In cross-zoned systems, what must occur after initial detector activation to trigger the alarm?

• A. A sprinkler head must activate
• B. The alarm will sound immediately
• C. A manual activation is required
• D. A second detector must activate

Answer: (B)

In cross-zoned systems, the way the zones are wired and monitored can be configured so that an alarm is triggered as soon as a detector in any zone activates. The main point here is that the system is set to produce an audible/visible alarm immediately after initial detector activation, rather than waiting for a second detector to confirm. This rapid response helps ensure occupants are warned without delay in a real fire scenario.

Context helps: cross-zoning is often used to reduce nuisance alarms by requiring cross-checks, but the specific system design in this question is arranged so the initiating detector’s signal itself is enough to set off the alarm. That’s why this option is considered the correct one.

The other ideas—needing a sprinkler head to activate, requiring a manual activation, or waiting for a second detector to go active—don’t apply to this configuration. The sprinkler actuation isn’t a trigger for the detector-based alarm, manual activation isn’t needed for automatic detection, and a second detector isn’t required in this setup.