Which statement about short circuits on Class X circuits is true?

Which statement about short circuits on Class X circuits is true?

• A. They always trigger an alarm
• B. They trigger a supervisory signal
• C. They cause a trouble signal
• D. They cause no signal

Answer: (C)

In fire alarm practice, signals fall into three categories: alarm, supervisory, and trouble. A short circuit in a circuit is a fault in the wiring or a device that impairs proper operation. It does not indicate that a fire has been detected (which would be an alarm) and it isn’t about a monitored device needing a specific state (which would be supervisory). Instead, it signals a fault condition in the circuit, which is reported as a trouble to alert maintenance to inspect and repair. That’s why a short on a Class X circuit is conveyed as a trouble signal.

In fire alarm practice, signals fall into three categories: alarm, supervisory, and trouble. A short circuit in a circuit is a fault in the wiring or a device that impairs proper operation. It does not indicate that a fire has been detected (which would be an alarm) and it isn’t about a monitored device needing a specific state (which would be supervisory). Instead, it signals a fault condition in the circuit, which is reported as a trouble to alert maintenance to inspect and repair. That’s why a short on a Class X circuit is conveyed as a trouble signal.