CALIFORNIA STATE LICENSING BOARD
CSLB C-10 Electrical Contractor
License Exam Test Bank
2026/2027
Official Practice Exam | 2026/2027 Edition
QUESTIONS MINUTES PASSING SCORE RECERTIFICATION
120 150 75% Biannual
TABLE OF CONTENTS
Section 1: Planning, Estimating, and Blueprint Reading (22 Q | Q1-Q22)
Section 2: Wiring and Protection (22 Q | Q23-Q44)
Section 3: Wiring Methods and Materials (22 Q | Q45-Q66)
Section 4: Equipment for General Use (20 Q | Q67-Q86)
Section 5: Special Occupancies and Equipment (18 Q | Q87-Q104)
Section 6: California Laws, Safety, and Business Practices (16 Q | Q105-Q120)
INSTRUCTIONS
This practice exam contains 120 multiple-choice questions divided into six sections. You have 150 minutes
to complete the entire exam. A passing score of 75% (90 correct answers out of 120) is required for
certification. Read each question carefully. Every question begins with a realistic field scenario. Select
the single best answer from the four options provided. Do not spend excessive time on any single question.
Review your work if time permits after completing all questions.
EXAM SECTIONS AND CONTENT AREAS
Section 1: Planning, Estimating, and Blueprint Reading (Q1 - Q22)
Load calculations, service sizing, blueprint symbols, material takeoffs, cost estimating, voltage drop calculations, and project
coordination for electrical construction projects.
Section 2: Wiring and Protection (Q23 - Q44)
NEC Articles 200-285 covering grounding and bonding, overcurrent protection, services, branch circuits, feeders, GFCI/AFCI
requirements, and conductor sizing per NEC tables.
Section 3: Wiring Methods and Materials (Q45 - Q66)
NEC Articles 300-399 covering conduit types and fill calculations, cable types, box fill, support requirements, underground installations,
and raceway selection criteria.
Section 4: Equipment for General Use (Q67 - Q86)
NEC Articles 400-490 covering motors and controllers, transformers, generators, appliances, heating equipment, panelboards,
disconnecting means, and overcurrent protection for equipment.
Section 5: Special Occupancies and Equipment (Q87 - Q104)
NEC Articles 500-695 covering hazardous locations, health care facilities, emergency systems, swimming pools, PV systems, EV
charging, fire alarm systems, and fire pumps.
Section 6: California Laws, Safety, and Business Practices (Q105 - Q120)
Business and Professions Code, CSLB licensing requirements, mechanic's lien laws, Cal/OSHA safety orders, prevailing wage, workers'
compensation, and contract law for California contractors.
SCORING INFORMATION
Total Questions: 120 | Passing Score: 75% | Minimum Correct to Pass: 90 | Time Limit: 150 minutes
Each question is worth one point.
CSLB There is no penalty
C-10 Electrical Exam --for incorrect
2026/2027 answers.
| Passing Unanswered
Score: 75% | Page 0questions count as incorrect.
This practice exam is for study purposes only and is not an official CSLB examination. Content is based on
, Section 1: Planning, Estimating, and Blueprint Reading | 2026/2027
Q1 Question 1 of 120
A contractor is reviewing a set of commercial construction drawings for a new retail building.
The electrical plans show a symbol consisting of a circle with two parallel lines extending
from one side and the letter 'T' inside the circle. This symbol represents which device on the
blueprint?
A. A transformer rated at the kVA indicated by the letter designation inside the symbol
B. A wall-mounted telephone outlet with dual-line capability
C. A thermostat controlling a heating and cooling system in the designated zone
D. A pull box for transitioning between conduit runs on the specified circuit
Correct Answer: A
Rationale:
In standard electrical blueprint symbols, a circle with two parallel lines and a letter inside typically designates a
transformer, with the letter indicating the type or kVA rating. Option A uses a different symbol typically showing a
phone icon; option C uses a distinct thermostat symbol; option D is represented by a rectangular box symbol.
Q2 Question 2 of 120
An electrical contractor is estimating the material cost for a 4,000-square-foot office building.
The general lighting load for commercial buildings is calculated at 1.9 VA per square foot
according to NEC Table 220.12. What is the minimum general lighting load the contractor
must account for in the service calculation?
