I always put the burglar alarm out side the front door. I find only one alarm is adequate for my sims homes. Burglars do turn up and wake the household when the alarm goes off, but they rarely get anything - and they almost never turn up so when they do it's mostly just a bit of entertainment that lasts a few minutes and probably won't happen again for a long time.
I've read that having a dog in the household will actually increase the chance of being burgled. Not sure if that's the case but thought it interesting. But I have noticed being burgled with a dog in the house, but haven't kept statistics on it to know if the dog has any affect on it.