Replacing a bathroom extractor fan

21 Jul 2009
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United Kingdom
I have bought a simple Wickes bathroom extractor fan to replace my noisy old Manrose one. I thought it would just be a case of taking off the old one and fitting the new one. However, the old one has 3 terminals - marked live, neutral, and switched whereas my new fan only has 2 terminals - live and neutral. 3 wires - red, blue and white come out of a small isolating switch box. On my old fan, red was connected to the live terminal, blue to the neutral, and the white to the middle "switched" one. Can anyone advise me on how I should connect these 3 wires to my new fan? I tried blue to neutral, red to live, leaving the white one unconnected and I also tried it with blue to neutral, white to live and red unconnected. In both cases, when I pull on the light cord, the fan does not work.
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don't you people ever sleep? it's 2AM for crying out loud..

I hope that that white cable is in fact just a faded yellow.. otherwise you're in America and we're in trouble here fellow.. :)

if your new fan has a pulcord and you want to use it, then you want the red and blue wire..
if it has a PIR or humidity sensor built in, then you still want the red and blue one..
if it has neither, or it has a pullcord but you want it to come on with the light, then you want the white ( yellow ) and the blue..

it likely doesn't have a run on timer as it's only 2 wires, unless it has PIR, then it may have as it "sees" you come into the bathroom..

as to why it's not working in either configuration as you've tried them already, did you turn the fan isolator back on? big lightswitch looking thing on the wall or ceiling by the fan?
Many thanks ColJack for such a speedy reply. What I said was "White" is a pale yellow in fact! As I said I have tried both configurations you describe but the fan is still not working. The fan isolator switch is definitely on - when I pull the light cord I can hear a quiet hum which is not there when the isolator switch is off. Do you think it means that the fan might be faulty?
as a thought, was the manrose one a 12V fan? is it installed near the shower?

might be there's a transformer somewhere to the fan..
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If so it would be the transformer which took L/SL/N - there'd just be two cores going to the fan.
why would there be only 2 wires if it's designed to have an overun timer?
granted this would mean either switching the SELV at the switch ( by use of a DP ceiling switch ) or having 2 transformers, one for the perm live and one for the switched..
give me a break, it was 2am for crying out loud..
and I was thinking of red white and black, the american wiring colours i think?
Fair enough, though you should have been snuggled up with whatever you hold most dear at that time (your Megger?)

Anyways, it set me off on the cable colour history and came across this article - credit (for once) to NICEIC - its from their Connections Magazine.

why would there be only 2 wires if it's designed to have an overun timer?
'cos the timer is in the transformer.

Transformer has L/SL/N, puts out 12V when first turned on and then for the duration of the timer after SL goes away.
Just a thought - I've got it connected blue to neutral, yellow to live, and the red unconnected (just taped it up). Is that OK or should the red be terminated or something

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