Discuss 230v neutral to earth ? row of lights gone out mcb not tripped in the Electrical Forum area at ElectriciansForums.net

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230v N-L 230v N - E and 230v E to N

That's not what you typed in post 18 and I think it's not what you mean. Or you're making it up as you go along...
 
Post 18 was your post
My bad, I meant the bit of your post 17 that I quoted in post 18.

230v N-L 230v N - E and 230v E to N
230v L - N 230v N-L and 230v N-E

See the difference? If you meant:
230V L-N, 230V L-E and 230V N-E that's different, and also impossible unless L and 'N' happen to be two lines from a 3-phase corner grounded delta supply which I somehow doubt. Test and report accurately or any help you might get will be meaningless.
 
you can have a bad connection on the N which shows 230V to L untill loaded.
 
But it won't also show 230V N-E under the same conditions, which is what he seems to be getting at. In any case if he has 230V L-N at a fitting (which was not mentioned at first) and it's not alight, that fitting is faulty. In which case there are two faults. Methinks the reported findings are inconsistent.
 
My bad, I meant the bit of your post 17 that I quoted in post 18.




See the difference? If you meant:
230V L-N, 230V L-E and 230V N-E that's different, and also impossible unless L and 'N' happen to be two lines from a 3-phase corner grounded delta supply which I somehow doubt. Test and report accurately or any help you might get will be meaningless.


Ok yes my bad just for clarity one more time the voltage I was reading at fitting was 230v L-N 230v L-E 230v N-E

And yes it is a 3 phase supply as I stated it's commercial offices so of course it's 3 phase Lucien ....

My guess is they have took a feed off another lighting circuit on a different phase but somehow lost a N to the circuit feeding both row of lights cos when I looked at db supply lighting in office area it looks like each phase done a different row of lights .

It seemed like the row of lights I was looking at , the ones that were not on but had power and the other half along the same row still was working . But couldn't turn more breakers off to prove what kills feed to it as was in hours busy open space.

But I have never come across 230v between all 3 voltage tests . Hence why I thought someone may have come across this before and have some fault finding advice . I'm still to do my test and inspect but planning to this year . For more fault finding knowledge. As knowledge is power !! Haha
 
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My reference to three-phase supply was tongue-in-cheek and does not relate to normal UK 230/400V supplies. If you lose a common neutral to two circuits on two different phases, the voltage across the two circuits in series will be 400V and something will probably have gone bang.

With a single-phase circuit from a 3-phase 230/400V supply it is almost impossible to have the readings you describe. If one connection is floating you might see ghost voltages at it as Tel points out, but they won't all be 230V at the same time. Either something was changing between readings (e.g. sensor operating) in which case it's not a true description, or your measurement was in error.

Try drawing an equivalent circuit to the fault, that will read 230V L-N, L-E and N-E at the same time on an MFT or DMM.
 
I bet testing out with a device which put a decent load on,would give you different results,and,probably point to exactly what your fault is :winkiss:
 
I was getting 230v N- L at fitting as well .. so how can it be broken ?

230v L - N 230v N-L and 230v N-E row of lights out mcb not tripped .

If they were the readings either all the lamps have failed, all the ballasts have failed or a combination of the 2.

If you truly have; "At the end fitting i was getting 230v between N-E and i haven't come across this before would appreciate any help"

You potentially have a dangerous situation, particularly to yourself when fault finding.

The only way you can get your readings is if E or N are a different phase to L.

Don't be distracted by the comment, they were previously working OK and no-one else has touched them,
ASSUME NOTHING.
 
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If they were the readings either all the lamps have failed, all the ballasts have failed or a combination of the 2.

If you truly have; "At the end fitting i was getting 230v between N-E and i haven't come across this before would appreciate any help"

You potentially have a dangerous situation, particularly to yourself when fault finding.

The only way you can get your readings is if E or N are a different phase to L.

Don't be distracted by the comment, they were previously working OK and no-one else has touched them,
ASSUME NOTHING.[/QUOTEt

thanks , but what do you mean when u say "The only way you can get your readings is if E or N are a different phase to L. "

do u mean if a N or a E is touching a Live somewhere ?
 
Ok,
1. Stop.
2. Sketch out a simple circuit showing a bulb L N and E including the substation transformer, with the N-E link.
3. Now have a look where breakis in the circuit could cause 230V N to E....
 
but what do you mean when u say "The only way you can get your readings is if E or N are a different phase to L. "

do u mean if a N or a E is touching a Live somewhere ?

More likely been deliberately connected to another phase and not serving the purpose of N or E.
Hence caution, assuming your readings are correct as the body of the fittings may be Live and not earth.
 
More likely been deliberately connected to another phase and not serving the purpose of N or E.
Hence caution, assuming your readings are correct as the body of the fittings may be Live and not earth.

How did you draw that conclusion? There is 240 N - E and 240 L - E with the L - N voltage unknown.
The logical conclusion is that the N has risen to the same potential as the L with respect to E
 
Hello all,

I have recently attended a job where a row of lights have gone out and was advised and seen for myself when i got there that no breakers have tripped.

First i took the cover off of the panel with the mcb's that feed all lighting circuits in open office area , and checked i have 230v on load side on mcb , which i did have on all mcbs to rule out a faulty breaker. I next went to the nearest light fitting to the riser where dbs where and found 230v at fittings with lights not working (all on sensors ) and ballast units also had 230v.

I then was advised (by site engineer) that sometime in the past these lights had lost power and had been rewired by someone ?? not sure if they were qualified or not ... i then went to a room at the end of the office area where he advised me they repowered this lighting circuit which has now gone out but power still there couldn't see any polarity faults but didn't get a chance to check all fittings as was in working hours of a office.

At the end fitting i was getting 230v between N-E and i haven't come across this before would appreciate any help :)

Is the MCB protecting the lighting circuit double pole? Is it an RCBO which is double pole? If it is double pole, did you check for 0 Volts between Lin and Lout and then for 0 Volts between Nin and Nout, both measured when the mcb is closed to confirm the closure of the pair of contacts?
 
How did you draw that conclusion? There is 240 N - E and 240 L - E with the L - N voltage unknown.
The logical conclusion is that the N has risen to the same potential as the L with respect to E

L-N voltage was 230v as well and thanks guys . Will have more info after the morning getting there for half 5am . :0 .
 
How did you draw that conclusion? There is 240 N - E and 240 L - E with the L - N voltage unknown.
The logical conclusion is that the N has risen to the same potential as the L with respect to E

Stated as 230v. Post 17

Personally I believe the test results are confused and it's a simple lost neutral.
 

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