L-N reverse

[Mike10695]

Hi, ive been to a house today which has a L-N reverse on the plug in tester, all sockets are working, some sockets check out fine but others are showing the fault, Ive checked each socket for correct connections which are alll fine & The IR on the circuit also checks out at 140 which is fine, im a bit baffled if im honest, Im newly qualified, any help on how to fo about his would be appreciated, the circuit is a 20amp radial socket circuit, cheers.

 

[DetlefSchmitz]

Hidden junction box?

 

[Mike10695]

Hi thanks for the quick response, the house has not long been rewired and theyre currently having flooring done so I have access to floors and the ceiling and at this moment I havent seen any jbs whilst tracing cables.

 

[EFLImpudence]

Just to be certain - do you mean some of the sockets on the same circuit are fine?


Remember the socket testers cannot distinguish between neutral and earth.

You need to test the suspect sockets with a proper two-pole tester to a known good earth.

 

[DetlefSchmitz]

If I had the time I would trace out the circuit in detail and draw it out. I would expect the crossover (if there is one) to happen someway down the circuit, and be consistent past that point. There may be another explanation relating to the earth not being what it seems beyond a certain point. Remember plug in testers work with the 3 signals they have access to. With a multimeter and a long wire to an earth you will get better information.

Edit: didn't see EFLI's reply - I think we have the same basic message.

 

[JohnW2]

Just to be certain - do you mean some of the sockets on the same circuit are fine?

That does seem to be what the OP is saying/implying - but if (as sounds to be the case), the OP has confirmed that all sockets have been 'wired correctly' (presumably in terms of conductor colours), that would be impossible, wouldn't it?

Kind Regards, John

 

[Mike10695]

Thanks for all the replies, yes on the same circuit some sockets test out correctly but others are coming up with a LtoN reverse, I do have access to a multimeter and the r2 wander lead.

 

[Mike10695]

So are you immplying I use the R2 method and from the CU check there is a earth connection at each socket outlet that has the fault?

 

[JohnW2]

Thanks for all the replies, yes on the same circuit some sockets test out correctly but others are coming up with a LtoN reverse ....

Thanks for clarifying - and was I also right in interpreting what you wrote as indicating that you have confirmed that (in terms of the conductor colours), all the sockets on the circuit are 'wired correctly'?

... I do have access to a multimeter and the r2 wander lead.

If you meanure between (alleged) L and N at each socket and a known true earth (NOT the earth/CPC at the socket), that will tell you what is going on and, in particular, if the polarity really is reversed at any of the sockets.

Kind Regards, John

 

[Mike10695]

Thanks for the awesome response John! Yes you are correct ive take off every socket front and made sure all the correct colours are connected in the correct terminals, so If I use the wander leave method, clamp onto the earth bar at the cu then with the meter check between Line and neutral at each socket this will either confirm reverse polarity or indicate something else

 

[JohnW2]

Thanks for the awesome response John! Yes you are correct ive take off every socket front and made sure all the correct colours are connected in the correct terminals ...

That's what I though you meant - in which case, as I said, it ought to be impossible for some sockets on the circuit to have reversed polarity and some correct polarity! (Edit: ... unless, as EFLI has said, there are some hidden, and incorrectly wired, JBs somewhere),

Do I take it that you are absolutely certain that the wiring is correct (bearing in mind that the L and N terminals are not always in the same positions on different makes/models of socket)?

... so If I use the wander leave method, clamp onto the earth bar at the cu then with the meter check between Line and neutral at each socket this will either confirm reverse polarity or indicate something else

Measure between the earth and the (alleged) L, then between the earth and the (alleged) N at each socket. In the absence of any polarity reversals, you should see ~230/240V between L and E and a very low voltage (if any) between N and E.

Kind Regards, John

 

[EFLImpudence]

Yes, you could measure from the CPC as well just to confirm its continuity.

If some sockets are indeed reversed then you must have a wrongly wired junction box somewhere.

Can you tell where the apparent reversed sockets are in relation to the circuit?
That is - are they at the CU end or at the other end.
It would be a huge coincidence if they are at the CU end and the wrongly wired JB 'corrected' the error.

 

[JohnW2]

If some sockets are indeed reversed then you must have a wrongly wired junction box somewhere. ... Can you tell where the apparent reversed sockets are in relation to the circuit? ... That is - are they at the CU end or at the other end.
It would be a huge coincidence if they are at the CU end and the wrongly wired JB 'corrected' the error.

Indeed, and if any reversed polarity ones were not 'adjacent' (circuit-wise), that would be even more amazing - since one would then need the even 'huger' coincidence of multiple JBs with more than one of them incorrectly wired!

Kind Regards, John

 

[Mike10695]

Cheers again John, I will meausre between LtoE and NtoE tomorrow with a 2 pole tester, I didnt quite have time today to have a thorough investigation, yes im 100% certain, the sockets the previous spark have used is very familiar, if all the checks come out ok, why could the plug in tester possibly be giving me this reading on certain sockets on the circuit? I know they arent a reliable source and cannot define between N and E but surely there must be a reason?

 

[Mike10695]

Hi Efl I have also spoken to the spark who rewired the property just now & he is pretty certain there are no jbs anywhere in the house, also he is going to drop a circuit diagram through email to confirm the way he run th circuit