Lighting Fault

[Power Ball]

I am a Part 'P' domestic electrician who just does a few odd jobs on a part time basis so don't have loads of experiance although compitent at the work I do, however a neighbour of mine has just moved house to a bungalow and after 1 week all accept 1 light has gone off. The wiring circuit for the bungalow is not what I have seen before. I have taken off 2 ceiling roses and pushed through a hole to the loft is a choc block.

3 single black cables (N)in one side

1 red Live in the other

Not seen it done like this before plus the red is perminant live and the 3 Black/Neutral are also live, when I split up the neutrals I can isolate the one that is live.

Can someone send me a diagram of how this circuit should be wired and any ides where I might start to look for the fault

I have isolated the lighting as he can use side lights plugged in for tonight

He assures me he has not touched any elecctrics since he moved in a week ago the light just went off !!

Living room 2 lights

Kitchen 2 lights 1 light still works ok

Other 4 Lights

By the way it's an old Wylex board with no RCD protection which he knows to get an upgrade a.s.a.p.

Thanks

Chas

 

[PC Electrics]

You've got a broken neutral somewhere and a light still switched on, that's why you've got a 'live neutral'. Either that or you are mistaking a black switched live for a neutral.

Get your continuity tester earning its keep.

 

[ProDave]

If it was really 3 blacks into one terminal, and one red into the other, it think someone has been messing about.

It sounds like "loop at the light" wiring.

So you should have a red and black pair that is permanent live in.

A second red and black pair that is permanent live looping out to feed the next light fitting

And a third red and black that connects to the switch.

Is that not the way you were taught to wire it? (possibly you are more familiar with brown and blue rather than red and black)

So to determine which is the switch pair, turn the light switch on and measure with a continuity tester. One pair will show a low reading, probably less than 1 ohm, and that's the switch drop.

So the two "loop in and loop out" blacks go to the light fitting neutral. ALL the reds join together but don't go to the light. The remaining black from the switch, should be sleeved red (or arguably brown now) and connects to the light fitting live.

As I say, I'll bet someone has been messing about. I'll bet it's not a standard ceiling rose, but a fancy light fitting. Someone has probably just removed the old ceiling rose, fitted the choc block in it's place, shoved it up through the hole in the ceiling, then found it doesn't work. But rather than come clean and say what they have done (which would make your job easier) just say "it stopped working"

I've met this many times. I just wish people would tell you the truth rather than pretending they did nothing.

EDIT:

Re reading your original post, are these SINGLES rather than twin and earth? in which case it's wired in conduit?

If so the wiring is correct, the blacks are the neutral looping through. The live will loop through directly to each switch, and the single red you are seeing is the switched live coming back from the switch.

In that case the choc block "pushed up through the ceiling" is in fact inside the conduit back box and is perfectly okay. Don't forget this sytem relies on the conduit for the CPC and relies on a metal screw into the threaded hole of the back box.

I think we need more information to determine if this is twin and earth or indeed singles in conduit.

 

[PC Electrics]

To me it sounds typical 60's wired in singles with the looping at the switches and the neutral going from light to light.

 

[Badger]

sounds like some neutral connection at fault further up the line towards the c/u, check the fitting nearest the c/u depending where the c/u is situated. hth

 

[SPECIAL LOCATION]

By the way it's an old Wylex board with no RCD protection which he knows to get an upgrade a.s.a.p.Chas

1/ The lights as ProD said are probably lives looped at switches neutrals looped at fittings....

Not hard to figure out how it is wired..

but probably easiest if you go back with a decent test meter and a pen and paper..

write down exactly what you have at each accessory..

then work back testing switched supplies and perm live supplies..

Sounds like a wire broken off somewhere early in the circuit knocking off all other fittings further down the circuit.

2/ Your comment about no RCD on lights..

He does NOT have to upgrade ASAP..

regs are NOT retrospective...

Just as old cars dont have to have rear seatbelts and ABS breaks fitted

 

[Theorysparky]

I would be tempted at this point to find out which light the working light feeds

because thats where to start,,,,,it could just be a loose neutral

 

[Guy]

I do not want to hi-jack this thread but I do want to follow it, can it be assumed that the only remaining working light is the first light on the circuit?

 

[Theorysparky]

yes.....if it is wired correctly

but in the olden days some lighting ccts were wired as rings not radials

 

[Power Ball]

If it was really 3 blacks into one terminal, and one red into the other, it think someone has been messing about.It sounds like "loop at the light" wiring.

So you should have a red and black pair that is permanent live in.

A second red and black pair that is permanent live looping out to feed the next light fitting

And a third red and black that connects to the switch.

Is that not the way you were taught to wire it? (possibly you are more familiar with brown and blue rather than red and black)

So to determine which is the switch pair, turn the light switch on and measure with a continuity tester. One pair will show a low reading, probably less than 1 ohm, and that's the switch drop.

