New Mexico Low Voltage Journeyman ES3J Exam Prep
2026/2027 | 200 Practice Questions & Detailed Answers | NM
CID Licensing Guide | A+ Graded
1. What is the maximum voltage allowed for work classified as "lowvoltage" under New Mexico ES3J
regulations?
A. 30 V AC
B. 50 V DC
C. 60 V AC
D. 120 V AC
Answer: B. New Mexico defines lowvoltage work as 50 volts or less, either AC or DC. This is the threshold
that separates lowvoltage special systems from standard electrical work requiring higherlevel licenses.
2. An ES3J journeyman is authorized to install which of the following systems without a separate
electrical contractor's license?
A. 120/240 V power circuits
B. Lowvoltage fire alarm signaling circuits (≤ 50 V)
C. Commercial HVAC control panels
D. Highvoltage motor starters
Answer: B. ES3J license holders may work on lowvoltage signaling and communication systems, but not
on standard power circuits above 50 volts.
3. What is the primary purpose of Ohm's Law in lowvoltage systems?
A. To calculate the power consumption of devices
B. To determine voltage, current, and resistance relationships
C. To measure signal attenuation over fiber optics
D. To specify circuit breaker sizes
,Answer: B. Ohm's Law states that V = I × R, which helps determine the relationship between voltage,
current, and resistance in electrical circuits, fundamental for lowvoltage system calculations.
4. In a series circuit, how is the total resistance calculated?
A. Sum of individual resistances
B. Product of resistances divided by their sum
C. The smallest resistance value
D. Resistance of the largest resistor only
Answer: A. The total resistance in a series circuit equals the sum of all individual resistances, which
affects voltage drop and current flow throughout the circuit.
5. Which component is primarily used to store electrical energy in a circuit?
A. Resistor
B. Capacitor
C. Diode
D. Transformer
Answer: B. Capacitors store electrical energy temporarily and are used in filtering, timing, and energy
storage applications within lowvoltage systems.
6. According to NEC Article 725, what is a key characteristic of Class 2 circuits?
A. They operate at voltages exceeding 600V
B. They are powerlimited and have low energy levels
C. They are used exclusively for highvoltage transmission
D. They require specialized fireproof conduit
Answer: B. Class 2 circuits are powerlimited (per NEC) and designed for lowvoltage, lowenergy
applications like control and signaling.
,7. What is the minimum bend radius for Cat6 cable as per NEC guidelines?
A. 2 times the diameter
B. 4 times the diameter
C. 6 times the diameter
D. 8 times the diameter
Answer: C. The minimum bend radius for Cat6 cable is 6 times its diameter to prevent damage and
maintain performance.
8. Which lowvoltage cable is rated for 100 MHz and is commonly used for Gigabit Ethernet installations?
A. Cat 3
B. Cat 5e
C. Cat 6
D. Coaxial
Answer: C. Cat 6 supports up to 250 MHz and is the standard for Gigabit Ethernet, offering better
performance than Cat 5e.
9. Under NEC Article 725, what is the maximum allowed voltage for a Class 2 powerlimited circuit?
A. 30 V AC or DC
B. 50 V AC or 120 V DC
C. 60 V AC or DC
D. 100 V AC or DC
Answer: A. Class 2 circuits are limited to 30 V (rms) AC or 30 V DC to reduce shock hazard.
10. Which formula correctly expresses Ohm's Law for a DC circuit?
A. P = V × I
B. V = I ÷ R
, C. I = V × R
D. V = I × R
Answer: D. Ohm's Law states that voltage (V) equals current (I) multiplied by resistance (R); V = I × R.
11. Which of the following best describes the primary purpose of grounding in lowvoltage systems?
A. To provide a reference potential for the system
B. To increase the operating voltage
C. To isolate the system from external noise
D. To reduce conductor size requirements
Answer: A. Grounding establishes a common reference potential (usually earth) for all parts of the
system, which enhances safety and helps stabilize the voltage levels.
12. Which component is most commonly used as a grounding electrode in lowvoltage installations?
A. Ground rod
B. Neutral conductor
C. Insulated cable
D. Metal conduit
Answer: A. A ground rod, typically made of copper or galvanized steel, is widely used as a grounding
electrode because it provides a direct connection to the earth.
