Neutral fault

[Sb8389]

Hi guys,
been to a fault today where customer is saying they have no power to 6 sockets but all other points ok (all power on one ring main)
when I arrived I checked for power with my martindale and got a L-E reverse symbol at the six points. I then checked voltage at the sockets and got 230v L-E and N-E but nothing L-N. So I thought I must have a neutral fault somewhere.
i then checked ring continuity and found the neutral open circuit. Why would it show voltage across my neutral to earth when all loads have being disconnected. I have checked all sockets and cannot find a loose connection. Any advice on where to go next. If you have any questions where I have not made myself clear just ask. Thanks

 

[telectrix]

1. socket testers do give L-E reverse if the N is missing.

2. you will get 230V N-E on the N conductors that are connected through loads to L supply. because the N return to the CU is broken, there's no current flow, therefore no volt drop.

 

[amlu]

draw the house layout on a piece of paper, mark where the sockets are, measure continuity using wander lead, figure how its been wired up, it maybe not a ring anymore. i would suspect a dodgy junction box under the floor.

 

[Octopus]

My Metrel shows L-N reversed if there isn't an earth!

 

[telectrix]

the wonders of modern technology.

 

[Sb8389]

There is still continuity across live and earth, I just found it strange that I was getting voltage across neutral to earth with no loads connected. I have just put everything back together and all sockets have come on with correct voltage but still no continuity,yet when I connect one leg of the neutral the six sockets go back to L-N reverse and then connect the other neutral the rest of the house goes into L-N reverse. Sorry if I'm sounding confusing but Am I basically looking for a break in the neutral that would cause this. Never came across this kind of fault so ur experience is appreciated.

 

[Sb8389]

By continuity I mean ring continuity

 

[Plonker 3]

Have you carried out a R1+R2 test on the RFC?

 

[ackbarthestar]

I had a problem similar to this, everything looked ok until I attempted to connect a load.
I found that the neutral had been connected in the RCBO but wasn't making contact. It happens with certain breaker terminals

 

[Pete999]

https://www.youtube.com/watch?v=zSATFrqlSpg
Like this

 

[Sb8389]

How would an R1+R2 sort the fault pal what am I looking for just so I know dillb.

 

[Plonker 3]

It will give you a chance to prove polarity on each socket. Also find out of there are any spurs which may be causing the issue.

 

[Sb8389]

Yea I'm back there tomorrow so need to get abit more in depth with the testing. Can tell it's not gonna be an easy fault to find seeing as I've checked all accessories so there must be a jb under the floor where the neutral has come loose.

 

[Guest77]

Hi guys,
been to a fault today where customer is saying they have no power to 6 sockets but all other points ok (all power on one ring main)
when I arrived I checked for power with my martindale and got a L-E reverse symbol at the six points. I then checked voltage at the sockets and got 230v L-E and N-E but nothing L-N. So I thought I must have a neutral fault somewhere.
i then checked ring continuity and found the neutral open circuit. Why would it show voltage across my neutral to earth when all loads have being disconnected. I have checked all sockets and cannot find a loose connection. Any advice on where to go next. If you have any questions where I have not made myself clear just ask. Thanks

Cut the nonsence regarding continuity checks and whack 500 volts between all cores as you were trained on site and at tech when you did your apprenticeship, it is the only way to check all is okay, 1000 even, any problems will show straight up.

 

[telectrix]

any plumbing been done recently? i ask because the other week i had the same fault. the wet-pants had put his circular saw through a 2.5mm. cut clean through the neutral. sod must have known he'd done it as his saw would have stopped. bugger fitted his pipes, nailed the boards back, said nowt. lucky i was in a good mood that day or i'd have nailed his pipes.

 

[Guest77]

any plumbing been done recently? i ask because the other week i had the same fault. the wet-pants had put his circular saw through a 2.5mm. cut clean through the neutral. sod must have known he'd done it as his saw would have stopped. bugger fitted his pipes, nailed the boards back, said nowt. lucky i was in a good mood that day or i'd have nailed his pipes.

Is geordie back on his feet? :biggrin:

 

[telectrix]

Cut the nonsence regarding continuity checks and whack 500 volts between all cores as you were trained on site and at tech when you did your apprenticeship, it is the only way to check all is okay, 1000 even, any problems will show straight up.

how will an IR test show a broken conductor?

 

[Deleted member 9648]

If it's a ring then all the sockets will have voltage regardless of a break in the rn. You need to check whether you have correct r1 and r2 to verify the circuit is actually wired as a ring,it sounds like it isnt. If r1 and r2 are good then that would suggest more than one break in rn.

 

[Guest77]

how will an IR test show a broken conductor?

meggar between the neutrals at the board, if there is a break in the ring it will show up, if there is a short between neutral and earth it will show up, I would meggar the cores and then do a r1+r2 as well afterwards, anytime there is a fault on a power circuit I would meggar all the cores to see if any breaks or shorts evident.

 

[Sb8389]

Should have said that I did an IR test and it showed 0.02 meg across one leg of neutral-E (no RCD fitted,no PME just some more info I missed sorry guys)everything else tested ok so I know there is a problem,I will start breaking circuit down tomorrow. No plumbing being done or DIY work.

 

[Guest77]

Should have said that I did an IR test and it showed 0.02 meg across one leg of neutral-E (no RCD fitted,no PME just some more info I missed sorry guys)everything else tested ok so I know there is a problem,I will start breaking circuit down tomorrow. No plumbing being done or DIY work.

Fair enough mate, I would have also done the same test.

 

[Deleted member 9648]

meggar between the neutrals at the board, if there is a break in the ring it will show up, if there is a short between neutral and earth it will show up, I would meggar the cores and then do a r1+r2 as well afterwards, anytime there is a fault on a power circuit I would meggar all the cores to see if any breaks or shorts evident.

Buggar that,do an insulation test instead.

 

[Sb8389]

It is wired as a ring wirepuller as I tested r1 and r2 so I think ur right there will be probably be more than one break.

 

[telectrix]

it's a 4 finger kitkat then?