Light fitting dead

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I have changed mostof the lights in the house and replaced the living room switch for a dimmer switch. all new lights and the dimmer work fine. However the dining room light does not work. I have changed the fitting, it is not that. I have also checked the voltage. From the switched live to earth there is 240v, from the circuit live to earth there is 240v. I have tested the switch with an ohm meter that works fine. When I go across the live to neutral on the other fittings there is 240v but on the dining room there is 0v. any ideas would be appreciated.

AttM · Posted: Sun Jan 12, 2003 12:51 pm Post Subject: Re: Light fitting dead

Obvious answer really, you have a broken netral somewhere. Possibly when you changed some other light fitting you neglected to reconnect a neutral wire that serves the loop. First place to check anyway.

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I think you're right, I've just checked the live switched live to earth and that has 240v aswell so there is power there. Maybe you could answer my other questions aswell. One: If i have left a neutral disconnected somewhere why doesn't this stop other lights further down the circuit working?
two: COuld it be a fitting I have changed upstairs or would that be on a separate circuit? Many thanks for your swift response, much appreciated.

AttM · Posted: Sun Jan 12, 2003 4:00 pm Post Subject: Re: Light fitting dead

1. If the broken neutral is in the light previous on the circuit to the one that doesnt work then all the other lights will still have a neutral, and therefore work.

2. The upstairs circuit would normally be separate, but doesnt have to be. You could try turning off a lighting circuit and seeing which lights are effected. (assuming your consumer unit has more than 1 lighting circuit)

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The fuse panel has three fuses for lighting but I don't know if that means there are three circuits or there are 2 fuses for one of the circuits. I have dropped all the new fitting this afternoon and checked the neutral connections and all were tight, though it crossed my mind that I could have wired in the cable and the screw is actually clamping the cable sheath and not allowing a clean connection. I will drop all the lights again next weekend and check so I'd appreciate it if you would check in again then for an update. Many thanks for your help. I'm an IT engineer by trade not a sparky do if you have a PC question you need answering let me know, I may be able to help return the favour.

AttM · Posted: Sun Jan 12, 2003 5:52 pm Post Subject: Re: Light fitting dead

Nice to know about the IT thing, how about joining then we know who to ask for when we need help.
If you have three fuses for lighting then you should have three circuits. Try removing (or turning off if they are MCB) each fuse in turn and see which set of lights stop working. This will give you some clues

redbull · Posted: Sun Jan 12, 2003 7:48 pm Post Subject: Re: Light fitting dead

as requsted, I have now joined...

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sorry for the slow uptake, just clicked, turn off each fuse in turn which will tell me which lights are on which circuits. The ones on the faulty circuits are the likely culprits right?

AttM · Posted: Mon Jan 13, 2003 7:19 am Post Subject:

As I understand things up to here you only have 1 fitting that is not working. If you identify which lights are on which circuits (a usual layout would be downstairs lights, upstairs lights, outside lights) then you get a good idea of where your problems DONT lie and hence where to start looking.

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redbull · Posted: Mon Jan 13, 2003 1:05 pm Post Subject:

Yep, you're right one light that doesn't work. I will attempt to determine which lights are on which fuse then work from there.

redbull

Right.. it's only taken me 3 weeks to have another crack at it. The dining room light is still dead, however I put the voltmeter from switched live to earth, when the light switch is in the on position there is 240v. However there is also 240v between the neutral and earth, so effectively I have two lives running to the fitting, though I've no idea how or why. I assume there should be 0v between neutral and earth, that's the case on the other fittings that work.

breezer

redbull wrote:

. I assume there should be 0v between neutral and earth, that's the case on the other fittings that work.

That is correct.

The answer is easy the solution is also easy, the question is where.

As you say the neutral is live you have connected it to a live at the other end, as i said the question is where, i would try the previous light on the circuit. which should be the room adjacent.

Switched lives are most often black, it sounds like you have put the neutral in with one fo these.

I am not going to say how, because anyone reading this may get the wrong idea, but as you seem to know how to use a multi meter, switch the mains off, put a short on the light that doesnt work, dissconnect the neutrals from what you think is the previous light and check for the short. repeat this until you find it, then you can correct your error. and don't forget
REMOVE THE SHORT BEFORE TURNING THE MAINS BACK ON

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redbull · Posted: Sun Feb 09, 2003 1:20 am Post Subject:

In no way will I hold anyone responsible for advice, hey if I really wanted to I could get a sparky in to find the fault.
I appreciate all advice offered here. You obviously know what you're talking about, and yes I am confident with an AVO, however I don't understand exactly what it is you're getting at.
Short what? the live and neutral? and is that perm live or switched live i short?
Assuming I get that far, the previous light ( I think) is one of the kitchen lights. How do I check for the short on the previous light neutrals? do i go across them and look for a circuit via the neutrals and the short at the other end? (hope that makes sense)
One thing that you said that did strike a chord though, the switched live is usually black, as is the neutrals, do you think it's possible i have bundled a switched live in with the neutrals on a previous light?
Many thanks for your patience and advice, I really appreciate it..

Redbull.

breezer · Posted: Sun Feb 09, 2003 2:09 am Post Subject:

as i said i do not want to say too much incase some one does it in error. But yes you have got a neutral wire in with the switched lives. if you think the kitchen is the one before the last light then yes check it from there.

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redbull · Posted: Sun Feb 09, 2003 6:24 pm Post Subject:

okay, now got it so that i have 240 on the main live. 240 on the switched live when the switch is made and 0v on the neutral. But the fitting still doesn't work (tried different bulbs and fittings.
The only thing i can think of is there is a break in the neutral circuit further on, would that make sense?