ceiling rose / two way landing light

[nm78]

Hello,
I've read a few similar posts relating to my problem but none of them have so far helped me resolve my issue. changed the ceiling rose in my spare room and fitted a dimmer switch. all ok, then a few days later nothing. so began checking wiring in both, all seemed ok, reset all wiring in rose found switch wire, well other two, two core wires caused shorts with lights operating lights in other rooms etc etc. also I live in a four storey terrace and found that my cellar is on the same circuit as the third and fourth floors!!!

In addition to this I have a rogue black wire (probably live) I hadnt made anote of the wiring as well to be honest it worked to start with so I hadn't bothered.

now have cellar, bedroom, attic bathroom working, not got spare room ( new rose) or attic or landing two switched stairs...please help

 

[ban-all-sheds]

//www.diynot.com/wiki/electrics:lighting

And a multimeter.

 

[nm78]

thanks, yes I have used a mm and found the live wires, All my lights are now working except the room with the new rose and my landing. I have not got the extra black wire fixed in anywhere therefore I can only think that this wire needs to be fitted to make the relevant circuit however i have tried numerous combinations of wiring config. and only succeed in either no lights or shorting and using a different rooms switch to light the new rose



any more help would be appreciated

 

[nm78]

swapped my red wires in L2 + Com, dimmer light now working for new rose. no lights on landing and attic stairs are dimmed, which tells me its shorting somewhere. tried the rogue black wire (live) in all three live ports, no difference.
Well stuck now

 

[flameport]

Rather than trying every combination of wires and randomly swapping wires around, you need to use the multimeter to identify what all of the wires are.
This is done with the power OFF and using the continuity setting on the meter.

After that, it is a simple matter of connecting the wires to the relevant terminals.