L-N reverse

EFLImpudence · 4 Nov 2019

Mike10695 said:
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?

They couldn't IF all the checks are ok.

I'm not saying it is likely nor the cause - but purely from the testers point of view, IF, in a correctly wired socket, the L and CPC were at 230V with neutral correct at 0V, then the tester would , I presume, give the reversed polarity signal.

AndyPRK · 4 Nov 2019

How many lights does your plug in tester have?

JohnW2 · 4 Nov 2019

Mike10695 said:
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...

Mike10695 said:
... yes im 100% certain, the sockets the previous spark have used is very familiar, if all the checks come out ok,

That's been my point/problem. IF there are no JBs, and IF all socket N terminals are connected to the same colour conductor and all L terminals to the same conductor colour (and all CPCs to the 'earth' terminal), then ...

Mike10695 said:
... 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?

.. the only conceivable way in which I think a tester could indicate reversed polarity is if the CPC were broken somewhere and the downstream part after the break had somehow got connected to L. On sockets beyond the break, the tester would then see "L-E" as roughly zero and "L-N" as roughly 230/240V - which it would presumably interpret as reversed polarity. However, that would be an incredibly unlikely combination of faults.

That would also only 'work' if the 'reversed polarity' was being seen in all of the sockets beyond some certain point in the circuit (relative to the CU). Is that the case?

Kind Regards, John

Mike10695 · 4 Nov 2019

I believe the sockets with the faults are all continuous after a certain point but like you said yourself that would have to be an unlikely akount of faults just cant get my head around this

sparkwright · 4 Nov 2019

Could there be a hidden fused spur connection unit somewhere?

They can be easy to wire up wrong.

Mike10695 · 4 Nov 2019

Im pretty certain on this specific circuit there are no fused spurs however there are 2 outside sockets which i will check. Its a strange one to crack

333rocky333 · 4 Nov 2019

Have you done an earth loop at each socket this should show up if theres a bad earth to the relevant sockets. some testers will show a reverse polarity and not allow the test, though in reality sometimes its not so.
Due to the way the tester works, i assume by the voltages between the 3 terminations, i have found if the earths iffy or theres a voltage between N and E this seems to affect the indication even though L and N are ok

JohnW2 · 4 Nov 2019

Mike10695 said:
I believe the sockets with the faults are all continuous after a certain point but like you said yourself that would have to be an unlikely akount of faults just cant get my head around this

It does seem like an incredibly improbable combination of faults.

However, depending upon the socket tester you're using, I suppose it's just possible that there is just a single fault (a broken CPC) and that the tester is interpreting the situation downstream of that break (with a 'floating' CPC) as being reversed polarity - but that seems pretty unlikely.

In any event, if you measure voltage from L and N (and CPC) at each socket to a reliable earth, that ought to at least reveal what the situation is (even if it does not reveal the cause of anything which is 'wrong').

Kind Regards, John

Mike10695 · 4 Nov 2019

I appreciate everyones replies! For instance say I test all of these sockets and the between live and earth is 230 and neutral to earth 0 and it checks out fine, also doing a continuity test to each cpc etc, could I put this down to the tester? Also

JohnW2 · 4 Nov 2019

Mike10695 said:
I appreciate everyones replies! For instance say I test all of these sockets and the between live and earth is 230 and neutral to earth 0 and it checks out fine, also doing a continuity test to each cpc etc, could I put this down to the tester?

As I have implied, I would personally say that the short answer to that is 'yes'.

Kind Regards, John

Mike10695 · 4 Nov 2019

Cheers John

plugwash · 5 Nov 2019

Another question, are all the sockets the same make and model? and if not does the problem follow the make/model of sockets.

I'm wondering if there is a manufacturing error in the sockets themselves. It's pretty unlikely but we are getting down to a realm of unlikely things.

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L-N reverse

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