Virginia Master Electrician Exam 2026 – 190 Practice Questions
with Answers & Detailed Rationales, NEC 2023, Electrical Theory,
Wiring & Protection, Wiring Methods, Equipment, Special
Occupancies, Motors & Controls, Code Compliance and Safety
Section 1: General Electrical Knowledge
Questions 1–19
Question 1
A licensed master electrician is designing a feeder for a new commercial building. The
calculated load is 185 amperes. The terminals are rated 75°C, and the ambient temperature
is 40°C. What is the minimum size THWN copper conductor required?
A. 2/0 AWG
B. 3/0 AWG
C. 4/0 AWG
D. 250 kcmil
Correct Answer: C
Explanation: A 185A continuous load requires 125% ampacity (231A). THWN at 75°C is 4/0
AWG (230A base), then apply ambient correction. 4/0 AWG is required after temperature
adjustment.
Question 2
,An electrician is installing a 3-phase, 4-wire feeder to a panelboard in a commercial kitchen.
The calculated demand load is 220 amperes. The terminals are rated 60°C. What is the
minimum size THWN copper conductor?
A. 300 kcmil
B. 350 kcmil
C. 400 kcmil
D. 500 kcmil
Correct Answer: C
Explanation: At 60°C, 220A requires 400 kcmil copper (225A rating). Terminal limitations
govern conductor selection per NEC 110.14(C).
Question 3
Which of the following best describes the purpose of an equipotential bonding grid around a
swimming pool?
A. To provide a low-impedance path for lightning strikes
B. To minimize voltage gradients in the pool area
C. To serve as the required equipment grounding conductor
D. To eliminate the need for GFCI protection
Correct Answer: B
Explanation: Equipotential bonding minimizes voltage differences between conductive
surfaces around pools, reducing shock risk from stray currents per NEC 680.26.
,Question 4
A master electrician is troubleshooting a circuit where the voltage drops excessively when a
large motor starts. Which of the following is the most likely cause?
A. Undersized equipment grounding conductor
B. Loose neutral connection at the panel
C. Undersized branch circuit conductors
D. Incorrectly installed GFCI receptacle
Correct Answer: C
Explanation: Voltage drop during motor starting is typically caused by excessive conductor
impedance. Undersized conductors increase resistance, causing significant voltage drop
under high current.
Question 5
What is the primary function of a surge protective device (SPD) installed at a service
entrance?
A. To protect against sustained overcurrent conditions
B. To limit transient voltage surges from reaching equipment
C. To replace the need for equipment grounding
D. To provide backup power during outages
Correct Answer: B
, Explanation: SPDs limit transient voltage surges (lightning, switching) by diverting excess
energy to ground, protecting downstream equipment per NEC Article 285.
Question 6
A commercial building has a 480V/277V, 3-phase, 4-wire service. The calculated neutral load
is 150 amperes, and the phase conductors are 350 kcmil. What is the minimum size neutral
conductor permitted?
A. 1/0 AWG
B. 2/0 AWG
C. 3/0 AWG
D. 4/0 AWG
Correct Answer: B
Explanation: NEC 220.61 permits neutral reduction only for specific loads. A 150A calculated
neutral requires 2/0 AWG at 75°C per Table 310.16.
Question 7
Which of the following is required when installing a grounding electrode system for a new
service?
A. A single ground rod always satisfies the requirement
B. A supplemental electrode is required if resistance exceeds 25 ohms
C. The grounding electrode conductor must be sized per Table 250.122
D. The water pipe electrode must be supplemented by an additional electrode
with Answers & Detailed Rationales, NEC 2023, Electrical Theory,
Wiring & Protection, Wiring Methods, Equipment, Special
Occupancies, Motors & Controls, Code Compliance and Safety
Section 1: General Electrical Knowledge
Questions 1–19
Question 1
A licensed master electrician is designing a feeder for a new commercial building. The
calculated load is 185 amperes. The terminals are rated 75°C, and the ambient temperature
is 40°C. What is the minimum size THWN copper conductor required?
A. 2/0 AWG
B. 3/0 AWG
C. 4/0 AWG
D. 250 kcmil
Correct Answer: C
Explanation: A 185A continuous load requires 125% ampacity (231A). THWN at 75°C is 4/0
AWG (230A base), then apply ambient correction. 4/0 AWG is required after temperature
adjustment.
Question 2
,An electrician is installing a 3-phase, 4-wire feeder to a panelboard in a commercial kitchen.
The calculated demand load is 220 amperes. The terminals are rated 60°C. What is the
minimum size THWN copper conductor?
A. 300 kcmil
B. 350 kcmil
C. 400 kcmil
D. 500 kcmil
Correct Answer: C
Explanation: At 60°C, 220A requires 400 kcmil copper (225A rating). Terminal limitations
govern conductor selection per NEC 110.14(C).
Question 3
Which of the following best describes the purpose of an equipotential bonding grid around a
swimming pool?
A. To provide a low-impedance path for lightning strikes
B. To minimize voltage gradients in the pool area
C. To serve as the required equipment grounding conductor
D. To eliminate the need for GFCI protection
Correct Answer: B
Explanation: Equipotential bonding minimizes voltage differences between conductive
surfaces around pools, reducing shock risk from stray currents per NEC 680.26.
,Question 4
A master electrician is troubleshooting a circuit where the voltage drops excessively when a
large motor starts. Which of the following is the most likely cause?
A. Undersized equipment grounding conductor
B. Loose neutral connection at the panel
C. Undersized branch circuit conductors
D. Incorrectly installed GFCI receptacle
Correct Answer: C
Explanation: Voltage drop during motor starting is typically caused by excessive conductor
impedance. Undersized conductors increase resistance, causing significant voltage drop
under high current.
Question 5
What is the primary function of a surge protective device (SPD) installed at a service
entrance?
A. To protect against sustained overcurrent conditions
B. To limit transient voltage surges from reaching equipment
C. To replace the need for equipment grounding
D. To provide backup power during outages
Correct Answer: B
, Explanation: SPDs limit transient voltage surges (lightning, switching) by diverting excess
energy to ground, protecting downstream equipment per NEC Article 285.
Question 6
A commercial building has a 480V/277V, 3-phase, 4-wire service. The calculated neutral load
is 150 amperes, and the phase conductors are 350 kcmil. What is the minimum size neutral
conductor permitted?
A. 1/0 AWG
B. 2/0 AWG
C. 3/0 AWG
D. 4/0 AWG
Correct Answer: B
Explanation: NEC 220.61 permits neutral reduction only for specific loads. A 150A calculated
neutral requires 2/0 AWG at 75°C per Table 310.16.
Question 7
Which of the following is required when installing a grounding electrode system for a new
service?
A. A single ground rod always satisfies the requirement
B. A supplemental electrode is required if resistance exceeds 25 ohms
C. The grounding electrode conductor must be sized per Table 250.122
D. The water pipe electrode must be supplemented by an additional electrode
