significant here too, but I'm not sure how.

If this is not a normal wiring setup then I'll have to get the electrician back out, so I'm keen to find out whether it sounds wrong. Thanks in advance for any info/help.

brightspark

Its wrong, and should have shown up in the testing.

brightspark

Also ring circuits are no longer permitted in kitchens.

ETCI Regs Annex 55A 5.1 "Ring circuits should not be used in kitchens"

Risteard81

brightspark wrote: »

Also ring circuits are no longer permitted in kitchens.

ETCI Regs Annex 55A 5.1 "Ring circuits should not be used in kitchens"

That is informative and not normative, and therefore ring final circuits are permissible in kitchens. (Informative annexes do not form part of the Wiring Rules.) RECI had the ETCI remove the normative reference, and indeed encourage it in kitchens.

salmocab

when the consumer unit was changed the installer simply split the ring main not realizing it was a ring and not 2 radials. He should have spotted this but its an easy fix. (probably)

brightspark

salmocab wrote: »

when the consumer unit was changed the installer simply split the ring main not realizing it was a ring and not 2 radials. He should have spotted this but its an easy fix. (probably)

Not only should he have spotted it, but it would have shown up in the testing...if he did any.

I think your REC should have marked up your board too, just as well he hadn't or you may not have discovered the fault.



@Risteard81, you are correct its only informative, So not obligatory.

Would make you wonder who are the experts RECI or the ETCI? But that is a debate for elsewhere.

Risteard81

brightspark wrote: »

Would make you wonder who are the experts RECI or the ETCI? But that is a debate for elsewhere.

LOL. Well, I largely agree that it is silly to state that a ring final circuit is permissible other than in a kitchen. (Notwithstanding the higher load profile in a kitchen - and indeed it would be prudent to balance the loads around the ring.)

But having two 20A radials as suggested is not guarantee that all or most of the load won't be used on one of these radial circuits, and this is why (at least in the case of my RECI Inspector) ring circuits are encouraged in kitchens.

I think it is regrettable that the Annex was inserted into the Wiring Rules, even if it is only Informative.

doozerie

Thanks a lot for the replies.

I was looking at the MCB's again today and noticed what may be another problem - of the MCB's feeding plug sockets, most of them are 20A but one of them is 10A (serving 5 plug sockets across both floors and several rooms/areas). I've not traced the lighting circuits yet but I'm now wondering whether I'll find that 10A MCB serves some lights as well, but either way that 10A MCB is wrong too, right?

I'm getting the impression that "testing" may be a dirty word to this particular electrician.

brightspark

Is he a member of RECI or ECSSA?

Calahonda52

doozerie wrote: »

Thanks a lot for the replies.

I was looking at the MCB's again today and noticed what may be another problem - of the MCB's feeding plug sockets, most of them are 20A but one of them is 10A (serving 5 plug sockets across both floors and several rooms/areas). I've not traced the lighting circuits yet but I'm now wondering whether I'll find that 10A MCB serves some lights as well, but either way that 10A MCB is wrong too, right?

I'm getting the impression that "testing" may be a dirty word to this particular electrician.

It MAY be that these are for lamps, I repeat MAY.
Are the sockets normal 13Amp

salmocab

doozerie wrote: »

Thanks a lot for the replies.

I was looking at the MCB's again today and noticed what may be another problem - of the MCB's feeding plug sockets, most of them are 20A but one of them is 10A (serving 5 plug sockets across both floors and several rooms/areas). I've not traced the lighting circuits yet but I'm now wondering whether I'll find that 10A MCB serves some lights as well, but either way that 10A MCB is wrong too, right?

I'm getting the impression that "testing" may be a dirty word to this particular electrician.

Sounds wrong, although as I presume the sparks didn't do the original wiring of the house and may have got stuck with circuits that were looped off very inappropriately lights to sockets or vice versa he may have been in a very difficult position. Not saying he was right just that there may be circumstances that were awkward to sort out without doing some rewiring.

brightspark

salmocab wrote: »

Sounds wrong, although as I presume the sparks didn't do the original wiring of the house and may have got stuck with circuits that were looped off very inappropriately lights to sockets or vice versa he may have been in a very difficult position. Not saying he was right just that there may be circumstances that were awkward to sort out without doing some rewiring.

He should at the very least have notified the householder in writing if there was further work to be done. It doesn't sound like the work was carried out by a REC!

