Download PrepIQ Duval County CoJ Florida Unlimited Master Electrical GITS Ultimate Exam and more Exams Technology in PDF only on Docsity!
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Question 1. Which NEC article specifically governs low-voltage communications circuits such as telephone, data, and video? A) Article 210 B) Article 800 C) Article 300 D) Article 500 Answer: B Explanation: Article 800 of the NEC addresses communications circuits, including requirements for installation, separation, and protection of low-voltage wiring. Question 2. Under NEC 725, a Class 2 circuit is limited to a maximum of: A) 30 VA and 100 V B) 100 VA and 150 V C) 60 VA and 30 V D) 50 VA and 120 V Answer: A Explanation: Class 2 circuits are limited to 30 VA and 100 V (or 30 V for fire alarm circuits) to ensure limited energy that cannot cause fire or shock hazards. Question 3. When installing a plenum-rated cable (CMP) in a building, the cable must be placed in: A) Open air only B) Riser shafts only C) Plenum spaces such as dropped ceilings D) Any conduit below 3 ft from the floor Answer: C Explanation: CMP (Communications Plenum) cables are fire-rated for use in plenum spaces where air circulates, such as dropped ceilings and raised floors. Question 4. The minimum separation distance between a power conductor and a Class 1 communication cable in a raceway, according to NEC 800.133, is:
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A) 1 in. B) 2 in. C) 4 in. D) No separation required if both are in the same raceway Answer: B Explanation: NEC 800.133 requires at least 2 in. separation between power conductors and low-voltage communication cables unless the raceway is listed for both. Question 5. Which labeling requirement is mandated by NEC 800.120 for communications cables? A) Color-coded heat-shrink tubing only B) Permanent, legible identification of the cable’s purpose at each termination point C) Only a tag on one end of the cable D) No labeling is required for cables less than 6 ft long Answer: B Explanation: NEC 800.120 requires permanent, legible identification of the circuit’s purpose at each termination, junction box, and panel. Question 6. For a low-voltage installation transitioning from an outdoor plant (OSP) to interior building cable (ISP), the point of entry must be protected with a: A) GFCI receptacle B) Surge Protective Device (SPD) rated for Class 2 circuits C) Weatherproof conduit only D) 15-amp circuit breaker Answer: B Explanation: An SPD at the point of entry protects interior low-voltage equipment from voltage transients originating outside the building. Question 7. OSHA’s lockout/tagout (LOTO) procedures are required when: A) Working on any low-voltage cable that is less than 10 A
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C) CAT 6A
D) CAT 7
Answer: B Explanation: CAT 6 can carry 10 Gbps up to 55 m (or 37 m in a 100 m run with higher crosstalk), whereas CAT 6A extends to 100 m. Question 11. The primary advantage of a single-mode fiber over multimode fiber is: A) Lower cost of connectors B) Higher bandwidth over longer distances due to smaller core size C) Ability to use LED light sources only D) Compatibility with RJ-45 connectors Answer: B Explanation: Single-mode fiber’s small core (≈ 9 μm) allows light to travel with minimal modal dispersion, enabling higher bandwidth over longer distances. Question 12. According to TIA/EIA- 568 - C, the T568B wiring scheme differs from T568A in the position of which pair? A) Pair 1 (blue) B) Pair 2 (orange) C) Pair 3 (green) D) Pair 4 (brown) Answer: B Explanation: T568B swaps the orange and green pairs compared to T568A, placing orange on pins 1-2 and green on pins 3-4. Question 13. When terminating a CAT-6 cable on an 110-block, the maximum allowed untwist length for each pair is: A) 0.5 in. B) 1 in. C) 2 in.
