"Chris Wilson" wrote in message
...
As of the last few days our house alarm outside bell (siren really) box
sounds if the mains goes down. It never used to, the only reason I first
noticed was an RCD tripping fault on a mains ring circuit tripped the
fuse box RCD, and the alarm sounded, although the control panel was in
"Daytime" mode, and no panel lights showed. Restoring mains stops the
alarm, but resetting the alarm panel has no effect. Any clues what's up
with the damned thing? Otherwise the system appears to function normally.
We get not infrequent power outages here, so this could be a damned
nuisance ;-) Thanks.

Battery in the alarm box. Test to see if there is an output

If no power gets to the bell (either mains or battery) then the siren will
activate from it own second battery