C7 Fire Alarm System Installation 2 — Questions and Answers
Question 1: Under NFPA 72, what is the maximum allowable spacing between smoke detectors on a smooth ceiling with a ceiling height of 10 feet?
- 25 feet
- 30 feet
- 50 feet (Correct answer)
- 60 feet
Correct answer: 50 feet
NFPA 72 permits a maximum 30-foot spacing (i.e., 900 sq ft coverage) between smoke detectors on smooth ceilings, but the listed spacing is up to 30 feet center-to-center — however the standard default area is 900 sq ft with a max 30-ft distance, so 30 feet is the correct maximum spacing.
Question 2: Which wire gauge is most commonly required for Class B initiating device circuits in a fire alarm system?
- 12 AWG
- 14 AWG
- 18 AWG
- 22 AWG (Correct answer)
Correct answer: 22 AWG
18 AWG or 22 AWG conductors are typically used for initiating device circuits; 22 AWG is the most common minimum for low-current Class B IDC wiring per manufacturer specifications and NFPA 72.
Question 3: A California C7 contractor installs a fire alarm panel in a mechanical room. What is the minimum clearance required in front of the panel for service access per the NEC?
- 18 inches
- 24 inches
- 30 inches (Correct answer)
- 36 inches
Correct answer: 30 inches
NEC 110.26 requires a minimum 30 inches of width and 36 inches of depth working clearance in front of electrical equipment, but the minimum clear width in front of the panel itself is 30 inches.
Question 4: When connecting a two-wire smoke detector to a Class B initiating device circuit, what component is typically placed at the end of the circuit?
- Isolator module
- End-of-line resistor (Correct answer)
- Supervisory relay
- Short-circuit protector
Correct answer: End-of-line resistor
An end-of-line (EOL) resistor is placed at the last device on a Class B circuit so the control panel can supervise the circuit for open conditions.
Question 5: Which NFPA standard specifically 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, is the primary standard governing the installation, testing, and maintenance of fire alarm systems.
Question 6: A duct smoke detector must be installed on the supply air duct. Where should the detector be positioned relative to air filters and heating or cooling equipment?
- Upstream of filters and equipment
- Downstream of filters and equipment (Correct answer)
- Adjacent to the air handler unit only
- At the return air plenum only
Correct answer: Downstream of filters and equipment
Duct smoke detectors on supply ducts must be located downstream of air filters and heating/cooling equipment to prevent nuisance alarms from dust and debris.
Question 7: Under California Title 19 and NFPA 72, how often must fire alarm systems in a commercial building receive a full inspection and test?
- Monthly
- Quarterly
- Annually (Correct answer)
- Every three years
Correct answer: Annually
NFPA 72 and California Title 19 require a complete fire alarm system inspection and test at least annually by a licensed contractor.
C7 Fire Alarm System Installation 2
Under NFPA 72, what is the maximum allowable spacing between smoke detectors on a smooth ceiling with a ceiling height of 10 feet?