Which statement correctly describes an alarm shunt?

• A. Used to bypass existing door contacts for an alarm system; it energizes the main relay and de-energizes 1 second after the door position switch input is closed.
• B. A device that monitors temperature in the panel
• C. A battery backup for alarms
• D. A siren without control

Answer: (A)

An alarm shunt is a temporary bypass device used to bypass a door contact input so the system can be worked on or tested without triggering a normal alarm. It is connected across the door position circuit and is designed to momentarily energize the main relay, then release about a second after the door position input is closed, allowing the system to return to its normal state once the door is shut. This behavior—bypassing the door contact and then resetting after a short delay when the door closes—is exactly what the described statement conveys. The other options describe unrelated components: a temperature monitor in the panel, a battery backup, or a standalone siren without control, none of which function as a shunt.