CFI Fire Alarm & Detection Systems 2 — Questions and Answers
Question 1: Under NFPA 72, what is the maximum allowable spacing between smoke detectors on a smooth ceiling with no obstructions?
- 30 feet
- 50 feet (Correct answer)
- 900 square feet coverage area
- One per 1,200 square feet
Correct answer: 50 feet
NFPA 72 allows smoke detector spacing up to 50 feet between detectors on smooth ceilings.
Question 2: A heat detector rated at 135°F (57°C) is classified as which type?
- Rate-of-rise only
- Fixed-temperature only (Correct answer)
- Combination fixed-temperature and rate-of-rise
- Restorable rate-of-rise
Correct answer: Fixed-temperature only
A detector rated at a specific temperature threshold (135°F) without a rate-of-rise element is a fixed-temperature detector.
Question 3: Which NFPA standard governs the installation of fire alarm systems in the United States?
- NFPA 13
- NFPA 25
- NFPA 72 (Correct answer)
- NFPA 101
Correct answer: NFPA 72
NFPA 72, the National Fire Alarm and Signaling Code, governs the installation, inspection, testing, and maintenance of fire alarm systems.
Question 4: What is the primary purpose of a 'supervisory signal' in a fire alarm system?
- Notify occupants to evacuate immediately
- Indicate a fault in the alarm wiring
- Alert personnel to an off-normal condition in a fire protection system (Correct answer)
- Signal a confirmed fire condition
Correct answer: Alert personnel to an off-normal condition in a fire protection system
A supervisory signal indicates that a fire protection system or component (such as a sprinkler control valve) is in an off-normal condition.
Question 5: Beam-type smoke detectors are best suited for protecting which type of area?
- Small enclosed offices
- Corridors less than 10 feet wide
- Large open areas with high ceilings such as atriums or warehouses (Correct answer)
- Elevator shafts
Correct answer: Large open areas with high ceilings such as atriums or warehouses
Projected beam smoke detectors are ideal for large open spaces with high ceilings where installing point-type detectors would be impractical.
Question 6: What does a 'Class A' wiring style provide in a fire alarm system that 'Class B' does not?
- Higher voltage capacity
- Supervison of all conductors
- Fault tolerance through a return path, allowing operation during a single open-circuit fault (Correct answer)
- Wireless communication backup
Correct answer: Fault tolerance through a return path, allowing operation during a single open-circuit fault
Class A wiring loops back to the control panel, so a single break in the circuit does not disable devices beyond the fault point.
Question 7: An inspector finds that a duct smoke detector's sampling tube is clogged with dust. What is the immediate concern?
- False alarms will occur more frequently
- The detector may fail to detect smoke in the HVAC duct (Correct answer)
- The HVAC system will shut down automatically
- Power to the control panel will be interrupted
Correct answer: The detector may fail to detect smoke in the HVAC duct
A clogged sampling tube prevents smoke-laden air from reaching the sensing chamber, making the detector unable to respond to a real fire event.
CFI Fire Alarm & Detection Systems 2
Under NFPA 72, what is the maximum allowable spacing between smoke detectors on a smooth ceiling with no obstructions?