In a normally closed switch that is supervised, what happens if the switch is left open or tampered?

• A. It triggers an alarm immediately when opened.
• B. The switch is monitored for status changes; if left open or tampered it triggers a supervisory signal.
• C. It uses battery backup to maintain operation.
• D. It remains silent regardless of tampering.

Answer: (B)

Supervision means the fire alarm control panel is always checking the switch’s status. With a normally closed switch, the circuit should stay closed in normal operation. If the switch is left open or someone tampers with it, the circuit changes state, and the panel detects this discrepancy. It then sends a supervisory signal to indicate a device or wiring fault that needs inspection. This is different from an alarm, which would indicate a true fire condition; the supervisory signal simply flags that the switch or its wiring may be compromised and requires attention.