Page 1 of 78
NEVADA C-2D LOW VOLTAGE CONTRACTORQUESTIONS
WITH VERIFIED ANSWERS DETAILED RATIONALES
GRADED A+
Nevada C-2D Low Voltage Contractor
Questions 1–50: Sound and Communications
1. A technician is installing a public address system in a commercial building and must ensure
the wiring is protected from physical damage, so which wiring method is most appropriate for
this application?
A. Type CL2P plenum-rated cable
B. Type NM-B nonmetallic sheathed cable
C. Type AC armored cable
D. Type MC metal-clad cable
Answer: A. Rationale: Plenum-rated cables (CL2P) are required in environmental air-handling
spaces to reduce fire hazard and smoke production. Articles 725 and 800 govern communication
circuit wiring.
2. A low-voltage contractor is installing a telephone system and must determine the minimum
separation distance between communications cables and electric light or power conductors,
so which of the following is correct?
A. 1 inch
B. 2 inches
C. 6 inches
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D. 12 inches
Answer: B. Rationale: NEC 800.133(A)(2) requires communications circuit conductors to
maintain at least 2 inches of separation from electric light, power, Class 1, or nonpower-limited
fire alarm circuit conductors.
3. A technician is terminating a 25-pair telephone cable in a distribution frame and must
identify the standard color code for the first pair, so which of the following is correct?
A. White-Blue
B. Blue-White
C. White-Orange
D. Orange-White
Answer: A. Rationale: In standard telephone color coding, the first pair is White-Blue (Tip) and
Blue-White (Ring).
4. A contractor is installing a sound system in a large auditorium and must account for voltage
drop over a long speaker run, so which factor has the greatest effect on voltage drop in the
speaker circuit?
A. The color of the insulation
B. The conductor length and wire gauge
C. The brand of the amplifier
D. The type of connector used
Answer: B. Rationale: Voltage drop is directly proportional to conductor length and inversely
proportional to conductor cross-sectional area (wire gauge). Longer runs and smaller gauges
increase voltage drop.
5. A technician is installing a paging system and must determine the maximum allowable
voltage for a Class 2 circuit, so which of the following is correct per NEC Article 725?
A. 30 volts
B. 60 volts
C. 91 volts
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D. 100 volts
Answer: B. Rationale: Class 2 circuits are limited to 30V or less for circuits up to 100VA, but can
be up to 60V for certain power-limited applications. The 91-volt threshold is a Nevada-specific
licensing limit, not an NEC Class 2 limit.
6. A contractor is installing a communications circuit and must select the correct cable
marking for a riser-rated cable, so which of the following designations is correct?
A. CMR
B. CMP
C. CMX
D. CMG
Answer: A. Rationale: CMR (Communications Riser) cable is rated for use in vertical riser shafts.
CMP is plenum-rated, CMX is for outdoor use, and CMG is general-purpose.
7. A technician is troubleshooting a dead telephone line and must identify the most likely
cause if the line tests shorted, so which of the following is the most probable cause?
A. An open conductor
B. A reversed pair
C. A short between tip and ring
D. A ground fault on the ring conductor
Answer: C. Rationale: A shorted condition indicates a low-resistance path between the tip and
ring conductors, often caused by moisture, damaged insulation, or a misplaced conductor.
8. A contractor is installing a sound reinforcement system and must ensure proper impedance
matching, so which of the following describes the relationship between amplifier output
impedance and speaker load impedance for maximum power transfer?
A. They must be equal
B. The speaker impedance must be higher than the amplifier
C. The amplifier impedance must be higher than the speaker
D. They are unrelated
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Answer: A. Rationale: Maximum power transfer occurs when the load impedance (speaker)
equals the source impedance (amplifier output).
9. A technician is installing a communications grounding system and must identify the correct
grounding conductor size for a communications circuit, so which of the following should be
used as a minimum?
A. 18 AWG
B. 14 AWG
C. 6 AWG
D. 1/0 AWG
Answer: B. Rationale: NEC 800.100 requires a minimum 14 AWG grounding conductor for
communications circuits, though larger sizes may be required based on the overcurrent device.
10. A contractor is installing a satellite dish antenna and must ensure the coaxial cable is
properly grounded, so which NEC article governs this installation?
A. Article 725
B. Article 760
C. Article 810
D. Article 820
Answer: D. Rationale: Article 820 covers community antenna television (CATV) and radio
distribution systems, including coaxial cable installations for satellite dishes.
11. A technician is installing a nurse call system and must determine the maximum allowable
voltage for the system, so which of the following is correct for a low-voltage nurse call
system?
