Live/Neutral problem On lighting circuit

Hi all,

Wonder if any one can help with this problem. Had a bulb blow yesterday morning and half the house went into darkness. Went to reset the MCB only to find it hadnt blown.

Initially i thought it was the MCB so changed that over with no joy.

On testing the voltage at the switch i find

L/E = 250 volts L/N = 8 volts N/E = 230 Volts

I have isolated the fitting where the lamp blew yesterday, with no luck.

There is a hard wired smoke detector on this circuit ? will this have an effect.

Any help in troubleshooting this would be greatly appreciatted.

Reply to
toggy
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On or around 23 Oct 2005 06:27:53 -0700, "toggy" mused:

Neutrals gone o\c somewhere. Find out where and repair it.

Reply to
Lurch

Thanks for that, thats what i kinda thought. Any easy way to isolate the fault?

Reply to
toggy

Thanks for that, thats what i kinda thought. Any easy way to isolate the fault?

Reply to
toggy

On or around 23 Oct 2005 06:47:07 -0700, "toggy" mused:

You'll just have to test the circuit and find where the damaged cable\loose connection is. First thing to do is see which lights do work and which ones don't. The job involves removing of fittings and testing of cables, no easy way to do it.

Reply to
Lurch

Just a thought but if there was a connection from live to neutral would the mcb no blow?

Reply to
toggy

toggy explained on 23/10/2005 :

Did you really mean the switch?

A wall switch would not normally have a nuetral at it, the black (you assume to be nuetral), is probably the 'switch wire' - which becomes live when the switch is turned on.

Reply to
Harry Bloomfield

On or around 23 Oct 2005 07:28:39 -0700, "toggy" mused:

Eh?

Reply to
Lurch

On or around Sun, 23 Oct 2005 15:38:38 +0100, "Harry Bloomfield" mused:

For some reason I assumed the fellow meant he'd tested it at the switch which happened to have a L, N and E in it. Looking at the thread now I realise the OP would be better advised to get someone in with an idea of what they're doing.

Reply to
Lurch

Yes i mean the switch. Sorry i should have explained, it would appear that the ring is wired straight to the switch i.e two live feeds, with 2 terminal blocks connecting the neutral and earth respectively all held within the switch box.

Reply to
toggy

Sorry if i didnt explain things as clearly as maybe you would have liked, but hopefully my previous post will clarify my/your confusion :)

Reply to
toggy

Describe exactly how these are connected. Giving the colours.

Reply to
Dave Plowman (News)

On or around 23 Oct 2005 07:49:46 -0700, "toggy" 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?

Reply to
Lurch

On or around 23 Oct 2005 07:50:16 -0700, "toggy" mused:

Basic principals of the domestic electrical system, live to neutral short, MCB blows. I'd still be inclined to get someone in if I were you.

Reply to
Lurch

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

Reply to
toggy

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

Reply to
toggy

That connection is provided by whatever you have on the circuit that is not turned off - as soon as you fix the break in the neutral, current will flow and the voltage will drop across that appliance, then your voltmeter will see approx. 240v difference between live and neutral.

Reply to
Rob Morley

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

Reply to
toggy

will try my best, any problems give me a shout and i will post a picture.

3 1mm cables into switch box

3 earth wires joined into a terminal block

3 black wires joined in terminal block

2 red wires to supply side of switch

1 red wire from other end of switch

I should just add there is a similar setup for all the switches on this circuit

Hope this helps

Reply to
toggy

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