Interesting. We have one opposite that went off fairly frequently. The first dozen times it was irritating, after that it became a pain. I called the police who said they were aware that there was an issue and due to the high volume of calls received about it they would "have a word" with the owner.

It has gone off once or twice in the last 2 years.

Ours went off the other day, a rat had chewed through a cable, police were there in 2 minutes.