Live neutral reverse
- Thread starter chippy5
- Start date
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Yes, it obviously should. Furthermore, as I wrote earlier, it it's very hard to see how, even if it were designed badly or faulty, it could end up displaying 'L-N reversal' when the true problem was actually a missing earth.
Kind Regards, John
Which would it show if you had a missing earth AND reverse polarity?
I don't think anyone knows exactly how these testers actually work.
Presumably they just measure voltage and/or continuity between the terminals and compare with what it should be.
That is: should be 240V L-N & L-E and low ohms N-E.
Do they recognise actual polarity of AC?
You could swap the L and N in one of the sockets and see what the tester shows.
HOWEVER, the point is that, I hope, no electrician would, after it being shown as reverse polarity by one of these testers, just blindly go ahead and swap L and N without further testing with accurate proper testing equipment.
Neither should you.
We can be talking about this until the cows come home. The reality is, the 'tester' has given an indication of a fault.
If you are responsible for the electrics then you cannot ignore this fault and should either:
Isolate the circuit and make it safe.
Start the continuity of conductors test using a proper test kit - as a minimum you should use a multi-meter.
If you are responsible for the electrics then you cannot ignore this fault and should either:
Isolate the circuit and make it safe.
Start the continuity of conductors test using a proper test kit - as a minimum you should use a multi-meter.
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If there is a missing earth, my Martindale one shows 'Missing Earth' whether the L-N polarity is correct or reversed. I think that makes sense since, in the absence of a usable earth, there's no way I can think of that the device (or even an electrician, if all they had to work with were the three terminals) could detect an L-N reversal.
The only one I've ever taken apart (a long time ago, so they may have changed) appeared to just look at the L-N, L-E and N-E pds.
I'm not sure what you mean. The one I took apart reported L-N reversal if the N-E pd was much greater than the L-E pd.
That's obviously correct. Given access to some 'known earth', the only 'proper testing equipment' one really needs is a voltage indicator or multimeter, but reliance on a plug-in thingy would be inappropriate.
Kind Regards, John
Ok, so it does not even see the continuity between N and E - just pd or no pd.
I mean it can't tell which is L and which is N - which it could do by detecting continuity between (real) N and E.
Just to show that these things are not that reliable, what would it read where the socket was wired correctly but the cpc had become disconnected from earth and had become live(240V)?
Now that's interesting, particularly in relation to this thread. I've just tried that with mine, and it reports an L-N reversal.
If you think about it, that's logical - it is seeing 230V between N and 'E' and 0V between L and 'E'. An electrician who had access to nothing other the three terminals of the socket (no access to a 'known good earth') would presumably come to the same initial conclusion ('L-N reversal'). However, to be fair, that situation requires two simultaneous faults (CPC disconnected from earth and CPC connected to L), so it probably very uncommon.
Kind Regards, John
Yes, logical for such a tester.
We had a discussion in the past where the same L-N reversal would be shown if all the conductors were rotated clockwise (looking at it in relation to the plug terminals).
An electrician may do an EFLI test - which would raise suspicions.
Two simultaneous faults or - one screw.
We had a discussion in the past where the same L-N reversal would be shown if all the conductors were rotated clockwise (looking at it in relation to the plug terminals).
An electrician may do an EFLI test - which would raise suspicions.
Two simultaneous faults or - one screw.
Which part is inaccurate?
Indeed.
Indeed, the test would presumably either be impossible or would result in a very strange reading. I've just tried with my Fluke and it refuses to do an EFLI test in that situation (just makes a noise at me) - presumably because it detects 0V L-'E' and/or 240V N-'E'.
Kind Regards, John
The part that says that I understood [all of] what he wrote. I understood as far as the comma, and responded just to that bit.
As for relevance to the thread, if I had £1 for every time you have commented on, questioned or 'picked up on', a comment/statement in post which had no relevance to the topic of the thread, I reckon I'd be a pretty rich man by now!
Kind Regards, John
I know, I know.
I did respectfully acknowledge all this by stating it would be TEMPORARY.
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