Page 1 of 153
CALIFORNIA C-10 ELECTRICAL CONTRACTOR
LICENSE EXAM Practice Questions With
Verified Answers & Rationales LATEST UPDATE
THIS YEAR
CALIFORNIA C-10 ELECTRICAL CONTRACTOR LICENSE EXAM
250 Practice Questions & Rationales
SUMMARIZED EXAM COVERAGE
Exam Structure – Five major sections: Planning & Estimating (28%), Rough Wiring (27%), Finish
Wiring & Trim (11%), Startup/Troubleshooting (16%), Safety (18%)
Planning & Estimating – System evaluation, plan interpretation, electrical calculations, code
requirements, material selection, energy production/storage project planning (PV, wind,
generators, batteries, capacitors)
Rough Wiring – System layout, clearance and accessibility requirements, conduit and panel
installation, cable and equipment installation, grounding and bonding
Finish Wiring & Trim – Device placement and installation, motor and equipment installation,
cable and equipment labeling, trim and sealants
Startup & Troubleshooting – System energization and testing, common electrical problems,
locating/repairing/replacing inoperable components, test equipment selection and use
Safety – Lockout/tagout procedures, Personal Protective Equipment (PPE), tools and
equipment, hazardous materials and workplace environments
Key References – National Electrical Code (NEC), California Electrical Code (Title 24), OSHA
requirements, California Building Standards Code
Exam Format – Multiple-choice, four choices per question, closed-book, calculator provided
Licensing Authority – California Contractors State License Board (CSLB)
SECTION 1: PLANNING & ESTIMATING (Questions 1-70)
1. What is the minimum working clearance required in front of a 480-volt electrical panel?
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A) 24 inches
B) 30 inches
C) 36 inches
D) 48 inches
Answer: C
NEC 110.26(A)(1) requires a minimum working clearance of 36 inches (3 feet) in front of
electrical equipment operating at 600 volts or less. This ensures safe access for maintenance
and emergency shutdown.
2. A contractor needs 13 receptacles that cost $3.56 each plus sales tax of 7.25%. The supplier
offers one free receptacle for every 10 purchased. What is the total cost?
A) $42.02
B) $42.72
C) $45.82
D) $49.66
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Answer: C
For 13 receptacles, 1 is free (for every 10 purchased), so 12 are paid. Cost = 12 × $3.56 = $42.72.
Tax = $42.72 × 0.0725 = $3.10. Total = $45.82.
3. What is the minimum burial depth for PVC conduit containing 120-volt circuits under a
residential driveway?
A) 6 inches
B) 12 inches
C) 18 inches
D) 24 inches
Answer: C
NEC Table 300.5 requires a minimum burial depth of 18 inches for PVC conduit under driveways
with branch circuits rated 600 volts or less. This protects the conduit from physical damage.
4. Voltage drop in a wire is a function of which of the following?
, Page 4 of 153
A) Wire gauge only
B) Length of wire only
C) Wire gauge and length of wire
D) Temperature only
Answer: C
Voltage drop is a function of both wire gauge (resistance per unit length) and the total length of
the wire. Longer runs and smaller gauge wires increase voltage drop.
5. 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
CALIFORNIA C-10 ELECTRICAL CONTRACTOR
LICENSE EXAM Practice Questions With
Verified Answers & Rationales LATEST UPDATE
THIS YEAR
CALIFORNIA C-10 ELECTRICAL CONTRACTOR LICENSE EXAM
250 Practice Questions & Rationales
SUMMARIZED EXAM COVERAGE
Exam Structure – Five major sections: Planning & Estimating (28%), Rough Wiring (27%), Finish
Wiring & Trim (11%), Startup/Troubleshooting (16%), Safety (18%)
Planning & Estimating – System evaluation, plan interpretation, electrical calculations, code
requirements, material selection, energy production/storage project planning (PV, wind,
generators, batteries, capacitors)
Rough Wiring – System layout, clearance and accessibility requirements, conduit and panel
installation, cable and equipment installation, grounding and bonding
Finish Wiring & Trim – Device placement and installation, motor and equipment installation,
cable and equipment labeling, trim and sealants
Startup & Troubleshooting – System energization and testing, common electrical problems,
locating/repairing/replacing inoperable components, test equipment selection and use
Safety – Lockout/tagout procedures, Personal Protective Equipment (PPE), tools and
equipment, hazardous materials and workplace environments
Key References – National Electrical Code (NEC), California Electrical Code (Title 24), OSHA
requirements, California Building Standards Code
Exam Format – Multiple-choice, four choices per question, closed-book, calculator provided
Licensing Authority – California Contractors State License Board (CSLB)
SECTION 1: PLANNING & ESTIMATING (Questions 1-70)
1. What is the minimum working clearance required in front of a 480-volt electrical panel?
,Page 2 of 153
A) 24 inches
B) 30 inches
C) 36 inches
D) 48 inches
Answer: C
NEC 110.26(A)(1) requires a minimum working clearance of 36 inches (3 feet) in front of
electrical equipment operating at 600 volts or less. This ensures safe access for maintenance
and emergency shutdown.
2. A contractor needs 13 receptacles that cost $3.56 each plus sales tax of 7.25%. The supplier
offers one free receptacle for every 10 purchased. What is the total cost?
A) $42.02
B) $42.72
C) $45.82
D) $49.66
,Page 3 of 153
Answer: C
For 13 receptacles, 1 is free (for every 10 purchased), so 12 are paid. Cost = 12 × $3.56 = $42.72.
Tax = $42.72 × 0.0725 = $3.10. Total = $45.82.
3. What is the minimum burial depth for PVC conduit containing 120-volt circuits under a
residential driveway?
A) 6 inches
B) 12 inches
C) 18 inches
D) 24 inches
Answer: C
NEC Table 300.5 requires a minimum burial depth of 18 inches for PVC conduit under driveways
with branch circuits rated 600 volts or less. This protects the conduit from physical damage.
4. Voltage drop in a wire is a function of which of the following?
, Page 4 of 153
A) Wire gauge only
B) Length of wire only
C) Wire gauge and length of wire
D) Temperature only
Answer: C
Voltage drop is a function of both wire gauge (resistance per unit length) and the total length of
the wire. Longer runs and smaller gauge wires increase voltage drop.
5. 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