So the two "loop in and loop out" blacks go to the light fitting neutral. ALL the reds join together but don't go to the light. The remaining black from the switch, should be sleeved red (or arguably brown now) and connects to the light fitting live.

As I say, I'll bet someone has been messing about. I'll bet it's not a standard ceiling rose, but a fancy light fitting. Someone has probably just removed the old ceiling rose, fitted the choc block in it's place, shoved it up through the hole in the ceiling, then found it doesn't work. But rather than come clean and say what they have done (which would make your job easier) just say "it stopped working"

I've met this many times. I just wish people would tell you the truth rather than pretending they did nothing.

EDIT:

Re reading your original post, are these SINGLES rather than twin and earth? in which case it's wired in conduit?

If so the wiring is correct, the blacks are the neutral looping through. The live will loop through directly to each switch, and the single red you are seeing is the switched live coming back from the switch.

In that case the choc block "pushed up through the ceiling" is in fact inside the conduit back box and is perfectly okay. Don't forget this sytem relies on the conduit for the CPC and relies on a metal screw into the threaded hole of the back box.

I think we need more information to determine if this is twin and earth or indeed singles in conduit.

This is how I was taught but wiring is not like this. It is in singles but no conduit singles loose in the loft laid on top of insulation By the way the house was built about thirtyplus years ago

and from the two fittings I took down there is only one red/live wire . I will give a good test tomorrow and let you all know

Thanks

Chas

 

[ProDave]

This is how I was taught but wiring is not like this. It is in singles but no conduit singles loose in the loft laid on top of insulation By the way the house was built about thirtyplus years ago and from the two fittings I took down there is only one red/live wire . I will give a good test tomorrow and let you all know

Thanks

Chas

I'm willing to bet it WAS in conduit originally. Nobody would use singles, laid loose in the loft would they (but then again...)

The fault therefore must be that somewhere the loop through neutral connection has broken. I say that as you say some of them tested as live.

Perversely, I would start at the one working light fitting. As that works, you know there's a good neutral there. you might be lucky and find the break is there, but if not that's your starting point to trace where the neutrals go.

But having determined you have loose singles in the loft, not in conduit, I would strongly be recommending at least a PIR which will highly likely recommend the lighting circuit is rewired.

With no conduit, you have no CPC to the lights, so lets hope there are no fancy metal light fittings anywhere.

 

[ccfc]

Hello mate

Are these sheathed singles , not unsheathed conduit singles . Ive seen this loads of times in house built in the 70's . They loop in the line at the switch then the neutral to first light and radiate from there from there to other lights octopus style or looped in at light or even looped in for first few then radiated to others from there. So you could have 3/4/5 neutrals at first light feeding the neutral to different lights then loop to next then radiate to 3 or 4 again. The earth is usually with the line but have seen then with both L&N.

Cheers

Neil

 

[batty]

Are they double insulated so to speak quite often the live will have a built in CPC think it is still available nowadays.

 

[SLIPSHOD & SLAPDASH]

I'm willing to bet it WAS in conduit originally. Nobody would use singles, laid loose in the loft would they (but then again...)The fault therefore must be that somewhere the loop through neutral connection has broken. I say that as you say some of them tested as live.

Perversely, I would start at the one working light fitting. As that works, you know there's a good neutral there. you might be lucky and find the break is there, but if not that's your starting point to trace where the neutrals go.

But having determined you have loose singles in the loft, not in conduit, I would strongly be recommending at least a PIR which will highly likely recommend the lighting circuit is rewired.

With no conduit, you have no CPC to the lights, so lets hope there are no fancy metal light fittings anywhere.

Come on now Dave, Whats the point of a PIR ?

The lighting needs rewiring and in this case as you are aware of its faults it needs doing now which may be quicker than fault finding.

 

[Power Ball]

Yes they are all double insulted with grey outer sheath.

Chas

 

[batty]

Is there a cpc though?

 

[ProDave]

Yes they are all double insulted with grey outer sheath.Chas

They say it's never too late to learn something, and I have today.

I've never encountered that wiring method, but providing they are double insulated then I can't fault it.

So it looks like it's just back to fault finding, have a good look at ALL the neutral connections in all the light fittings. Somewhere there's got to be one broken, or just pulled out of the terminal.

 

[SLIPSHOD & SLAPDASH]

I haven't seen that method for so long i had forgotten about it. I always wondered why it was done like that when twin and twin and earth was available and cheaper.

 

[Power Ball]

Is there a cpc though?

There is no cpc on the light circuit, at present all fittings are moulded plastic basic ceiling rose in each room.

Not seen lights wired like this before usually as Pro dave says live neutral in - live neutral to next light - live/sw-live back from switch Simples!!

Chas

 

[batty]

Long term a rewire probably will be best have they put stuff up in loft and pulled a cable out somewhere. its going to be a lost cable somewhere you just need to find it.