Light switch with overrun timer...

[tony9i9i9i]

I went to swap a fan for a customer, they wanted a humidistat one. When I dropped the old fan I found it was wired with T&E.
I explained there was no permanent live so no overrun was possible, and that I'd either have to make a lot of mess running a three-core or they'd be best off leaving the light on after using the shower, they said to put it back for now.
Then I thought, could the switch act as the overrun timer leaving the live live after switching off for a period of time? I've looked on live and can only see the push button on for a certain time switches, for hallway lights etc.
You'd probably want two switches, one to isolate the supply to the the timer switch and hence the light (and FIS), the other to be the timer switch.
Does anyone know is a switch like that exists?

 

[UNG]

Could you not use a delay to off relay to switch the fan

 

[littlespark]

where does the fans t&e come from? The switch, the light or a joint box above?

You could put in a second switch for fan, or a timer module or occupancy sensor where you have a live and neutral.

 

[tony9i9i9i]

Four cables in the switch, all neutrals in a connector, so feed in, feed out, 2 Sw/L's 1 going to the light, one to the FIL, I assume.
I could move the Sw/l to the FIS to the perm live side of the light switch.
Don't suppose you have a link to an example of a timer module?
And would a sensor have a built-in overrun?

 

[tony9i9i9i]

Could you not use a delay to off relay to switch the fan

I've not used one before, could you share a link please?

 

[Avo Mk8]

I've not used one before, could you share a link please?

Example: Bathroom Fan Delay-Off Timer Switch Socket 100W - https://crwltd.co.uk/bathroom-fan-delay-off-timer-switch-socket-100w-3096-p.asp?
It might be a squeeze to get the above in the back box if that's already full of wires1
Manrose do switch-plate size one which you'd have to mount next to the light switch but it's £30 ish

Manrose 1351 Remote Bathroom Fan Timer Control - Screwfix

Order online at Screwfix.com. Surface-mounted fan controller. White, ABS thermoplastic construction. Suitable for domestic use. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

 

[Risteard]

If it's a humidistat fan could you not just make the switched phase a permanent phase instead?

 

[tony9i9i9i]

If it's a humidistat fan could you not just make the switched phase a permanent phase instead?

I did wonder about that, but it had L1 and L2 terminals, so just leave it permanently live and let the humidistat decide when to run?

 

[tony9i9i9i]

Example: Bathroom Fan Delay-Off Timer Switch Socket 100W - https://crwltd.co.uk/bathroom-fan-delay-off-timer-switch-socket-100w-3096-p.asp?
It might be a squeeze to get the above in the back box if that's already full of wires1
Manrose do switch-plate size one which you'd have to mount next to the light switch but it's £30 ish

Manrose 1351 Remote Bathroom Fan Timer Control - Screwfix

Order online at Screwfix.com. Surface-mounted fan controller. White, ABS thermoplastic construction. Suitable for domestic use. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

Thanks, never seen these before, but this requires a perm live and sw/l.

 

[Risteard]

I did wonder about that, but it had L1 and L2 terminals, so just leave it permanently live and let the humidistat decide when to run?

Yes. It would mean that it wouldn't trigger with the light, but the humidistat should still kick in when the relative humidity is at the level for that.

 

[Avo Mk8]

Thanks, never seen these before, but this requires a perm live and sw/l.

From post 4, I understood you have N, Lperm, Lswitch and Lfanfeed at the switch, so the Manrose would work placed adjacent to the switch.
Apologies about the module, which I assumed could be fitted at the switch. There is a version (from the same supplier) with both a start delay and a run-on delay for the fan, that seems to use one of the tails common with Lin, so that might work, though I see some poor reviews for it now!

 

[brianmoooore]

There are other reasons to have an extractor fan in a bathroom, other than moisture extraction. The other likely main reason won't be triggered by a humidistat.

 

[Risteard]

There are other reasons to have an extractor fan in a bathroom, other than moisture extraction. The other likely main reason won't be triggered by a humidistat.

Smells?

 

[brianmoooore]

AFAIK, no one markets a fartsensor.

 

[Jock from the north]

AFAIK, no one markets a fartsensor.

A superior inline fan would take the smell of excrement away but even then would still take 15 mins or so .a fart can linger but just a fact of both genders diet etc.its just a fact of life toilets or bathrooms as some countries call them are primarily for evacuating your bowel

 

[tony9i9i9i]

Thanks again for your help guys. They went with a non-timer fan and swapped the existing light for an LED bulkhead in the end.