Tony Beetroot

Once there is power in the sockets its grand, no point arguing over a ring or a radial.

brightspark

Tony Beetroot wrote: »

Once there is power in the sockets its grand, no point arguing over a ring or a radial.

Did you read any of the OPs posts?

He has a ring fed from two separate MCBs and other sockets apparently fed from a 10A MCB! and these are just items the untrained OP has discovered.

It's not "grand":rolleyes:

Tony Beetroot

Op sounds confused to be, Brightspark what is dangerous of having sockets fed off a 10 amp mcb?

Tuco88

I'd stay away from the ring main anyway its an outdated art if you ask me. Balance the radials correctly it's better imo, why have the risk of a 2.5mm^ on a 32 amp mcb? even a break in an earth may alter the required impedance value.

doozerie

Traced the lighting circuits earlier and none of them are on the 10A MCB that has the 5 plug sockets on it. All 5 sockets are normal 13amp, they are an eclectic mix of 2 in a bedroom, 1 on the landing, 1 in a downstairs room, and 1 in the hallway, so some little used sockets in there I'd imagine. Also, there are two wires into this MCB, so it's presumably a ring circuit.

It could be that my electrician accidentally replaced an old 20A MCB with a new 10A MCB, a worry in itself, or maybe the one he replaced was already a 10A and he never noticed what it was feeding, which is also a worry as it suggests he didn't test anything (or just didn't care).

As for whether he is a member of RECI or ECSSA, I checked the websites for both just now and can't find him listed. I'm very surprised by that, I used him because he is the electrician used by a company that is doing a bunch of other work on the house, upgrading the consumer unit was a separate piece of work that I needed done so I deal with him directly for that. I've been impressed by the company in all of our dealings so far, I (far too casually, it seems) assumed that all of their contractors would be fully qualified/accredited. In fact, checking just now they even list ECSSA accreditation on their own website. Also, he got "one of his guys" to do some, and perhaps all, of this work (not what I expected either) which muddies things even further.

It'll be an interesting phone conversation tomorrow. I haven't paid him yet so he should be well motivated to address the issues. The wiring in the house might have been a disaster before he ever got near it, but I'm paying for it to be done so that it'll be done right but it's clearly a mess. I could have made a mess of it myself for no cost. I'm actually shocked that any electrician would leave this shambles behind without a word. If he had told me there were wiring issues that needed to be addressed then I'd have asked him to quote for resolving them, but instead he said nothing at all and it's just lucky that I discovered the mess myself. So either he created a dangerous mess out of reasonable wiring, or he willingly replicated a dangerous mess from the previous consumer unit, and just left - in the circumstances I consider him entirely responsible for sorting it out.

It looks like the house has seen its fair share of cowboys already. I opened some sockets earlier to find myself looking at bare live, bare neutral, and bare earth wires all in very close proximity to each other. The sockets were working when I was tracing the circuits so the wires obviously popped out when I pulled the face plate (gently) away. They must have been paying for the cable by the millimetre because slack on the wires was non-existent, they were a bugger to put back together.

Also, one of the ring sockets looks like it has 2 spurs off it. It's a 1-gang socket and one of those spurs is another 1-gang socket literally 2 inches to its left (and sitting about an inch lower too, which makes me twitch involuntarily). I'm not even going to try to figure out the thinking behind that fiasco. I've thought more than once that this house should be burnt to the ground and built from scratch, properly this time, it's looking like someone else felt even more strongly about it and tried to achieve just that via some dodgy wiring.

2011

Obviously there are issues with the wiring that need to be addressed. However a few points:

1) Radial socket circuits may have 2 wires into one MCB. There is nothing wrong with this and it is not against regulations.

2) Unless you are a qualified electrician you should not be removing the cover from a distribution board. Apart from the safety implications you may be accused of tampering with the wiring at a later stage. Then the electrician may use this as an excuse not to fix the wiring.

3) This any "go legal" so act accordingly.

4) Just because you do not see the electrician on the ECSSA or RECI website does not mean he is not registered. You might not recognize the company name.

5) If I were in your shoes I would get the ECSSA, RECI or CER to carry out an inspection and produce an independent report. This is a free service. My experience of RECI inspectors has been very negative so my advice is to make it clear to them that you will follow up with CER.

6) Demand a completion certificate, the electrician is legally obliged to issue this to you.

SpaceTime

Get an electrician to sort this out. It sounds like something is messed up at the board.

