Extractor fan

Hannibal

I am looking to put an extractor fan in my bathroom, the one i have is timed. I know most are wired off the lights and am looking at how to do this.

The lights in my bathroom are four downlights and are on a dimmer.

Thanks

Steve

Won't work off a dimmer, push to start is the only option.

aido79

Hannibal wrote: »

I am looking to put an extractor fan in my bathroom, the one i have is timed. I know most are wired off the lights and am looking at how to do this.

The lights in my bathroom are four downlights and are on a dimmer.

Thanks

This is probably not a diy job.

You will need a separate switch for the fan as it won't work from the dimmer.

Easiest way would be to find the feed for the spotlights and take live, neutral and earth from there. Connect the neutral and earth terminals to the fan neutral and earth and connect the live to the timer of the fan(has to be the feed live rather than the switched live). Then run a wire from the timer terminal to the new switch and back to the switched terminal of the fan. This can be done with a twin brown rather than 2 separate cables.

Hannibal

aido79 wrote: »

This is probably not a diy job.

You will need a separate switch for the fan as it won't work from the dimmer.

Easiest way would be to find the feed for the spotlights and take live, neutral and earth from there. Connect the neutral and earth terminals to the fan neutral and earth and connect the live to the timer of the fan(has to be the feed live rather than the switched live). Then run a wire from the timer terminal to the new switch and back to the switched terminal of the fan. This can be done with a twin brown rather than 2 separate cables.

i'm guessing this is for a normal light switch?
in what way would you use one of the 3 pole isolators or would the normal switch be better?

aido79

Hannibal wrote: »

i'm guessing this is for a normal light switch?
in what way would you use one of the 3 pole isolators or would the normal switch be better?

A normal light switch would be sufficient. I don't see any advantage of using a 3 pole isolator.

Hoagy

aido79 wrote: »

A normal light switch would be sufficient. I don't see any advantage of using a 3 pole isolator.

Wiring Rules.

The fan needs to have an isolator breaking all three live conductors.

aido79

Hoagy wrote: »

Wiring Rules.

The fan needs to have an isolator breaking all three live conductors.

What 3 live conductors? It's a single phase fan. Am I missing something?

Bruthal

aido79 wrote: »

What 3 live conductors? It's a single phase fan. Am I missing something?

The neutral can be said to be a live conductor. It's carrying current during normal circuit operation.

aido79

Bruthal wrote: »

The neutral can be said to be a live conductor. It's carrying current during normal circuit operation.

That's true. What's the 3rd conductor though?

It's been a long time since I've had anything to do with extractor fans but is it the done thing to actually switch the neutral or would most guys just put it on a single pole switch?

Shred

I'm no sparks but I got one of these installed a couple of years ago and got the installer to connect it to the pull cable for the (electric) shower on it's own switch. It works a treat and means the lights don't have to be left on after a shower to demist the room.

Stoner

Shred wrote:

I'm no sparks but I got one of these installed a couple of years ago and got the installer to connect it to the pull cable for the (electric) shower on it's own switch. It works a treat and means the lights don't have to be left on after a shower to demist the room.

Could be some issues here, the size of the mcb or rcbo feeding the shower might be too big for the isolater / fan etc.
Also this arrangement won't allow the fan to run for a while after its been switched off, unless the sparks had one of those units with a battery fitted.

Bruthal

aido79 wrote: »

That's true. What's the 3rd conductor though?

It's been a long time since I've had anything to do with extractor fans but is it the done thing to actually switch the neutral or would most guys just put it on a single pole switch?

Switched live, permanent live (for continuation on timer when switched live is switched off), and neutral.

Bruthal

Shred wrote: »

It works a treat and means the lights don't have to be left on after a shower to demist the room.

That's why fans with run on timers are used.

Shred

Stoner wrote: »

Could be some issues here, the size of the mcb or rcbo feeding the shower might be too big for the isolater / fan etc.
Also this arrangement won't allow the fan to run for a while after its been switched off, unless the sparks had one of those units with a battery fitted.

A friend of mine is a sparks and he looked it over with no issue found (he rewired the house for me a few years ago). Buy the point of it being connected to the pull for the shower is I can get out of the shower and leave the extractor running for a while and then switch it off by tugging the pull for the shower to turn it off.

aido79

Shred wrote: »

A friend of mine is a sparks and he looked it over with no issue found (he rewired the house for me a few years ago). Buy the point of it being connected to the pull for the shower is I can get out of the shower and leave the extractor running for a while and then switch it off by tugging the pull for the shower to turn it off.

Are you sure he wired it directly to the pull cord of the shower? It sounds like a crazy thing to do. You are talking about putting a fan that draws a very small amount of current on a 40 amp circuit breaker/rcbo. If there was ever a fault in the fan your bathroom might be up in smoke long before any breaker trips.

The point of the timer on the fan is so that you can leave the fan running and not have to come back into the bathroom to turn it off once the room has been demisted.

Sleeper12

Shred wrote:

I'm no sparks but I got one of these installed a couple of years ago and got the installer to connect it to the pull cable for the (electric) shower on it's own switch. It works a treat and means the lights don't have to be left on after a shower to demist the room.

I don't think a fan should be fitted to the pull cord switch. The shower is supposed to be totally on its own is my understanding.

Shred

aido79 wrote: »

Are you sure he wired it directly to the pull cord of the shower? It sounds like a crazy thing to do. You are talking about putting a fan that draws a very small amount of current on a 40 amp circuit breaker/rcbo. If there was ever a fault in the fan your bathroom might be up in smoke long before any breaker trips.

Well I should have mentioned it's connected via a fused spur, although my sparks mate isn't overjoyed with how it was fitted he has confirmed there are no safety concerns, fire or otherwise.

aido79

Shred wrote: »

Well I should have mentioned it's connected via a fused spur, although my sparks mate isn't overjoyed with how it was fitted he has confirmed there are no safety concerns, fire or otherwise.

The fused spur makes a big difference. It's not unsafe but still not something I would ever consider doing.