Hi can you tell me is it possible to wire a extract fan using
The red blue and earth from my bathroom light so it will come
On when I switch on the light from the out side switch
Red / blue is an odd combination, is it 3c+e cable?
If there is only a 2c+e cable then there will be no neutral at the switch, only permanent live and switch live hence no. You may have better luck running it from the bathroom ceiling rose / jb.
Also better check out the score with building warrants before doing it.
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