Which type of security system circuit uses devices that are all normally closed when there is no abnormal condition present?

Which type of security system circuit uses devices that are all normally closed when there is no abnormal condition present?

• A. Open loop circuit
• B. Closed loop circuit
• C. Voice verification
• D. Cross zoning

Answer: (B)

The main idea is how a security circuit is monitored for normal conditions and tampering. In a closed loop arrangement, every device stays closed when no abnormal condition exists, so the control panel sees a continuous circuit. If a sensor is triggered or a wire opens, the circuit is interrupted and the panel signals an alarm. This built‑in supervision is why the description matches a closed loop circuit. The other terms don’t describe the wiring state: cross zoning is a technique for reducing false alarms by requiring two zones to be tripped, and voice verification is about authenticating with voice, not the circuit’s normal state.

The main idea is how a security circuit is monitored for normal conditions and tampering. In a closed loop arrangement, every device stays closed when no abnormal condition exists, so the control panel sees a continuous circuit. If a sensor is triggered or a wire opens, the circuit is interrupted and the panel signals an alarm. This built‑in supervision is why the description matches a closed loop circuit. The other terms don’t describe the wiring state: cross zoning is a technique for reducing false alarms by requiring two zones to be tripped, and voice verification is about authenticating with voice, not the circuit’s normal state.