Lighting Problem

[BronteBloke]

Evening all,

I've got a problem with some lights in my house.

I have a 3-gang light switch. The left one is 2 way for the landing light, this works fine. The middle one is one way for a wall light, this has stopped working. The right one is 2 way for ceiling lights, this has also stopped working.

The ceiling lights were on last night and all of a sudden went off but didn't trip the fuse box. So far I have identified that the bulbs are fine, the light switch is fine and I've tried a multimeter on it tonight which shows that there is power running through the cables.

Can anyone point me in the right direction or suggest what the problem might be?

Thanks in advance!

Chris

 

[Luckyphil]

Check there isnt a link across the back of the Switch that has maybe broken near the termination point , or have you been doing any work where maybe a Cable has become loose in a Ceiling Rose

Pics of the inside of the Switch may help

TURN OFF THE LECCY BEFORE UNSCREWING SWITCHES.

Lucky

 

[sparkwright]

I've tried a multimeter on it tonight which shows that there is power running through the cables.

Can you elaborate on that a bit please?

 

[BronteBloke]

I've tried a multimeter on it tonight which shows that there is power running through the cables.

Can you elaborate on that a bit please?

Ok just done a thorough check on all the cables with an analogue multimeter..

Left Switch, 2 way for Landing Light (Which Works)
L1 & L2 - 100v
L1 & L - 0
L2 & L - 140v

Middle Switch, 1 way for Wall Light (Doesn't Work)
L2 & L - 120v

Right Switch, 2 way for Ceiling Lights (Doesn't Work)
L1 & L2 - 80v
L1 & L - 0
L2 & L - 110v

Seperate Switch, 2 way for Celing Lights (Doesn't work)
L1 & L2 - 0
L1 & L - 120v
L2 & L - 80v

Does this shed any more light on what might be wrong?? Thanks very much.

 

[riveralt]

A clear photograph of the rear of the switch would be helpful.

If you are using the multi-meter properly you should be getting around 240v across the closed switches and 0v across open switches.
Switches sometimes stick in the open or closed positions.

The photograph would show it but is there a terminal block with neutral cables in the rear of the back box and or is there a link cable between any of the cables.

Look here for help for one way and two switches
//www.diynot.com/wiki/electrics:lighting:two_way_lighting

One final thing lighting circuits operate in a radial format so that a break in the circuit results in no power to the remaining part of that circuit after the break.
I have had voltage figures like those when a neutral cable has come lose.

 

[BronteBloke]

Here's a photo:

 

[riveralt]

The biggest difficulty here is trying to determine where the power is coming from. Assuming you don't have a sticky switch - i.e. you have tested that the middle switch for example has zero vaults when open (not on). It is worth flicking the switch a number of times just incase.

On the assumption that your three core cable (red, yellow and blue) on the left is working - Yes?
This will likely derive its power from the other switch.

The right hand gang is possibly wired using the conduit method- see wiki link.

The red conductor(s) going to the middle gang L and right gang L which on the face of it would appear to be the left most cable are probably your live feed in.
You need to trace back this cable to its source and check both live and neutral are properly terminated - sometimes the insulation gets stuck between the terminals. I still think you may have a loose neutral problem given your readings.

 

[bernardgreen]

It is highly likely that the two reds to the middle switch ( one way ) should both come from the same cable. It doesn't look like they do.

Has the switch been changed ? It is a metal switch and the earths are not connected to the front plate ( as they should be ) but are terminated in the back box, as they would be with a plastic front plate.

 

[BronteBloke]

It is highly likely that the two reds to the middle switch ( one way ) should both come from the same cable. It doesn't look like they do.

Has the switch been changed ? It is a metal switch and the earths are not connected to the front plate ( as they should be ) but are terminated in the back box, as they would be with a plastic front plate.

It was changed about a year ago and has been fine until last week and I just copied the wire locations as they were in the old switch. I could swap the Live from the right hand switch with the middle and see if it makes a difference. I will also put the earths to the switch rather than the back box and report back!

 

[BronteBloke]

It is highly likely that the two reds to the middle switch ( one way ) should both come from the same cable. It doesn't look like they do.

Has the switch been changed ? It is a metal switch and the earths are not connected to the front plate ( as they should be ) but are terminated in the back box, as they would be with a plastic front plate.

Ok checked it again. The photo is actually a little misleading.. The 2 reds to the middle switch both come from different cables. All 3 of the left switch come from the same cable. The right switch has the live from 1 cable and the two others from a different one. Will the wall light and the ceiling light be on the same circuit meaning if there was a problem with one of them it would affect both? Also on that floor I also have various kitchen lights which work fine.

 

[bernardgreen]

I still think that is a new switch that was changed recently and that has caused the fault. If it isn't a new switch or the wires to the switch have not been touched then the fault is not in this switch.

If the switch has been changed then the wires have not been put back correctly. It is possible to work out the correct connections.

 

[RMS]

Why don't you test between line(live) and the cpc at the switch? All you tests seem to be between you commons and switch lines/strappers.

 

[BronteBloke]

I still think that is a new switch that was changed recently and that has caused the fault. If it isn't a new switch or the wires to the switch have not been touched then the fault is not in this switch.

If the switch has been changed then the wires have not been put back correctly. It is possible to work out the correct connections.

Its been working fine for a year though (which is when I fitted new lights and switches) until a few nights ago which makes it all the more strange.

 

[BronteBloke]

Why don't you test between line(live) and the cpc at the switch? All you tests seem to be between you commons and switch lines/strappers.

Sorry I'm not sure exactly what you mean, can you explain in simple terms what I should test and I will. Thanks.

 

[RMS]

Between the lives and the earths connected to the metal back boxes. You should have 230 volts switching through to the associated lights. Its possible you may have a neutral out in one of the lights.