Doing a PIR lately and found no continuity on one of the ring final neutral circuits. I am not familiar with fault finding and would appreciate any help and hints. IR test on the circuit passed.
- Thread starter woodywoodpecker
- Start date
M
malcolmsanford
There would seem to be a break in the neutral somewhere, hopfully at a socket and not a in-accessible junction box.
Split the ring at it's geographical centre, or as near as you can. Do an R1 +RN test on both sides of the ring, with luck you will get one side showing an open circuit and just keep spliting that side of the ring until until you find it.
Split the ring at it's geographical centre, or as near as you can. Do an R1 +RN test on both sides of the ring, with luck you will get one side showing an open circuit and just keep spliting that side of the ring until until you find it.
N
nickblake
As malcome has said there is also another possability if its concrete floors the cables normally drop check to see if there and any pictures above sockets ,see this a few times if there is do a long lead test between the neutral and the nail i know it sounds daft but you,d be suprised how many live nails stick out of walls , yes i know it the neutral same scinario
surprised the chippy didn't nail directly below socket otlet. he'd have missed it then ! :death:
S
SirKit Breaker
Some good help given already. When fault finding start with the basics, keep it simple and methodical. It is all too easy to get in too deep when you don't need to.
Your IR test will give a good result because the circuit is broken, so you are only testing up to the point of the break, and it wont help you in anyway to find the open circuit problem.
As you say that you have little experience fault finding, then getting and reading Guidance note 3 is a must, even more so if you are doing PIR's. This book shows you how to test properly all the circuits you will come across. Once you have grasped a good understanding of testing, fault finding will fall into place for you, because the test procedures are designed to show up faults, but it is too much to write in a forum post.
Cheers..........Howard
M
mickys86
Hi guys, I'm just entering my third yr in September and after reading this post I have gone and bought guidance note 3, £6.70 from eBay! Bargain!
E
Electricalserv
Instead of going round takeing all the socket facias off he needs to do a proper fault finding tests.
THE HALF TEST METHOD!
Afterall it might not just be a loose connection inside a socket!
THE HALF TEST METHOD!
Afterall it might not just be a loose connection inside a socket!
I always split the ring somewhere at the middle and go from there straight off eliminate half the possibilities.
Some good advice as usual here but it really worries me that someone without the competence to find a broken ring conductor is carrying out a Periodic Inspection, it doesn't get much more basic than this!
I had removed all the covers on the circuit to check all connections and found them to be secure. I had then also tried to follow the ring; slightly awkward as 2 of the sockets are in the upstairs bedroom and the rest below in the kitchen/diner. It appeared to be down to a couple of points but is proving difficult to pin down. The cables are buried in the walls and won't pull through and the upstairs floor is sheet board. I was wondering if there was a non-invasive way of locating or is it a case of rip everything up and take the newly tiled kitchen apart.?
N
nickblake
remove tails from board (for that circuit that is not the main tails lol ) do a r2rn test link out the neutral and earth lever wagos are brill for this thne use you meter and do a continuity test at each socket across the cpc and neutral , if you have a tester that has a plug lead for Zs testing install the neutral to the live terminal on you meter and then the earth lead to the earth terminal then test at each socket till you locate the fault it could well be below the floor in a junction box doing this method saves taking all the fronts off again
S
sparkinlee
As nickblake says you should be able to pin it down by testing which does not require taking all the fronts off. But if the order of circuits on the ring is not obvious you might need to take a few fronts off in the area you pin it down to - if the configuration is really confusing take a few fronts right off and then bell test the legs between sockets to work out where the ring goes.
Then IR test each leg separately to find the fault. Once you've identified which leg has the fault, consider replacing that leg with a new cable run along a route you choose to avoid too much damage to decoration etc - don't worry about trying to dig out all the faulty cable from behind the tiles etc.
This does risk isolating anything which you've not found that is spurred off the cable you abandon, so make sure you've found all the sockets, fcus...
Then IR test each leg separately to find the fault. Once you've identified which leg has the fault, consider replacing that leg with a new cable run along a route you choose to avoid too much damage to decoration etc - don't worry about trying to dig out all the faulty cable from behind the tiles etc.
This does risk isolating anything which you've not found that is spurred off the cable you abandon, so make sure you've found all the sockets, fcus...
N
nickblake
Agreed with that mate , how every that depends where the fault lies if its in a juction box under the floor say you could end up with sockets without a neutral
Is there a maximum number of outlets per radial though?
Have you got a copy of BS7671:2008? (the book that your Periodic Inspection should be based on)I'm out.
I have but was being too lazy to go out to the van and get it
You're missing my point.
Do you think you are competent to carry out periodic inspections?
I always try to offer help and advice on this forum but you are being paid for your 'expertise and knowledge', ultimately deciding if someone's installation is satisfactory for continued service.
