One for the electricians - wiring

[Killer_K]

I need to install an extractor fan in the bathroom from scratch. It came with instructions and wiring diagram but I’m a little confused now. The model I have is Silhouette 100 (no timer and etc. just a standard extractor fan). In the setup I require I would like the fan to turn on when bathroom light is switched on and go off when the light is switched off.

My wiring for the second floor is in a loop, the loop ends in the bathroom i.e. ceiling rose has two wires, one live (looped from another ceiling rose) and one for the switch.

What is the best way to insert an extractor fan in this equation?

In the Wiring Diagram I have a red circle - Is this area on diagram showing a Double Pole Isolating Switch, if so why does it show a 3amp here but in the instruction leaflet it says ‘Fuse Rating to be 1 amp’, see further below on screenshot.

Any help will be appreciated.

 

[Diddy]

You need to run a 1.5 T+E cable from the light fitting to the isolator(usually outside the bathroom door is where i usually put them. Then a second 1.5T+E cable from isolator to the fan.

At the light fitting you will see a black cable on its own (poss marked with red sleeving) this cable currently goes into the L terminal of the light. You want to put the red from your new T+E together with this "black" cable into the light. Put the remaining black from your new T+E in with the rest of the blacks on the terminal marked N. All earth wires go together in earth terminal. Fix light fitting back together.
Move onto isolator You have an "Incoming" which is the T+E from the light, and an outgoing/load.....this is the terminals for the cable to the fan. These are straight forward. Red goes to live black to the neutral.......again all earth wires together.
Once its all connected up then sort the fan connections out....once again straight forward.
Regarding the fuse. Most spurs come with anything between 3-13amp fuses, just pop the fuse out and replace it with a 1 amp.
Job done. Basically when the isolator is on the "on" position then the fan will switch on and off with the light. You can turn the fan off from the isolator if you want the light on without the fan.
Hope thats clear enough as im not the greatest at explaining things lol
T+E = Twin and Earth cable
1.0mm or 1.5mm will be sufficient.

 

[Killer_K]

nice one Diddy - that is very well explained mate.

just one more question fo you now - will the incoming wire into the isolator switch (that comes from ceiling rose) only become live when the bathroom light is switched ON. In other words if bathroom light is OFF the isloator switch should have no Live in it. is this correct?

thanks for your help buddy.

 

[Diddy]

correct mate, whe the light is out the isolator isnt live.

Edit to add - remember to switch off the upstairs lighting circuit Before going ahead lol.

 

[Killer_K]

top man....thanks again mate. ;-)

 

[Mick]

Why not run a 3 core T+E cable to the isolator and fan and just do not use the 3rd (usually grey) cable, i am not sure without getting my book out (and i cannot be arsed lol) but i am sure there are regulations that the fan must over run for more than 2 minutes to remove all steam / condensation etc.

I am not 100% though.

But if you was to try and sell your house and that was the case you might be asked to upgrade this by building control or even the new owners ?

You could leave the grey unused but have a piece of mind that if there was ever a problem or you wanted to upgrade you would have the option of SWITCH LIVE being there.

The cable is almost the same price and would cost no more than 50p extra on a 5 meter run

Regards
Mickie D

 

[Killer_K]

Thanks Mickie D - u've made a good point there, I need to buy cable anyway so i may as well buy the one you've suggested... ;-)....long term planning - i like it.

cheers,

K