Examination — Local Jurisdiction
Practice Exam 2026 | 100 Questions &
Answers with Detailed Rationales |
Complete Exam Prep & Study Guide
1.
A 120/240-volt, single-phase dwelling service has a calculated load of 150
amperes. The service conductors are copper and installed under the conditions
permitted by the applicable NEC dwelling-service provisions. Which minimum
conductor ampacity is generally required when the dwelling-service conductor
allowance applies?
A. 125 A
B. 150 A
C. 175 A
D. 200 A
Answer: B. 150 A
,Rationale: The dwelling-service conductor provisions permit certain reductions
from standard conductor sizing when the specified conditions are satisfied. The
calculated service load still establishes the minimum required ampacity.
2.
A 120/240-volt multiwire branch circuit supplies two 120-volt loads from opposite
legs. What happens to the neutral current when the two loads are equal and
properly connected to opposite ungrounded conductors?
A. It doubles
B. It equals one of the phase currents
C. It is approximately zero
D. It becomes the equipment grounding conductor current
Answer: C. It is approximately zero
Rationale: In a properly connected single-phase multiwire branch circuit, the
neutral carries only the imbalance between the two opposite-phase currents.
Equal loads therefore produce essentially zero neutral current.
3.
A 20-ampere, 120-volt branch circuit supplies several receptacles in a commercial
occupancy. Which conductor is generally required for the ungrounded circuit
conductor under normal copper-conductor conditions?
A. 16 AWG
B. 14 AWG
C. 12 AWG
D. 10 AWG
Answer: C. 12 AWG
,Rationale: A 20-ampere branch circuit normally requires a conductor with an
ampacity of at least 20 amperes. Copper 12 AWG is the standard minimum
conductor size in typical installations.
4.
A conductor is rated 90°C but is terminated on equipment whose terminals are
limited to 75°C. Which temperature rating generally controls the final conductor
ampacity adjustment?
A. 60°C
B. 75°C
C. 90°C
D. 105°C
Answer: B. 75°C
Rationale: Equipment termination temperature limitations must be observed.
The 90°C rating can be useful for adjustment and correction calculations where
permitted, but the final ampacity cannot exceed the terminal limitation.
5.
An electrician installs three current-carrying conductors in a raceway. Under
normal conditions, what adjustment factor applies solely because of the number
of current-carrying conductors?
A. 70%
B. 80%
C. 90%
D. No adjustment is required solely for three current-carrying conductors
Answer: D. No adjustment is required solely for three current-carrying
conductors
, Rationale: The NEC adjustment-factor table begins requiring ampacity
adjustment when the number of current-carrying conductors exceeds the
specified threshold. Three current-carrying conductors do not trigger an
adjustment by themselves.
6.
What is the primary purpose of an equipment grounding conductor?
A. To carry normal neutral current
B. To increase circuit voltage
C. To provide a low-impedance fault-current path
D. To replace the grounded conductor
Answer: C. To provide a low-impedance fault-current path
Rationale: The equipment grounding conductor connects normally non-current-
carrying metal parts to the grounding system so that a fault can produce
sufficient current to operate the overcurrent protective device.
7.
A grounding electrode conductor connects a service grounding electrode to the
service equipment. What is its primary function?
A. Carry normal load current
B. Establish a connection to earth for the grounding electrode system
C. Replace overcurrent protection
D. Serve as the branch-circuit neutral
Answer: B. Establish a connection to the grounding electrode system