This isn't DIY work don't attempt to do it yourself.

Leaving it as is could result in a fire hazard if the circuit were overloaded and didn't trip.

In the mean time I would suggest that you avoid using that circuit, and certainly do not use it with heavy loads like heaters, major appliances (especially dishwashers, washing machines or dryers that draw high loads for a long time)

doozerie

Thanks for the advice. I'll be on to the electrician today, I'm hoping that he'll acknowledge the issues and sort them out quickly but at the same time my confidence in him is completely undermined at this stage so I may have to get someone else in just for peace of mind.

Re some of the suggestions/points:

* The distribution board cover isn't actually closed, it's just resting in place. There is a new cable still to be attached, the original reason for the upgrade, which is why it has been left as is. Despite that I was still wary even of lifting the cover off, I definitely don't want to be anywhere near it, but thought it might help me identify other issues with a casual glance - that was a bit optimistic of course, I have just about half a clue what I'm looking at, at best. It's a very good point though, the electrician could use it against me if he chooses to be contrary.

* The kitchen circuit fed by the two MCBs supplies both the dishwasher and washing machine. We haven't moved in yet so they are not being used, thankfully.

* I checked the RECI and ECSSA sites for the electrician's company name too. I appreciate though that there may be valid reasons that I'm not finding him/them listed.

* I wasn't aware of the legal obligation for a completion certificate, or of the free service to get an independent report, both of which could be very useful so thanks for that.

Oh, and it occurred to me since my previous post that the socket that I thought was feeding 2 spurs is itself a spur, which means it's actually feeding 3 further spurs. Would the testing that should accompany a distribution board upgrade be expected to identify such a specific issue or is that a whole other level of exploratory work?

2011

This would be a good time to start taking photos of anything that concerns you.

Phone the ECSSA and RECI and provide them with all relevant details including the electrician's phone number. They should be able to ascertain whether he is registered or not from this information. Failing that ask him out straight who he is registered with.

2011

Tony Beetroot wrote: »

Op sounds confused to be, Brightspark what is dangerous of having sockets fed off a 10 amp mcb?

In isolation this alone does not present a danger.
However it is against regulations and would be considered unacceptable.
Furthermore it is likely to be the tip of the iceberg in terms of the standard of workmanship for the installation. Let's not forget that the OP has paid for a new distribution board.

doozerie

I gave the electrician the opportunity to sort things out. He didn't contest my description of the issues over the phone, which was promising, he said he'd get the same guy back out to resolve them, which was less promising.

I had a look last night after he was finished, and one of the two MCB's on the same ring is now labelled as spare, I guess he just swapped the cable over to the other so at least the ring circuit is now on one MCB.

He replaced the 10A MCB on the plug socket circuit with a 25A. I'm not sure why he didn't just use the now spare 20A MCB above instead. Should I have any concerns about it being 25A instead of 20A?

I discovered another issue with his work though. I was paying for him to install outdoor sockets which were to be controlled by a FCU. He had a room of 6 sockets, all on the same radial circuit, to spur from. The ceiling was exposed so he had access to any of the sockets. Turns out he opted to spur from the only socket that already had a spur on it, probably because it was closest to the location for the FCU. The existing spur is to a 2-gang socket, which itself feeds under- and in- cabinet lighting in the kitchen (is powering cabinet lighting from a spurred socket within the regs?). The new spur is to feed two 2-gang outdoor sockets.

So he knowingly added a second spur to a socket. As I understand it this is against regulations. What I don't know is how dodgy it would be to leave it like this. The ceiling has since been slabbed and skimmed so there is no longer access to any other socket without chasing at least 2 walls (one of them an external wall, this is in an extension of the original house) or wall plus newly finished ceiling, so it'll be messy and patching it will require skill and effort to restore the (new) finish. So, despite paying for a so-called qualified electrician I now find myself wondering whether leaving the wiring as is, against regs, is likely to pose a real risk? The outdoor sockets would be used for the likes of a circular saw and lawnmower on occasion, so probably not high loads at any stage but...

I'm done with this guy, I'll be on to the "main" electrician again today and I'll be telling him so, he is the kind of guy that gives tradesmen a bad name. I'll be going the formal route from here on, not something I wanted to do, I'd much prefer to sort things out amicably and person-to-person but that's clearly not working.

Risteard81

Are you suggesting that the cable feeding the outside socket is fed from a radial circuit?

