DSC Wireless Pet Immune Motion Sensor
A Wireless motion sensor can cover a room approximately 100 sqm and with the built in Pet Immunity can ignore your pets up to 27Kg.
The wireless motion sensor should be installed in ground floor rooms and at minimum 1 at the top of the stairs in a landing area in a 2 story home.
The corner of a room that you want to cover with respect to the size. If larger than 100spm (10m x 10m) room, you may consider adding an addition motion sensor located diagonally opposite in a corner. There is no issues if the room is smaller. Ideally not facing windows. Compatible with DSC only.