"David" wrote in message
. uk...
On 05/08/2012 13:22, Arfa Daily wrote:
Hi all. Has anyone seen / used a 'light' switch that is just momentary
rather than latching like a normal switch ? I'm sure that somewhere in
the dim distant past, I have seen something that looks exactly like a
single gang flat-plate rocker light switch, but is actually spring
loaded back to the 'off' position. Or am I just imagining this in a
senior moment ? I've looked all through the Tool Station catalogue, but
nothing springs out at me.

Help confirming that they exist, or pointers to one, anyone ??

TIA

Arfa

I have lights that use a momentary switch in some labs at work,but the
switch is connected to a controller that uses the momentary output to
toggle the state of the light.Other inputs come from PIRs so the lights go
out when the area is unoccupied.

So,yes this type of switch is certainly available.try the MK Grid range


cheers

David


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