Bathroom Extractor Fan Wires

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I have pulled my humidity/timer fan down to replace. What’s what here? So I have brown, black, grey and unsleaved. So brown is live, unsleaved that wasn’t in anything so assume that’s earth. What one is switched live and neutral?
 

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Is there any Isolation switch upstream? The Black or Grey should be the Neutral and switched live but impossible to be certain.

One should have been sleeved blue and one sleeved with some brown to denote it's a switched live.
 
Is there any Isolation switch upstream? The Black or Grey should be the Neutral and switched live but impossible to be certain.

One should have been sleeved blue and one sleeved with some brown to denote it's a switched live.
Yes there is an isolation switch outside the bathroom for the fan
 
Presumably that cable goes to the fan isolator. The other cable from the fan isolator hopefully goes either to the light or to the switch where you can see what is connected to what. Turn the power off and look inside, and post photos.

The wiring in the fan isolator might give a clue, but you can't be sure that the wires are necessarily connected to what they say they are!
 
I have pulled my humidity/timer fan down to replace. What’s what here? So I have brown, black, grey and unsleaved. So brown is live, unsleaved that wasn’t in anything so assume that’s earth. What one is switched live and neutral?
What makes you think brown is permanent live?

I often find it's switched live
 

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