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D) 3 in. Answer: B Explanation: NEC and TIA standards recommend no more than 1 in. of untwisted wire to preserve performance and reduce crosstalk. Question 14. A fusion splice of multimode fiber typically results in an insertion loss of: A) 0.1 dB or less B) 0.5 dB to 1.0 dB C) 1.5 dB to 2.5 dB D) Greater than 3 dB Answer: A Explanation: Fusion splicing aligns the fiber cores precisely, often achieving ≤0.1 dB loss, superior to mechanical splices. Question 15. In a rack cabinet, the recommended maximum vertical spacing between cable managers and equipment to maintain proper airflow is: A) 2 U B) 4 U C) 6 U D) 8 U Answer: B Explanation: Providing at least 4 U of vertical clearance between equipment and cable managers allows adequate airflow for cooling. Question 16. Which certification test parameter measures the amount of signal reflected back toward the source? A) Insertion loss B) Return loss C) Near-End Crosstalk (NEXT) D) Power Sum NEXT (PSNEXT)
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Explanation: A 10 dB SNR ensures clear speech intelligibility even in reverberant environments. Question 20. In a four-wire analog intercom system, the two “voice” wires are typically: A) Shielded twisted pair B) Coaxial cable C) Fiber optic cable D) Unshielded single conductor Answer: A Explanation: Four-wire analog intercoms use a shielded twisted pair for each direction of voice to reduce noise and crosstalk. Question 21. When configuring a multi-zone paging system, which feature allows an emergency announcement to override background music? A) Zone priority matrix B) Automatic gain control C) Dual-tone multi-frequency (DTMF) signaling D) Band-pass filtering Answer: A Explanation: A zone priority matrix assigns higher priority to emergency inputs, causing them to pre-empt lower-priority audio sources. Question 22. HDMI extenders that use HDBaseT technology can transmit an uncompressed 4K video signal over a single Cat-6 cable up to: A) 30 m B) 50 m C) 100 m D) 150 m Answer: C
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Explanation: HDBaseT supports up to 100 m (328 ft) of CAT-6 cable for 4K/60 Hz video, audio, Ethernet, and control signals. Question 23. Power over Ethernet (PoE) according to IEEE 802.3at (PoE+) can deliver a maximum power of: A) 15.4 W per port B) 25.5 W per port C) 30 W per port D) 60 W per port Answer: D Explanation: IEEE 802.3at (PoE+) provides up to 30 W, while IEEE 802.3bt (PoE++) raises the limit to 60 W per port. The question asks for 802.3at, so the correct answer is 30 W. (Correction: The maximum for 802.3at is 30 W.) Answer: C Explanation: IEEE 802.3at (PoE+) supplies up to 30 W per port, sufficient for most IP cameras and access-control readers. Question 24. A CCTV camera that draws power from a PoE switch must be installed using a cable that meets which minimum category? A) Cat 3 B) Cat 5e C) Cat 6 D) Cat 6A Answer: B Explanation: PoE standards require at least Category 5e cabling to support the necessary power and data rates. Question 25. In an access-control system, a maglock is considered a fail-safe device because: A) It remains unlocked when power is lost B) It remains locked when power is lost C) It requires a constant voltage to stay energized
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Explanation: Class 1 circuits are not limited by the low-energy restrictions of Class 2/3 and may carry higher voltages and power. Question 29. A “riser” cable (CMR) is approved for installation in: A) Plenum spaces only B) Horizontal runs between floors, not in plenums C) Direct burial only D) Outdoor aerial runs Answer: B Explanation: CMR (Communications Riser) cables are fire-rated for vertical shafts between floors but are not permitted in plenum spaces. Question 30. The minimum conduit fill for a raceway containing three #12 AWG THHN conductors is: A) 15 % B) 20 % C) 30 % D) 40 % Answer: C Explanation: NEC Table 1 allows up to 40 % fill for three or more conductors, but for small conductors like #12, 30 % is commonly used to maintain heat dissipation; however, the code permits 40 % fill for three or more conductors. Answer: D Explanation: NEC Table 1 states a maximum of 40 % conduit fill for three or more conductors of the same size. Question 31. Which of the following is the correct method for grounding a coaxial cable shield in a CATV distribution system? A) Connect the shield to the chassis at both ends B) Connect the shield only at the source end (single-point grounding) C) Leave the shield ungrounded to avoid ground loops D) Ground the shield at every connector
