S95 Supervisory and Trouble Signals 2 — Questions and Answers
Question 1: A supervisory signal is received at the fire alarm control panel indicating a valve has moved from its normal position. What is the FIRST action required?
- Silence the supervisory signal and log it
- Investigate and restore the valve to its normal position (Correct answer)
- Transmit an alarm signal to the fire department
- Disable the supervisory zone until the next inspection
Correct answer: Investigate and restore the valve to its normal position
Supervisory signals indicate off-normal conditions that must be investigated and corrected by restoring the device to its normal supervised position.
Question 2: Which of the following conditions would generate a TROUBLE signal rather than a supervisory signal?
- A dry-pipe valve that has operated
- A fire pump that has started automatically
- A ground fault on a signaling line circuit (Correct answer)
- A pressure switch indicating low system pressure
Correct answer: A ground fault on a signaling line circuit
A ground fault on a signaling line circuit indicates a wiring or circuit integrity problem, which is classified as a trouble condition.
Question 3: According to NFPA 72, how often must supervisory signals be tested in a system with central station monitoring?
- Monthly
- Quarterly
- Semiannually
- Annually (Correct answer)
Correct answer: Annually
NFPA 72 requires supervisory signal devices to be tested annually unless the authority having jurisdiction specifies a different frequency.
Question 4: A building fire alarm system displays a trouble signal with an 'open circuit' fault on initiating device circuit 3. What does this indicate?
- A device on circuit 3 has activated
- A wire break or disconnection exists on circuit 3 (Correct answer)
- Too many devices are connected to circuit 3
- Circuit 3 has a short circuit condition
Correct answer: A wire break or disconnection exists on circuit 3
An open circuit trouble indicates a wire break, loose connection, or disconnected device that has interrupted the circuit continuity.
Question 5: Which signal type is generated when a sprinkler control valve is closed more than 20% from the fully open position?
- Alarm signal
- Trouble signal
- Supervisory signal (Correct answer)
- Supervisory or alarm depending on local AHJ
Correct answer: Supervisory signal
A tamper switch on a sprinkler control valve generates a supervisory signal when the valve moves significantly from its fully open (normal) position.
Question 6: A sprinkler system water flow switch activates but no sprinkler heads have operated. The MOST likely cause is:
- Pressure surge or water hammer in the system (Correct answer)
- A supervisory signal being converted to alarm
- A trouble condition on the flow switch wiring
- Normal system test in progress without notification
Correct answer: Pressure surge or water hammer in the system
Pressure surges or water hammer can momentarily activate a flow switch without actual water flow, often called a false alarm.
Question 7: When a trouble signal is received at a protected premises FACP, NFPA 72 requires the trouble signal to be:
- Silenced immediately to avoid nuisance
- Acknowledged and investigated within 24 hours (Correct answer)
- Transmitted only if it persists for more than one hour
- Escalated directly to an evacuation alarm
Correct answer: Acknowledged and investigated within 24 hours
NFPA 72 requires trouble signals to be acknowledged and the cause investigated and corrected within 24 hours of receipt.
S95 Supervisory and Trouble Signals 2
A supervisory signal is received at the fire alarm control panel indicating a valve has moved from its normal position.
What is the FIRST action required?