How it works
A motion sensor reports movement within its effective detection area. Different products use different sensing methods and reporting rules. A passive infrared model responds to changes in infrared radiation across its zones, while other technologies may detect movement differently. The event is commonly used for lighting or alerts, but it is not automatically a reliable count of people.
Important differences and limits
Motion and continued occupancy are different states. A seated person can remain still long enough for a movement event to clear. Coverage, installation height, obstacles and sensitivity affect detection. Some disturbances create unwanted events, while blind areas miss movement; a wider advertised range does not resolve every placement problem.
A useful practical check
Walk through the expected routes and check the event log rather than only the indicator light. Test room entry, slow movement and the normal seated activity. Review clear time and how the automation responds to repeated events. Keep manual control available and avoid a short fixed timer that switches lighting off during legitimate use.
An example in practice
For example, hallway movement can start a lighting timer, but a quiet desk user may need a different control approach. Test the actual activity before treating absence of movement as an empty room. Combining suitable sensors and conditions can improve behaviour, yet the resulting rule still needs verification against ordinary use and failure cases.