Wall mounted motion detectors are normally used to monitor the interior spaces of small rooms. Mounting a motion detector in the corner of a room allows you to take advantage of the wedge-shaped detection pattern put out by a typical motion detector to get the maximum useful coverage.
However, when it comes to large areas with high ceilings, wall mounted motion detectors are less useful. In the video below, Ari Erenthal and Jim Grenier discuss using a panoramic ceiling mounted motion detector in these applications.
Industry best practice is to mount wall-mounted motion detectors so that they are monitoring critical spaces such as doors, or to take advantage of the layout the room contents to funnel an intruder past a wall-mounted motion detector. However, this leaves the interior unprotected if a well-informed intruder can gain access to the space through the roof or skylight.
A better way of protecting very large spaces is with ceiling mounted, panoramic motion detectors.
The Bosch DS9370 is a 360 degree panoramic TriTech motion detector. It uses three technologies; passive infrared, microwave, and advanced analytics to detect movement while filtering out false positives from mechanical sources while decreasing time to detection of human-caused movement. It can detect movement in a 46 foot diameter area. It can be mounted from 8 feet to 20 feet from the ground. For higher ceilings, the motion detector mounts to a standard octagonal workbox suspended from the ceiling.
The DS9370 uses very little power- just 12mA on standby and 20mA on alarm, allowing you to install lots of these detectors without needing an auxiliary power supply. It also features a form C relay, allowing you to trigger a secondary device such as a sounder when it detects movement.