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Answer: B Explanation: Single-point grounding at the source prevents ground loops while providing a low-impedance path for interference. Question 32. A surge protective device (SPD) installed on a telephone line must have a clamping voltage no greater than: A) 30 V B) 60 V C) 90 V D) 120 V Answer: C Explanation: For low-voltage telephone lines, the SPD clamping voltage is limited to 90 V to protect sensitive equipment without causing damage. Question 33. When using a fiber-optic patch panel, the recommended bend radius for a 9/125 μm multimode fiber is at least: A) 5 mm B) 10 mm C) 15 mm D) 20 mm Answer: C Explanation: NEC and fiber standards specify a minimum bend radius of 15 mm for 9/125 μm multimode fiber to avoid excessive loss. Question 34. In a structured-cabling design, the “horizontal cabling” portion typically does not exceed: A) 30 m B) 45 m C) 90 m D) 120 m Answer: C
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Question 38. For an IP-based intercom system, the minimum network bandwidth per simultaneous video stream at 1080p/30 fps is approximately: A) 2 Mbps B) 4 Mbps C) 6 Mbps D) 8 Mbps Answer: C Explanation: Uncompressed 1080p/30 fps requires about 3 Gbps, but typical IP intercoms use H.264 compression, bringing the required bandwidth to roughly 4 - 6 Mbps; 6 Mbps provides a safe margin. Question 39. When installing a ceiling-mounted speaker in a tiled ceiling, the recommended distance from the nearest wall to avoid acoustic reflections is: A) 2 ft B) 4 ft C) 6 ft D) 8 ft Answer: B Explanation: Placing speakers at least 4 ft from walls reduces early reflections that can degrade speech intelligibility. Question 40. Which of the following is a primary benefit of using a “rack-mount” power distribution unit (PDU) in a data center? A) Reduces cable length for fiber runs B) Provides centralized surge protection and circuit monitoring C) Eliminates the need for grounding D) Allows wireless power transmission to equipment Answer: B Explanation: Rack-mount PDUs consolidate power, often include surge protection, and can monitor load per outlet.
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Question 41. In a PoE system, the term “mid-span” refers to: A) A device that injects power onto the cable between the switch and the powered device B) A switch that both supplies data and power C) A passive splitter that separates data from power D) A cable that runs only half the distance of a full run Answer: A Explanation: A mid-span injector adds PoE to a non-PoE Ethernet link, placed between the network switch and the powered device. Question 42. The NEC requires that any low-voltage cable passing through a fire-rated wall must be sealed with a fire-stop mortar that is rated for: A) 30 minutes fire resistance B) 1 hour fire resistance C) 2 hours fire resistance D) 3 hours fire resistance Answer: B Explanation: NEC 300.21 requires fire-stop systems that maintain the wall’s fire-rating, typically a 1-hour rating for most building assemblies. Question 43. Which of the following is the correct definition of “Power Sum NEXT (PSNEXT)”? A) The sum of all NEXT values measured at a single port B) The combined crosstalk effect of multiple pairs measured at the far end of a cable bundle C) The total insertion loss across all pairs in a cable D) The crosstalk between a pair and its own image signal Answer: B Explanation: PSNEXT accounts for the cumulative effect of crosstalk from all adjacent pairs on a given pair, measured at the far end.
