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Updated Nevada C-2D Low Voltage Practice Exam 2026 - 2027
DESCRIPTION
The Nevada C-2D Low Voltage license is an open-book trade certification for contractors installing systems up to 91 volts , including fiber optics, networking, audio/video, and security alarms.
Exam Summary
- Trade Exam: 35 questions | 60 minutes | 70% to pass.
- CMS Exam: 60 questions | 120 minutes | 75% to pass (Business & Law).
- Provider: All exams are administered by PSI.
Core Topics
- NEC Standards: Heavy focus on Articles 725 (Control), 770 (Fiber), 800 (Comms), and 250 (Grounding).
- Electrical Theory: Mastery of Ohm’s Law ( ) and Watt’s Law ( ).
- System Knowledge: Circuitry (Series/Parallel), Voltage Drop calculations, and Conduit Fill limits.
- Safety: OSHA standards and Class C fire prevention.
Key Licensing Requirements
- Experience: 4 years of verifiable journeyman-level experience.
- Financial: Must provide a financial statement and a Surety Bond.
- Law: Must provide a Notice to Owner regarding liens for residential work.
1. A low-voltage system is generally defined as operating at or below:
A. 24 volts B. 50 volts C. 120 volts D. 240 volts Answer: B The NEC generally defines low voltage (Class 2 and Class 3 circuits) as systems operating at 50 volts or less.
2. Class 2 circuits are limited primarily to reduce risk of:
A. Data loss B. Electrical shock and fire C. Signal interference D. Voltage drop Answer: B Class 2 power supplies limit current and voltage to reduce fire and shock hazards.
3. When running low-voltage cable in the same pathway as 120V conductors, you
must:
A. Tape the cables together B. Maintain separation unless rated for the same enclosure C. Use smaller wire D. Increase voltage Answer: B NEC requires separation between power-limited and non-power-limited conductors unless properly rated or separated by barriers.
4. Plenum-rated cable (CMP) is required when installed in:
A. Underground conduit B. Open air C. Air-handling spaces D. Exterior walls
A. Painted red B. Bundled tightly C. Fire-stopped with approved materials D. Wrapped in tape Answer: C Fire-rated assemblies must be restored using approved fire-stopping systems.
9. A PoE (Power over Ethernet) device receives power at approximately:
A. 12V
B. 24V
C. 48V
D. 120V
Answer: C PoE typically operates around 48 volts DC.
10. Shielded cable is most appropriate in environments with:
A. Low humidity B. High EMI C. Low voltage drop D. Short runs Answer: B Shielding reduces interference in electrically noisy environments.
11. Access control systems commonly use which type of wiring?
A. Coaxial only B. Twisted pair and low-voltage multi-conductor cable C. 12/2 Romex D. Aluminum feeder cable Answer: B Access control uses multi-conductor low-voltage cable for readers, strikes, and controls.
12. When installing CCTV cameras outdoors, connectors must be:
A. Painted B. Waterproof and weather-rated C. Shortened D. Grounded separately Answer: B Outdoor installations require weatherproof protection.
13. A voltage drop problem is most likely caused by:
A. Excessive cable length B. Shielded cable C. Fiber optic use D. Fire stopping Answer: A Long cable runs increase resistance and voltage drop.
14. Fiber optic cable is immune to:
A. Voltage drop B. EMI C. Signal loss D. Bending Answer: B Fiber uses light signals and is immune to electromagnetic interference.
15. The primary purpose of a patch panel is to:
A. Amplify signals B. Provide organized terminations C. Increase voltage D. Encrypt data Answer: B Patch panels allow organized structured cabling management.
Rationale: Article 725 is the primary reference for low-voltage control and signaling circuits.