13. What is the primary difference between grounding and bonding?
A. Grounding provides a lowresistance path to earth; bonding ensures electrical continuity between
metal parts
B. Grounding increases voltage; bonding decreases voltage
C. Grounding isolates circuits; bonding connects circuits
D. There is no significant difference
2026/2027 | 200 Practice Questions & Detailed Answers | NM
CID Licensing Guide | A+ Graded
1. What is the maximum voltage allowed for work classified as "lowvoltage" under New Mexico ES3J
regulations?
A. 30 V AC
B. 50 V DC
C. 60 V AC
D. 120 V AC
Answer: B. New Mexico defines lowvoltage work as 50 volts or less, either AC or DC. This is the threshold
that separates lowvoltage special systems from standard electrical work requiring higherlevel licenses.
2. An ES3J journeyman is authorized to install which of the following systems without a separate
electrical contractor's license?
A. 120/240 V power circuits
B. Lowvoltage fire alarm signaling circuits (≤ 50 V)
C. Commercial HVAC control panels
D. Highvoltage motor starters
Answer: B. ES3J license holders may work on lowvoltage signaling and communication systems, but not
on standard power circuits above 50 volts.
3. What is the primary purpose of Ohm's Law in lowvoltage systems?
A. To calculate the power consumption of devices
B. To determine voltage, current, and resistance relationships
C. To measure signal attenuation over fiber optics
D. To specify circuit breaker sizes
,Answer: B. Ohm's Law states that V = I × R, which helps determine the relationship between voltage,
current, and resistance in electrical circuits, fundamental for lowvoltage system calculations.
4. In a series circuit, how is the total resistance calculated?
A. Sum of individual resistances
B. Product of resistances divided by their sum
C. The smallest resistance value
D. Resistance of the largest resistor only
Answer: A. The total resistance in a series circuit equals the sum of all individual resistances, which
affects voltage drop and current flow throughout the circuit.
5. Which component is primarily used to store electrical energy in a circuit?
A. Resistor
B. Capacitor
C. Diode
D. Transformer
Answer: B. Capacitors store electrical energy temporarily and are used in filtering, timing, and energy
storage applications within lowvoltage systems.
6. According to NEC Article 725, what is a key characteristic of Class 2 circuits?
A. They operate at voltages exceeding 600V
B. They are powerlimited and have low energy levels
C. They are used exclusively for highvoltage transmission
D. They require specialized fireproof conduit
Answer: B. Class 2 circuits are powerlimited (per NEC) and designed for lowvoltage, lowenergy
applications like control and signaling.
,7. What is the minimum bend radius for Cat6 cable as per NEC guidelines?
A. 2 times the diameter
B. 4 times the diameter
C. 6 times the diameter
D. 8 times the diameter
Answer: C. The minimum bend radius for Cat6 cable is 6 times its diameter to prevent damage and
maintain performance.
8. Which lowvoltage cable is rated for 100 MHz and is commonly used for Gigabit Ethernet installations?
A. Cat 3
B. Cat 5e
C. Cat 6
D. Coaxial
Answer: C. Cat 6 supports up to 250 MHz and is the standard for Gigabit Ethernet, offering better
performance than Cat 5e.
9. Under NEC Article 725, what is the maximum allowed voltage for a Class 2 powerlimited circuit?
A. 30 V AC or DC
B. 50 V AC or 120 V DC
C. 60 V AC or DC
D. 100 V AC or DC
Answer: A. Class 2 circuits are limited to 30 V (rms) AC or 30 V DC to reduce shock hazard.
10. Which formula correctly expresses Ohm's Law for a DC circuit?
A. P = V × I
B. V = I ÷ R
, C. I = V × R
D. V = I × R
Answer: D. Ohm's Law states that voltage (V) equals current (I) multiplied by resistance (R); V = I × R.
11. Which of the following best describes the primary purpose of grounding in lowvoltage systems?
A. To provide a reference potential for the system
B. To increase the operating voltage
C. To isolate the system from external noise
D. To reduce conductor size requirements
Answer: A. Grounding establishes a common reference potential (usually earth) for all parts of the
system, which enhances safety and helps stabilize the voltage levels.
12. Which component is most commonly used as a grounding electrode in lowvoltage installations?
A. Ground rod
B. Neutral conductor
C. Insulated cable
D. Metal conduit
Answer: A. A ground rod, typically made of copper or galvanized steel, is widely used as a grounding
electrode because it provides a direct connection to the earth.
13. What is the primary difference between grounding and bonding?
A. Grounding provides a lowresistance path to earth; bonding ensures electrical continuity between
metal parts
B. Grounding increases voltage; bonding decreases voltage
C. Grounding isolates circuits; bonding connects circuits
D. There is no significant difference
