Mark wrote:
Hi,

Can anyone recommend a reliable PIR unit? I have had several over
recent years and they always seem to fail forcing the light to stay
on all the time.

The last one I purchased from B&Q which looks exactly like the one
from screwfix (http://www.screwfix.com/app/sfd/cat/pro.jsp?id=11291)
and that only lasted about 6 months. If I can find the receipt I
will return it but I would like to replace it with a more reliable
unit.

TIA, Mark

I have a suspicion that these things fail because of moisture getting
in. My reasoning is that when one goes I replace it and throw the old
one in a (dry) corner awaiting a toit to see if I can fix it. When the
next one goes, I dig out the previous one and find it's working
perfectly. Latterly, I used to apply some silicone sealant to the cable
entry. Nowadays, I use the combined detector and lamp model as they're
so cheap. They have a lot more gubbins between the cable entry and the
electronics, which tends to support my theory. I certainly don't have
to change them as often as I did. I realise a combined unit may not be
suitable for your application, though.

Chris