2. What is the maximum voltage for a Class 2 power-limited circuit? A. 12 volts B. 24 volts C. 30 volts D. 91 volts Rationale: Class 2 circuits are typically limited to 30V to prevent electric shock and fire hazards. 3. According to the NEC, what is the minimum clearance for low-voltage communication cables crossing over a flat roof? A. 8 feet B. 10 feet C. 12 feet D. 15 feet Rationale: To ensure safety and maintenance access, a 8 - foot clearance is standard. 4. When installing fiber optic cables, which NEC Article must be followed? A. Article 725 B. Article 800 C. Article 770 D. Article 300 Rationale: Article 770 specifically governs the installation of optical fiber cables and raceways. 5. What is the primary purpose of "Grounding" a low-voltage system rack? A. To increase signal speed B. To limit the voltage imposed by lightning or line surges C. To reduce electricity bills D. To prevent the rack from rusting Rationale: Grounding provides a path for fault current, protecting equipment and personnel from surges. 6. Which type of cable is required for use in environmental air-handling spaces (plenums)? A. CL B. CL2R C. CL2P D. CL2X
Rationale: The "P" in CL2P stands for Plenum, indicating the cable has fire-resistant and low-smoke properties.
7. Ohm’s Law states that Voltage (E) equals: A. I / R B. I x R C. R / I D. P / I Rationale: Voltage = Current (Amps) x Resistance (Ohms). 8. If a circuit has a resistance of 10 Ohms and a current of 2 Amps, what is the Voltage? A. 5V B. 12V C. 20V D. 100V Rationale: 10 Ohms x 2 Amps = 20 Volts. 9. In a series circuit, if one bulb burns out, what happens to the other bulbs? A. They all go out B. They stay lit C. They get brighter D. They flicker Rationale: In a series circuit , there is only one path for current; a break anywhere stops all flow. 10. What is the maximum percentage of "Conduit Fill" allowed for a single cable in a raceway? A. 31% B. 53% C. 40% D. 60% Rationale: NEC Table 1 allows 53% fill for 1 wire, 31% for 2 wires, and 40% for 3 or more. 11. Which color is typically used to identify a "Hot" conductor in a DC circuit? A. Red B. Black C. White D. Green
B. To convert AC to DC C. To convert DC to AC D. To store a charge Rationale: Rectifiers allow current to flow in only one direction, turning AC into DC.
18. Which NEC Article covers the installation of "Communication Circuits" (Telephone/Data)? A. Article 725 B. Article 800 C. Article 430 D. Article 250 Rationale: Article 800 is the standard for general communication systems. 19. When a cable is installed vertically in a "Riser" between floors, what rating is required? A. CL2P B. CL2R C. CL2X D. CL Rationale: CL2R (Riser) cables are designed to prevent the spread of fire between floors. 20. What is the maximum length of a standard Ethernet cable (Cat5e/6) run? A. 50 meters B. 100 meters (328 feet) C. 200 meters D. 500 meters Rationale: Signal degradation becomes significant beyond 100 meters in copper networking. 21. A "Capacitor" is used to: A. Store an electrical charge temporarily B. Increase resistance C. Measure voltage D. Protect against lightning Rationale: Capacitors act like tiny batteries that can discharge quickly. 22. Which tool is used to test for "Continuity" in a wire? A. Ammeter B. Voltmeter C. Ohmmeter (or Multimeter)
D. Wattmeter Rationale: An Ohmmeter checks if a continuous path exists by measuring resistance.
23. What is the minimum bending radius for a standard UTP data cable? A. 2 times the diameter B. 4 times the diameter C. 10 times the diameter D. 20 times the diameter Rationale: Bending more than 4x the diameter damages the internal copper pairs. 24. In a low-voltage intrusion alarm system, what does "Normally Closed" (NC) mean? A. The circuit is complete when the door/window is shut B. The circuit is broken when the door is shut C. The alarm is always on D. The battery is charging Rationale: In NC systems, the alarm triggers when the circuit is "opened" (broken). 25. What color represents a "Potable Water" line when marking utilities? A. Blue B. Red C. Yellow D. Orange Rationale: Blue is the universal color for water. 26. According to NEC Article 250, what is the maximum resistance to ground for a single made electrode? A. 5 Ohms B. 10 Ohms C. 25 Ohms D. 100 Ohms Rationale: If resistance is higher than 25 Ohms , an additional electrode must be installed. 27. What is the definition of a "Junction Box"? A. An enclosure where multiple conductors are joined or spliced B. A box used only for switches C. A box used to store batteries D. A protective sleeve for fiber optics Rationale: Junction boxes protect splices and provide access for future maintenance.
