ceiling rose (spaghetti junction) please help with this prob

[djc8818]

HELP... Took down ceiling rose in kitchen to replace with a nice new fitting from b&q.. got into some thing out of my depth..
ceiling rose has 4 cables coming in.. cable one has red, yellow, blue. second has red, black. third has red, black, earth. forth has red, black, earth. light switch is a double switch one for concealed lighting, second is for main light. one of the blacks seem to be switchable live, another seems to be permantly live the last black does not show any signs of being live, so i persume this a nuetral, yellow seems to be a live aswell but when the switch is off the eletrical screw driver light dims, 3 of the reds which i have bunched altogether in a connector block as that is how they were in the rose the other red is blocked together with the blue as that is how that also came out of the ceiling rose....

 

[securespark]

Does one cable have no earth or is it just cut back?

What wiring have you attached to the switch?

 

[djc8818]

Does one cable have no earth or is it just cut back?

What wiring have you attached to the switch?

Cant see that any earth have been cut back....
as far as the switch goes i have not touched that.
on removal of the swicth
Yellow is common for main light (ceiling)
Blue is common for concealed lights
Red is live for main light with a bridge to live for concealed lights.
Earth goes to earth on socket.

 

[electronicsuk]

ceiling rose has 4 cables coming in.. cable one has red, yellow, blue. second has red, black. third has red, black, earth. forth has red, black, earth. light switch is a double switch one for concealed lighting, second is for main light.

Are we to presume switching is only single way, there are no other switches for the same lights elsewhere? You need to buy yourself a multimeter so you can test this properly rather than just guessing at where to put wires and seeing what happens, as that is a dangerous way to work.

My guess would be that the 3 core red/yellow/blue runs to the switch, with red as the common and yellow/blue as switched live returns. One red/black will be incoming live, another the outgoing supply, and the final red/black probably feeds the concealed lighting.

With a meter and all connections isolated in a terminal block then it shouldn't be too hard to determine what everything does. Using as a voltmeter with all cores terminated into a terminal block and the supply on you'll be able to identify the incoming supply as there will be 230v between black and red. With supply off, you can use the meter as a continuity checked to identify the switched lives.

Again, with the supply off, you could do a continuity check to another ceiling rose on the same circuit using a wander lead and identify the outgoing live. As a final check (again, supply off) you could check for resistance across the remaining unidentified cable between the black and red cores, if the concealed lighting is mains fed (no transformer) then you could expect a relatively low resistance. That said, a more reliable test would be to con check back to the fitting(s) themselves, although if my theory is right then the concealed lights would be fed off the red/black cable connected to the blue core.

I would have expected all these cables to have a CPC, so I'd check again and be absolutely sure that the bare copper earth conductor hasn't been chopped back.

If you're not confident with any of the above then call an electrician.

 

[ColJack]

the 2 cables without the earths will be the original wiring and are the live in and live out..
the reds of these need to go with the red of the 3 core and earth..

the blacks of these wires will be the neutrals and will go into the block with the light fixtures neutral, as well as the black from the 2 core cable that has an earth..

the yellow wire is the switched live for the main light and goes in the new fixtures switched live terminal

the blue wire is the switched live for the concealed lights and goes with the red from the 2 core cable that has an earth..

 

[electronicsuk]

the 2 cables without the earths will be the original wiring and are the live in and live out.

Are you sure you don't mean the two cables with earths? Otherwise you'd be saying that the 3C cable is original on account of not having a CPC, which I doubt.

Nontheless, I'd advise you test this properly before making assumptions. Who knows, if you already have some DIY wiring then there's every chance the circuit could be incorrectly fused/protected, in which case any wiring mistake could turn out to be very costly. Not worth the £10 it costs for a cheap meter, imo.