CCTV CCTV Power and Cabling Infrastructure 1 — Questions and Answers
Question 1: What does PoE stand for in the context of IP CCTV systems?
- Point of Entry
- Power over Ethernet (Correct answer)
- Protocol of Encryption
- Port over Extension
Correct answer: Power over Ethernet
PoE (Power over Ethernet) allows electrical power to be transmitted along with data over standard Ethernet cabling, eliminating the need for separate power supplies at each camera.
Question 2: Which PoE standard provides up to 30W of power per port to connected devices?
- IEEE 802.3af (PoE)
- IEEE 802.3at (PoE+) (Correct answer)
- IEEE 802.3bt (PoE++)
- IEEE 802.1Q
Correct answer: IEEE 802.3at (PoE+)
IEEE 802.3at (PoE+) provides up to 30W of power per port, compared to the 15.4W limit of the original 802.3af standard.
Question 3: What type of cable is most commonly used for analog CCTV camera installations?
- Cat6 UTP
- Fiber optic
- RG-59 coaxial cable (Correct answer)
- RS-485 twisted pair
Correct answer: RG-59 coaxial cable
RG-59 coaxial cable is the industry standard for analog CCTV video signal transmission, providing shielding against electromagnetic interference.
Question 4: What is the maximum recommended cable run length for an analog CCTV camera using RG-59 coax without amplification?
- 100 meters
- 300 meters (Correct answer)
- 500 meters
- 750 meters
Correct answer: 300 meters
RG-59 coaxial cable is typically recommended for runs up to 300 meters (approximately 1,000 feet) before signal degradation requires a video amplifier.
Question 5: What is the primary purpose of a UPS (Uninterruptible Power Supply) in a CCTV system?
- To reduce power consumption of cameras
- To maintain system operation during power outages (Correct answer)
- To regulate voltage spikes from lightning
- To distribute power evenly across all cameras
Correct answer: To maintain system operation during power outages
A UPS provides battery backup power to keep the CCTV system operational during electrical outages, ensuring continuous surveillance coverage.
Question 6: Which wiring standard is used for RS-485 communication in PTZ CCTV camera control?
- Single-conductor coaxial
- Two-wire twisted pair (differential signaling) (Correct answer)
- Four-conductor shielded cable
- Standard Cat5 UTP with RJ45
Correct answer: Two-wire twisted pair (differential signaling)
RS-485 uses differential signaling over two wires (A and B), which provides noise immunity and allows control signals to travel up to 1,200 meters.
CCTV CCTV Power and Cabling Infrastructure 1
What does PoE stand for in the context of IP CCTV systems?