MARYLAND MASTER ELECTRICIAN NEC
BRANCH CIRCUITS EXAM WITH QUESTIONS
AND VERIFIED ANSWERS, PLUS DETAILED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
Question 1
A 120/240-volt, single-phase dwelling-unit panelboard supplies a 20-
ampere multiwire branch circuit consisting of two ungrounded
conductors sharing one neutral conductor. The two ungrounded
conductors are connected to opposite legs of the single-phase system.
Under NEC requirements, which statement most accurately describes the
neutral current when the loads are balanced?
A. The neutral carries the sum of the two ungrounded-conductor
currents.
B. The neutral carries only the difference between the two ungrounded-
conductor currents.
C. The neutral must carry twice the rating of either ungrounded
conductor.
D. The neutral carries no current under any circumstances because it is
grounded.
Answer: B. The neutral carries only the difference between the two
ungrounded-conductor currents.
Rationale: When the two ungrounded conductors of a single-phase,
120/240-volt multiwire branch circuit are on opposite phases, their
currents are 180 electrical degrees apart. Consequently, the neutral
carries the imbalance rather than the arithmetic sum. For example, if
1
,one ungrounded conductor carries 15 amperes and the other carries
10 amperes, the neutral carries approximately 5 amperes. This
principle is fundamental when evaluating neutral loading, conductor
ampacity, and multiwire branch-circuit installations.
Question 2
A 20-ampere branch circuit supplies several receptacles in a dwelling-
unit kitchen. The circuit is wired with 12 AWG copper conductors. A
contractor proposes installing a 15-ampere duplex receptacle as the only
receptacle on the circuit. Assuming the branch circuit has no special
equipment requirements that alter the general rule, which statement is
correct?
A. A 15-ampere receptacle is prohibited because every 20-ampere
circuit must have a 20-ampere receptacle.
B. A 15-ampere receptacle is permitted only if the circuit is protected by
a 15-ampere breaker.
C. A 15-ampere duplex receptacle may generally be installed on a 20-
ampere circuit when the circuit supplies two or more receptacles or
outlets.
D. A 15-ampere receptacle can never be installed on a 20-ampere branch
circuit.
Answer: C. A 15-ampere duplex receptacle may generally be
installed on a 20-ampere circuit when the circuit supplies two or
more receptacles or outlets.
Rationale: NEC 210.21(B) establishes receptacle-rating requirements
in relation to branch-circuit ampere ratings. A 15-ampere receptacle is
generally permitted on a 20-ampere branch circuit when the circuit
supplies two or more receptacles or outlets. However, special
circumstances, such as certain individual receptacle or specific
equipment applications, must be evaluated separately. The key exam
2
,distinction is between a 20-ampere branch circuit supplying multiple
receptacles and a 20-ampere circuit supplying a single receptacle.
Question 3
A dwelling-unit kitchen contains countertop receptacles supplied by two
20-ampere small-appliance branch circuits. The electrician proposes
using one of these circuits to supply a permanently installed dishwasher
in addition to countertop receptacles. What is the best NEC-based
conclusion?
A. The dishwasher may always be connected because all kitchen loads
can share small-appliance circuits.
B. The dishwasher can be connected only if its load is less than 5
amperes.
C. The small-appliance branch circuits are subject to specific
restrictions, and a permanently installed dishwasher generally should not
simply be added to a required countertop small-appliance circuit without
determining whether a permitted exception applies.
D. The dishwasher must be connected to a 15-ampere circuit.
Answer: C. The small-appliance branch circuits are subject to
specific restrictions, and a permanently installed dishwasher
generally should not simply be added to a required countertop
small-appliance circuit without determining whether a permitted
exception applies.
Rationale: Dwelling-unit small-appliance branch circuits have specific
purposes under Article 210.52(B). They are intended primarily for
receptacle outlets serving countertop and similar small-appliance loads
in specified areas. Certain permanently connected loads may have
dedicated or separately required circuits. The master electrician must
identify whether the proposed equipment falls within an exception
before combining it with a required small-appliance branch circuit.
3
, Question 4
A 120-volt, 15-ampere branch circuit supplies lighting outlets in a
dwelling unit. The electrician wants to connect a 1,500-watt portable
heater to one of the receptacles on the same circuit. The circuit also
supplies approximately 6 amperes of lighting load. What is the most
significant concern?
A. The heater is automatically prohibited on any 15-ampere circuit.
B. The combined calculated load may exceed the circuit's permitted
capacity.
C. Portable heaters must always be supplied by 30-ampere circuits.
D. Lighting circuits cannot contain receptacles under any circumstances.
Answer: B. The combined calculated load may exceed the circuit's
permitted capacity.
Rationale: A 1,500-watt load at 120 volts draws approximately 12.5
amperes. Adding 6 amperes of lighting produces approximately 18.5
amperes, exceeding the 15-ampere branch-circuit rating. The problem
illustrates why branch-circuit loading must be calculated rather than
judged merely by the fact that an individual appliance can operate
from a standard receptacle. The electrician must consider the total
calculated load and applicable continuous-load requirements.
Question 5
A branch circuit supplies a continuous load of 16 amperes. No other load
is connected to the circuit. The branch-circuit overcurrent device is
required to be sized according to the standard continuous-load rule.
What minimum circuit ampere rating is generally required?
