Wiring an extractor fan in a bathroom

[zinger3891]

Hi, I have been using this site to get information about installing an extractor fan and found the information very useful - However having purchased an Xpelair in line shower fan, I was considering connecting the fan using a 3 pole pull switch connected through the lighting circuit. The fan is double insulated and so does not require an earth.
It seems to me that if I use the lighting circuit, then I would have to turn the lights on to make the fan work. Using the shower in the daytime, this would seem pointless and not very energy efficient. Am I misunderstanding something or just being thick?

 

[jj4091]

No you understand it correctly, you need to connect to an independant switched live if you want it to work without utilising the light switch. Just use the pull switch if it is not a timer type fan.

 

[zinger3891]

Hi, thanks for that. Could I connect the permanent live from the light swith to both feeds for the extractor fan?

 

[jj4091]

Does it have a timer?

 

[zinger3891]

Yes

 

[jj4091]

Then you will not be able to use the pull switch as that will disable the supply to the timer at the same time as switching off the fan & it will not run on to remove steam & fumes after you have left the bathroom. You need a method of keeping a permanent supply, which can be easily isolated( even if it comes from the light fitting) to the fan to maintain the supply to the timer & a separate switched live to switch on & off as required. Can you fit a fused down FCU for the permanent supply & use the pull switch to switch on/off.

 

[CallEdsFirst]

Just set the run on for 30 minutes, and if you don't want the light on but want the fan on, just slick the light on then off. This should be enough to get the fan running!

Normal wiring then applies, and don't "consider" a three pole isolator! You have to put one in! There are three poles that need isolating so it's not optional.

 

[zinger3891]

Thanks for all your help. I have a mains socket fitted in the loft. Could I use a plug with a 3 amp fuse fitted as my permanent supply for the timer and connect the other supply through a double pole?

 

[CallEdsFirst]

Single point of isolation is advised! You don't wanna have to make sure the plug is out of the socket and the DP is off to work on the fan/stop someone who is touching the fan getting electrocuted. Unless you are suggesting permanent live from plug to fan and separate switch, then back to fan's switched live terminal, but I can't see you coming up with that.

I really can't stress enough that, having bought a timer fan, it would be most wise to wire it up as every other timer fan in the country should, and is likely to, be.

Why the desire to complicate?

Am I missing some reason as to why it can't be wired up normally?

If you really really want, you could do as you suggested and link out the permanent and switched lives then it will only ever work when the light is on, unless you then switch the linked lives from another pull cord, which in my opinion would look odd.

How big is the opaque window in the bathroom? You seriously never need extra light whilst in the bathroom during the day? If you wanna save energy, stop turning your computer on to argue with people giving sensible advice!

 

[zinger3891]

No need to get nasty, ok I will wire it up to the lights, but I do consider that in this day and age when we are being encouraged to save energy, you would think that you could wire up a fan without the need for putting the lights on.
As for the window in the bathroom, yes it does let in sufficient light to see during the day, or perhaps its my diet of raw carrots that makes my vision good.

 

[CallEdsFirst]

Not being nasty, but you keep coming back to suggest new and improved ways of doing it! Got a low energy lamp? If its on for three minutes while you have wee, thats 0.009 times 0.05 times 18p for a kWh these days? £0.000081 if my maths is correct. I dont think that amount of electricity is gonna have a major impact.

Let me rephrase, my original suggestion. It is entirely possible to wire your fan so it only runs when you want it too, but having paid for the timer version of the fan, that is supposed to introduce an element of automation, ie, preventing it from being left on, wasting energy when the last person forgot to turn it off, you should use this facility.

Maybe replace the timer fan for a PIR fan that only comes on when someone is in the room. Only needs a permanent live too! You could even ceiling mount one with a combined photocell to control the lights.

 

[jj4091]

Not being nasty, & I understand what you are trying to achieve as I have the same concerns myself, but it seems like you are determined to codge the job up & do not have the knowledge of how to do it properly, why not call a spark in & explain what you want to achieve & he will do it in a safe & professional manner. It is difficult without being on site to say what you can & cannot do or how it should or should not be done.