Regular question:- How does one wire a ceiling rose?
On to the real wiring the switch wires should be both red/brown or at least have a red/brown sleeve but in practice this is rarely the case. Where red/brown and black/blue are used the sleeve on the black/blue often falls off or was never put there in the first place. If the ceiling rose is removed without noticing which is the switch wire. This is how to work out which black/Blue wire is which when all three cables are the same colours. These are:-
The feed,
The Switch,
The next Lamp.
Easy way is meter or buzzer across the cables with power all off and flick light switch until switch wire is found.
Often the DIY man has no meter or buzzer so next method.
Do not use energy saving bulbs as we need to be able to see bulbs working on half power use normal bulbs only. Do not use this method if you have dimmers or discharge lamps in any of the house lights. Starting with power off.

  1. With power off connect all cables except for neutrals and switch cable i.e. Reds/Browns centre and Earths to clamp and lamp it's self to outer two connections. The black/blue are left disconnected. Put one into spare block connecter, and other two in the two outer connectors of the ceiling rose i.e. one to each wire feeding lamp. Now turn on power and try it. If it works jump to 4. If not turn off power.
  2. Swap either of two blacks (or blues) connected with one in spare block connecter and then turn on power again. If it works then jump to 4. If not turn off power.
  3. Swap the wire in spare block connector with other black (or blue) in ceiling rose. It should now work when switched on again. If not there is another fault not at rose and it is beyond this simple check.
  4. Turn off power again and mark cable in spare block connector with black or blue type or some other way to find it again. Then put it in spare hole with other Black (or blue) then turn on power.
  5. Test all lights if all work OK then all is done.
    On the other hand you may find odd things happening like with light you have been working on being switched on other lights don't work and with it off the other lights work as glow only and light you were working on will also start to glow. If this is the case switch off power and swap the two unmarked black (or blue) wires.
    Now all should work. So what are we doing?
    Well we can't connect any of the three blacks (or blue) together as one is live when switched on. So to start with we find out which wire connects to the next rose in circuit by time 1, 2, and 3 have been completed we know this is wire is spare block connector.
    At this point, we don't know which of the other two blacks (or blue) is neutral and which is the switch wire. But if we connect the next lamp in series to switch instead of neutral it will do no harm, but the next lamp can only get a return through the lamp in the light we have been working on, so either the one we were working on will come on dim, or the next in line will come on dim, which is all to do with what size bulbs are fitted.
    But we now know exactly which two wires are the wrong way around. So finally we have in the eight holes in rose (earths normally under clamp screw) Feed to lamp, Feed from switch, break, Three live wires at all times all red or brown (one feed, one out to switch and one to next lamp), break, Neutral (in or out), Neutral (out or in), Neutral to lamp.

Next we look at two position switching.
As school boys were were shown the diagram on the left. This of course works well but in practice the cables do not go round in a circle but go from the fuse box called a consumer unit to the first light the then from that to switch and second light and so on so each ceiling rose has three cables, when two or more switches are used it goes from first switch to second and so on. The diagram to left will require a connection inside the switch so we use the second diagram to right with this we can use the switch to make all connections. It will be noted the live feed goes to both switches when the second switch is part of a two switch arrangement sometimes the live is bridged from other switch so only twin and earth is required.

Note1:- Years ago there was a method used that only had two wires between switches and the line was taken from an adjacent switch. This has two problems. It can cause mains hum on radios etc. and it can lead to a shared neutral situation if the adjacent switch is not from same supply.

Note2:- Many call two position switching "Two way switching" as the switch used has two ways. However with three position switching the change over or intermediate switch does not have three ways so the terminology then becomes confusing.

Note3:- Today there are radio controlled switches the luminite easyswitch is an example. As a result there is no need to hard wire. 

When we move to three position switching we use a special switch called an intermediate between the two position switches here we normally do use one block connector inside the intermediate switch which will connect the bottom wire in the diagram below.

Some times the 2 two position switch cables are returned to ceiling rose and an extra connector is used below is how wires are run.
On all diagrams earths have been missed out for clarity.