Hi,Our alarm has gone off before now.We were told the alarms are pretty sensitive and if you leave your window open in the day and a fly gets in sometimes this sets it off! We have had problems with the grille on the front of the air-con.We were sleeping and there must have been some expansion which pushed off the grille.It gave us quite a fright.I was then too worried to put the grille back on in case when we left the apartment, it would bounce off again and trigger the alarm.Hopefully we have managed to glue it now.Also I have seen upstairs apartments with windows left slightly open,people then go out ,put their alarm on and a gust of wind has triggered the alarm,due to curtain movement.