I am trying to change a ceiling rose, but did not make a note of the switch wire and no wires are marked. I have tested all blue wires with a terminal screw driver and only one shows current, so I assumed this must be the switch, but when I wire this into the switch the light is permanently on - what am I doing wrong?
First wrong thing you have done is using a terminal screw driver (I guess you mean a neon screw driver) these are not a reliable test instrument.
Throw it away before it kills you!
The second wrong thing is you've worked on a live circiut! That too could kill you!
So now lets be sensible and safe!
So you guessed you need to find the switch wire then.
Firstly connect all (CPC) that's the earths, to the earth terminal.
then all the reds or browns if new colours cables to the loop in section on ceiling rose (this does not include the flex on the lamp/light)
You will be now left with blacks or blues if new colours from ceiling, one of these is a switch wire and others are neutrals.
The neutrals should be connected to the neutral side of rose with the blue flex of lamp.
The switch wire should be marked with a brown sleave to stop confusing in the future then, connected to the brown flex side of lamp/line side of rose.
You may need to identify the switch wires, best way is buy a multi meter (remember the neon is now in the bin) and check using the continuity test device on it. Using ceiing rose as point of test and the functional switch closed.
Safe isolate before you start work never work on a live circiut!
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