CAT Troubleshooting & Diagnostics 3 — Questions and Answers
Question 1: A glass-break detector does not respond during a walk-test when a glass-break simulator is used. After confirming the simulator works elsewhere, what should you check?
- The panel's entry delay programming
- The detector's mounting surface, angle, and maximum coverage range (Correct answer)
- The zone's end-of-line resistor value
- Whether the siren is wired correctly
Correct answer: The detector's mounting surface, angle, and maximum coverage range
Glass-break detectors must be mounted within the manufacturer's specified range and aimed correctly at the protected glass to reliably detect breakage.
Question 2: During diagnostics, you find that a normally-open contact device keeps the zone in alarm state even when the device is physically closed. What is the likely cause?
- The zone is programmed as normally-closed in the panel (Correct answer)
- The end-of-line resistor is missing or open
- The panel battery is low
- The device has been bypassed intentionally
Correct answer: The zone is programmed as normally-closed in the panel
If the panel zone type is programmed for normally-closed contacts but the device uses normally-open contacts, the zone will always appear in alarm.
Question 3: Which tool is most appropriate for locating an intermittent open in a buried door contact wire run?
- Clamp meter
- TDR (Time Domain Reflectometer) (Correct answer)
- Oscilloscope
- Multimeter set to DC voltage
Correct answer: TDR (Time Domain Reflectometer)
A TDR sends a pulse down the cable and measures the reflection to precisely locate faults including intermittent opens in buried or in-wall wire runs.
Question 4: A dual-technology (PIR + microwave) motion detector produces frequent false alarms in a warehouse. Switching to PIR-only mode eliminates the problem. What does this suggest?
- The PIR element is more sensitive than the microwave element
- Microwave energy is reflecting off moving equipment such as conveyor belts or fans (Correct answer)
- The detector needs a firmware update
- The zone wiring has a partial short
Correct answer: Microwave energy is reflecting off moving equipment such as conveyor belts or fans
Microwave technology can pick up subtle vibration or motion from machinery, so dual-tech false alarms in industrial environments are often caused by microwave energy reflecting off moving equipment.
Question 5: A keypad is mounted 300 feet from the control panel over a 4-conductor run and displays garbled characters. What is the most likely cause?
- Incorrect keypad address setting
- Excessive voltage drop due to long wire run gauge mismatch (Correct answer)
- Panel firmware incompatibility
- Defective keypad LCD
Correct answer: Excessive voltage drop due to long wire run gauge mismatch
Long keypad data runs can suffer voltage drop that corrupts serial communication, causing garbled display characters.
Question 6: After replacing a smoke detector head on a 4-wire circuit, the zone shows a trouble condition rather than normal. What should be checked?
- The panel's smoke sensitivity setting
- Whether the replacement detector model matches the zone's required power and relay specifications (Correct answer)
- The siren polarity
- The panel's access code programming
Correct answer: Whether the replacement detector model matches the zone's required power and relay specifications
4-wire smoke detectors require specific power draw and relay contact characteristics; installing an incompatible model causes zone trouble conditions.
Question 7: A CO detector triggers a supervisory alert, not an alarm, on the panel. What condition does a supervisory signal from a CO detector typically indicate?
- Carbon monoxide has reached alarm threshold
- The detector has detected a maintenance issue such as end-of-life or sensor fault (Correct answer)
- The detector's zone wire is open-circuited
- The panel's AC power has failed
Correct answer: The detector has detected a maintenance issue such as end-of-life or sensor fault
A supervisory signal from a CO detector indicates a device-level issue such as sensor expiration, self-test failure, or end-of-life condition rather than CO presence.
CAT Troubleshooting & Diagnostics 3
A glass-break detector does not respond during a walk-test when a glass-break simulator is used.
After confirming the simulator works elsewhere, what should you check?