Electrical Contractor Licensing Exam
Questions and Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which of the following is the primary purpose of a grounding
electrode in an electrical system?
A. To reduce the voltage in a circuit
B. To prevent short circuits
C. To provide a low-resistance path to earth for fault currents
D. To increase current flow
Rationale: The grounding electrode ensures that any fault current has
a direct path to the earth, reducing the risk of shock and equipment
damage.
2. According to the National Electrical Code (NEC), which conductor
is typically used for grounding?
A. Black
, B. Red
C. Green or bare copper
D. White
Rationale: NEC specifies that green or bare conductors are used
exclusively for grounding to clearly distinguish them from current-
carrying conductors.
3. What is the maximum allowable voltage drop for feeders and
branch circuits in a commercial electrical system?
A. 1%
B. 2%
C. 3%
D. 5%
Rationale: The NEC recommends that the combined voltage drop of
feeders and branch circuits not exceed 5% to ensure adequate voltage
for proper operation of equipment.
4. Which type of circuit breaker provides protection against both
overcurrent and short circuits?
A. Ground-fault circuit interrupter
B. Standard thermal-magnetic circuit breaker
C. Arc-fault circuit interrupter
D. Fusible link
,Rationale: Thermal-magnetic breakers protect against overloads
(thermal) and short circuits (magnetic) in a single device.
5. What is the purpose of an arc-fault circuit interrupter (AFCI)?
A. Protects against overvoltage
B. Prevents fires caused by arcing faults in branch circuits
C. Reduces harmonic distortion
D. Serves as a ground-fault protector
Rationale: AFCIs detect unintended arcing, which can ignite
combustible materials, providing enhanced fire safety.
6. Which NEC article covers the installation of receptacles in dwelling
units?
A. 210
B. 210
C. 230
D. 240
Rationale: Article 210 details branch circuits, including receptacle
spacing and installation requirements in residential units.
7. For a residential 15-amp branch circuit, what is the minimum size
of copper wire allowed?
A. 10 AWG
B. 12 AWG
, C. 14 AWG
D. 16 AWG
Rationale: NEC specifies 14 AWG copper for 15-amp circuits to safely
handle expected current without overheating.
8. Which type of conduit is typically required for outdoor direct
burial applications?
A. EMT
B. PVC Schedule 40 or 80
C. FMC
D. IMC
Rationale: PVC conduit is non-corrosive, suitable for direct burial, and
protects wiring in outdoor environments.
9. A 240-volt single-phase motor is rated at 20 amps. What minimum
size conductor should be used assuming copper wire?
A. 10 AWG
B. 8 AWG
C. 6 AWG
D. 4 AWG
Rationale: NEC requires sizing conductors for continuous loads and
starting currents; a 20-amp motor at 240V generally requires 6 AWG
copper for safety and voltage drop considerations.
Questions and Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which of the following is the primary purpose of a grounding
electrode in an electrical system?
A. To reduce the voltage in a circuit
B. To prevent short circuits
C. To provide a low-resistance path to earth for fault currents
D. To increase current flow
Rationale: The grounding electrode ensures that any fault current has
a direct path to the earth, reducing the risk of shock and equipment
damage.
2. According to the National Electrical Code (NEC), which conductor
is typically used for grounding?
A. Black
, B. Red
C. Green or bare copper
D. White
Rationale: NEC specifies that green or bare conductors are used
exclusively for grounding to clearly distinguish them from current-
carrying conductors.
3. What is the maximum allowable voltage drop for feeders and
branch circuits in a commercial electrical system?
A. 1%
B. 2%
C. 3%
D. 5%
Rationale: The NEC recommends that the combined voltage drop of
feeders and branch circuits not exceed 5% to ensure adequate voltage
for proper operation of equipment.
4. Which type of circuit breaker provides protection against both
overcurrent and short circuits?
A. Ground-fault circuit interrupter
B. Standard thermal-magnetic circuit breaker
C. Arc-fault circuit interrupter
D. Fusible link
,Rationale: Thermal-magnetic breakers protect against overloads
(thermal) and short circuits (magnetic) in a single device.
5. What is the purpose of an arc-fault circuit interrupter (AFCI)?
A. Protects against overvoltage
B. Prevents fires caused by arcing faults in branch circuits
C. Reduces harmonic distortion
D. Serves as a ground-fault protector
Rationale: AFCIs detect unintended arcing, which can ignite
combustible materials, providing enhanced fire safety.
6. Which NEC article covers the installation of receptacles in dwelling
units?
A. 210
B. 210
C. 230
D. 240
Rationale: Article 210 details branch circuits, including receptacle
spacing and installation requirements in residential units.
7. For a residential 15-amp branch circuit, what is the minimum size
of copper wire allowed?
A. 10 AWG
B. 12 AWG
, C. 14 AWG
D. 16 AWG
Rationale: NEC specifies 14 AWG copper for 15-amp circuits to safely
handle expected current without overheating.
8. Which type of conduit is typically required for outdoor direct
burial applications?
A. EMT
B. PVC Schedule 40 or 80
C. FMC
D. IMC
Rationale: PVC conduit is non-corrosive, suitable for direct burial, and
protects wiring in outdoor environments.
9. A 240-volt single-phase motor is rated at 20 amps. What minimum
size conductor should be used assuming copper wire?
A. 10 AWG
B. 8 AWG
C. 6 AWG
D. 4 AWG
Rationale: NEC requires sizing conductors for continuous loads and
starting currents; a 20-amp motor at 240V generally requires 6 AWG
copper for safety and voltage drop considerations.
