Master Electrician Practice Exam – Questions And
Correct Answers (Verified Answers) Plus Rationales
2026 Q&A
What is the minimum size copper grounding electrode conductor required for a
200-amp residential service?
A. #8 AWG
B. #6 AWG
C. #4 AWG
D. #2 AWG
Rationale: NEC Table 250.66 specifies #4 AWG copper for 2/0 AWG copper service
conductors.
2. What is the maximum allowable voltage drop for a branch circuit in a
dwelling unit?
A. 2%
B. 3%
C. 5%
D. 10%
Rationale: NEC recommends no more than 3% voltage drop for branch circuits.
3. What is the standard nominal voltage for a three-phase, four-wire wye
system?
A. 208/240 V
B. 120/208 V
C. 277/480 V
D. 240/480 V
Rationale: A common three-phase wye system provides 120 V to neutral and 208
V phase-to-phase.
,4. What is the color code for the neutral conductor in a 120/208 V system?
A. Red
B. Black
C. White
D. Blue
Rationale: White or gray indicates a grounded (neutral) conductor per NEC 200.6.
5. A motor circuit is rated at 40 A. What size copper conductor (THHN) is
required?
A. #10 AWG
B. #8 AWG
C. #6 AWG
D. #4 AWG
Rationale: NEC Table 310.16 – #8 THHN rated at 50 A (75°C), sufficient for 40 A
continuous load.
6. Which of the following is NOT considered a grounding electrode?
A. Metal underground water pipe
B. Concrete-encased electrode
C. Ground ring
D. Metal building frame not effectively grounded
Rationale: The metal frame must be effectively grounded to qualify per NEC
250.52.
7. What is the minimum burial depth for a rigid metal conduit under a
residential driveway?
A. 6 inches
B. 12 inches
C. 18 inches
, D. 24 inches
Rationale: NEC Table 300.5 requires 18 inches for RMC under a driveway.
8. How often must a metal raceway be supported?
A. Every 3 ft
B. Every 5 ft
C. Every 10 ft
D. Every 12 ft
Rationale: NEC 344.30 requires RMC support within 3 ft of boxes and every 10 ft.
9. What is the maximum overcurrent protection allowed for #12 AWG copper?
A. 15 A
B. 20 A
C. 25 A
D. 30 A
Rationale: NEC 240.4(D) limits #12 AWG copper to 20 A.
10. Which conductor is used as an equipment grounding conductor?
A. Black
B. White
C. Red
D. Green or bare
Rationale: Green or bare conductors are designated for grounding per NEC
250.119.
11. What is the maximum distance between supports for EMT (Electrical
Metallic Tubing)?
A. 3 ft
B. 5 ft
C. 10 ft
Correct Answers (Verified Answers) Plus Rationales
2026 Q&A
What is the minimum size copper grounding electrode conductor required for a
200-amp residential service?
A. #8 AWG
B. #6 AWG
C. #4 AWG
D. #2 AWG
Rationale: NEC Table 250.66 specifies #4 AWG copper for 2/0 AWG copper service
conductors.
2. What is the maximum allowable voltage drop for a branch circuit in a
dwelling unit?
A. 2%
B. 3%
C. 5%
D. 10%
Rationale: NEC recommends no more than 3% voltage drop for branch circuits.
3. What is the standard nominal voltage for a three-phase, four-wire wye
system?
A. 208/240 V
B. 120/208 V
C. 277/480 V
D. 240/480 V
Rationale: A common three-phase wye system provides 120 V to neutral and 208
V phase-to-phase.
,4. What is the color code for the neutral conductor in a 120/208 V system?
A. Red
B. Black
C. White
D. Blue
Rationale: White or gray indicates a grounded (neutral) conductor per NEC 200.6.
5. A motor circuit is rated at 40 A. What size copper conductor (THHN) is
required?
A. #10 AWG
B. #8 AWG
C. #6 AWG
D. #4 AWG
Rationale: NEC Table 310.16 – #8 THHN rated at 50 A (75°C), sufficient for 40 A
continuous load.
6. Which of the following is NOT considered a grounding electrode?
A. Metal underground water pipe
B. Concrete-encased electrode
C. Ground ring
D. Metal building frame not effectively grounded
Rationale: The metal frame must be effectively grounded to qualify per NEC
250.52.
7. What is the minimum burial depth for a rigid metal conduit under a
residential driveway?
A. 6 inches
B. 12 inches
C. 18 inches
, D. 24 inches
Rationale: NEC Table 300.5 requires 18 inches for RMC under a driveway.
8. How often must a metal raceway be supported?
A. Every 3 ft
B. Every 5 ft
C. Every 10 ft
D. Every 12 ft
Rationale: NEC 344.30 requires RMC support within 3 ft of boxes and every 10 ft.
9. What is the maximum overcurrent protection allowed for #12 AWG copper?
A. 15 A
B. 20 A
C. 25 A
D. 30 A
Rationale: NEC 240.4(D) limits #12 AWG copper to 20 A.
10. Which conductor is used as an equipment grounding conductor?
A. Black
B. White
C. Red
D. Green or bare
Rationale: Green or bare conductors are designated for grounding per NEC
250.119.
11. What is the maximum distance between supports for EMT (Electrical
Metallic Tubing)?
A. 3 ft
B. 5 ft
C. 10 ft
