bathroom fan - power from two sources?

doubtfir3

I have a standard setup in my main bathroom with an extractor fan wired to the light fitting which stays on for a few mins after the light is turned off.

Have just recently moved into the house and just put up my shower screen this morning so today was the first time I've come across this..

Basically, in the morning I don't need a light in the bathroom when I'm having a shower but there's still plenty of steam from the (hot!) shower.

Is there a way to wire the fan to both the light and the shower switch? Is there some form of a 240v relay which I could use to have two input power sources for one device which won't "leak" back to either?

Needless to say, I don't want the shower powered when I turn on the light and vice-versa!

I know I can just wire the fan independently switched, but was hoping for a tidy wall outside the bathroom!

Thanks

davelerave

an occupancy sensor (pir)and 3-pole switch(wired from lighting cct. feed) would give independent automatic fan operation .to connect to shower wiring you would need an additional fused spur or a 'current sensing relay' .connecting to shower cct. wouldn't be standard practice afaik.

youtheman

Your fan has a timer relay with two live connections, a 'switched' live from the light (this gives it the signal to start) and a 'permanent' live to give it the power so that it runs after the 'switched' live has been turned off (via a timer relay).

If you disconnect the 'switched' live from the light then the fan will no longer start when the light is switched on. So your light is a 'normal' light, i.e. it doesn't start the fan when activated.

You now need a second switch and use a separate live to give the fan the start stop signal (this is you new 'switched' live to give the fan the start signal).

So if you want light only you turn on one switch. If you want fan only you turn on the second switch. If you want both you turn on both switches.

doubtfir3

Thanks for the replies, but what I would ideally like is to have the fan fed from both the shower switch and from the light unit.

When one or the other is switched on then the fan comes on, and I would prefer not to install a PIR or additional switch on the wall outside the bathroom.

Any ideas if this is possible?

youtheman wrote:

Your fan has a timer relay with two live connections, a 'switched' live from the light (this gives it the signal to start) and a 'permanent' live to give it the power so that it runs after the 'switched' live has been turned off (via a timer relay).

I know that I could for example connect both the shower switch and the light fitting to the "switched" live, but in this case I'm sure I'd get leakage back - (e.g. turn on the shower switch and the light and fan come on).

SilverBER

If the shower is wired correctly you will also trip the RCD

doubtfir3

youtheman wrote: »

If you disconnect the 'switched' live from the light then the fan will no longer start when the light is switched on. So your light is a 'normal' light, i.e. it doesn't start the fan when activated.

You now need a second switch and use a separate live to give the fan the start stop signal (this is you new 'switched' live to give the fan the start signal).

So if you want light only you turn on one switch. If you want fan only you turn on the second switch. If you want both you turn on both switches.

I guess I'll have to do this so.. or just leave it as it is currently wired.

Thanks for the help guys!

eoghan.geraghty

Open up the light switch for bathroom.
*There should be two wires connected to the L1 terminal on your lightswitch*.
One of these is for fan, one is for light.
If the switch you are working on is a 1 gang switch, change it for a 2 gang, if 2 gang change for 3.
Changing from a 3 gang to a 4 will require more work and skill.
Make sure you loop all the common terminals together with the live feed, then give both fan and light switch wires their respective switch.

Leave all the neutral wires alone.

If its already a 2gang or 3 gang switch do not mix up the other switch wires and feeds.


* This is the way I and any electrician I have ever worked with has wired a bathroom light and fan switch, it is best practice. If one wire does both its a lot harder to do.*

Good luck with it and hey, be careful out there!

Joey the lips

With the greatest respect to all. A simpler solution would be to buy a fan with a 5 min timer. Set the timer to full turn the light on when your getting into the shower then turn it off again. You will get a 5 min shower with the fan on and guess what! No light!

No need for expensive tricks

Joey the lips

I think you are missing my point! but thats fine your idea sounds ok!

The timer is already on the fan i am just telling you to extend it to its limit!

cast_iron

Joey the lips wrote: »

A simpler solution would be to buy a fan with a 5 min timer.

Except that would probably be the most expensive solution suggested:D