D. Article 400 Rationale: Article 250 is the foundational reference for grounding all electrical systems.
34. A "Step-down Transformer" does what? A. Increases voltage B. Decreases voltage C. Changes DC to AC D. Increases amperage only Rationale: It reduces the primary voltage to a lower secondary voltage. 35. What is the minimum depth for a direct-buried low-voltage cable (less than 30V) under a residential driveway? A. 6 inches B. 12 inches C. 18 inches D. 24 inches Rationale: Per NEC Table 300.5, 18 inches is required under driveways. 36. "Signal-to-Noise Ratio" (SNR) measures: A. The strength of the desired signal compared to background noise B. The length of the cable C. The speed of the processor D. The voltage of the battery Rationale: A high SNR is necessary for clear data and audio transmission. 37. Which material is the best conductor of electricity? A. Gold B. Silver C. Copper D. Aluminum Rationale: Silver has the highest conductivity, though copper is most common due to cost. 38. What is a "Relay"? A. An electrically operated switch B. A type of fuse C. A high-voltage cable D. A battery charger Rationale: A relay uses a small current to control a much larger current. 39. "Crosstalk" is defined as: A. Two people talking over each other
B. Unwanted signal transfer from one circuit to another C. A broken wire D. High voltage in a data line Rationale: Crosstalk usually occurs due to poor cable shielding or too much untwisting.
40. What is the purpose of a "Fishtape"? A. To pull wires through conduit B. To measure cable length C. To strip insulation D. To test for voltage Rationale: A fishtape is a flexible metal or fiberglass tool used to navigate raceways. 41. How are "Amps" measured? A. In series with the load B. In parallel with the load C. Across the battery terminals D. At the ground rod Rationale: Current must flow through the ammeter to be measured. 42. How is "Voltage" measured? A. In series with the load B. In parallel with the load C. By disconnecting the wire D. Using a screwdriver Rationale: Voltmeter leads are placed across the two points being measured. 43. Which cable is used for outdoor, direct burial applications? A. CL2P B. CL2R C. CMX D. CL Rationale: CMX is outdoor rated and resists moisture and sunlight. 44. What does "PoE" stand for? A. Power over Electric B. Power over Ethernet C. Pressure on Equipment D. Point of Entry Rationale: PoE sends power and data over a single network cable. 45. What is the resistance of a "Closed" switch? A. 0 Ohms
Follow-up: Would you like a more detailed breakdown of the Nevada CMS (Business and Law) exam topics, or should we focus on Ohm's Law calculations? 51 - 120 This batch of 70 practice questions (51–120) completes the comprehensive study set for the Nevada C-2D Low Voltage trade exam. Nevada C-2D Low Voltage Practice Exam (Part 2)
51. According to NEC Article 725, Class 2 cables are permitted to be in the same raceway as power conductors if they are separated by a: A. Plastic tie B. Permanent barrier or 2-inch separation C. Grounding wire D. Rubber sleeve Rationale: To prevent high-voltage induction or fire, physical separation is mandatory. 52. What is the standard impedance of a typical RG-6 coaxial cable? A. 50 Ohms B. 75 Ohms C. 100 Ohms D. 300 Ohms Rationale: 75 - Ohm cable is the standard for video and cable TV distribution. 53. In a parallel circuit, if you add more resistors, what happens to the total resistance? A. It increases B. It decreases C. It stays the same D. It doubles Rationale: Adding paths in parallel provides more ways for current to flow, lowering overall resistance. 54. Which device is used to protect low-voltage equipment from transient voltage surges? A. Surge Protective Device (SPD) B. Transformer C. Capacitor
