PIR sensor failure modes

[John Rumm]

I have a PIR controlled light (that controls itself and one slave - it in turn is also controlled by an external PIR).

It has started exhibiting behaviour where it will trigger as normal. However once triggered it will then retrigger all by itself every time the delay expire. Hence the light is in effect kept on until the dusk / dawn sensor turns it off. You can in fact see it retrigger as every seconds the bulb flashes off very briefly.

Anyone know of a likely cause of this? I have tried masking off areas of the sensor - but the problem persists.

[NT]

They never seem to last very well. If its not seeing its own reflection, time to replace. Then again sounds like a gone cap on a supply line, tho not normally worth mucking with.

NT

[John Rumm]

I probably concur - it is only a cheapie built into the fitting. Just thought I would check there is not a well know cause like "spiders in the works".

I will probably just add another standalone unit to the system.