If so then this is not spurred from it - it is simply a branch of the radial circuit.

SpaceTime

2011 wrote: »

In isolation this alone does not present a danger.
However it is against regulations and would be considered unacceptable.
Furthermore it is likely to be the tip of the iceberg in terms of the standard of workmanship for the installation. Let's not forget that the OP has paid for a new distribution board.

Is this an extremely old installation with a board upgrade?

10amp and circuits were often used with non-fused plugs and radials. There are definitely some old pre 1970s homes that may well have originally had 5amp & 15amp round pin plugs or continental style 16amp Schuko.

They often protected those circuits with 10 and 16A fuses.

I've seen homes where they "upgraded" the wiring by just changing the board and the sockets back in the day but it's in reality the same 1950s (or older) wiring.

doozerie

Risteard81 wrote: »

Are you suggesting that the cable feeding the outside socket is fed from a radial circuit?

If so then this is not spurred from it - it is simply a branch of the radial circuit.

It's a radial circuit with six 2-gang sockets "directly" on it. From the third socket along there is wiring to another 2-gang socket, which itself feeds the under-cabinet lights in the kitchen. The wiring to the FCU for the outdoor sockets runs to that same third socket.

I didn't think you could branch a radial circuit, I thought you could either extend it or add up to one spur per socket, but I'm certainly open to correction.

doozerie

As regards age, the house dates from 1980. The need for a board upgrade arose because I was having a SWA cable run to a shed, the electrician told me this necessitated an upgrade, I assumed it was due to insufficient capacity in the existing board but I didn't actually check that with him.

Risteard81

doozerie wrote: »

I didn't think you could branch a radial circuit, I thought you could either extend it or add up to one spur per socket, but I'm certainly open to correction.

It isn't by definition a spur, unless you were to reduce the cross-sectional area of the cable branching off. It is simply an end (of which you have more than one) of the radial circuit. This reduces earth fault loop impedance and volt drop, so as long as the terminals can accomodate this there is nothing untoward about it.

SpaceTime

doozerie wrote: »

As regards age, the house dates from 1980. The need for a board upgrade arose because I was having a SWA cable run to a shed, the electrician told me this necessitated an upgrade, I assumed it was due to insufficient capacity in the existing board but I didn't actually check that with him.

Way too young for those kinds of issues then.

doozerie

Risteard81 wrote: »

It isn't by definition a spur, unless you were to reduce the cross-sectional area of the cable branching off. It is simply an end (of which you have more than one) of the radial circuit. This reduces earth fault loop impedance and volt drop, so as long as the terminals can accomodate this there is nothing untoward about it.

So 4 wires into one socket on the radial circuit is actually okay?

2011

doozerie wrote: »

So 4 wires into one socket on the radial circuit is actually okay?

Generally not.
It would only be acceptable if the terminals in the socket were specifically designed to connect 4 wires of that size and type together. I do not think that such a socket exists.

Risteard81

doozerie wrote: »

So 4 wires into one socket on the radial circuit is actually okay?

I thought you had three sets.

But it's what the manufacturer states is appropriate for their accessories which is relevant.

As stated this is typically 3 conductors per terminal.

doozerie

This might help clarify, this is the current wiring situation:

Board --- Socket1 --- Socket2 --- Socket3 --- Socket4 --- Socket5 --- Socket6
/ \
/ \
Socket Switched FCU
/ \
/ \
Cabinet lights 2x 2-gang outdoor sockets


There is currently no accessible route from the FCU to any socket other than Socket3, so either I live with the wiring as is or go chasing walls to wire the FCU to some other socket. Neither option is appealing, the simplest one is certainly to live with it but if there is real risk associated with that then I'm reluctant to expose us to that.

I've already encountered one existing socket in the house that appears to have been wired exactly like that for some time before we bought the place but I've no idea what devices might have been run off that so the fact that it doesn't have scorch marks around it doesn't give me much comfort. Fundamentally I'm trying to figure out whether the risk involved in the new botched wiring above is largely academic or very real. I imagine there is much worse wiring in active use daily in many places but that's not much comfort either.

doozerie

..well, that "diagram" didn't work very well, though it's probably more representative of some of the wiring in the house now!

Here is another effort, just showing the additions to Socket3 (i.e.in addition to the two wires to Socket3 for the radial circuit):

Socket3

---

Switched FCU

---

2x 2-gang outdoor sockets
|
|
Socket
|
|
Cabinet lights