Adding PIR to lights in garage

[ban-all-sheds]

What's wrong with a switch?

 

[Tigercubrider]

I used to have an office that was repurposed from a storage room. Quite nice, 5mx3m but th pir / microwave would plunge me into darkness if I stayed at my desk. It was a pita

External pir floods can be "tricked" by switching them on and off then on again and they will stay on until the next dawn setting. Maybe something like that of you were staying

 

[Harry Bloomfield]

I used to have an office that was repurposed from a storage room. Quite nice, 5mx3m but th pir / microwave would plunge me into darkness if I stayed at my desk. It was a pita

External pir floods can be "tricked" by switching them on and off then on again and they will stay on until the next dawn setting. Maybe something like that of you were staying

Or a simple override switch in parallel with the PIR.

I remember a certain company, which advised a certain bank, that it would be a worthwhile economy measure to fit PIR type switches in place of all of its single office switches. They worked fine for cleaners nipping in round and out of the offices, but for anyone working at a desk....

 

[fluorescence]

Microwave sensors are the same price as PIRs.
https://www.screwfix.com/p/-/8029R

So they are. Last time I looked at microwave sensors they were a lot more than that, was some years ago though now that I think about it!

 

[JohnW2]

Microwave sensors react to movement of any kind, including that of people, objects, animals, trees waving in the breeze and anything else. ..... PIR sensors only react to moving items that emit IR radiation, and then only if the object moves far enough to move from the area covered by one of the lens facets into another one.

All true, but I would add (from lots of bitter experience!) that, as a cause of PIR triggering, "moving items that emit IR radiation" can, and sometimes does, include things such as "trees waving in the breeze"!

I think it often goes overlooked that, just as with animals, the metabolism of plants results in the generation and emission of heat, albeit usually less than is the case with animals (something partially cancelled by the fact that tress can be much larger than animals!).

Even non-biological things can also do it. For example, washing on a line will often be at a different temp from the surrounding air and, in any event, its movement can stir up the surrounding air, leading to movement of 'pockets' of air at slightly different temperatures.

All in all, I would say that, even with PIRs (let alone microwave sensors), it's best to try to avoid pointing them at 'anything that can move' (e.g. in the wind).

Kind Regards, John