A. 12 volts
B. 24 volts
C. 48 volts
D. 120 volts
4|Page
NEVADA C-2D LOW VOLTAGE CONTRACTORQUESTIONS
WITH VERIFIED ANSWERS DETAILED RATIONALES
GRADED A+
Nevada C-2D Low Voltage Contractor
Questions 1–50: Sound and Communications
1. A technician is installing a public address system in a commercial building and must ensure
the wiring is protected from physical damage, so which wiring method is most appropriate for
this application?
A. Type CL2P plenum-rated cable
B. Type NM-B nonmetallic sheathed cable
C. Type AC armored cable
D. Type MC metal-clad cable
Answer: A. Rationale: Plenum-rated cables (CL2P) are required in environmental air-handling
spaces to reduce fire hazard and smoke production. Articles 725 and 800 govern communication
circuit wiring.
2. A low-voltage contractor is installing a telephone system and must determine the minimum
separation distance between communications cables and electric light or power conductors,
so which of the following is correct?
A. 1 inch
B. 2 inches
C. 6 inches
1|Page
,Page 2 of 78
D. 12 inches
Answer: B. Rationale: NEC 800.133(A)(2) requires communications circuit conductors to
maintain at least 2 inches of separation from electric light, power, Class 1, or nonpower-limited
fire alarm circuit conductors.
3. A technician is terminating a 25-pair telephone cable in a distribution frame and must
identify the standard color code for the first pair, so which of the following is correct?
A. White-Blue
B. Blue-White
C. White-Orange
D. Orange-White
Answer: A. Rationale: In standard telephone color coding, the first pair is White-Blue (Tip) and
Blue-White (Ring).
4. A contractor is installing a sound system in a large auditorium and must account for voltage
drop over a long speaker run, so which factor has the greatest effect on voltage drop in the
speaker circuit?
A. The color of the insulation
B. The conductor length and wire gauge
C. The brand of the amplifier
D. The type of connector used
Answer: B. Rationale: Voltage drop is directly proportional to conductor length and inversely
proportional to conductor cross-sectional area (wire gauge). Longer runs and smaller gauges
increase voltage drop.
5. A technician is installing a paging system and must determine the maximum allowable
voltage for a Class 2 circuit, so which of the following is correct per NEC Article 725?
A. 30 volts
B. 60 volts
C. 91 volts
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,Page 3 of 78
D. 100 volts
Answer: B. Rationale: Class 2 circuits are limited to 30V or less for circuits up to 100VA, but can
be up to 60V for certain power-limited applications. The 91-volt threshold is a Nevada-specific
licensing limit, not an NEC Class 2 limit.
6. A contractor is installing a communications circuit and must select the correct cable
marking for a riser-rated cable, so which of the following designations is correct?
A. CMR
B. CMP
C. CMX
D. CMG
Answer: A. Rationale: CMR (Communications Riser) cable is rated for use in vertical riser shafts.
CMP is plenum-rated, CMX is for outdoor use, and CMG is general-purpose.
7. A technician is troubleshooting a dead telephone line and must identify the most likely
cause if the line tests shorted, so which of the following is the most probable cause?
A. An open conductor
B. A reversed pair
C. A short between tip and ring
D. A ground fault on the ring conductor
Answer: C. Rationale: A shorted condition indicates a low-resistance path between the tip and
ring conductors, often caused by moisture, damaged insulation, or a misplaced conductor.
8. A contractor is installing a sound reinforcement system and must ensure proper impedance
matching, so which of the following describes the relationship between amplifier output
impedance and speaker load impedance for maximum power transfer?
A. They must be equal
B. The speaker impedance must be higher than the amplifier
C. The amplifier impedance must be higher than the speaker
D. They are unrelated
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Answer: A. Rationale: Maximum power transfer occurs when the load impedance (speaker)
equals the source impedance (amplifier output).
9. A technician is installing a communications grounding system and must identify the correct
grounding conductor size for a communications circuit, so which of the following should be
used as a minimum?
A. 18 AWG
B. 14 AWG
C. 6 AWG
D. 1/0 AWG
Answer: B. Rationale: NEC 800.100 requires a minimum 14 AWG grounding conductor for
communications circuits, though larger sizes may be required based on the overcurrent device.
10. A contractor is installing a satellite dish antenna and must ensure the coaxial cable is
properly grounded, so which NEC article governs this installation?
A. Article 725
B. Article 760
C. Article 810
D. Article 820
Answer: D. Rationale: Article 820 covers community antenna television (CATV) and radio
distribution systems, including coaxial cable installations for satellite dishes.
11. A technician is installing a nurse call system and must determine the maximum allowable
voltage for the system, so which of the following is correct for a low-voltage nurse call
system?
A. 12 volts
B. 24 volts
C. 48 volts
D. 120 volts
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