Wiring extractor fan from the shower pull-switch - yes or no?

Many moons ago, I recall an extractor which had rechargeable batteries in a little well quite big box which also had a mains to low voltage psu in it.. The idea was that the batteries kept the fan on for a few minutes after the mains went off. I remember at the time thinking, this looks like a bit of a problem when the batteries start to not hold a charge!

Brian

Yes that's how I'd like to do it but a home built one would not pass inspection. Is there a commercial version i can buy off the shelf?

Inspection by who?

I would have thought that by its very nature, most relay switching and transient suppression is going to be built up for a special purpose and hence "home built" in pretty much any case.

The fan I used and the humidistat were standard off the shelf parts - but separate.

There are versions that combine timer operation with humidistat if you want as well:

Part of the attraction of having the functions separated is that you can place the humidistat in a place where its easy to access and tweak the settings, without needing to get into the fan itself.

Note that many fans with integrated electronics will specify that transient suppression be installed to protect them if the circuit also contains a number of other potential sources of mains transient including SMPSUs, Dimmers, Florescent lights etc.

For example on the one above:

"EMV regulation Important indication for the electromagnetic compatibility

Interference resistance according to DIN EN 55014-2 depending upon impulse form and energy rate of 1000 V to 4000 V. With operation with fluorescent tubes, switch power supplies, electronically regulated halogen bulbs etc. these values can be exceeded. In this case additional suppression shielding activities are necessary (L -, C or RC elements, protection diodes, resistors)."

John thanks for the reply. I referenced the wrong thing, I meant the self-build current sensing switch you posted a link to. I could build one of those but as I say, inspection by the local council spark almost certainly won't pass because it obviously will have no industry standard test marks. So I found exactly the type of thing I would like on Amazon here:

Yes that's how I'd like to do it but a home built one would not pass

ah, ok sorry talking at cross purposes.

Its relatively easy to find current sensing extension leads with slaved sockets. So it turns off the other sockets when you stop drawing power through a sense socket.

Needless to say not much use for a shower.

For that something like: