Switch question ...

Similar sort of thing here. I have just replaced the shower extractor fan / light, the original having a motor that wouldn't run any more due to collapsed bearings. The reason for this is that in its 'standard' form, the fan is controlled from the lighting switched live. That means that the fan always runs if the lights are on. The shower room is at the top of the stairs, and its lights cast a gentle light in the area through the fanlight over the door, so tend to get left on all evening until I finally go to bed (usually very late !!) and turn them off. So I've done a mod to the new one, and designed and built a little controller that senses when the shower pump motor is drawing current, and produces a DC voltage to drive a mains-rated relay that I managed to fit inside the fan run-on controller's casing. This means that the light on the fixture can just come on normally from the switched live, along with the other lights in there, and the fan won't run. When the shower is used, the fan starts, and runs as long as my sensor circuit detects that the pump is running. When it stops, the relay drops, and the run-on timer takes over to continue extraction for a few minutes. An added advantage of this is that in the summer when people take a shower without putting the lights on, the extraction will still come on.

I want the momentary switch to mount outside the shower room to bridge the relay contacts. That way, if I want extraction without the shower running (there's a bog in there as well, so use your imagination ... ) I can just stab the switch, which will start the extractor fan. It will then run for the run-on time controlled by its own timer. It does all work exactly as planned, and I have the wire running down the inside of the airing cupboard which is next to the shower room, so all that's now needed is to bring it through the wall, and obtain and connect the switch :-)

Arfa

Reply to
Arfa Daily
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Yes indeed. I *don't* want the neon on when the light is off. I'm pretty sure I've got two neutrals joined by a choccy connector (or even a crimp maybe) in the back box - so providing a neutral won't be a problem.

I'd thought of getting a neon from Maplins and mounting it in the switch, but I'd rather have something which looks as if it's meant to be there.

I've just ordered one of these from Ebay, which seemed worth a punt for a couple of quid including postage!

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that's no good[1], I'll go for one of the switches suggested by Owain.

[1] There may be a reason why they're selling them off cheap!
Reply to
Roger Mills

I was referring to one of these - which can be fitted to the existing switch.

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Reply to
Bob Eager

I don't see what the problem is

Just use a stock switch - unless you need an intermediate or changeover type it does exactly what is wanted....I've got several here controlling extractor fans.

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Reply to
The Natural Philosopher

I know...but he was looking for a possible alternative. The neon-round- the-edge allows retention of the existing switch, maybe for aesthetic reasons. Switches with built-in neons tend to be double pole and heavy to operate.

Reply to
Bob Eager

All ranges of switches up to an including gold plated brass will have somewhere a double pole with neon in the range. I have such.

Switches with built-in neons tend to be double pole

yes

and heavy to

Not in my experience.

Reply to
The Natural Philosopher

Reply to
Phil Wieland

Screwfix (and many other websites) pad their URLs out with un-necessary search engine fodder, you can't omit them, but you can change them for product URLs starting /p/

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category URLs starting /c/

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Reply to
Andy Burns

You can get either fans with humidistats, or standalone humidistats to do much the same job. ;-)

Yup, that's handy.

Reply to
John Rumm

Usually, or a knockout on the front.

They are normally "ordinary" terminals IME.

Only thing about 20A plate switches is that they are a heavier action than normal light switches with a bit more of a "snap".

Reply to
John Rumm

Yeah, I know you can, but as the ductwork was already in place, and the ceiling has a bloody great hole of a specific size in it, I really wanted to replace like for like, but with an improvement (for me anyway) to the way it worked. The circuitry to do it was dead easy to design and knock up on a bit of Veroboard, and it was a fun little project for the weekend. I had all the parts to hand, so it didn't even cost anything. Do you ever order semicons from Farnell ? They quite often put them in a nice little black antistatic plastic box with a hinged lid. They make lovely little enclosures for this sort of thing :-)

Arfa

Reply to
Arfa Daily

I'm not a fan of redundant packing/tracking in URLs so I trim out as much as I can or make short substitutions. If it takes off, 'arse' may rise to be the most popular pre purchase search string on Sfx!

Reply to
fred

Yup I can see why you would not want to change the fan itself. In these cases I go for a stanalone humidistat (TLC do one) to drive the existing fan.

Do you fancy sketching it out? Might be a handy thing to stick on the wiki.

I usually order from CPC rather than Farnell itself. Alas their packaging seems less elaborate.

Reply to
John Rumm

I'll get on it, scan it, and send it directly to you in the next day or two

Arfa

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Reply to
Arfa Daily

That would be nice, thanks.

Reply to
John Rumm

Should be with you now

Arfa

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Reply to
Arfa Daily

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