A. 16 amperes
B. 18 amperes
4
BRANCH CIRCUITS EXAM WITH QUESTIONS
AND VERIFIED ANSWERS, PLUS DETAILED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
Question 1
A 120/240-volt, single-phase dwelling-unit panelboard supplies a 20-
ampere multiwire branch circuit consisting of two ungrounded
conductors sharing one neutral conductor. The two ungrounded
conductors are connected to opposite legs of the single-phase system.
Under NEC requirements, which statement most accurately describes the
neutral current when the loads are balanced?
A. The neutral carries the sum of the two ungrounded-conductor
currents.
B. The neutral carries only the difference between the two ungrounded-
conductor currents.
C. The neutral must carry twice the rating of either ungrounded
conductor.
D. The neutral carries no current under any circumstances because it is
grounded.
Answer: B. The neutral carries only the difference between the two
ungrounded-conductor currents.
Rationale: When the two ungrounded conductors of a single-phase,
120/240-volt multiwire branch circuit are on opposite phases, their
currents are 180 electrical degrees apart. Consequently, the neutral
carries the imbalance rather than the arithmetic sum. For example, if
1
,one ungrounded conductor carries 15 amperes and the other carries
10 amperes, the neutral carries approximately 5 amperes. This
principle is fundamental when evaluating neutral loading, conductor
ampacity, and multiwire branch-circuit installations.
Question 2
A 20-ampere branch circuit supplies several receptacles in a dwelling-
unit kitchen. The circuit is wired with 12 AWG copper conductors. A
contractor proposes installing a 15-ampere duplex receptacle as the only
receptacle on the circuit. Assuming the branch circuit has no special
equipment requirements that alter the general rule, which statement is
correct?
A. A 15-ampere receptacle is prohibited because every 20-ampere
circuit must have a 20-ampere receptacle.
B. A 15-ampere receptacle is permitted only if the circuit is protected by
a 15-ampere breaker.
C. A 15-ampere duplex receptacle may generally be installed on a 20-
ampere circuit when the circuit supplies two or more receptacles or
outlets.
D. A 15-ampere receptacle can never be installed on a 20-ampere branch
circuit.
Answer: C. A 15-ampere duplex receptacle may generally be
installed on a 20-ampere circuit when the circuit supplies two or
more receptacles or outlets.
Rationale: NEC 210.21(B) establishes receptacle-rating requirements
in relation to branch-circuit ampere ratings. A 15-ampere receptacle is
generally permitted on a 20-ampere branch circuit when the circuit
supplies two or more receptacles or outlets. However, special
circumstances, such as certain individual receptacle or specific
equipment applications, must be evaluated separately. The key exam
2
,distinction is between a 20-ampere branch circuit supplying multiple
receptacles and a 20-ampere circuit supplying a single receptacle.
Question 3
A dwelling-unit kitchen contains countertop receptacles supplied by two
20-ampere small-appliance branch circuits. The electrician proposes
using one of these circuits to supply a permanently installed dishwasher
in addition to countertop receptacles. What is the best NEC-based
conclusion?
A. The dishwasher may always be connected because all kitchen loads
can share small-appliance circuits.
B. The dishwasher can be connected only if its load is less than 5
amperes.
C. The small-appliance branch circuits are subject to specific
restrictions, and a permanently installed dishwasher generally should not
simply be added to a required countertop small-appliance circuit without
determining whether a permitted exception applies.
D. The dishwasher must be connected to a 15-ampere circuit.
Answer: C. The small-appliance branch circuits are subject to
specific restrictions, and a permanently installed dishwasher
generally should not simply be added to a required countertop
small-appliance circuit without determining whether a permitted
exception applies.
Rationale: Dwelling-unit small-appliance branch circuits have specific
purposes under Article 210.52(B). They are intended primarily for
receptacle outlets serving countertop and similar small-appliance loads
in specified areas. Certain permanently connected loads may have
dedicated or separately required circuits. The master electrician must
identify whether the proposed equipment falls within an exception
before combining it with a required small-appliance branch circuit.
3
, Question 4
A 120-volt, 15-ampere branch circuit supplies lighting outlets in a
dwelling unit. The electrician wants to connect a 1,500-watt portable
heater to one of the receptacles on the same circuit. The circuit also
supplies approximately 6 amperes of lighting load. What is the most
significant concern?
A. The heater is automatically prohibited on any 15-ampere circuit.
B. The combined calculated load may exceed the circuit's permitted
capacity.
C. Portable heaters must always be supplied by 30-ampere circuits.
D. Lighting circuits cannot contain receptacles under any circumstances.
Answer: B. The combined calculated load may exceed the circuit's
permitted capacity.
Rationale: A 1,500-watt load at 120 volts draws approximately 12.5
amperes. Adding 6 amperes of lighting produces approximately 18.5
amperes, exceeding the 15-ampere branch-circuit rating. The problem
illustrates why branch-circuit loading must be calculated rather than
judged merely by the fact that an individual appliance can operate
from a standard receptacle. The electrician must consider the total
calculated load and applicable continuous-load requirements.
Question 5
A branch circuit supplies a continuous load of 16 amperes. No other load
is connected to the circuit. The branch-circuit overcurrent device is
required to be sized according to the standard continuous-load rule.
What minimum circuit ampere rating is generally required?
A. 16 amperes
B. 18 amperes
4
