no continuity on ring final neutrals

[woodywoodpecker]

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.

 

[nikmet]

remove the fronts and check connections, then retest

 

[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.

 

[telectrix]

and remember, it's "be kind to spiders week". try not to break any webs.

 

[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

 

[DaveyD]

Or new skirting? - had one yesterday. Old cables (not in zones to be fair to the Chippy) so nail rignt through neutral - good shot!

 

[telectrix]

Or new skirting? - had one yesterday. Old cables (not in zones to be fair to the Chippy) so nail rignt through neutral - good shot!

surprised the chippy didn't nail directly below socket otlet. he'd have missed it then ! :death:

 

[SirKit Breaker]

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.

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

 

[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!

 

[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!

 

[james the spark]

I always split the ring somewhere at the middle and go from there straight off eliminate half the possibilities.

 

[IQ Electrical]

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.

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!

 

[woodywoodpecker]

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.?

 

[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

 

[telectrix]

if you find that it's not viable to locate the fault due to it being inaccessible without major damage, you could split the ring into 2 radials and replace the 32A MCB with 2 16A MCBs, 1 for each radial.

 

[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...

 

[nickblake]

if you find that it's not viable to locate the fault due to it being inaccessible without major damage, you could split the ring into 2 radials and replace the 32A MCB with 2 16A MCBs, 1 for each radial.

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

 

[telectrix]

he would have to make the split between the 2 sockets that each have a N from each leg.if that makes sense. i.e cut out the section where the N is broke.

 

[woodywoodpecker]

Is there a maximum number of outlets per radial though?

if you find that it's not viable to locate the fault due to it being inaccessible without major damage, you could split the ring into 2 radials and replace the 32A MCB with 2 16A MCBs, 1 for each radial.

 

[IQ Electrical]

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.