In cross zoning, when is the cross zoning timer started?

• A. The cross zoning timer starts after the initial zone violation.
• B. The cross zoning timer starts after a second zone is violated.
• C. The timer is started when the system is disarmed.
• D. The timer never starts.

Answer: (A)

Cross zoning works to confirm an alarm by requiring two different zones to be violated within a short, fixed window. The timer starts when the first zone is violated. If a second zone is violated within that window, the system triggers an alarm. If no second zone is violated before the timer expires, the event is treated as a nuisance and no alarm is sent. The exact duration of that window is set by the installer and can vary, but the key idea is to give a brief period for a second, different zone to be involved. This also helps reduce false alarms from a single trigger, such as a door sensor sticking or a sensor being bumped. The timer is canceled if the system is disarmed.