PIR or Microwave Occupancy Sensor?

[brummydave]

Morning,

I'm looking for current thinking on the best type and application of occupancy sensors as many threads on here are quite old.

When is it better to use Microwave or PIR or a dual sensor for lighting?

Ideally, which would you use in:

Kitchen

Corridor

Store room

Stairwell

Large Hall

if any.

I've had issues with standalone PIRs, when controlling LED replacement fittings, that needed the Danlers Capload to prevent flashing. I try to go for fittings with built in sensors but this isn't always possible.

Are there sensors better designed for LED or do I need to keep a supply of caploads?

Many thanks!!

 

[NozSpark]

I don't think that the LED lights are flashing because of the PIR sensors.... It's usually because the LED lamps/fittings have a high impedance and the internal electronics charge up enough to flash the lamp due to capacitive coupling

 

[Essex1]

Is this in a domestic setting?

 

[Richard-the-Ninth]

Microwave motion sensors use radio waves to detect a person and can easily travel through walls so giving rise to "false activations" (whoopee the lights come on)

A Passive Infra Red motion sensor looks for the movement of heat across its field of view. (This is dependant on the mirror or lens configuration of said sensor)

I would say most "problems" are due to the wrong detector being fitted" (One with a short range lens instead of a long range lens) OR the sensor being mounted at the wrong angle OR being mounted at the wrong height OR is / can be obscured by something.

PIR sensors are usually considerably cheaper than a microwave sensor. I have not heard of a duel sensor for lighting. (Doesn't mean they don't exist, just pointless as all that will happen  is lights will come on.)

For 99.9% of applications I would suggest a PIR motion sensor.

 

[brummydave]

I don't think that the LED lights are flashing because of the PIR sensors.... It's usually because the LED lamps/fittings have a high impedance and the internal electronics charge up enough to flash the lamp due to capacitive coupling

Thanks Noz, I've heard that theory before. The 'capload' certainly cured the flashing issue on a pair of 10W floods

Is this in a domestic setting?

I'm currently looking at use in church buildings, but I have been asked for domestic use as well.

 

[brummydave]

Microwave motion sensors use radio waves to detect a person and can easily travel through walls so giving rise to "false activations" (whoopee the lights come on)

A Passive Infra Red motion sensor looks for the movement of heat across its field of view. (This is dependant on the mirror or lens configuration of said sensor)

I would say most "problems" are due to the wrong detector being fitted" (One with a short range lens instead of a long range lens) OR the sensor being mounted at the wrong angle OR being mounted at the wrong height OR is / can be obscured by something.

PIR sensors are usually considerably cheaper than a microwave sensor. I have not heard of a duel sensor for lighting. (Doesn't mean they don't exist, just pointless as all that will happen  is lights will come on.)

For 99.9% of applications I would suggest a PIR motion sensor.

Thank you Richard, a very comprehensive explanation.

Part of my confusion has come about from pricing and part from not having a full understanding of the tecnology. Some fittings from LEDhut have a microwave sensor option for only a fiver extra, and Denmans are doing a microwave sensor for less than the price of PIRs.

 

[Essex1]

I would not consider using microwave sensors in a domestic setting.  As Richard says they work through walls so would not work great in this situation.  

 

[brummydave]

I would not consider using microwave sensors in a domestic setting.  As Richard says they work through walls so would not work great in this situation.  

Good point, thank you.

I'm guessing it's PIRs rather than microwave used in hotel corridors as sensors so that anybody coming out of their bedroom switches the corridor lighting on. Otherwise the lights would be on more often than not?

 

[Essex1]

Maybe.  Microwave sensors are perfect for corridors as it means the lights are on before you open the door.  You can set the range so they do not turn on too early.