Switch off the power at the consumer unit for the circuit concerned. If you have removable fuses at your consumer unit, switch off the power at the consumer unit and remove the fuse for this circuit.
Identify the cables
Unscrew the ceiling rose cover to examine and identify all the cables. Typical arrangements are shown in the diagrams below. If your ceiling rose houses cabling which you are unable to identify, or differs from this description, or has no earth conductor, seek the services of a professional electrician.
Ceiling rose connection terminals
Understanding the array of connection terminals on a ceiling rose makes things easier. As you can see in the diagram, the outermost terminals are the live and neutral for the flex. Immediately next to these at either end are the live and the neutral terminals. In the middle there is the loop terminal. This allows the live in, live out, and live to the switch to all be connected at the ceiling rose. There is also one earth terminal connector for all the earth conductors.
Loop system
In this arrangement, there is a switch cable and two light circuit cables. Firstly, identify the switch cable. This will have its brown (old cable colour = red) conductor attached to the live loop terminal, and it’s blue (old cable colour = black) conductor – which should have been tagged with brown (old tag colour = red) because it is the switch return conductor – attached to the live terminal block. This same terminal block will also have a flex connection with the brown (live) of the flex going to the light itself.
The earth conductor of the switch cable will be housed with all the other earth conductors.
There are also two lighting circuit cables at the ceiling rose. One is the supply coming in to this fitting from the previous light. The other is the supply carrying on to the next light. Each has a brown (old cable colour = red) conductor connected to the live loop terminal and a blue (old cable colour = black) conductor connected to the neutral terminal. This neutral terminal block will also have a flex connection with the blue (neutral) of the flex going to the light itself.
The earth conductors of the circuit cables will be housed with all the other earth conductors. This may house an earth from the flex depending on the earth requirements of the light fitting
If this is the last ceiling rose on the circuit, there will be only one circuit cable as there are no further lights to supply.
Junction box system
In this arrangement, there is no switch cable at the ceiling rose. If there is no switch cable here, then it will have been switched via a junction box system in the lighting circuit above.
We simply have a live, neutral, and earth coming in and a live, neutral, and earth for the flex going to the lampholder.
The brown (old cable colour = red) conductor is connected to the live terminal block. This same terminal block will also have a flex connection with the brown (live) of the flex going to the light itself
The blue (old cable colour = black) conductor is connected to the neutral terminal block. This same terminal block will also have a flex connection with the blue (neutral) of the flex going to the light itself.
The earth conductor is connected to the earth terminal. This may house an earth from the flex depending on the earth requirements of the light fitting.