Ask a tradesman


Replacing an extractor fan (wiring question)

Hi, I'm just replacing an old bathroom extractor fan for a very slimier model. The one I am taking out has 3 wires connected to it. L, N, SW.
The unit I'm installing just has a L & N connectors. This would leave the SW wire. I'd like to ask if it's ok to just terminate the SW wire in the fan. Also, if I was to use the SW instead and terminate the L wire would that mean the fan would come on when the light is switched on. This I would prefer rathe than having the fan on constantly. Thanks for your help.

3 Answers from MyBuilder Electricians

Best Answer

It sounds like your original fan was a timer fan and your new fan is a standard fan so you won't need the permanent live. The switch live will connect into your new fan but will only come on and off with your light so no over run.


Answered 17th Mar 2015

Hi, The first thing you must discover where is the location of the extractor fan. We have 3 zone in bathroom. If in zone 1 or 2 must have minimum IP rate X4, the new extractor fan. Check what is the IP rate the new fan. The fan you bought it is standard only has L & N. The old one is timer has L, N & SW. If you want use this fan connect N & SW only work as standard when light is on fan is work when light is off fan is stop work. The L wire you must be disconnected from lighting circuit this wire all the time is live dangerous. I I suggest you to find a qualified electrician. Using electrical equipment in bath or shower rooms has always needed care to ensure safety. Now the IEE Wiring Regulations (17th Edition) have identified particular zones within the bathroom to indicate what type of electrical equipment can be installed.


Answered 17th Mar 2015

Sounds like you have bought the wrong type of fan. The SW will be live when the light is on, so can be used with N to power the fan. But the other permanent live must not just be left unconnected. Best bet is to get the fan exchanged for another more suitable one that has a time in like the original.


Answered 18th Mar 2015

Post your job to find high quality tradesmen and get free quotes

Can’t find an answer? Ask a new question

Question Categories