Movement switching of groups of luminaires.

[says-les]

Been asked if I could install a PIR detector to bring on luminaires in a meeting room which has two way switching.
I have seen this in new builds but this is an existing build.
What happens when there is a meeting taking place and movement ceases.
How is this arranged and what materials are required?
I only have experience working with 12v dc PIR's in intruder alarm systems.
I am a spark but have never done this before.

 

[Geoff1946]

The ones I've seen the existing switches become redundant.

 

[says-les]

That is the point, the normal switch control would be unable to over-ride the sensor.
would connecting the floating contacts of the sensor in parallel across the line and switch-wire
During a meeting the room would be plunged into darkness after the sensor timed out.
I can't see how this would be acceptable.
How about wiring the line and switch-wire across the sensor's "floating" 240V rated" contacts.
Even so, if the wall switch was "on" the lights would be unable to be switched off by the timed out sensor.
Any other thoughts on this enquiry?

 

[Geoff1946]

I don't think the sensor would switch off even if everyone in the meeting falls asleep. The ones referred to as occupancy sensors are very sensitive to the presence of bodies. If you keep manual switch control you will cause confusion as no-one can tell if the lights are on because of the sensor or the manual switch.

 

[Sharpend]

Set the pir to a sensible time, no one can sit that still for too long, so rest assured the sensor will be triggered.
I think you are over thinking the scenario, as said they are pretty sensitive. We install them all the time in offices and have no complaints!

 

[binky]

Set the pir to a sensible time, no one can sit that still for too long, so rest assured the sensor will be triggered.
I think you are over thinking the scenario, as said they are pretty sensitive. We install them all the time in offices and have no complaints!

if it's a very large room, then multiple sensors may be needed - it's the only issue I've encountered, high ceilings and poorly located sensor putting some areas of the room out of range.

 

[Sharpend]

if it's a very large room, then multiple sensors may be needed - it's the only issue I've encountered, high ceilings and poorly located sensor putting some areas of the room out of range.

Well I would expect that from my guys as common sense approach, despite what the architect thinks!!

 

[mort2376]

Change one of the switches for a key switch, blank plate the other. If the meeting is long and boring the keyswitch bypasses the pir and lights on. Down to the key holder to turn back to auto.

 

[says-les]

Thanks for that info and advice.
What is the diff between these sensors and the micro sensors that can be installed inside a luminaire?