You need to learn this (basic) theory stuff in the classroom, not while carrying out periodic inspections.
1
1shortcircuit
:nopity:
I know of an unqualified Electrical Trainee Domestic Installer that could come and find the fault for you
hone:
:nopity:
I know of an unqualified Electrical Trainee Domestic Installer that could come and find the fault for you
a Electrical Trainee couldn't find a socket in a wholesaler's
1
1shortcircuit
That's easy, just post on here and wait for someone to assist pmsl
S
SirKit Breaker
That will probably be one of the best £6.70 you will ever spend in your quest to become and Electrician. Master that book and you will with a bit of practical experience, in time be putting post's on here saying things like "The 2391 was a doddle, i dont know what all the fuss is about".
Cheers...........Howard
S
SirKit Breaker
I agree mate, but i find that on a small install it can be just as quick to whip them off one by one and have a look saves time finding the mid "ish' point especilally when DIY charlie has visited. But you are right the mid point method the best way for a larger circuit.
Cheers......Howard
L
Ladders
Hi. Sorry to jump on thread but do not know how to start a new one for myself!
1) When doing a domestic periodic on a 32 A ring final circuit it did not show a r2 CPC end to end reading, however all other tests Zs etc were OK. Did a long lead test and it's the first leg from consumer unit to 1st socket. What code would be appropriate?
2) When testing 6A lighting circuit no R1+R2 reading. Again all other tests Zs etc were OK. What code would be appropriate?
Thanks.
1) When doing a domestic periodic on a 32 A ring final circuit it did not show a r2 CPC end to end reading, however all other tests Zs etc were OK. Did a long lead test and it's the first leg from consumer unit to 1st socket. What code would be appropriate?
2) When testing 6A lighting circuit no R1+R2 reading. Again all other tests Zs etc were OK. What code would be appropriate?
Thanks.
N
nickblake
do you want new or old codes well go for old both would be a code 3 requires further investigation , bit curiouse as to why you couldnt get an R1R2 reading when you got a Zs mind ,way to find the fault is to remove all sockets and check connections or more complicated do an R2Rn test around the sockets till you loose the reading
oh to start a new thread double click on general electrical forum then when it opens new thread is at the top
oh to start a new thread double click on general electrical forum then when it opens new thread is at the top
Last edited by a moderator:
Don't forget that 'new codes' and the EICR don't take effect until 01/01/12.
L
Ladders
Thank you. I am curious as well why no R1+R2 on lighting when Zs was OK, didn't have long enough ladders with me to reach all the fittings. Think I'm going to get the repair work, so may have to find out! Thanks for the new thread pointer as well
M
malcolmsanford
you may have got the Zs on the R1+ Rn.
L
Ladders
Hm, interesting. So therefore I may well need to break the legs down on the lighting circuit to find out where the issue is...
N
nickblake
thats a good point malcome has said there is always a posibility there is also a neutral to earth fault or cross connection so you have no continuity to the last on the run cross wire between CPC and the N you then would get the Zs but that would trip the RCD or may just be a combination of a broken cpc and a Earth to Neutral fault but i would have thought that would have tripped the RCD too unless there is a bonding conductor from say a shower to the bathroom light , combined with an open circuit cpc that will give you a Zs as you then have a path to earth via the bonding , this is another reason why you should never rely on a Zs test for testing continuity as you could well have false readings and leave the installation potentially un safe
L
Ladders
The lighting is not RCD protected...
N
nickblake
well could well be shorting cpc to neutral thus giving a fasle reading best bet is to joint the live and cpc together as you would with an R1R2 test and test at every point till you loose the continuity
L
Ladders
Thanks. So to summarise, periodic code 3 for the lighting and then if they want the work doing test until continuity is gone. (Although I did try a couple of points just in case I hit lucky and none of them gave a reading. O boy!)
On a recent EICR I had a ring circuit with no rn readings. It had 2 cables from attic going down the wall, but only 1 to be found in the socket. Traced in using r2 & rn connected method.
Ended up having to junction it and lose the socket as there was no neutral in the socket.
Possibly adjoining room had a socket and was strip connected together and single cable fed through the wall. It is now a bathroom and couldn't access the adjacent socket area.
2nd EICR had no R1/R2 reading in lighting circuit. Traced it to the 1st light on the circuit. An extended cable had a push fit junction box, but the CPC hadn't been pushed in !!
Oh the joys of testing ?
Ended up having to junction it and lose the socket as there was no neutral in the socket.
Possibly adjoining room had a socket and was strip connected together and single cable fed through the wall. It is now a bathroom and couldn't access the adjacent socket area.
2nd EICR had no R1/R2 reading in lighting circuit. Traced it to the 1st light on the circuit. An extended cable had a push fit junction box, but the CPC hadn't been pushed in !!
Oh the joys of testing ?
Vortigern
Arms
The thread is a decade old @Gasmeter65
But still useful !!
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