What about fog?
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
wrote in message
...
When I re-furb'ed my last house I fitted window switches to all accessible
windows and external doors, so didn't need to bother with PIRs. The
current house already has a "professionally installed" alarm with PIRs and
door contacts, but no window contacts.
I was going to replace the PIRs with (a large quantity of) window switches
but am having second thoughts because of the unsightly wiring.

SWMBO is concerned about staying with the PIRs because, if we set the
downstairs ones at night, of what happens if someone goes down for a drink
or a wander around in the night. How does everyone else cope with this?

I'm wondering whether it's viable to set-up an external boundary around
the house using infra red or laser beams/detectors (above animal height).
Has anyone used this technique?