"Ashton Crusher" wrote in message
...

The installations I've seen of burglar alarms, fire alarms, pbx and
computer network boxes have all been set up with the electric
completely separate. Typically the electric is run in and terminated
with regular three prong 120 volt outlets. Then the alarm installers
(and other system installers) nail a hunk of plywood to the wall, hang
all their stuff on that, and plug it in to the 120 volt outlet just
like you'd plug in a toaster.

That's how we do it.

_Years_ ago (decades, actually), alarms were wired with 120v directly into
the back of the box, either hard-wired or plug-in.

I prefer the current way of doing it - with a 16.5v transformer!