combining switched lives?

[zetecuk]

Just rewiring my bathroom atm, I have two sets of lights on seperate switches, and a timed extractor fan which will be connected via a fcu from the lighting circuit, and the switched live from the light switch.

What I wanted to know was whether there is any way of combining the two switched lives so that the fan will come on with either or both of the light switches? Obviously I can't just wire both the switched lives into the fan as this would cause both lights to come on with either switch too... I think?!

Thanks,
Andrew

 

[AL]

I think you're talking about a double pole switch? Sure, you can get these from loads of places. My Grans house has this arrangement however she had it converted from one switch for both, to two separate switches like you have, because the fan was a bit noisey at 2 am in the morning apparently!

 

[zetecuk]

I'm not sure... I have a double switch which controls two seperate sets of lights in the bathroom - I wanted the fan to come on when either of these lights is switched on, but I'm not sure if this is possible? I can switch the fan off completely if necessary using the switched FCU.

 

[breezer]

you would need to have 2 double ploe switches, as if the live feed the fan was to be connected in any way to the lights it would "backfeed" and all connected come on

 

[zetecuk]

Ah right, I get it now, getting confused between poles, gangs and ways. Not sure if you can get a double pole double light switch though? So I'll probably just connect the fan to one of the lights...

 

[ban-all-sheds]

Ah right, I get it now, getting confused between poles, gangs and ways. Not sure if you can get a double pole double light switch though? So I'll probably just connect the fan to one of the lights...

You can't get any sort of double light switch for a bathroom, as they have to be pullcord, and I've never seen a pullswitch with 2 cords coming from it. You can get 2-way ones, but not 2-gang ones.

But if you get 2 x 2-pole switches which are usually used as isolation switches to interrupt both live and neutral in a circuit you could use them to switch 2 lives simultaneously - one for the light and one for the fan, then you could join the two fan switched lives together and keep independent control of the lights.

If your switches are outside the bathroom, and you therefore want normal wall jobbies you may find that you can get 2-pole switch modules for one of the gridplate systems.

Plan B would be to use 2 relays controlled by the lighting - joining together the output contacts of 2 relays would not affect the lights.

Plan C would be to use a PIR detector so that the fan comes on automagically whenever someone goes into the bathroom, assuning thats what you want.

Plan D would be to advertise the position of punkah wallah - not very PC though