Wiring problem

Hello,
I'm trying to change some light switches for PIW switches so they come on
when my disabled brother walks into the room.
My problem is that the PIW switches require a live in, a live out and a
neutral and light switches in the UK only have a live in and a neutral.

Can I connect the live out to the neutral as well as the neutral to the
neutral as shown inn my diagram here:

http://www.flickr.com/photos/[email protected]/8267477718/in/photostream

The crossed out line is what don't have and want to replace with the dashed
line.
Being as the switch controller is drawing such a low current will this make
any difference to the outcome? Will they now be in series rather than
parallel and would this matter?

Thank you

David

 

Obviously one drawback would be that the bulb would be live at all times,
but would that matter? Would it only have 0.2W passing through the
filament when the switch was off?

D

 

The unit should work if wired they way it was before you crossed out stuff.
The 'live out' is the output from the device.

 

Yes, that's how it should be wired. The problem is I can't wire it like
this without a lot of rewiring between the light and the switch.
Will it still work the way I've drawn it (even though there will be a
constant low current going through the bulb?

D

 

You are not supplying neutral to the device the way you drew it.

 

I am, through the filament of the bulb, so it would be like having a 0.25A
fuse in line which should make no difference to the device.

D

 

The bulb filament would act like a resistor and the device may not
function properly. AND, do you wish to violate all your electrical codes?

 

What you've drawn will not work. Once the contact for the live in/out wires
close, you will be cutting out power to the PIW device. This will cause the
contacts to again open. This cycle will repeat and in turn giving you a
blinking bulb effect.

With the style of wiring in your house, what you need is a PIW up at the
light fixture. Once installed you would just keep the wall switch on all the
time, except possibly when he's asleep.

 

You can get a few light fittings with a PIR built in, although they're
not particularly pretty looking (tend to be a plain circular dome), e.g.
http://cpc.farnell.com/eterna/cf28pir/ceiling-light-with-pir-28w/dp/SR08250?Ntt=SR08250

Another option, if you can easily get to the wiring above the ceiling,
and if the switch drop cable is in conduit or behind capping and can
be used to draw a new cable through, is to replace the cable with
triple-and-earth, so you can get a neutral supply to the switch point.

(And before anyone suggests it, no you can't use the earth as a neutral
return in the twin-and-earth cable.)

 

I hate when that happens in a public bathroom.

 

Even worse if you're at home, it's dark, and you're standing up!

 

Hello, and this isn't rocket science. The motion detector (MD)
electrical circuit should be connected to the AC power source which in
your case would be live in (hot) and neutral so that the MD internal
circuits are continuously energized. The live out goes to the
controlled device (lamp). I can certainly understand why you might have
a light switch in a box without a neutral but I would avoid trying to
kluge something together. It would probably be in violation of your UK
electrical codes. Sincerely,

 

Memory! it's what we old people have to do when the hose and the aiming
control are obscured by the belly-depend on aural feedback. If the
hearing aid batteries have gone dead-sonar is also dead. Sit down to be
sure.