Which component terminates protective loops and enables supervision of field wiring?

• A. Battery backup.
• B. End of line resistor.
• C. Siren.
• D. Keypad.

Answer: (B)

End-of-line resistance at the far end of a protective loop provides a defined impedance that lets the control panel supervise the entire wiring. When the loop is intact, the panel reads a normal resistance value; if the wiring is opened or shorted along the run, the resistance changes and the panel raises a supervisory fault or alarm. This continuous monitoring detects wiring faults, tampering, or device failures, ensuring the loop’s integrity remains verified.

Battery backup is about power, not wiring supervision; the siren is an audible alert device; and the keypad is a user interface. None of these terminate the loop or enable supervision of the field wiring the way an end-of-line resistor does.