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Question 47. Which of the following is a common method for terminating a multimode fiber connector (LC) in a patch panel? A) Crimping with a RJ-45 tool B) Soldering the fiber to a PCB C) Using a pre-polished ferrule and a mechanical splice tray D) Fusion splicing directly to the panel Answer: C Explanation: LC connectors are installed using a pre-polished ferrule placed into a mechanical splice tray or a push-pull connector system. Question 48. In a data center, the recommended temperature range for equipment operation is: A) 0 °C to 10 °C B) 10 °C to 20 °C C) 18 °C to 27 °C D) 30 °C to 40 °C Answer: C Explanation: ASHRAE recommends 18 °C–27 °C (64 °F–80 °F) for optimal equipment reliability. Question 49. When installing a ceiling-mounted drop-ceiling speaker, the recommended mounting hardware should provide: A) A rigid, non-adjustable mount only B) Adjustable tilt and swivel to aim sound C) Integrated LED lighting D) A built-in amplifier Answer: B Explanation: Adjustable mounts allow precise aiming of the speaker’s acoustic axis, improving coverage and intelligibility. Question 50. A “wire-wound” transformer used in a 70-V audio system provides:
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A) Voltage regulation only B) Impedance matching and isolation between the amplifier and speaker taps C) Signal processing for equalization D) Power factor correction Answer: B Explanation: The transformer steps down the line voltage and presents the correct impedance to each speaker tap while providing isolation. Question 51. The most common connector type for CAT-6A cable termination in a patch panel is: A) RJ- 11 B) RJ-45 with 8P8C contacts C) SC D) LC Answer: B Explanation: RJ-45 (8P8C) connectors are standard for CAT-6A and other twisted-pair Ethernet terminations. Question 52. Which of the following statements about “shielded” vs. “unshielded” twisted-pair cable is true? A) Shielded cable always reduces attenuation compared to unshielded cable B) Shielded cable is required for all 10 Gbps Ethernet installations C) Shielded cable provides better protection against electromagnetic interference (EMI) but is more expensive and harder to terminate D) Unshielded cable cannot be used in plenum spaces Answer: C Explanation: Shielding adds EMI protection but increases cost and termination complexity; it is not mandatory for all high-speed runs. Question 53. In a fire-alarm interface, a “dry-contact” relay is used to: A) Supply power to the fire-alarm panel
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B) Fiber optic or high-capacity copper links between telecommunications rooms and the main distribution frame (MDF) C) Twisted-pair cables within a single room D) Coaxial cable for TV distribution only Answer: B Explanation: Backbone cabling interconnects equipment rooms and the MDF, often using fiber or high-capacity copper. Question 57. Which of the following is the correct definition of “cable tray fill factor” according to NEC Table 392.12? A) The ratio of cable weight to tray weight capacity B) The percentage of the tray’s cross-sectional area occupied by cables C) The number of cables per foot of tray length D) The voltage drop across the tray Answer: B Explanation: Fill factor is the percent of the tray’s cross-sectional area that is filled with cables, limited to 40 % for most installations. Question 58. A “balanced-line” microphone input on a mixing console typically expects a: A) 600 Ω impedance, 48 V phantom power B) 150 Ω impedance, 12 V bias C) 600 Ω impedance, no external power D) 150 Ω impedance, 48 V phantom power Answer: A Explanation: Professional balanced microphones use 600 Ω impedance and often require 48 V phantom power supplied by the console. Question 59. For a 25-V constant-voltage audio system, the maximum allowable tap impedance per speaker is: A) 8 Ω
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B) 16 Ω
C) 32 Ω
D) 64 Ω
Answer: B Explanation: NEC 720.8 limits each tap on a 25-V system to a maximum of 16 Ω. Question 60. The “Near-End Crosstalk (NEXT)” test is performed at which end of the cable? A) The transmitting end B) The receiving end C) Both ends simultaneously D) Only at the midpoint of the cable Answer: A Explanation: NEXT measures interference from adjacent pairs at the same end where the signal is transmitted. Question 61. A “shielded” conduit (e.g., EMT with a metal armor) provides which of the following benefits for low-voltage cables? A) Complete protection from all types of interference B) Additional grounding path and reduced EMI exposure C) Eliminates the need for cable labeling D) Allows higher voltage operation without a breaker Answer: B Explanation: Metal conduit offers a grounding path and can reduce electromagnetic interference, but does not eliminate all interference. Question 62. In a VoIP intercom system, Quality of Service (QoS) is most commonly implemented by: A) Assigning a higher priority to voice packets using DSCP values B) Using a separate physical network for intercom traffic only C) Increasing the network’s overall bandwidth to 10 Gbps
