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(MN) Minnesota (DLI) Class B Master Electrician
(Residential-Only) Exam | Latest Verified Questions and
Detailed Answers
OVERVIEW DESCRIPTION:
This Comprehensive set of questions is designed for candidates preparing for the
Minnesota (DLI) Class B Master Electrician (Residential-Only) Exam. Administered by the
Minnesota Department of Labor and Industry (DLI), this open-book examination
assesses a candidate's knowledge and application of the 2023 National Electrical Code
(NEC) and Minnesota-specific electrical rules as they pertain to one- and two-family
dwellings and associated residential occupancies. The exam evaluates competency in
areas critical to residential electrical work, including load calculations, grounding and
bonding, wiring methods, overcurrent protection, and the specific safety requirements
for residential installations.
QUESTION 1
A residential contractor is hired to wire a new 3,200-square-foot single-family dwelling.
The homeowner requests a 240-volt, 50-ampere receptacle in the attached garage for a
future electric vehicle charger. The service is 200 amperes, 120/240 volts, single-phase.
Which of the following is the most significant Code consideration for adding this new
load?
A. The receptacle must be GFCI-protected.
B. A load calculation must be performed to ensure the existing service can handle the
additional load.
C. The receptacle must be on a dedicated 50-ampere circuit.
D. The garage requires a separate sub-panel for the EV charger.
CORRECT ANSWER: B
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EXPERT RATIONALE: NEC Article 220 requires that a load calculation be performed to
determine if the existing service capacity is adequate for any new load. Even if the
receptacle is on a dedicated circuit, the total calculated load must not exceed the service
rating.
QUESTION 2
A homeowner in Minnesota wants to add a 30-ampere, 240-volt outlet for a new electric
dryer in a basement laundry room. The existing 100-ampere service panel is full. What is
the most practical and Code-compliant solution?
A. Replace the 100-ampere panel with a 200-ampere panel.
B. Install a sub-panel fed from the main service.
C. Use a tandem breaker to free up space.
D. Install a new dedicated 30-ampere circuit from the main panel.
CORRECT ANSWER: C
EXPERT RATIONALE: Using a tandem breaker to create space for the new 30-ampere
breaker is a common and Code-compliant method, provided the panel's busbar is listed
for tandem breakers and the total load does not exceed the panel's rating. Replacing
the entire panel is more costly and may not be necessary.
QUESTION 3
An electrician is installing a new 20-ampere branch circuit for a bathroom receptacle in a
Minnesota home. The circuit will also supply a single vanity light. Which of the following
is required by the 2023 NEC?
A. The receptacle must be GFCI-protected.
B. The circuit must be AFCI-protected.
C. The circuit must be dedicated to the bathroom.
D. The circuit must be 12 AWG copper.
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CORRECT ANSWER: A
EXPERT RATIONALE: NEC 210.8(A)(1) requires all 125-volt through 250-volt receptacles
installed in bathrooms to have GFCI protection. While AFCI protection may be required
for the circuit, GFCI is specifically mandated for the receptacle location.
QUESTION 4
A single-family dwelling has a 200-ampere, 120/240-volt service. The calculated load is
180 amperes. The homeowner wants to add a 40-ampere, 240-volt circuit for a tankless
water heater. What is the minimum action required?
A. The service must be upgraded to 400 amperes.
B. A load calculation must be performed to determine if the service is adequate.
C. The water heater must be on a 30-ampere circuit.
D. The service is adequate as long as the water heater is not used simultaneously with
other major appliances.
CORRECT ANSWER: B
EXPERT RATIONALE: A new load calculation must be performed to determine if the
existing 200-ampere service can handle the additional 40-ampere load. The calculated
load must not exceed the service rating.
QUESTION 5
An electrician is installing a new 15-ampere, 125-volt receptacle in a residential garage.
The receptacle is located 18 inches above the floor. What is the minimum requirement
for this receptacle?
A. It must be GFCI-protected.
B. It must be AFCI-protected.
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C. It must be on a dedicated circuit.
D. It must be tamper-resistant.
CORRECT ANSWER: A
EXPERT RATIONALE: NEC 210.8(A)(2) requires all 125-volt through 250-volt receptacles
installed in garages to have GFCI protection. Tamper-resistant receptacles are also
required in dwelling units, but GFCI protection is the specific requirement for garages.
QUESTION 6
A 1,200-square-foot single-family dwelling has a 100-ampere, 120/240-volt service. The
calculated load is 85 amperes. The homeowner wants to add a 30-ampere, 240-volt
circuit for a new central air conditioner. What is the minimum action required?
A. The service must be upgraded to 200 amperes.
B. A load calculation must be performed to determine if the service is adequate.
C. The air conditioner must be on a 20-ampere circuit.
D. The service is adequate as long as the air conditioner is not used simultaneously with
the electric range.
CORRECT ANSWER: B
EXPERT RATIONALE: A new load calculation must be performed to determine if the
existing 100-ampere service can handle the additional 30-ampere load. The calculated
load must not exceed the service rating.
QUESTION 7
An electrician is installing a new 20-ampere branch circuit in a residential kitchen. The
circuit will supply a countertop receptacle and a built-in microwave. Which of the
following is required by the 2023 NEC?
