California Electrical Contractor License
Exam (C-10) Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. What is the minimum burial depth for a direct burial cable (Type UF)
under a residential driveway?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
Rationale: According to NEC Table 300.5, the minimum cover for UF cable
under a residential driveway is 18 inches.
2. What is the purpose of a GFCI device?
A. To detect voltage surges
B. To provide arc fault protection
C. To prevent electrical shock from ground faults
D. To prevent short circuits
Rationale: A GFCI (Ground-Fault Circuit Interrupter) detects imbalances in
current and shuts off power to prevent electric shock.
,3. Which of the following is required to be grounded?
A. PVC conduit
B. Wood framing
C. Ceramic insulators
D. Metal electrical enclosures
Rationale: Metal enclosures must be grounded to prevent shock hazard in
case of a fault.
4. What is the maximum overcurrent protection for a 12 AWG copper
conductor with THHN insulation?
A. 15 amps
B. 20 amps
C. 25 amps
D. 30 amps
Rationale: NEC Table 310.16 allows 20 amps for 12 AWG copper with THHN
insulation.
5. What type of circuit breaker is used to protect against both overcurrent
and short circuits?
A. GFCI
B. AFCI
C. Standard thermal-magnetic breaker
D. SPD
Rationale: Thermal-magnetic breakers provide overcurrent and short
circuit protection.
6. How many cubic inches are required for four 12 AWG conductors in a
metal box?
A. 8 cu. in.
B. 8.8 cu. in.
C. 10 cu. in.
D. 12 cu. in.
,Rationale: Each 12 AWG conductor requires 2.25 cu. in.; 4 x 2.25 = 9 cu. in.
rounded up slightly per code allowances.
7. According to NEC, how often must supports be placed for EMT conduit?
A. Every 5 ft
B. Every 10 ft
C. Every 15 ft
D. Every 20 ft
Rationale: EMT must be supported within 3 ft of each box and every 10 ft
along its length (NEC 358.30).
8. A 120/240V single-phase panel supplies 48,000 VA of load. What is the
current on each hot leg?
A. 100 A
B. 200 A
C. 150 A
D. 125 A
Rationale: Current = 48,000 VA ÷ 240 V = 200 A.
9. What is the color code for the high-leg in a 120/240V delta system?
A. Blue
B. White
C. Black
D. Orange
Rationale: NEC 110.15 requires the high-leg to be orange.
10. What is the minimum working clearance in front of a 480V
panelboard?
A. 2 ft
B. 3 ft
C. 4 ft
D. 5 ft
Rationale: NEC 110.26(A)(1) requires 3 ft for up to 600V.
, 11. Which code governs energy efficiency standards in California?
A. Title 22
B. NEC
C. Title 24
D. OSHA
Rationale: Title 24 of the California Code of Regulations addresses energy
efficiency.
12. What type of outlet is required for countertop receptacles in kitchens?
A. Standard
B. GFCI
C. AFCI
D. Labeled
Rationale: NEC 210.8 requires GFCI outlets in kitchens.
13. Which tool is used to measure current in an energized conductor?
A. Ohmmeter
B. Clamp-on ammeter
C. Megger
D. Voltmeter
Rationale: A clamp-on ammeter allows current measurement without
disconnecting the wire.
14. What is the most common residential service entrance rating?
A. 100 A
B. 200 A
C. 300 A
D. 400 A
Rationale: Most modern homes have 200 A service for typical loads.
Exam (C-10) Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the minimum burial depth for a direct burial cable (Type UF)
under a residential driveway?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
Rationale: According to NEC Table 300.5, the minimum cover for UF cable
under a residential driveway is 18 inches.
2. What is the purpose of a GFCI device?
A. To detect voltage surges
B. To provide arc fault protection
C. To prevent electrical shock from ground faults
D. To prevent short circuits
Rationale: A GFCI (Ground-Fault Circuit Interrupter) detects imbalances in
current and shuts off power to prevent electric shock.
,3. Which of the following is required to be grounded?
A. PVC conduit
B. Wood framing
C. Ceramic insulators
D. Metal electrical enclosures
Rationale: Metal enclosures must be grounded to prevent shock hazard in
case of a fault.
4. What is the maximum overcurrent protection for a 12 AWG copper
conductor with THHN insulation?
A. 15 amps
B. 20 amps
C. 25 amps
D. 30 amps
Rationale: NEC Table 310.16 allows 20 amps for 12 AWG copper with THHN
insulation.
5. What type of circuit breaker is used to protect against both overcurrent
and short circuits?
A. GFCI
B. AFCI
C. Standard thermal-magnetic breaker
D. SPD
Rationale: Thermal-magnetic breakers provide overcurrent and short
circuit protection.
6. How many cubic inches are required for four 12 AWG conductors in a
metal box?
A. 8 cu. in.
B. 8.8 cu. in.
C. 10 cu. in.
D. 12 cu. in.
,Rationale: Each 12 AWG conductor requires 2.25 cu. in.; 4 x 2.25 = 9 cu. in.
rounded up slightly per code allowances.
7. According to NEC, how often must supports be placed for EMT conduit?
A. Every 5 ft
B. Every 10 ft
C. Every 15 ft
D. Every 20 ft
Rationale: EMT must be supported within 3 ft of each box and every 10 ft
along its length (NEC 358.30).
8. A 120/240V single-phase panel supplies 48,000 VA of load. What is the
current on each hot leg?
A. 100 A
B. 200 A
C. 150 A
D. 125 A
Rationale: Current = 48,000 VA ÷ 240 V = 200 A.
9. What is the color code for the high-leg in a 120/240V delta system?
A. Blue
B. White
C. Black
D. Orange
Rationale: NEC 110.15 requires the high-leg to be orange.
10. What is the minimum working clearance in front of a 480V
panelboard?
A. 2 ft
B. 3 ft
C. 4 ft
D. 5 ft
Rationale: NEC 110.26(A)(1) requires 3 ft for up to 600V.
, 11. Which code governs energy efficiency standards in California?
A. Title 22
B. NEC
C. Title 24
D. OSHA
Rationale: Title 24 of the California Code of Regulations addresses energy
efficiency.
12. What type of outlet is required for countertop receptacles in kitchens?
A. Standard
B. GFCI
C. AFCI
D. Labeled
Rationale: NEC 210.8 requires GFCI outlets in kitchens.
13. Which tool is used to measure current in an energized conductor?
A. Ohmmeter
B. Clamp-on ammeter
C. Megger
D. Voltmeter
Rationale: A clamp-on ammeter allows current measurement without
disconnecting the wire.
14. What is the most common residential service entrance rating?
A. 100 A
B. 200 A
C. 300 A
D. 400 A
Rationale: Most modern homes have 200 A service for typical loads.
