Ceiling roses are common in UK properties. Typically, one was fitted in each room, located in the centre of the ceiling.
The cable marked 'IN' is the supply from the consumer unit or fusebox. This contains live, neutral and earth wires. These are permanently connected to the supply.
The 'SWITCH' cable connects to a one way switch.
The 'LAMP' cable connects to the light bulb or lamp. This is what hangs down into the room with the lampholder and lampshade on the end.
The neutral from the supply is permanently connected to the neutral for the lamp, just as in the earlier example. Both neutral wires are coloured blue.
The live from the consumer unit connects to the Loop terminal. This is permanently live. One of the switch wires also connects here, and is also permanently live. Both of these wires are coloured brown.
The other wire from the switch is blue with a brown sleeve and connects to the Live terminal. The live wire to the lamp also connects here.
This terminal is only live when the switch is on - the switch is connecting the Loop and Live terminals together.
The switch wires are BOTH LIVE - although one is only live when the switch is on. Cable can be obtained which has two brown cores, but it is more usual to find a short length of sleeving to indicate the switched live wire.
DANGERThe Loop terminals are permanently live, even if the light switch is off. Always switch off the power at the consumer unit or fusebox before working on any circuit.
All of the earth wires connect to the earth terminal. Green and yellow sleeving will need to be placed over the earth wires, as these will be bare copper.
Lampholders do not have earth wires, unless they are metal.
people rip down the ceiling rose to put up a fancy light fitting they just purchased?
First, the small piece of brown sleeving falls off, or was never there in the first place.
Second, the new fitting only has 3 terminals - live, neutral and earth.
Third, the wires in the ceiling all get connected Blue-Neutral, Brown-Live, Green/Yellow-Earth.
This has an interesting result. The light is permanently ON, because the live from the consumer unit is permanently connected to the lamp. The second switch wire is connected to the neutral, and while the switch is off, nothing happens.
When the switch is turned ON, this connects the live and neutral wires together. Hundreds of amps flow through the circuit and the circuit breaker operates, or the fuse is blown. If the switch was a dimmer, it has just been destroyed. An expensive mistake.
Remember - switches do not connect to the neutral. Although one wire might be blue, this should have brown sleeving to indicate it is a switched live. Always mark the switch wire before removing a ceiling rose.