D. Rectifier Rationale: SPDs shunt excess voltage to ground to protect sensitive electronics.
55. What is the maximum distance a support must be from a box or terminal in a low-voltage run? A. 12 inches B. 24 inches C. 36 inches D. 48 inches Rationale: Proper securing within 12 inches prevents strain on the connections. 56. A "Class 3" circuit is distinguished from "Class 2" by having: A. Lower voltage B. Higher allowable voltage and power levels C. Only fiber optics D. No grounding Rationale: Class 3 circuits allow for higher power but require stricter insulation and wiring methods. 57. What is the primary function of a "Balun"? A. To match the impedance between balanced and unbalanced lines B. To boost the signal C. To ground the system D. To convert DC to AC Rationale: Baluns are commonly used to run video signals over twisted-pair (UTP) cabling. 58. Which NEC Article covers "Fire Alarm Systems"? A. Article 800 B. Article 725 C. Article 760 D. Article 640 Rationale: Article 760 governs the installation of wiring and equipment for fire alarm systems. 59. What is the maximum number of Category 6 cables allowed in a 1-inch EMT conduit at 40% fill? A. 2 B. 5 C. 6 to 8 (depending on cable OD) D. 15
65. Which tool is used to identify a specific wire in a bundle without stripping it? A. Multimeter B. Tone Generator and Probe (Fox and Hound) C. Wire Strippers D. Lineman's Pliers Rationale: The probe detects the inductive signal from the tone generator. 66. What is the purpose of an "End-of-Line" (EOL) resistor? A. To stop the electricity B. To allow the control panel to monitor the integrity of the loop C. To increase volume D. To act as a fuse Rationale: EOL resistors detect if a wire has been cut or shorted. 67. A "Bridge Tap" in a phone line causes: A. Better signal B. Signal reflections and interference C. Higher voltage D. Faster data Rationale: Bridge taps are unused extensions that degrade high-frequency signals like DSL. 68. What is the maximum voltage drop recommended by the NEC for branch circuits? A. 1% B. 3% C. 5% D. 10% Rationale: A 3% drop ensures efficient operation of connected equipment. 69. What is the frequency of standard AC power in the United States? A. 50 Hz B. 60 Hz C. 120 Hz D. 440 Hz Rationale: 60 cycles per second is the US standard. 70. "Plenum" space is defined as: A. An area used for environmental air return (e.g., above a drop ceiling) B. A closet for batteries C. An outdoor trench
D. A server rack Rationale: Plenum areas require special fire-rated cabling (CMP/CL2P).
71. What does the term "Inductance" refer to? A. The property of a circuit that opposes changes in current B. The property that stores charge C. Heat loss in a wire D. Signal speed Rationale: Inductance is common in coils and transformers. 72. Which type of fiber optic cable is used for long-distance transmissions? A. Multimode B. Single-mode C. Plastic fiber D. Copper fiber Rationale: Single-mode fiber has a smaller core and lower signal loss over distance. 73. What is the primary purpose of a "Shielded" cable? A. To make the cable stronger B. To protect the signal from electromagnetic interference (EMI) C. To allow for higher voltage D. To prevent water damage Rationale: The shield (foil or braid) drains interference to ground. 74. NEC Article 110.12 requires that electrical equipment be installed in a: A. Fast manner B. Cheap manner C. Neat and workmanlike manner D. Hidden manner Rationale: This is the most cited quality control article in the NEC. 75. What is the result of connecting two 12V batteries in "Series"? A. 12V with double capacity B. 24V with the same capacity C. 6V with double capacity D. 0V Rationale: Series connections add voltage; Parallel adds amperage/capacity. 76. "PSTN" stands for: A. Public Switched Telephone Network B. Private System Tele-Network C. Power Source Terminal Node