A. 3,800 VA based on 0.95 VA per square foot for office occupancies
B. 7,600 VA calculated as 4,000 square feet multiplied by 1.9 VA per square foot
C. 4,000 VA calculated at exactly 1 VA per square foot for all commercial occupancies
D. 11,400 VA calculated at 2.85 VA per square foot for high-intensity office use
Correct Answer: B
Rationale:
NEC Table 220.12 specifies a unit load of 1.9 VA per square foot for office buildings, so 4,000 x 1.9 = 7,600 VA is
the correct minimum general lighting load. Option A uses an incorrect unit load; option C applies a round-number
simplification not found in the code; option D uses a fabricated multiplier.
CSLB C-10 Electrical Exam -- 2026/2027 | Passing Score: 75% | Page 1
,Q3 Question 3 of 120
A journeyman electrician is reviewing a one-line diagram for a 480/277V, three-phase,
four-wire service entrance. The diagram shows the main service disconnect rated at 400
amperes. The electrician needs to verify the minimum conductor size for the service
entrance conductors. Using the 75-degree Celsius column of NEC Table 310.16, which
copper conductor size is rated for at least 400 amperes?
A. 500 kcmil copper rated at 380 amperes, which is close enough for the application
B. 400 kcmil copper rated at 335 amperes, acceptable because the breaker will limit current flow
C. 600 kcmil copper rated at 420 amperes in the 75-degree column, providing adequate capacity
for the 400-ampere service
D. 250 kcmil copper rated at 255 amperes, which can be doubled for a three-phase system
Correct Answer: C
Rationale:
Per NEC Table 310.16, 600 kcmil copper is rated at 420 amperes in the 75-degree Celsius column, which meets the
400-ampere requirement. Option A at 380 amperes does not meet the rating; option B at 335 amperes is insufficient;
option D doubles the rating incorrectly because three-phase calculations do not work that way.
Q4 Question 4 of 120
During a job walk-through, the project manager notices that the electrical drawings specify a
200-ampere panelboard on the second floor but the feeder conduit shown on the plans runs
only to the first floor. The most appropriate action for the contractor to take is which of the
following?
A. Install the conduit to the first floor as shown and add a junction box to extend to the second
floor
B. Install the conduit to the second floor as intended and back-charge the engineer for the
change
C. Stop all electrical work on the project until the entire drawing set is re-reviewed
D. Submit a request for information (RFI) to the design engineer to clarify the conduit routing
discrepancy before proceeding with installation
Correct Answer: D
Rationale:
When a discrepancy is found between drawings and field conditions, the contractor should submit an RFI to clarify
before proceeding, preventing costly rework. Option A creates an unauthorized design change; option B involves
unilateral changes without approval; option C is an overreaction that halts unrelated work.
CSLB C-10 Electrical Exam -- 2026/2027 | Passing Score: 75% | Page 2
, Q5 Question 5 of 120
An electrical estimator is calculating the demand load for a multi-family dwelling with 20
dwelling units. According to NEC 220.84, the demand factor for 20 dwelling units is 35
percent applied to the total connected load. If each unit has a calculated load of 8,000 VA,
what is the total demand load for the building after applying the demand factor?
A. 56,000 VA calculated by multiplying 20 units by 8,000 VA by 0.35
B. 160,000 VA which is simply the total connected load without applying any demand factor
C. 80,000 VA calculated by applying a 50 percent demand factor instead of the correct 35
percent
D. 120,000 VA calculated by applying a 25 percent demand factor to the total connected load
Correct Answer: A
Rationale:
Using NEC 220.84 Table, 20 dwelling units have a 35 percent demand factor: 20 x 8,000 x 0.35 = 56,000 VA. Option
B omits the demand factor; option C uses an incorrect 50 percent factor; option D uses an incorrect 25 percent
factor.
Q6 Question 6 of 120
A contractor is reading a site plan that shows a dashed line running from the utility pole to
the building with the notation 'UG 3-4C 1/0 AL.' This notation indicates which underground
installation?
A. An underground run of three 4-conductor cables sized 1/0 AWG aluminum
B. An underground feeder with three phase conductors and one neutral, all 1/0 AWG aluminum,
in a single conduit
C. Three underground conduits each containing four 1/0 AWG aluminum conductors
D. A ground ring consisting of four 1/0 AWG aluminum conductors buried 3 feet deep
Correct Answer: B
Rationale:
The notation 'UG 3-4C 1/0 AL' typically denotes an underground installation with three phase conductors plus one
neutral (4 conductors total) of 1/0 AWG aluminum in one conduit. Option A misreads the conduit configuration;
option B describes three separate conduits; option D describes a grounding electrode, not a service feeder.
