PIR priority

[ss]

I have 2 external PIRs operating 2 floodlights all in different locations but connected so that 1 PIR will turn both lights on. I need to adjust the timings lux/sensitivity. Before I climb a ladder can someone advise what the priority is for the LEDs, eg if say the 2 LEDs are set for timing at say 15 seconds and the other at 3 minutes, if the 15 second LED triggers the lights does it go off after 15 seconds or 3 minutes. Does the one that triggers it set the timings or can that be overruled by the other? Hope this makes sense but the less time up a ladder making adjustments the better as I hate heights.

[Andy Burns]

It's a "logical inclusive OR", so both lights will be on at the same time, if one, the other, or both PIRs are within their activation period.

[ARW]

Is it worth mentioning that the activation period is reset/restarted every time movement is detected?

[ss]

Yes I understand both lights on at the same time but if the PIRs are set for different duration times will it be the activated one that decides how long they stay on for?

YesI understand that.

[ARW]

Yes.

[ss]

OK thanks for replies that answers my questions.

[Andy Burns]

if one is activated it will be that PIR's duration, if both are activated, it will be the one that remains activated longest.

[John Rumm]

+1 what he said. This picture may help:

[Dave Liquorice]

Assuming simple parallel switch wiring. The OP is not clear if the second PIR also turns both lights on or only the one associated with it.

[Andy Burns]

Not having both PIRs control both lights would take e.g. some relay logic to arrange, and if they'd done that, they'd know what they'd wired?

[dennis]

It will be the end of the last one activated, whichever finishes last.

[dennis]

I'm not sure that it should be called two way switching as it doesn't do the same as two way switching does in the rest of the circuits.

Myybe multiple PIR switching?

[John Rumm]

Yup I see your point in that there is no capability for the second PIR to force the lamp off... so not true two way switching - although for many it kind of fits since it allows for two separate switches to turn the same lamp on.

ok I renamed the section:

[ss]

I have it sorted now but to clarify its like an alley at the side of the house the PIRs are either both activated or just one depending on circumstances, it is wired so that both lights come on regardless of one or both PIRs being activated.

It was set up a few years back but for some reason the settings unsetted themselves when they came on they would stay on for say 2 minutes turn off then straight back on again, the problem was in the PIR settings not the LED lamps. (and I lost the instructions), maybe due to the hot weather or some other reason so I had to bring them back to a useable sequence.

[John Rumm]

PIRs often have dusk/dawn sensing as well. So they won't trigger the lamps in daylight (there is usually a control to adjust the sensitivity). That does mean you need to be careful with placement of the lamps wrt to the PIR though - you can get a situation where triggering the lamp can then trip the ambient light sensor which then turns the lamp off again even if the PIR is still being triggered.

[dennis]

Ta.