A. The receptacle must be GFCI-protected.
(MN) Minnesota (DLI) Class B Master Electrician
(Residential-Only) Exam | Latest Verified Questions and
Detailed Answers
OVERVIEW DESCRIPTION:
This Comprehensive set of questions is designed for candidates preparing for the
Minnesota (DLI) Class B Master Electrician (Residential-Only) Exam. Administered by the
Minnesota Department of Labor and Industry (DLI), this open-book examination
assesses a candidate's knowledge and application of the 2023 National Electrical Code
(NEC) and Minnesota-specific electrical rules as they pertain to one- and two-family
dwellings and associated residential occupancies. The exam evaluates competency in
areas critical to residential electrical work, including load calculations, grounding and
bonding, wiring methods, overcurrent protection, and the specific safety requirements
for residential installations.
QUESTION 1
A residential contractor is hired to wire a new 3,200-square-foot single-family dwelling.
The homeowner requests a 240-volt, 50-ampere receptacle in the attached garage for a
future electric vehicle charger. The service is 200 amperes, 120/240 volts, single-phase.
Which of the following is the most significant Code consideration for adding this new
load?
A. The receptacle must be GFCI-protected.
B. A load calculation must be performed to ensure the existing service can handle the
additional load.
C. The receptacle must be on a dedicated 50-ampere circuit.
D. The garage requires a separate sub-panel for the EV charger.
CORRECT ANSWER: B
,2|Page
EXPERT RATIONALE: NEC Article 220 requires that a load calculation be performed to
determine if the existing service capacity is adequate for any new load. Even if the
receptacle is on a dedicated circuit, the total calculated load must not exceed the service
rating.
QUESTION 2
A homeowner in Minnesota wants to add a 30-ampere, 240-volt outlet for a new electric
dryer in a basement laundry room. The existing 100-ampere service panel is full. What is
the most practical and Code-compliant solution?
A. Replace the 100-ampere panel with a 200-ampere panel.
B. Install a sub-panel fed from the main service.
C. Use a tandem breaker to free up space.
D. Install a new dedicated 30-ampere circuit from the main panel.
CORRECT ANSWER: C
EXPERT RATIONALE: Using a tandem breaker to create space for the new 30-ampere
breaker is a common and Code-compliant method, provided the panel's busbar is listed
for tandem breakers and the total load does not exceed the panel's rating. Replacing
the entire panel is more costly and may not be necessary.
QUESTION 3
An electrician is installing a new 20-ampere branch circuit for a bathroom receptacle in a
Minnesota home. The circuit will also supply a single vanity light. Which of the following
is required by the 2023 NEC?
A. The receptacle must be GFCI-protected.
B. The circuit must be AFCI-protected.
C. The circuit must be dedicated to the bathroom.
D. The circuit must be 12 AWG copper.
,3|Page
CORRECT ANSWER: A
EXPERT RATIONALE: NEC 210.8(A)(1) requires all 125-volt through 250-volt receptacles
installed in bathrooms to have GFCI protection. While AFCI protection may be required
for the circuit, GFCI is specifically mandated for the receptacle location.
QUESTION 4
A single-family dwelling has a 200-ampere, 120/240-volt service. The calculated load is
180 amperes. The homeowner wants to add a 40-ampere, 240-volt circuit for a tankless
water heater. What is the minimum action required?
A. The service must be upgraded to 400 amperes.
B. A load calculation must be performed to determine if the service is adequate.
C. The water heater must be on a 30-ampere circuit.
D. The service is adequate as long as the water heater is not used simultaneously with
other major appliances.
CORRECT ANSWER: B
EXPERT RATIONALE: A new load calculation must be performed to determine if the
existing 200-ampere service can handle the additional 40-ampere load. The calculated
load must not exceed the service rating.
QUESTION 5
An electrician is installing a new 15-ampere, 125-volt receptacle in a residential garage.
The receptacle is located 18 inches above the floor. What is the minimum requirement
for this receptacle?
A. It must be GFCI-protected.
B. It must be AFCI-protected.
, 4|Page
C. It must be on a dedicated circuit.
D. It must be tamper-resistant.
CORRECT ANSWER: A
EXPERT RATIONALE: NEC 210.8(A)(2) requires all 125-volt through 250-volt receptacles
installed in garages to have GFCI protection. Tamper-resistant receptacles are also
required in dwelling units, but GFCI protection is the specific requirement for garages.
QUESTION 6
A 1,200-square-foot single-family dwelling has a 100-ampere, 120/240-volt service. The
calculated load is 85 amperes. The homeowner wants to add a 30-ampere, 240-volt
circuit for a new central air conditioner. What is the minimum action required?
A. The service must be upgraded to 200 amperes.
B. A load calculation must be performed to determine if the service is adequate.
C. The air conditioner must be on a 20-ampere circuit.
D. The service is adequate as long as the air conditioner is not used simultaneously with
the electric range.
CORRECT ANSWER: B
EXPERT RATIONALE: A new load calculation must be performed to determine if the
existing 100-ampere service can handle the additional 30-ampere load. The calculated
load must not exceed the service rating.
QUESTION 7
An electrician is installing a new 20-ampere branch circuit in a residential kitchen. The
circuit will supply a countertop receptacle and a built-in microwave. Which of the
following is required by the 2023 NEC?
A. The receptacle must be GFCI-protected.
