Minnesota Class B Electrical Contractor
Examination Questions and Correct Answers
(Verified Answers) Plus Rationale 2027 Q&A|
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1. What is the primary purpose of overcurrent protection in an
electrical circuit?
A. To increase circuit voltage
B. To improve power factor
C. To protect conductors and equipment from excessive current
D. To reduce the resistance of the circuit
Answer: C. To protect conductors and equipment from excessive
current
Rationale: Overcurrent protection devices such as fuses and circuit
breakers are designed to open a circuit when current exceeds a safe
level. This helps prevent conductor overheating, insulation damage,
equipment damage, and fire hazards.
,2. Which unit is used to measure electrical current?
A. Volt
B. Ohm
C. Watt
D. Ampere
Answer: D. Ampere
Rationale: Electrical current is measured in amperes, commonly called
amps. Voltage is measured in volts, resistance in ohms, and power in
watts.
3. What is the basic relationship expressed by Ohm’s Law?
A. P = VI
B. V = IR
C. I = PR
D. R = VP
Answer: B. V = IR
,Rationale: Ohm’s Law states that voltage equals current multiplied by
resistance (V = I × R). This relationship can also be rearranged to
calculate current or resistance.
4. A 120-volt circuit supplies a 12-ohm load. What current does the
load draw?
A. 5 A
B. 8 A
C. 10 A
D. 12 A
Answer: C. 10 A
Rationale: Using Ohm’s Law, I = V/R. Therefore, 120 volts ÷ 12 ohms =
10 amperes.
5. What is the purpose of a grounding electrode system?
A. To increase circuit voltage
B. To provide a connection to earth for the electrical system
C. To replace circuit overcurrent protection
D. To increase conductor ampacity
, Answer: B. To provide a connection to earth for the electrical system
Rationale: The grounding electrode system connects the electrical
system to earth through approved grounding electrodes. It helps
stabilize system voltage with respect to earth and provides a path for
certain electrical disturbances.
6. Which conductor normally carries current back to the source on a
grounded 120-volt branch circuit?
A. Equipment grounding conductor
B. Grounding electrode conductor
C. Neutral conductor
D. Bonding jumper
Answer: C. Neutral conductor
Rationale: The grounded conductor, commonly called the neutral,
normally carries return current from a line-to-neutral load back to the
source. The equipment grounding conductor is intended for fault-
current paths rather than normal load current.
7. What is the primary purpose of an equipment grounding
conductor?
Examination Questions and Correct Answers
(Verified Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
1. What is the primary purpose of overcurrent protection in an
electrical circuit?
A. To increase circuit voltage
B. To improve power factor
C. To protect conductors and equipment from excessive current
D. To reduce the resistance of the circuit
Answer: C. To protect conductors and equipment from excessive
current
Rationale: Overcurrent protection devices such as fuses and circuit
breakers are designed to open a circuit when current exceeds a safe
level. This helps prevent conductor overheating, insulation damage,
equipment damage, and fire hazards.
,2. Which unit is used to measure electrical current?
A. Volt
B. Ohm
C. Watt
D. Ampere
Answer: D. Ampere
Rationale: Electrical current is measured in amperes, commonly called
amps. Voltage is measured in volts, resistance in ohms, and power in
watts.
3. What is the basic relationship expressed by Ohm’s Law?
A. P = VI
B. V = IR
C. I = PR
D. R = VP
Answer: B. V = IR
,Rationale: Ohm’s Law states that voltage equals current multiplied by
resistance (V = I × R). This relationship can also be rearranged to
calculate current or resistance.
4. A 120-volt circuit supplies a 12-ohm load. What current does the
load draw?
A. 5 A
B. 8 A
C. 10 A
D. 12 A
Answer: C. 10 A
Rationale: Using Ohm’s Law, I = V/R. Therefore, 120 volts ÷ 12 ohms =
10 amperes.
5. What is the purpose of a grounding electrode system?
A. To increase circuit voltage
B. To provide a connection to earth for the electrical system
C. To replace circuit overcurrent protection
D. To increase conductor ampacity
, Answer: B. To provide a connection to earth for the electrical system
Rationale: The grounding electrode system connects the electrical
system to earth through approved grounding electrodes. It helps
stabilize system voltage with respect to earth and provides a path for
certain electrical disturbances.
6. Which conductor normally carries current back to the source on a
grounded 120-volt branch circuit?
A. Equipment grounding conductor
B. Grounding electrode conductor
C. Neutral conductor
D. Bonding jumper
Answer: C. Neutral conductor
Rationale: The grounded conductor, commonly called the neutral,
normally carries return current from a line-to-neutral load back to the
source. The equipment grounding conductor is intended for fault-
current paths rather than normal load current.
7. What is the primary purpose of an equipment grounding
conductor?
