CSLB C-10 ELECTRICAL CONTRACTOR LICENSE EXAM 300
ACTUAL QUESTIONS AND CORRECT ANSWERS WITH
RATIONALE ALREADY GRADED A+ NEW!!!!!!!!!!!!!!!!!!!!!
The CSLB C-10 Electrical Contractor License Exam is the comprehensive
licensing examination required by the Contractors State License Board to
become a certified electrical contractor in California. The exam is divided into
two separate, closed-book tests: the Law and Business exam and the Trade
exam. Candidates must pass both exams with a score of 72% or higher, with
each containing 115 questions and a 3.5-hour time limit. The Trade exam
covers planning and estimating, rough wiring, finish wiring, startup and
troubleshooting, and safety. The Law and Business exam covers contract law,
lien procedures, employment regulations, and business management.
Applicants must also meet experience requirements, file a bond, and pass the
California Asbestos Open-Book Exam for licensure.
1. What is the minimum number of receptacles required in a residential garage?
A) 1
B) 2
C) 3
D) 4
Correct Answer: A
Rationale: According to NEC requirements, at least one receptacle outlet must be
installed in each garage for general use. This ensures basic electrical accessibility
in the garage space .
2. Mobile home service equipment shall be installed in line of sight and no more
than what distance from the exterior wall of the home?
A) 15 feet
B) 30 feet
C) 45 feet
D) 60 feet
Correct Answer: B
,Rationale: Mobile home service equipment must be within 30 feet of the exterior
wall of the home to ensure accessibility and safety for disconnecting the service in
an emergency .
3. What is the minimum clearance required for a service conductor operating
between 300V and 600V in residential and commercial areas not subject to traffic?
A) 10 feet
B) 12 feet
C) 15 feet
D) 18 feet
Correct Answer: B
Rationale: Service conductors operating between 300V and 600V must maintain a
minimum clearance of 12 feet in areas not subject to vehicular traffic to ensure
safety from accidental contact .
4. Which of the following applies to solar modules, metal frames, and metal
mounting equipment on a roof-mounted PV system?
A) They must be weatherproof
B) They must be wind resistant
C) They must be anodized aluminum
D) They must be bonded and grounded
Correct Answer: D
Rationale: All metal components of a photovoltaic system, including modules,
frames, and mounting equipment, must be bonded and grounded for electrical
safety and NEC 690 compliance .
5. What must be considered when selecting a replacement for a defective branch
circuit breaker?
A) The frame type, AIC rating, and ampacity
B) A circuit breaker with higher ampacity
C) A circuit breaker with a higher AIC rating
D) The frame type, UL rating, and color
Correct Answer: A
Rationale: The replacement breaker must match the original's frame type, AIC
(Ampere Interrupting Capacity) rating, and ampacity to ensure safe and reliable
operation .
6. What is the maximum distance from any point of a work area to a fire
extinguisher?
A) 25 feet
,B) 50 feet
C) 75 feet
D) 150 feet
Correct Answer: C
Rationale: OSHA and Cal/OSHA regulations require that fire extinguishers be
located no more than 75 feet from any p oint in a work area to ensure rapid access
in an emergency .
7. If a service conductor is over 300V but less than 600V, what is the minimum
clearance over residential and commercial areas subject to traffic?
A) 15 feet
B) 18 feet
C) 20 feet
D) 25 feet
Correct Answer: B
Rationale: Service conductors operating in this voltage range must maintain a
clearance of at least 18 feet over areas subject to vehicular traffic to prevent
accidental contact with vehicles .
8. What is the allowable ampacity of a #12 AWG copper conductor with 60°C
insulation?
A) 15 amps
B) 20 amps
C) 25 amps
D) 30 amps
Correct Answer: B
Rationale: According to NEC Table 310.16, a #12 AWG copper conductor with
60°C insulation has an ampacity of 20 amps. This is the standard rating for
general-purpose branch circuits .
9. According to the NEC, what is the maximum allowable fill for a conduit
containing more than two conductors?
A) 30%
B) 40%
C) 50%
D) 60%
Correct Answer: B
Rationale: NEC Chapter 9, Table 1 limits conduit fill to 40% for three or more
conductors to allow for proper heat dissipation and ease of pulling .
, 10. What is the minimum size Equipment Grounding Conductor (EGC) required
for a 100-amp branch circuit?
A) #10 AWG
B) #8 AWG
C) #6 AWG
D) #4 AWG
Correct Answer: B
Rationale: According to NEC Table 250.122, a 100-amp overcurrent device
requires a minimum #8 AWG equipment grounding conductor for copper
installations .
11. What is the required clearance for a service drop over a residential driveway?
A) 10 feet
B) 12 feet
C) 15 feet
D) 18 feet
Correct Answer: B
Rationale: Service drops must maintain a minimum clearance of 12 feet over
residential driveways to ensure safe passage of vehicles .
12. Which NEC article covers grounding and bonding requirements?
A) Article 210
B) Article 220
C) Article 240
D) Article 250
Correct Answer: D
Rationale: NEC Article 250 contains the comprehensive requirements for
grounding and bonding of electrical systems, including equipment grounding
conductors, grounding electrode systems, and bonding jumpers .
13. What is the maximum number of conductors permitted in a 4-inch square box
with a volume of 21 cubic inches?
A) 6
B) 8
C) 10
D) 12
Correct Answer: C
Rationale: Box fill calculations require summing the volume allowances for all
conductors, devices, and fittings. A 21 cubic inch box can accommodate up to 10
#14 AWG conductors based on the 2.0 cubic inches per conductor allowance .
