Contractor Practice Exam |
Questions, Verified Answers
& Detailed Rationales |
Complete Contractor
License Exam Prep Study
Guide | Updated 2026
1.
What is the primary purpose of the National Electrical Code
(NEC)?
A. To provide design recommendations only
B. To establish minimum requirements for electrical safety
C. To determine electrical utility rates
D. To regulate electrical contractor advertising
Correct answer: To establish minimum requirements for
electrical safety
Rationale: The NEC establishes minimum safety
requirements for electrical installations and is intended
to protect people and property from hazards arising
from the use of electricity.
2.
In a 120/240-volt single-phase residential service, what is the
voltage between the two ungrounded conductors?
A. 120 volts
B. 208 volts
C. 240 volts
D. 480 volts
,Correct answer: 240 volts
Rationale: A typical single-phase 120/240-volt system
has 120 volts from either ungrounded conductor to the
neutral and 240 volts between the two ungrounded
conductors.
3.
What is the general rule for identifying a grounded conductor?
A. Green
B. White or gray
C. Orange
D. Red
Correct answer: White or gray
Rationale: The NEC generally requires grounded
conductors to be identified by white or gray insulation
or by an appropriate marking method permitted by the
Code.
4.
What color is normally used to identify an equipment grounding
conductor?
A. White
B. Gray
C. Green or bare
D. Red
Correct answer: Green or bare
Rationale: Equipment grounding conductors are
generally identified by green insulation, a green stripe,
or are permitted to be bare depending on the wiring
method.
5.
What is the purpose of an equipment grounding conductor?
,A. To increase circuit voltage
B. To provide a low-impedance path for fault current
C. To carry normal neutral current
D. To reduce conductor resistance
Correct answer: To provide a low-impedance path for
fault current
Rationale: The equipment grounding path allows fault
current to return to the source quickly enough to
operate the overcurrent protective device.
6.
What is the maximum general-purpose branch-circuit rating
commonly associated with 14 AWG copper conductors?
A. 15 amperes
B. 20 amperes
C. 25 amperes
D. 30 amperes
Correct answer: 15 amperes
Rationale: Under the normal ampacity rules, 14 AWG
copper conductors are protected at no more than 15
amperes unless a specific Code rule provides otherwise.
7.
What is the common maximum overcurrent protection for 12
AWG copper conductors?
A. 15 amperes
B. 20 amperes
C. 30 amperes
D. 40 amperes
Correct answer: 20 amperes
Rationale: The standard ampacity rule permits 12 AWG
copper conductors to be protected at 20 amperes,
subject to applicable NEC requirements and exceptions.
, 8.
What is the common maximum overcurrent protection for 10
AWG copper conductors?
A. 20 amperes
B. 25 amperes
C. 30 amperes
D. 40 amperes
Correct answer: 30 amperes
Rationale: The standard ampacity of 10 AWG copper
conductors is commonly protected at 30 amperes,
subject to the applicable temperature, equipment, and
adjustment rules.
9.
What does ampacity mean?
A. The resistance of a conductor
B. The maximum current a conductor can carry continuously
under specified conditions
C. The voltage rating of a circuit
D. The physical diameter of a conductor
Correct answer: The maximum current a conductor can
carry continuously under specified conditions
Rationale: Ampacity is the current-carrying capacity of a
conductor under the conditions of use specified by the
NEC.
10.
Which NEC article primarily covers branch circuits?
A. Article 110
B. Article 210
C. Article 250
D. Article 430
Correct answer: Article 210