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.

 

[ebee]

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?

 

[ebee]

Well if you could join the 2.5 ring to a 6.0 (or 4.0) radial, so long as it`s substantially half way around the ring then all the usual ring type considerations should pan out adequately. Again not elegant but hey ho. I feel the double triple or quadrouple ring is easier and just as valid as a single ring. Indeed, on one foru, I hasd a remasrk by someone saying theyd take one end of each ring asnd join them in the consumer unit thereby producing one ring. If it does not end up oversize (abnormal length) it would be OK but not an improvement though because you`ve then increased R1 +R2 from what it was (and therefore increased Zs) and you`ve increased volt drop too. If I found a two, three or 4 ringed circuit I would glance asgain but so long as all the sums add up and the connections are mechanically and electrically sound then hey ho not a defect. Not a standard circuit you`d find in regs informative appx 15 or in the OSG but nothing "wrong" with it.

Same as ""trees" branches yada yada on radials etc

Circuits can be unusual "strange" but still compliant and safe.

You could actually have a ring final with just one point on it. Again unusual and probably pointless but still compliant and safe

 

[pc1966]

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).

 

[DPG]

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).

And there are two #331 posts.

 

[ackbarthestar]

I'm getting postings via my email regarding 'connecting two rings into one protective device' which appear to be linked to another thread posted back in the Jurassic period.

My final answer is that there is nothing wrong as they are still separate circuits but is it safe? and that depends on the way each circuitis loaded.
If the loading is small on both rings then it will pass unnoticed. The heavier the loading the greater the electrical stress.

 

[JBW175]

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).

i can see why it’s been done, looks original on a 1970’s 3 bed semi, only other 30A way was feeding the cooker.

it’s been coded C3, but the board was C2, so will get properly sorted when I put a new fully RCBO CU in along with other remedial works over the coming weeks.

 

[ebee]

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).

 

[ebee]

I cant be a C3 because it complies though

 

[littlespark]

I cant be a C3 because it complies though

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.

 

[ebee]

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.

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

 

[ipf]

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

Well, if they're old colours, sleeve one 'ring' brown and blue.......there's your C3. ?

 

[ebee]

Well, if they're old colours, sleeve one 'ring' brown and blue.......there's your C3. ?

correct. wheras 2,3 or 4 rings on one fuseway is one cct therefore not a C3 or C2 or C1. It is compliant

 

[Soi disant]

Absolutely no chance should there be 2 RFC in a 32A MCB.

If each one is safe if on 2 devices, what makes them become unsafe when put on 1?

Neither should there be a 2.5mm2 radial let alone 2,3 or 4.

There aren't.

It is covered in the regs and is further legislated against in test and inspection.

It isn't

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.

But why, other than testing aggro?

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.

By exactly the same logic we should not have any ring finals, because if the ring is broken then the circuit becomes 2 radials.

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.

A figure-of-8 actually decreases the chances of a break leading to an overload potential.

 

[OnlQQker]

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.

 

[littlespark]

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.