ACTUAL QUESTIONS AND CORRECT ANSWERS WITH
RATIONALE ALREADY GRADED A+ NEW!!!!!!!!!!!!!!!!!!!!!
The CSLB C-10 Electrical Contractor License Exam is the comprehensive
licensing examination required by the Contractors State License Board to
become a certified electrical contractor in California. The exam is divided into
two separate, closed-book tests: the Law and Business exam and the Trade
exam. Candidates must pass both exams with a score of 72% or higher, with
each containing 115 questions and a 3.5-hour time limit. The Trade exam
covers planning and estimating, rough wiring, finish wiring, startup and
troubleshooting, and safety. The Law and Business exam covers contract law,
lien procedures, employment regulations, and business management.
Applicants must also meet experience requirements, file a bond, and pass the
California Asbestos Open-Book Exam for licensure.
1. What is the minimum number of receptacles required in a residential garage?
A) 1
B) 2
C) 3
D) 4
Correct Answer: A
Rationale: According to NEC requirements, at least one receptacle outlet must be
installed in each garage for general use. This ensures basic electrical accessibility
in the garage space .
2. Mobile home service equipment shall be installed in line of sight and no more
than what distance from the exterior wall of the home?
A) 15 feet
B) 30 feet
C) 45 feet
D) 60 feet
Correct Answer: B
,Rationale: Mobile home service equipment must be within 30 feet of the exterior
wall of the home to ensure accessibility and safety for disconnecting the service in
an emergency .
3. What is the minimum clearance required for a service conductor operating
between 300V and 600V in residential and commercial areas not subject to traffic?
A) 10 feet
B) 12 feet
C) 15 feet
D) 18 feet
Correct Answer: B
Rationale: Service conductors operating between 300V and 600V must maintain a
minimum clearance of 12 feet in areas not subject to vehicular traffic to ensure
safety from accidental contact .
4. Which of the following applies to solar modules, metal frames, and metal
mounting equipment on a roof-mounted PV system?
A) They must be weatherproof
B) They must be wind resistant
C) They must be anodized aluminum
D) They must be bonded and grounded
Correct Answer: D
Rationale: All metal components of a photovoltaic system, including modules,
frames, and mounting equipment, must be bonded and grounded for electrical
safety and NEC 690 compliance .
5. What must be considered when selecting a replacement for a defective branch
circuit breaker?
A) The frame type, AIC rating, and ampacity
B) A circuit breaker with higher ampacity
C) A circuit breaker with a higher AIC rating
D) The frame type, UL rating, and color
Correct Answer: A
Rationale: The replacement breaker must match the original's frame type, AIC
(Ampere Interrupting Capacity) rating, and ampacity to ensure safe and reliable
operation .
6. What is the maximum distance from any point of a work area to a fire
extinguisher?
A) 25 feet
,B) 50 feet
C) 75 feet
D) 150 feet
Correct Answer: C
Rationale: OSHA and Cal/OSHA regulations require that fire extinguishers be
located no more than 75 feet from any p oint in a work area to ensure rapid access
in an emergency .
7. If a service conductor is over 300V but less than 600V, what is the minimum
clearance over residential and commercial areas subject to traffic?
A) 15 feet
B) 18 feet
C) 20 feet
D) 25 feet
Correct Answer: B
Rationale: Service conductors operating in this voltage range must maintain a
clearance of at least 18 feet over areas subject to vehicular traffic to prevent
accidental contact with vehicles .
8. What is the allowable ampacity of a #12 AWG copper conductor with 60°C
insulation?
A) 15 amps
B) 20 amps
C) 25 amps
D) 30 amps
Correct Answer: B
Rationale: According to NEC Table 310.16, a #12 AWG copper conductor with
60°C insulation has an ampacity of 20 amps. This is the standard rating for
general-purpose branch circuits .
9. According to the NEC, what is the maximum allowable fill for a conduit
containing more than two conductors?
A) 30%
B) 40%
C) 50%
D) 60%
Correct Answer: B
Rationale: NEC Chapter 9, Table 1 limits conduit fill to 40% for three or more
conductors to allow for proper heat dissipation and ease of pulling .
, 10. What is the minimum size Equipment Grounding Conductor (EGC) required
for a 100-amp branch circuit?
A) #10 AWG
B) #8 AWG
C) #6 AWG
D) #4 AWG
Correct Answer: B
Rationale: According to NEC Table 250.122, a 100-amp overcurrent device
requires a minimum #8 AWG equipment grounding conductor for copper
installations .
11. What is the required clearance for a service drop over a residential driveway?
A) 10 feet
B) 12 feet
C) 15 feet
D) 18 feet
Correct Answer: B
Rationale: Service drops must maintain a minimum clearance of 12 feet over
residential driveways to ensure safe passage of vehicles .
12. Which NEC article covers grounding and bonding requirements?
A) Article 210
B) Article 220
C) Article 240
D) Article 250
Correct Answer: D
Rationale: NEC Article 250 contains the comprehensive requirements for
grounding and bonding of electrical systems, including equipment grounding
conductors, grounding electrode systems, and bonding jumpers .
13. What is the maximum number of conductors permitted in a 4-inch square box
with a volume of 21 cubic inches?
A) 6
B) 8
C) 10
D) 12
Correct Answer: C
Rationale: Box fill calculations require summing the volume allowances for all
conductors, devices, and fittings. A 21 cubic inch box can accommodate up to 10
#14 AWG conductors based on the 2.0 cubic inches per conductor allowance .
