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California C-10 Electrical Contractor License Exam ACTUAL
EXAM COMPLETE QUESTIONS AND DETAILED SOLUTIONS
LATEST UPDATE THIS YEAR-JUST RELEASED
SUMMARIZED EXAM COVERAGE (ALL CONTENTS COVERED)
The California C-10 Electrical Contractor License Exam tests knowledge of CSLB contractor law, business
practices, estimating, contracts, safety compliance, and California Electrical Code requirements. It
includes electrical theory, conductor sizing, voltage drop, grounding and bonding, load calculations,
service and feeder sizing, motor circuits, lighting systems, fire alarm and low-voltage wiring, wiring
methods, blueprint reading, troubleshooting, and Cal-OSHA electrical safety practices such as
lockout/tagout and arc flash awareness.
1.
A contractor advertises electrical services on a truck but does not display the CSLB license number. What
is the most likely consequence?
A. No consequence because vehicle advertising is exempt
B. CSLB disciplinary action and possible fines for advertising violations
C. Only a verbal warning from the city inspector
D. The contractor automatically loses their contractor bond
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Answer: B
Rationale: California law requires contractors to display the license number on advertising, including
vehicles.
2.
A homeowner requests additional recessed lights not included in the original contract. What is the best
legal method to proceed?
A. Install lights and bill later based on verbal agreement
B. Prepare a written change order describing work and cost before starting
C. Tell homeowner to pay cash to avoid documentation
D. Refuse because changes are never allowed once contract is signed
Answer: B
Rationale: Written change orders protect both parties and are required for proper contract compliance.
3.
An electrician measures 120 volts at a receptacle but the device plugged in will not operate. What
should be checked next?
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A. Replace the breaker immediately without testing
B. Check for loose neutral connection or voltage drop under load
C. Assume the device is defective and stop troubleshooting
D. Increase breaker size to provide more current
Answer: B
Rationale: Loose neutrals or voltage drop can show correct voltage with no load but fail under load.
4.
A contractor installs a subpanel and bonds the neutral bar to the enclosure. What is the major problem?
A. It reduces voltage drop in the system
B. It creates parallel neutral paths and improper grounding conditions
C. It improves grounding for branch circuits
D. It is required by NEC for all panels
Answer: B
Rationale: Neutrals must be isolated in subpanels to prevent objectionable current on grounding
conductors.
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5.
A 20-amp branch circuit is supplying continuous lighting load of 18 amps for more than three hours.
What is the correct NEC issue?
A. No issue because breaker rating is 20 amps
B. Circuit is overloaded because continuous loads must not exceed 80% of breaker rating
C. Circuit must use aluminum wire instead of copper
D. Circuit must be changed to a 15-amp breaker
Answer: B
Rationale: Continuous loads must be limited to 80% of breaker capacity, meaning 20A circuit supports
only 16A continuous.
6.
A contractor installs receptacles near a kitchen sink but does not use GFCI protection. What code
requirement is violated?
A. AFCI requirements only
B. GFCI protection requirement for receptacles serving countertop surfaces
C. Neutral isolation requirements
D. Box fill requirements
California C-10 Electrical Contractor License Exam ACTUAL
EXAM COMPLETE QUESTIONS AND DETAILED SOLUTIONS
LATEST UPDATE THIS YEAR-JUST RELEASED
SUMMARIZED EXAM COVERAGE (ALL CONTENTS COVERED)
The California C-10 Electrical Contractor License Exam tests knowledge of CSLB contractor law, business
practices, estimating, contracts, safety compliance, and California Electrical Code requirements. It
includes electrical theory, conductor sizing, voltage drop, grounding and bonding, load calculations,
service and feeder sizing, motor circuits, lighting systems, fire alarm and low-voltage wiring, wiring
methods, blueprint reading, troubleshooting, and Cal-OSHA electrical safety practices such as
lockout/tagout and arc flash awareness.
1.
A contractor advertises electrical services on a truck but does not display the CSLB license number. What
is the most likely consequence?
A. No consequence because vehicle advertising is exempt
B. CSLB disciplinary action and possible fines for advertising violations
C. Only a verbal warning from the city inspector
D. The contractor automatically loses their contractor bond
, Page 2 of 124
Answer: B
Rationale: California law requires contractors to display the license number on advertising, including
vehicles.
2.
A homeowner requests additional recessed lights not included in the original contract. What is the best
legal method to proceed?
A. Install lights and bill later based on verbal agreement
B. Prepare a written change order describing work and cost before starting
C. Tell homeowner to pay cash to avoid documentation
D. Refuse because changes are never allowed once contract is signed
Answer: B
Rationale: Written change orders protect both parties and are required for proper contract compliance.
3.
An electrician measures 120 volts at a receptacle but the device plugged in will not operate. What
should be checked next?
, Page 3 of 124
A. Replace the breaker immediately without testing
B. Check for loose neutral connection or voltage drop under load
C. Assume the device is defective and stop troubleshooting
D. Increase breaker size to provide more current
Answer: B
Rationale: Loose neutrals or voltage drop can show correct voltage with no load but fail under load.
4.
A contractor installs a subpanel and bonds the neutral bar to the enclosure. What is the major problem?
A. It reduces voltage drop in the system
B. It creates parallel neutral paths and improper grounding conditions
C. It improves grounding for branch circuits
D. It is required by NEC for all panels
Answer: B
Rationale: Neutrals must be isolated in subpanels to prevent objectionable current on grounding
conductors.
, Page 4 of 124
5.
A 20-amp branch circuit is supplying continuous lighting load of 18 amps for more than three hours.
What is the correct NEC issue?
A. No issue because breaker rating is 20 amps
B. Circuit is overloaded because continuous loads must not exceed 80% of breaker rating
C. Circuit must use aluminum wire instead of copper
D. Circuit must be changed to a 15-amp breaker
Answer: B
Rationale: Continuous loads must be limited to 80% of breaker capacity, meaning 20A circuit supports
only 16A continuous.
6.
A contractor installs receptacles near a kitchen sink but does not use GFCI protection. What code
requirement is violated?
A. AFCI requirements only
B. GFCI protection requirement for receptacles serving countertop surfaces
C. Neutral isolation requirements
D. Box fill requirements
