Mystery grey wire in ceiling rose

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My mum and dad have just had their house rewired by electricians. But after they'd gone dad wanted to replace a ceiling rose with a fancier light fitting.

In a move classic for my dad, he took the ceiling rose off without noting down where the wires came from or taking a photo.

Normally replacing a light is a simple job. But I've taken a look and I'm not sure what to do with the 3-core cable that is there. Here's what's coming out of the ceiling:

One 2-core cable (brown, blue, earth)
One 3-core cable (brown, black, grey, earth)

None of the wires are labelled with tape to indicate switched live, but it appears to be the black wire because it becomes live when the switch is pressed. There is no sign of a grey wire in the switch and there is no second switch controlling the light (apparently the electrician's forgot to put it in).

The ceiling rose is on a ceiling along with downlights. As the ceiling rose is disconnected at the moment, half of the downlights are on and half are off suggesting a break in the circuit.

Does anyone have any advice about how to identify what each wire does? I have a multimeter and voltage detector pen.

Many thanks
 
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Were all the wires bared?

ie, had been connected before the fitting was taken down?

Could do with pictures.
 
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Many thanks for all your replies. Here is a picture of inside the switch:
Light-Switch.jpg

y0vNyRz


And here is the ceiling rose (don't take any notice of how they may be connected as it's almost certainly wrong! Also this was yesterday. All the wires are now separated so grey and brown are no longer touching).
PXL-20210807-160958869.jpg

RQ5gw4N


Let me know if you need any further info.

Many thanks

Katie
 
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There must be more wires behind that switch, or possibly behind the plastic box, as that single black would be part of a black/brown/grey cable, and there should be several green/yellow protective conductors there as well.
 
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Not sure if it is an illusion but some of the Brown switch wires may be Brown SLEEVING slid possibly over the Grey wire
 
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I have it as thicker wire: maybe 1,5?

OP......where is the grey wire?
 
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Thanks folks,

Below is a picture from behind the switch. This shows the grey wires, as you suspected 333rock333. The greys appear to be connected to two blues, from the photo, which would correlate with AndyPRK's suggestion that it could be neutral.

Inside-switch-2-3.jpg


With this in mind, do you think I should do the following in the light?
  • Connect Earths together (the light should not be earthed)
  • Connect all browns together
  • Connect grey to blue and and feed that into Neutral of light
  • Connect black (switched live?) to Live of light.
Happy to take further advice if you recemmend further testing or have any questions!

Many thanks again :)

Katie
 
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Seems possible but i am struggling to think why only half the downlights are currently off
 
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the brown blue must be the supply.

the next lights are taken off the switch (hence the need for neutral)
or vice versa
 
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None of the wires are labelled with tape to indicate switched live, but it appears to be the black wire because it becomes live when the switch is pressed.

At the light, when this Black wire was switching on and off, did you have the two Browns joined at the time.

I would want to confirm the 2core and E cable is indeed a supply from the Mcb and reads 240v with the lightswitches off if can be done safely.
Whats the reason for a 4 gang switch
 
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That looks like a pretty rough re-wire. Connections outside of an enclosure behind the switch, not compliant, and no brown or blue sleeving on the live/neutral cables. That black cable connected to the switch has a little too much copper on show for my liking too! I wonder what else they couldn't be bothered to do properly yet still got paid for a 'proper' job.
 
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At the light, when this Black wire was switching on and off, did you have the two Browns joined at the time.

Yes, the two browns were joined in the ceiling rose when I checked the black wire. When the switch is turned off, none of the wires in the ceiling rose are live. No voltage is detected with voltage detector pen.

When all 4 switches are on, voltage is detected in all of the wires (black, brown, blue) except for grey which registers no voltage.

I would want to confirm the 2core and E cable is indeed a supply from the Mcb and reads 240v with the lightswitches off if can be done safely.

As mentioned above, none of the wires in the ceiling rose register any voltage when the switches are off. Should the browns in the ceiling rose be joined together when doing this test? Would you like us to do the test differently - not sure if voltage detector pen is sufficient?

What's the reason for a 4 gang switch

To control the spotlights at the front (working), spotlights at the back (not currently working), outside light (working)centre light (yet to be wired in).

The other detail (may not be relevant but thought it was not good practice?) is that one of the black wires in the switch is just dangling free. It has no exposed wire but it is not connected to anything and not terminated with tape or terminal. It's just been cut. This is not visible in the photo. Also, just to reiterate, all lights were working before dad removed the ceiling rose so I guess this dangling wire can't be the cause.

Thanks again,

Katie
 

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