CSLB C-10 Electrical Exam -- 2026/2027 | Passing Score: 75% | Page 3
CSLB C-10 Electrical Contractor
License Exam Test Bank
2026/2027
Official Practice Exam | 2026/2027 Edition
QUESTIONS MINUTES PASSING SCORE RECERTIFICATION
120 150 75% Biannual
TABLE OF CONTENTS
Section 1: Planning, Estimating, and Blueprint Reading (22 Q | Q1-Q22)
Section 2: Wiring and Protection (22 Q | Q23-Q44)
Section 3: Wiring Methods and Materials (22 Q | Q45-Q66)
Section 4: Equipment for General Use (20 Q | Q67-Q86)
Section 5: Special Occupancies and Equipment (18 Q | Q87-Q104)
Section 6: California Laws, Safety, and Business Practices (16 Q | Q105-Q120)
INSTRUCTIONS
This practice exam contains 120 multiple-choice questions divided into six sections. You have 150 minutes
to complete the entire exam. A passing score of 75% (90 correct answers out of 120) is required for
certification. Read each question carefully. Every question begins with a realistic field scenario. Select
the single best answer from the four options provided. Do not spend excessive time on any single question.
Review your work if time permits after completing all questions.
EXAM SECTIONS AND CONTENT AREAS
Section 1: Planning, Estimating, and Blueprint Reading (Q1 - Q22)
Load calculations, service sizing, blueprint symbols, material takeoffs, cost estimating, voltage drop calculations, and project
coordination for electrical construction projects.
Section 2: Wiring and Protection (Q23 - Q44)
NEC Articles 200-285 covering grounding and bonding, overcurrent protection, services, branch circuits, feeders, GFCI/AFCI
requirements, and conductor sizing per NEC tables.
Section 3: Wiring Methods and Materials (Q45 - Q66)
NEC Articles 300-399 covering conduit types and fill calculations, cable types, box fill, support requirements, underground installations,
and raceway selection criteria.
Section 4: Equipment for General Use (Q67 - Q86)
NEC Articles 400-490 covering motors and controllers, transformers, generators, appliances, heating equipment, panelboards,
disconnecting means, and overcurrent protection for equipment.
Section 5: Special Occupancies and Equipment (Q87 - Q104)
NEC Articles 500-695 covering hazardous locations, health care facilities, emergency systems, swimming pools, PV systems, EV
charging, fire alarm systems, and fire pumps.
Section 6: California Laws, Safety, and Business Practices (Q105 - Q120)
Business and Professions Code, CSLB licensing requirements, mechanic's lien laws, Cal/OSHA safety orders, prevailing wage, workers'
compensation, and contract law for California contractors.
SCORING INFORMATION
Total Questions: 120 | Passing Score: 75% | Minimum Correct to Pass: 90 | Time Limit: 150 minutes
Each question is worth one point.
CSLB There is no penalty
C-10 Electrical Exam --for incorrect
2026/2027 answers.
| Passing Unanswered
Score: 75% | Page 0questions count as incorrect.
This practice exam is for study purposes only and is not an official CSLB examination. Content is based on
, Section 1: Planning, Estimating, and Blueprint Reading | 2026/2027
Q1 Question 1 of 120
A contractor is reviewing a set of commercial construction drawings for a new retail building.
The electrical plans show a symbol consisting of a circle with two parallel lines extending
from one side and the letter 'T' inside the circle. This symbol represents which device on the
blueprint?
A. A transformer rated at the kVA indicated by the letter designation inside the symbol
B. A wall-mounted telephone outlet with dual-line capability
C. A thermostat controlling a heating and cooling system in the designated zone
D. A pull box for transitioning between conduit runs on the specified circuit
Correct Answer: A
Rationale:
In standard electrical blueprint symbols, a circle with two parallel lines and a letter inside typically designates a
transformer, with the letter indicating the type or kVA rating. Option A uses a different symbol typically showing a
phone icon; option C uses a distinct thermostat symbol; option D is represented by a rectangular box symbol.
Q2 Question 2 of 120
An electrical contractor is estimating the material cost for a 4,000-square-foot office building.
The general lighting load for commercial buildings is calculated at 1.9 VA per square foot
according to NEC Table 220.12. What is the minimum general lighting load the contractor
must account for in the service calculation?
