Live/Neutral problem On lighting circuit

mused:

There is no ring, unless you happen to live in a commercial premises with some unusally large lighting demands.
Are you sure the neutral is actually a neutral?
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Hi again,
I assume its a ring a. due to the double live feed going into the same connection of the switch and b. the two live wires coming off the mcb.
Again assumption that the black is neutral based on 3 black wires going into the same terminal block, i.e 2 from ring (assumed) and one going to light fitting.also what i didnt mention previously was with the switch on i am getting similar voltages as stated previously and with the switch off
L/E = 0V L/N = 0 V N/E = 230V
Hope this is clearer, thanks again
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mused:

Before we go on, there is a sying which fits quite well here, "assumption is the mother of all fuck ups".

Then you shouldn't be intefering with it as you are assuming that your house is the only one that I would have ever seen wired with the lights as a ring.

Put down the tools and step away from the switch.
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Hi again,
I assume its a ring a. due to the double live feed going into the same connection of the switch and b. the two live wires coming off the
mcb.
Again assumption that the black is neutral based on 3 black wires going into the same terminal block, i.e 2 from ring (assumed) and one
going to light fitting.also what i didnt mention previously was with the switch on i am getting similar voltages at the lamp fitting as in op and with the switch off
L/E = 0V L/N = 0 V N/E = 230V
Hope this is clearer, sorry for any confusion, i know what i mean unfortunately no one else does. thanks again
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On 23 Oct 2005 08:56:25 -0700 someone who may be "toggy"

You undoubtedly assume wrongly. As has been said, the circuit is probably wired using the loop-in system. One of these wires is probably the feed and the other is a feed to another fitting.

Probably feeding two parts of the lighting circuit.
To be blunt, it sounds like you don't know enough about electric wiring in the UK to be fiddling with such things. Put everything back together and get hold of someone who knows what they are doing.
A little knowledge is a dangerous thing. It can be fatal to those who don't know what they are doing.
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Hi again,
I assume its a ring a. due to the double live feed going into the same connection of the switch and b. the two live wires coming off the mcb.
Again assumption that the black is neutral based on 3 black wires going into the same terminal block, i.e 2 from ring (assumed) and one going to light fitting.also what i didnt mention previously was with the switch on i am getting similar voltages at the light fitting as stated previously and with the switch off
L/E = 0V L/N = 0 V N/E = 230V
Hope this is clearer, sorry for any confusion, i must learn to proof read :) thanks again
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I'm way out of practice to give advice (and go by what the guys have said above) - I just offer my 4p's worth out of interest.
IF it's a ring, I think you'd need to open the ring at (say) the switch in order to take sensible readings - ie treat the ring as two circuits. But the wiring in your picture could be just a LNE in, a LNE out (to next light) and LNE used as switchwire to the fitting (as the others have said). Strange and mad things are possible of course - like both those reds from the mcb feeding two different lighting circuits or even a ring on the red conductor but no loop back on the return neutral! (Which indeed would look like an open N on a loop). But those are in the realms of rougue traders antics.
An open neutral on a ring wouldn't be seen as fault in the way you describe (as it'd get a N fed from the other end too - I think)
You say half the lights went out - which half? All upstairs/dowstairs. Maybe a clue there.
I think I'd do first is turn off the power, measure to make sure it's off and open ALL the light switch covers looking for a failed/broken connection(s). After that, the fittings.
Gotta go with the "get an electrician in" though if your in any doubt. Post the solution when it's found eh!
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wrote:

SNIP
Thats a thought provoking detail - when did the problem reveal itself and has anyone drilled any holes or driven any picture hanging nails into walls anywhere? I once got called to a house where the (whole house) lighting fuse had started blowing. The client had "repaired" it with ever increasing thiickness of wire until it stayed in for a few seconds before going off with a big bang. At that point the get someone in idea had kicked in. My first question to the lady of the house was have you done anything to make a hole in a wall etc and she looked at me as though I was an idiot (could be true but thats aside) and said in a puzzled voice they had hung a picture up on the landing. As the problem only showed up in the evening when dusk fell and the lights woudn't work they didn't connect it. Taking down the picture revealed a burnt and blackened hole in the plaster around one of the nails of the two nail picture hanger. After that it was a minor repair to extract the nail, clear the damaged plaster and pull out the damaged section through the cable capping using it as a draw wire to draw a new piece in. A small patch over the capping and a cupfull of polyfilla left them with a bit of decor to sort out. (Oh and I rehung the picture slightly to one side to miss the cable)
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The problem presented early sat morn, no other lights were on. i had switched the dining room lights on, they were on for 30 secs then pop like a bulb going and all other lights on that circuit went.
No drilling or nails in the wall not for a few months anyway, but one curious thing (? red herring) the smoke detectors (which are off the same lighting circuit) went off last thing friday night (burn toast).
I work shifts, so getting daylight time to look at it is getting hard, so have isolated that circuit, bought a load of small lamps, will have one last good look on wed, then out with yellow pages.
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Disconnect smoke detectors to eliminate red herring. (Replace if faulty disclaimer etc etc)
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wrote:

Have you looked in the consumer unit terminals for broken wire/termination?
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Sorted, Smoke Detectors were a red herring.
Fault was in last switch checked!!. One of the neutral wires was pushed into the terminal block, between the metal and insulation, instead of being screwed in. Simple enough job to remake connection and voila we have light.
Thank you one and all for your help
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On 23 Oct 2005 06:27:53 -0700 someone who may be "toggy"
Anyone who knew what they were doing would have tested it, rather than changing it. Did you really have a spare handy?

The best advice you can be given is to leave it alone, before you kill yourself or someone else.
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