Help with lighting

[Chris Brennan]

Hi All,

I'm going to qualify this post with "I know I should have looked before I unscrewed the cables but...erm... I didn't"

Anyhow... I have a kitchen light that is controlled by two separate switches. I unscrewed the ceiling rose to replace it but none of the guides I've looked at here seem to match the cables I have.

One cable has just the red wire stripped for connection to the rose with the black snipped back and connected to nothing. Another cable is the opposite with the red snipped back and the black wire ready to be connected.

There are two other cables with both red and black wires stripped to be conneced to the rose. One of these goes to the final light in the loop (I assume) and the other is the power in from the previous light. (I assume)

I'm not sure how to re-wire this and any help would be greatly appreciated.

 

[Spark123]

If you connect your multimeter set to ohms range across the single red and the single black wire whilst someone operates the switch does the resistance change i.e. go high/low?

 

[Chris Brennan]

If you connect your multimeter set to ohms range across the single red and the single black wire whilst someone operates the switch does the resistance change i.e. go high/low?

Erm.. I don't have a multimeter. I thought I'd just do a quick change yet managed to screw it up by not taking enough care to look at the cables. If I get a multimeter and the resistance does change what should I do?

 

[Spark123]

Put some red sleeve over the black wire to signify it is a live (phase) wire.
Then connect all reds to loop, both blacks to N, red sleeve black to L, all earths to the earth terminal.
You need to verify those wires are the switch circuit first though, if they are not it could go bang!!

 

[Chris Brennan]

Right. Cool thanks for that.

Why are there single wires connected to the lights?

I don't understand why the black wire is snipped back and unused in one cable and the red wire snipped back and unused in the other. The setup I have here doesn't seem to match anything I can find in any diagrams or descriptions anywhere.

thanks so much for your help

 

[sparkyspike]

I'd guess that all three red wires would be connected to 'loop', the single black wire to 'live' and the remaing two black wires to 'neutral'.

To confirm this, look at the two switches: One may have COM = black and the other COM = red.

 

[Spark123]

It depends who wired it and how they did it, my initial thoughts are one of those wires will go to one switch, there will be a 2c&e from that switch to the other switch and the other single used core cables will return to the light from the other switch. If this is correct, why they used the black for a switched live is beyond me. It could be on the other hand that the black may be a neutral out to another fitting i.e. outside light. The red could be a switched live from one switch whereas it picks its feed up in the other switch via a looped common, the combinations are endless. Like I said, you need to check it first before connecting up.

 

[sparkyspike]

It may be due to the location of your lightswitches in relation to the pendant.

The installer may not have had 3 core cable and installed it in a triangle: 2 core from light to switch 1 (COM). 2 core from switch 1 (L2 and L1) to switch 2 (L2 and L1). 2 core return to light (Sw Live)

 

[sparkyspike]

I'll just shut up and let spark 123 explain!

 

[Spark123]

You'll have to type faster next time!!

 

[sparkyspike]

I'll have to type faster next time...



Oh *******s

 

[Sarahspark]

If you connect your multimeter set to ohms range across the single red and the single black wire whilst someone operates the switch does the resistance change i.e. go high/low?

Just to state the obvious, this must be done with the power OFF!

Sarah