Intrusion Detection System
CSI Division 28, Electronic Safety and Security
Door and window contacts, motion sensors, and a central control panel that detect unauthorized entry into a building after hours and signal an alarm, either locally or to a monitoring service, distinct from [[concept-access-control-system|access control]], which manages authorized entry rather than detecting unauthorized entry.
Why it matters
An intrusion detection system's sensor placement has to account for how the specific space is actually used, a motion sensor placed without considering after-hours cleaning crews or scheduled deliveries generates enough false alarms that staff start ignoring or disabling the system entirely, defeating its purpose.
On a real project
A warehouse's intrusion detection system is programmed with a separate arming schedule for its loading dock area, accounting for a scheduled early-morning delivery that would otherwise trigger a false alarm every time it occurred.
Who this matters most to
An Electrician or specialty security integrator installs the sensors and control panel. A Facilities Manager manages the arming schedule and monitoring service relationship after occupancy.
Where this goes wrong
An installer sets a building's intrusion detection system with a single arming schedule that doesn't account for a cleaning crew's actual after-hours schedule. The system triggers a false alarm nearly every night the crew works, and facility staff eventually disable the zone entirely rather than dealing with the constant false alarms, leaving that area effectively unmonitored.