Switch that turns off after a delay

Sam Russell · 07-03-2022 01:30PM #1

Is there such a module that will turn off after a delay? Module would have L+N in with L+N out, and when L in gets turned on, the L out stays live for a pre-determined time - say 5 mins (screw adjustable)? I think a hall light in apartment blocks may have them, but I have not come across any for sale.

I have heated mirrors that is wired to a light, but I want the mirrors only to be heated for long enough to clear the fog on them, even if the light is left on unintentionally. The opposite to the one that a bathroom fan has that is kept running for a while after the light is turned off.

I have found it completely impossible to explain to the electrical suppliers what I want. Grateful for any suggestions.

Wearb · 07-03-2022 02:24PM

Bathroom extractor fans also have time delay switches.

cruizer101 · 07-03-2022 02:33PM

But the fans ones stay one for a while after being turned off.

Op wants one that turns off automatically after initially being switched on even if the switch is still on.

Closest thing I can think of is security lights. We've one out the back which has a timer that switches off after being switch on, the switching on is usually triggered by the motion sensor but can also be triggered by the switch, cycling off and back on again.

It may be possible to wire a standard time delay switch to work the way you want.

Would another option be a temperature based switch?

Wearb · 07-03-2022 03:31PM

I was thinking of using it with a momentary switch.

Sam Russell · 07-03-2022 03:52PM

A momentary switch will not do.

Currently, the mirror heating is on while the light is on - no matter how long. I want the mirror heating to switch off if the light is on - obviously if the light switch is turned off, then it does not matter. The heater is to defog the mirror, not heat the bathroom - five minutes would be fine - if it needs more, the light switch can be cycled but five minutes should be enough to clear the mirror.

The fan works the other way - the fan is on while the light is on and stays on after the light is off.

So no obvious solution readily available. Thanks for your comments.

Bruthal. · 07-03-2022 04:56PM

You could use a sonoff light switch on it. They link to WiFi and phone so you can setup a 5 minute timer or any time up to 1 hour so it goes off 5 minutes etc after you switch on at its wall switch. Once setup via sonoff app it will work independently with the timer you setup.

If you prefer a setup from existing light switch, a modular timer can be used.