A. 3,800 VA based on 0.95 VA per square foot for office occupancies
B. 7,600 VA calculated as 4,000 square feet multiplied by 1.9 VA per square foot
C. 4,000 VA calculated at exactly 1 VA per square foot for all commercial occupancies
D. 11,400 VA calculated at 2.85 VA per square foot for high-intensity office use
Correct Answer: B
Rationale:
NEC Table 220.12 specifies a unit load of 1.9 VA per square foot for office buildings, so 4,000 x 1.9 = 7,600 VA is
the correct minimum general lighting load. Option A uses an incorrect unit load; option C applies a round-number
simplification not found in the code; option D uses a fabricated multiplier.
CSLB C-10 Electrical Exam -- 2026/2027 | Passing Score: 75% | Page 1
,Q3 Question 3 of 120
A journeyman electrician is reviewing a one-line diagram for a 480/277V, three-phase,
four-wire service entrance. The diagram shows the main service disconnect rated at 400
amperes. The electrician needs to verify the minimum conductor size for the service
entrance conductors. Using the 75-degree Celsius column of NEC Table 310.16, which
copper conductor size is rated for at least 400 amperes?
A. 500 kcmil copper rated at 380 amperes, which is close enough for the application
B. 400 kcmil copper rated at 335 amperes, acceptable because the breaker will limit current flow
C. 600 kcmil copper rated at 420 amperes in the 75-degree column, providing adequate capacity
for the 400-ampere service
D. 250 kcmil copper rated at 255 amperes, which can be doubled for a three-phase system
Correct Answer: C
Rationale:
Per NEC Table 310.16, 600 kcmil copper is rated at 420 amperes in the 75-degree Celsius column, which meets the
400-ampere requirement. Option A at 380 amperes does not meet the rating; option B at 335 amperes is insufficient;
option D doubles the rating incorrectly because three-phase calculations do not work that way.
Q4 Question 4 of 120
During a job walk-through, the project manager notices that the electrical drawings specify a
200-ampere panelboard on the second floor but the feeder conduit shown on the plans runs
only to the first floor. The most appropriate action for the contractor to take is which of the
following?
A. Install the conduit to the first floor as shown and add a junction box to extend to the second
floor
B. Install the conduit to the second floor as intended and back-charge the engineer for the
change
C. Stop all electrical work on the project until the entire drawing set is re-reviewed
D. Submit a request for information (RFI) to the design engineer to clarify the conduit routing
discrepancy before proceeding with installation
Correct Answer: D
Rationale:
When a discrepancy is found between drawings and field conditions, the contractor should submit an RFI to clarify
before proceeding, preventing costly rework. Option A creates an unauthorized design change; option B involves
unilateral changes without approval; option C is an overreaction that halts unrelated work.
CSLB C-10 Electrical Exam -- 2026/2027 | Passing Score: 75% | Page 2
, Q5 Question 5 of 120
An electrical estimator is calculating the demand load for a multi-family dwelling with 20
dwelling units. According to NEC 220.84, the demand factor for 20 dwelling units is 35
percent applied to the total connected load. If each unit has a calculated load of 8,000 VA,
what is the total demand load for the building after applying the demand factor?
A. 56,000 VA calculated by multiplying 20 units by 8,000 VA by 0.35
B. 160,000 VA which is simply the total connected load without applying any demand factor
C. 80,000 VA calculated by applying a 50 percent demand factor instead of the correct 35
percent
D. 120,000 VA calculated by applying a 25 percent demand factor to the total connected load
Correct Answer: A
Rationale:
Using NEC 220.84 Table, 20 dwelling units have a 35 percent demand factor: 20 x 8,000 x 0.35 = 56,000 VA. Option
B omits the demand factor; option C uses an incorrect 50 percent factor; option D uses an incorrect 25 percent
factor.
Q6 Question 6 of 120
A contractor is reading a site plan that shows a dashed line running from the utility pole to
the building with the notation 'UG 3-4C 1/0 AL.' This notation indicates which underground
installation?
A. An underground run of three 4-conductor cables sized 1/0 AWG aluminum
B. An underground feeder with three phase conductors and one neutral, all 1/0 AWG aluminum,
in a single conduit
C. Three underground conduits each containing four 1/0 AWG aluminum conductors
D. A ground ring consisting of four 1/0 AWG aluminum conductors buried 3 feet deep
Correct Answer: B
Rationale:
The notation 'UG 3-4C 1/0 AL' typically denotes an underground installation with three phase conductors plus one
neutral (4 conductors total) of 1/0 AWG aluminum in one conduit. Option A misreads the conduit configuration;
option B describes three separate conduits; option D describes a grounding electrode, not a service feeder.
CSLB C-10 Electrical Exam -- 2026/2027 | Passing Score: 75% | Page 3
