Re: Question about how alarm triggers work

["Jim" <alarminex@xxxxxxx>]

BIOSMonkey wrote:
> My home is prewired for a security system and it appears that there are single
> wires going to each window/door.  I am confused, though, how a single wire can
> detect the state of a trigger on the end when there is no common ground?


The following is not likely but you never know .....  someone may have
just put single condutors for two possible reasons. And I mention this
because I've run into to both situations on prewires that were done by
DIY'ers or people with no experience whatsoever.

It could be that someone left a "drop" wire from each window to use as
a pull wire to get the "real" wire up to the window at a later date.

Or, if you think about it from a novice point of view, you only "need"
one single wire conductor to each window, if you run a single conductor
up from the basement to a window, across the wall, to the next window
and then back down to the basement again from the second window. If you
interpret the drawing of a burglar alarm system literally, the loop
starts at the panel, all the contacts are in series and the other end
of the loop goes back to the panel. A guy who'd pre-wired his own home
called me for a service call on a system like this once. Try and
trouble shoot that ........... !!!!!!!!!

At least he didn't go up to the first window with the wire and come
down at the last one.