Ceiling PIR senor

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Looking as another web side it seems it does need a neutral.
In which case you would need 3 core and earth cable. Does the existing switch have a neutral there (post a photo if you not sure).

EDIT, if it were me i would leave the existing switch in place as well as the PIR, you can then have an over-ride facility for the light.
 
Thanks.
The wiring is in a junction box which is very difficult to get to without opening up the ceiling so I don't think it is going to be possible if it needs the 3 core unless anyone else suggests otherwise as I've never wired in PIRs before
 
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There are PIRs that do not need a neutral.
This link shows a selection of PIRs, those that do not need a neutral are highlighted
The type will depend on how the wiring in the switch is organised and the type of light that you are switching.
 
Bit of googling and I can find plenty of wall PIR switches that are 2 wire to replace a normal switch.
Anything stopping me from attaching one of those to a ceiling. It's quite a low ceiling anyway.
 
Bit of googling and I can find plenty of wall PIR switches that are 2 wire to replace a normal switch. Anything stopping me from attaching one of those to a ceiling. It's quite a low ceiling anyway.
Nothing to stop you doing it, electrically speaking.

However, bear in mind that the nature and design of 'wall PIRs' is such that they are primarily sensitive to movement in only one plane ('from side to side', rather than 'up and down', if mounted conventionally). That presumably means that, if mounted on a ceiling (pointed downwards), it would probably be much more sensitive to movement, say, 'across' (rather than 'along') the room, or vice versa. You might therefore need to be careful in choosing the orientation of the PIR, so as to make it most sensitive to movement in the 'most likely' direction.

High on a wall, angled downwards, but orientated in the conventional ('horizontal') fashion, might be more effective.

Kind Regards, John
 
At the moment it is just a standard ceiling rose with an energy efficient bulb. Probably going to change it to either a down light or some sort of flush ceiling light but happy to adjust the light to suit the sensor as that's probably more important
 
The 2 wire switches don't often work properly with low energy lamps, usually causing them to flash all the time they are not on. There are some ways around the problem but it's not ideal. A normal incandescent bulb will work without problems.
 
The 2 wire switches don't often work properly with low energy lamps, usually causing them to flash all the time they are not on. There are some ways around the problem but it's not ideal. A normal incandescent bulb will work without problems.
Thanks. I've got a little endoscope so might have a look where the junction box is and try and do it correctly because if I used a downlight it would be with an LED bulbs which I suspect wouldnot work either
 
Thanks. I've got a little endoscope so might have a look where the junction box is and try and do it correctly because if I used a downlight it would be with an LED bulbs which I suspect wouldnot work either
Fair enough - but, as Echo said, there are potential ways around the problem of 2-wire PIRs (and dimmers/timers/electronic switches/whatever) with low-energy/LED lights which, although (as he said) are 'not ideal', are simple enough to implement and often/usually work.

Kind Regards, John
 
Thanks. I've got a little endoscope so might have a look where the junction box is and try and do it correctly because if I used a downlight it would be with an LED bulbs which I suspect wouldnot work either
Fair enough - but, as Echo said, there are potential ways around the problem of 2-wire PIRs (and dimmers/timers/electronic switches/whatever) with low-energy/LED lights which, although (as he said) are 'not ideal', are simple enough to implement and often/usually work.

Kind Regards, John
Thanks John.
If I wanted to use it with a downlight and LED bulb what would the way around be?
 
Thanks John. ... If I wanted to use it with a downlight and LED bulb what would the way around be?
If you experienced the problem of the LED flashing or glowing when it was meant to be off (which, if you're lucky, you might not experience), you could try fitting one of these across the connections to the lamp:
http://www.maplin.co.uk/p/rc-contact-suppressor-rg22y

Kind Regards, John
Edit: link re-pasted; seems to work now!
 
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