C7 Low Voltage System Design & Installation 3 — Questions and Answers
Question 1: When installing a security system control panel in a commercial building, where must the primary AC power connection originate?
- A dedicated branch circuit (Correct answer)
- Any available general-purpose circuit
- The lighting panel closest to the panel
- The HVAC circuit for convenience
Correct answer: A dedicated branch circuit
Security control panels require a dedicated branch circuit to prevent power interruption from other loads and ensure reliable operation.
Question 2: What is the minimum bend radius for a standard 4-pair Category 5e UTP cable during installation?
- 4 times the cable diameter (Correct answer)
- 10 times the cable diameter
- 2 times the cable diameter
- 8 times the cable diameter
Correct answer: 4 times the cable diameter
TIA-568 requires a minimum bend radius of 4 times the cable outer diameter for 4-pair UTP cables to prevent pair untwisting and signal degradation.
Question 3: A low voltage technician needs to separate fire alarm wiring from power-limited security wiring in the same raceway. Which CEC article governs this separation?
- CEC Article 760 for fire alarm systems (Correct answer)
- CEC Article 725 for Class 2 and Class 3 circuits
- CEC Article 800 for communications circuits
- CEC Article 820 for CATV systems
Correct answer: CEC Article 760 for fire alarm systems
CEC Article 760 governs fire alarm circuits and restricts mixing them with other wiring types to maintain system integrity.
Question 4: In a video surveillance system design, what is the primary purpose of using shielded twisted pair (STP) cable instead of coaxial cable for analog camera runs?
- To reduce installation cost and allow longer runs using active video baluns (Correct answer)
- To increase the video resolution of analog cameras
- To eliminate the need for power supplies at camera locations
- To comply with UL listing requirements for CCTV systems
Correct answer: To reduce installation cost and allow longer runs using active video baluns
STP with video baluns is less expensive than coaxial and can achieve longer runs, making it cost-effective for large surveillance installations.
Question 5: What documentation must a C7 contractor provide to the building owner upon completion of a fire alarm system installation?
- As-built drawings, operation and maintenance manuals, and a record of completion (Correct answer)
- Only a final inspection certificate from the AHJ
- A list of all devices installed and their serial numbers only
- The original shop drawings submitted for permit
Correct answer: As-built drawings, operation and maintenance manuals, and a record of completion
NFPA 72 Section 7.8 requires as-built drawings, O&M documentation, and a record of completion be provided to the owner upon system completion.
Question 6: When designing a nurse call system in a California healthcare facility, which standard primarily governs the installation requirements?
- NFPA 99 and local AHJ requirements (Correct answer)
- UL 2560 exclusively
- ANSI/TIA-570 residential cabling standard
- California Plumbing Code Section 4
Correct answer: NFPA 99 and local AHJ requirements
NFPA 99 (Health Care Facilities Code) governs nurse call and patient communication systems in healthcare facilities, along with AHJ requirements.
Question 7: A C7 contractor is installing access control wiring. At what point must a separate license be required if the contractor also installs the electric door strikes powered at 24V DC?
- No additional license is needed; 24V DC door strikes fall within C7 low voltage scope (Correct answer)
- A C-10 Electrical license is required for any door strike wiring
- A C-28 Doors license is required for the mechanical portion
- A C-7 contractor must subcontract all door hardware to a C-28
Correct answer: No additional license is needed; 24V DC door strikes fall within C7 low voltage scope
24V DC door strikes are within the C7 contractor's scope as they are low-voltage devices integral to the access control system.
C7 Low Voltage System Design & Installation 3
When installing a security system control panel in a commercial building, where must the primary AC power connection originate?