Minnesota Class B Electrical Contractor
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. What is the primary purpose of the National Electrical Code (NEC)?
A. To design electrical appliances
B. To provide minimum safety standards for electrical installations
C. To regulate electrical product pricing
D. To certify electrical contractors
Answer: B
The NEC establishes minimum safety requirements to protect people
and property from electrical hazards in installations.
2. Ohm’s Law is expressed as:
A. P = VI
B. V = IR
C. I = PR
, D. V = P/R
Answer: B
Ohm’s Law defines the relationship between voltage, current, and
resistance as V = IR.
3. The standard voltage for most residential branch circuits in the United
States is:
A. 120/240V
B. 277/480V
C. 240/415V
D. 600V
Answer: A
Most residential systems in the U.S. use 120/240V split-phase power
for general and appliance loads.
4. The purpose of a circuit breaker is to:
A. Increase voltage
B. Store electrical energy
C. Protect circuits from overcurrent
D. Reduce resistance
Answer: C
Circuit breakers automatically disconnect power when overcurrent
conditions occur to prevent damage and fire.
5. Which material is commonly used as an electrical conductor?
A. Rubber
, B. Copper
C. Glass
D. Plastic
Answer: B
Copper is widely used due to its excellent conductivity and durability.
6. Grounding in an electrical system is primarily used to:
A. Increase current flow
B. Provide a return path for normal load current
C. Stabilize voltage and provide a safe fault path
D. Increase resistance
Answer: C
Grounding ensures safety by providing a low-resistance path for fault
current to prevent shock hazards.
7. A GFCI is designed to protect against:
A. Overvoltage
B. Short circuits
C. Ground faults
D. High resistance
Answer: C
Ground Fault Circuit Interrupters detect imbalance between hot and
neutral conductors to prevent shock.
8. The unit of electrical power is:
A. Volt
, B. Ampere
C. Watt
D. Ohm
Answer: C
Watts measure the rate of electrical energy consumption or
production.
9. A 20-amp circuit typically uses wire rated at least:
A. 18 AWG
B. 16 AWG
C. 14 AWG
D. 10 AWG
Answer: C
14 AWG copper wire is the minimum standard for 20-amp circuits
under typical NEC guidelines.
10. Which device provides overcurrent protection?
A. Transformer
B. Fuse
C. Motor
D. Conduit
Answer: B
Fuses melt when excessive current flows, interrupting the circuit for
protection.
Exam Practice Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of the National Electrical Code (NEC)?
A. To design electrical appliances
B. To provide minimum safety standards for electrical installations
C. To regulate electrical product pricing
D. To certify electrical contractors
Answer: B
The NEC establishes minimum safety requirements to protect people
and property from electrical hazards in installations.
2. Ohm’s Law is expressed as:
A. P = VI
B. V = IR
C. I = PR
, D. V = P/R
Answer: B
Ohm’s Law defines the relationship between voltage, current, and
resistance as V = IR.
3. The standard voltage for most residential branch circuits in the United
States is:
A. 120/240V
B. 277/480V
C. 240/415V
D. 600V
Answer: A
Most residential systems in the U.S. use 120/240V split-phase power
for general and appliance loads.
4. The purpose of a circuit breaker is to:
A. Increase voltage
B. Store electrical energy
C. Protect circuits from overcurrent
D. Reduce resistance
Answer: C
Circuit breakers automatically disconnect power when overcurrent
conditions occur to prevent damage and fire.
5. Which material is commonly used as an electrical conductor?
A. Rubber
, B. Copper
C. Glass
D. Plastic
Answer: B
Copper is widely used due to its excellent conductivity and durability.
6. Grounding in an electrical system is primarily used to:
A. Increase current flow
B. Provide a return path for normal load current
C. Stabilize voltage and provide a safe fault path
D. Increase resistance
Answer: C
Grounding ensures safety by providing a low-resistance path for fault
current to prevent shock hazards.
7. A GFCI is designed to protect against:
A. Overvoltage
B. Short circuits
C. Ground faults
D. High resistance
Answer: C
Ground Fault Circuit Interrupters detect imbalance between hot and
neutral conductors to prevent shock.
8. The unit of electrical power is:
A. Volt
, B. Ampere
C. Watt
D. Ohm
Answer: C
Watts measure the rate of electrical energy consumption or
production.
9. A 20-amp circuit typically uses wire rated at least:
A. 18 AWG
B. 16 AWG
C. 14 AWG
D. 10 AWG
Answer: C
14 AWG copper wire is the minimum standard for 20-amp circuits
under typical NEC guidelines.
10. Which device provides overcurrent protection?
A. Transformer
B. Fuse
C. Motor
D. Conduit
Answer: B
Fuses melt when excessive current flows, interrupting the circuit for
protection.
