When two or more automatic fire detectors in two separate zones both sense fire in the same area, this is known as __________.

When two or more automatic fire detectors in two separate zones both sense fire in the same area, this is known as __________.

• A. Cross-zoning
• B. Parallel detection
• C. Redundant zoning
• D. Independent zoning

Answer: (A)

Cross-zoning is when two or more detectors in different zones are required to sense fire in the same area to trigger an alarm. This setup provides a form of confirmation—one detector alone may be fooled by dust, steam, or a false signal, but when a second, separate zone also detects fire, the system can confidently declare a real event. In the scenario described, two detectors in separate zones both sensing the same fire area fits this approach, making cross-zoning the best term. Parallel detection would typically alarm if any one detector signals, not only when both do. Redundant zoning adds duplicate zones for reliability but doesn’t specifically describe the cross-check between zones that confirms the fire. Independent zoning means each zone operates separately without this cross-check.

Cross-zoning is when two or more detectors in different zones are required to sense fire in the same area to trigger an alarm. This setup provides a form of confirmation—one detector alone may be fooled by dust, steam, or a false signal, but when a second, separate zone also detects fire, the system can confidently declare a real event. In the scenario described, two detectors in separate zones both sensing the same fire area fits this approach, making cross-zoning the best term.

Parallel detection would typically alarm if any one detector signals, not only when both do. Redundant zoning adds duplicate zones for reliability but doesn’t specifically describe the cross-check between zones that confirms the fire. Independent zoning means each zone operates separately without this cross-check.