Bathroom extractor fan switching on when lights off!

[Katrinatrieshard2]

Hi I've just joined in hope that someone maybe able to help!!! I've fitted the bathroom extractor fan as per instructions & wired it into the light switch but the fan comes on when the light goes off! Like much in my life! I've tried wiring it the oposite way round but the same thing happens- any ideas??? thx, Katrina

 

[ColJack]

you've got a neutral and a switched live backwards somewhere..

at the ceiling rose... 6,7 and 8 would be the neutral, not 1 and 2...

View media item 13602 View media item 13604

 

[Goldberg]

I've fitted the bathroom extractor fan as per instructions & wired it into the light switch...

Please could you give specific details of the switch and how you've connected the fan to it?

For example, is it a two-way switch or a one-way? What were the markings on the switch terminals that you used?

 

[ColJack]

ah ok, missed the switch bit..

you've fallen for the common mistake.. if you've only got a red and black at the switch, the black wire IS NOT NEUTRAL... you cannot wire it from the switch.. wire it from the fitting..

 

[holmslaw]

..

 

[ColJack]

You have a 2 way switch being used as a 1 way switch and you've connected the fan to the unused terminal, thats why the fan runs when you switch off.

Connect the fan to one of the other switch terminals.

If the fan cannot be switched off, move to the other terminal.

cobblers does the same thing if it's a one way switch too..
with the switch on there is no PD between the red and black wires.. with the switch off the black wire effectively becomes neutral as it's connected through the light itself..