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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> bathroom extractor fans https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1103412023 Message started by spongebob on Dec 18^th, 2004, 11:20pm

Title: bathroom extractor fans
Post by spongebob on Dec 18^th, 2004, 11:20pm

I've installed a couple of replacement extractor fans with timer and linked to light switch in the past, but always with the benefit of using the existing wiring. I seem to remember a switched live being used on them. I'm wanting to fit a fan in my own bathroom so I took the cover off a friends fan today to jog my memory. There was only a live and neutral to be seen. Has the wiring for these fans changed or am I missing something? ???

Title: Re: bathroom extractor fans
Post by L.Spark on Dec 18^th, 2004, 11:24pm

That one must only come on when the lights on, usualy you have a switched live and a permanent live and so when the light is switched off the fan runs on timer until time duration is up ::)

Title: Re: bathroom extractor fans
Post by The_Trician on Dec 18^th, 2004, 11:25pm

Its sounds like your mate's fan doesn't have a timer fitted.

The timer needs what is known as a 'permenant live' to run. This can be picked up from the 'common' terminal of the lightswitch.
If there's only a live and a neutral, then its my guess that the fan you looked at doesn't have a timer.

TT

Title: Re: bathroom extractor fans
Post by spongebob on Dec 19^th, 2004, 12:56am

Guys...I agree with what you say and therein lies the problem. The fan does come on with the lights but it is also timed. No sign of an extra core anywhere. I'm baffled to say the least. I picked up a brochure for a "Aircon" fan recently that gave the impression that all you needed was a live and a neutral for the fan and timer to run but this was not one of those fans. it's a bit of a mystery! ???

Title: Re: bathroom extractor fans
Post by L.Spark on Dec 19^th, 2004, 1:47am

There’s many possibilities

The earth may have been used as a live conductor, and since most fans don't require Earthing this is a possibility.

Another is that you may have a hidden cable that is not visible, did you look directly at the connections to the fan?

The former seems to be the most likely

Title: Re: bathroom extractor fans
Post by spongebob on Dec 19^th, 2004, 11:44pm

ah! Can't remember if there was an earth wire or not. Maybe I'll pay him another visit, although twice in a year, he may think I'm after something. 8)

Title: Re: bathroom extractor fans
Post by L.Spark on Dec 20^th, 2004, 12:09am

Yep, check it out, I think you might be surprised :)

hopefully not in for a shock so becarefull ;)

Title: Re: bathroom extractor fans
Post by molerat on Dec 21^st, 2004, 8:47am

Or, as in my bathroom fan, the timer is a seperate external unit ;)

Title: Re: bathroom extractor fans
Post by supersparky on Dec 21^st, 2004, 12:35pm

i wouldent bother mate

just wire it in 3 core and earth

its what we do as standard anyway, because if you change your mind you have that extra core

from lighting rose, to an isolator by fan/ above door outside (see zones)

to the fan

if you dont need the third core chock block it

8)
ss

Title: Re: bathroom extractor fans
Post by tellondon on Dec 21^st, 2004, 7:54pm

It could be a extra low voltage fan that are commonly used in bathrooms, it would have the timer control located elsewhere, perhaps in the loft?

Title: Re: bathroom extractor fans
Post by spongebob on Dec 22^nd, 2004, 12:02am

Thanks for all the replies. Fan dilemma is being put on hold until other matters are sorted. :)