Nuisance Tripping, ring is 2 radials with loops!

[Octopus]

Hi, I'm in the process of trying to eradicate nuisance tripping in a house and in the course of my fault finding I've discovered that the "ring" concerned is in fact 2 radials off one 32A MCB.

1 leg goes to one socket and tests confirm circuit is OK
The other leg feeds a total of 25 outlets (possibly more) and without ripping up their floors appears to have hidden junction boxes. The house has had at least 2 extensions - and the identified sockets (except spurs) all have 2 cables coming out of them so the radial doesn't appear to have an end or ends!

My issue is that I'm getting very poor IR readings on the "2nd" leg.

Any suggestions for speeding up the process to find the fault would be useful.

 

[solo2771]

Disconect from cu and do end to end or r1+r2 and record results then the highest reading other than spures should be the last 2 points then see if there is 1 or 2 t&e in each if you got 2 you have a break in circuit somewhere between and would need to find it and reconnect the ring. If you are 100% sure it is 2 SAFE radials you need to connect to 2 seperate mcb's max 20A.
Paul

 

[solo2771]

sorry just re read thread. You still need to do above to sort out circuit safety and then test 1/2 the circuit to find which half then 1/2 that ect untill you find where problem is. What are thr readings? are you sure nothing is plugged in? sure there are no neons ect?
Paul

 

[Octopus]

paul, thanks for your thoughts.

The "bad" half has very low IR readings and due to the nature of the additions to the circuit thats why I'm a bit perplexed - purely because the "bad" half doesn't appear to have an end, or possibly 2 ends. Oh for x ray to see where the cables run to and from!

Have thought ahead and will be recommending 2 x 20 Amp circuits - fortunately the CU has 3 spare slots.

 

[pushrod]

Is it in 2.5mm if so a radial should not have been put in on a 32A breaker. What i think is more likely is a damaged ring. - are the the two cables identical? I assume you have checked for continuity on r1, rN and r2.
Just a thought but i would have a good look for pictures hanging on nails directly above sockets or recently fitted dado and picture rails, curtain poles etc.

 

[Octopus]

Yes, tests for continuity were almost the first thing I did and hence why I found that the ring is not a ring. The house has been extended twice and there are 3 types of 2.5mm cable in evidence.

As previously mentioned I have confirmed one leg as a radial and I "think" that the other is a radial with 2 loops on the end -got me and my mate scratching our heads yesterday.

Its not easy to explain but the home owner assures me they haven't done anything recently.

The house layout is not logical, parts of it date back at least 200 years, nor is the "hidden" routing of the cabling.

Looks like I'll be taking sockets off again, doing continuity tests and making notes again.

 

[ezzzekiel]

always a nightmare, floorboards up and start tracing

 

[oldtimer]

Before you start ripping up boards start spliting the circuit up as they say split it in half if the half from the cu is fine then again split the second half and so on you should be able to track it down ie first 12 socket are fine the next 4 are ok but the next 4 have a fault and the last 5 are clear. To acertain if there is a joint box again split the circuit put your meter to bleep and connect accross N-E then get a plug top link out N-E then plug them in to each socket evertime you hear the bleep you know that socket is on the circuit. now if it was a pure radial then you would have a pair at each socket until you hit the last one but if there is tap offs via junction boxes then you need to track it down.
I had a problem with 3 room lights not having an earth and somebody was going to rip up floors to rewire I got a lead plugged it into a socket linked the earth to one of the lights switches and all 3 rooms now had an earth so I was asked what does that prove and I said well the circuits are ok but some fool has not put the link in between the earth connectors in the junction box

 

[mcummins7]

Am I missing something - shouldn't all socket circuits be on a ring now (17th Ed.) unless just feeding one socket? You need to make those radials into a ring if they are radials.

 

[mcummins7]

Sorry guys. I'm wrong - as long as the radials don't exceed 40M in length and are RCD protected you're OK.

 

[DurhamSparky]

when i rewire the house im buying to do up all my power circuits are going on 4mm Radials and will Be 32a RCBO as well!
10mm for 2x Showers and 1x cooker on 40A RCBO!
and 1.5 for lights on 6a RCBO

not messing about with rings and problems that they bring!

 

[Des 56]

when i rewire the house im buying to do up all my power circuits are going on 4mm Radials and will Be 32a RCBO as well!
10mm for 2x Showers and 1x cooker on 40A RCBO!
and 1.5 for lights on 6a RCBO

not messing about with rings and problems that they bring!

Fine sensible decisions Durham

You could even become the Uk representative to the EU on circuit design
You may become famous as the member without a ring

 

[DaveyD]

you may become famous as the member without a ring

lol !!

 

[Octopus]

UPDATE:

Customer is having some major building work done so I decided to pay them a visit to see what would be revealed when they removed cladding hiding an old steel which is being replaced.

The builders have noticed that its now possible to see "outside" whilst looking at the inner wall of the "music" room. In this space is a conduit running down to a light switch and another running down to a socket. The customer had said that "horizontal rain" was the main problem - looks like they need some repointing done!