Ohio Electrical Contractor Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationales
2025|2026 Q&A | Instant Download Pdf
1. What is the maximum allowable voltage drop for branch circuits in a
commercial building?
A. 2%
B. 3%
C. 5%
D. 10%
B. 3%
Rationale: The National Electrical Code (NEC) recommends a
maximum voltage drop of 3% for branch circuits to ensure efficiency
and proper operation of equipment.
2. Which conductor is typically used for grounding in residential
installations?
A. Aluminum
, B. Copper
C. Steel
D. Silver
B. Copper
Rationale: Copper conductors are preferred for grounding due to
their excellent conductivity and resistance to corrosion.
3. The NEC requires a minimum of how many 20-ampere branch circuits
in a dwelling unit kitchen?
A. One
B. Two
C. Three
D. Four
B. Two
Rationale: NEC Section 210.11(C)(1) mandates at least two 20-
ampere circuits for kitchen countertop outlets to handle appliance
loads.
4. What is the primary purpose of a ground-fault circuit interrupter
(GFCI)?
A. Prevent overcurrent
B. Protect equipment from voltage spikes
C. Protect people from electrical shock
D. Reduce energy consumption
C. Protect people from electrical shock
, Rationale: GFCIs quickly disconnect power if current leakage to
ground is detected, reducing the risk of electrocution.
5. What is the maximum number of 15-ampere receptacles allowed on a
15-ampere branch circuit?
A. 8
B. 10
C. 12
D. 13
D. 13
Rationale: NEC Table 210.21(B)(2) allows up to 13 receptacles on a
15A circuit, assuming general-purpose loads.
6. Which type of conduit is most resistant to corrosion?
A. EMT
B. PVC
C. RMC
D. IMC
B. PVC
Rationale: PVC (polyvinyl chloride) conduit is highly resistant to
moisture and many chemicals, making it ideal for corrosive
environments.
7. A transformer has a primary voltage of 480V and secondary voltage of
120V. What type of transformer is this?
A. Step-up
, B. Step-down
C. Isolation
D. Autotransformer
B. Step-down
Rationale: The voltage decreases from 480V to 120V, classifying it as
a step-down transformer.
8. What is the minimum height for mounting a commercial service
disconnect switch?
A. 4 feet
B. 5 feet
C. 6 feet
D. 7 feet
C. 6 feet
Rationale: NEC 230.70(A)(1) requires service disconnects to be readily
accessible, typically between 4 and 6 feet above finished floor.
9. In a 3-phase, 4-wire wye system, what is the voltage between any two
phases?
A. Phase voltage
B. Line voltage
C. Neutral voltage
D. Ground voltage
B. Line voltage
Questions And Correct Answers
(Verified Answers) Plus Rationales
2025|2026 Q&A | Instant Download Pdf
1. What is the maximum allowable voltage drop for branch circuits in a
commercial building?
A. 2%
B. 3%
C. 5%
D. 10%
B. 3%
Rationale: The National Electrical Code (NEC) recommends a
maximum voltage drop of 3% for branch circuits to ensure efficiency
and proper operation of equipment.
2. Which conductor is typically used for grounding in residential
installations?
A. Aluminum
, B. Copper
C. Steel
D. Silver
B. Copper
Rationale: Copper conductors are preferred for grounding due to
their excellent conductivity and resistance to corrosion.
3. The NEC requires a minimum of how many 20-ampere branch circuits
in a dwelling unit kitchen?
A. One
B. Two
C. Three
D. Four
B. Two
Rationale: NEC Section 210.11(C)(1) mandates at least two 20-
ampere circuits for kitchen countertop outlets to handle appliance
loads.
4. What is the primary purpose of a ground-fault circuit interrupter
(GFCI)?
A. Prevent overcurrent
B. Protect equipment from voltage spikes
C. Protect people from electrical shock
D. Reduce energy consumption
C. Protect people from electrical shock
, Rationale: GFCIs quickly disconnect power if current leakage to
ground is detected, reducing the risk of electrocution.
5. What is the maximum number of 15-ampere receptacles allowed on a
15-ampere branch circuit?
A. 8
B. 10
C. 12
D. 13
D. 13
Rationale: NEC Table 210.21(B)(2) allows up to 13 receptacles on a
15A circuit, assuming general-purpose loads.
6. Which type of conduit is most resistant to corrosion?
A. EMT
B. PVC
C. RMC
D. IMC
B. PVC
Rationale: PVC (polyvinyl chloride) conduit is highly resistant to
moisture and many chemicals, making it ideal for corrosive
environments.
7. A transformer has a primary voltage of 480V and secondary voltage of
120V. What type of transformer is this?
A. Step-up
, B. Step-down
C. Isolation
D. Autotransformer
B. Step-down
Rationale: The voltage decreases from 480V to 120V, classifying it as
a step-down transformer.
8. What is the minimum height for mounting a commercial service
disconnect switch?
A. 4 feet
B. 5 feet
C. 6 feet
D. 7 feet
C. 6 feet
Rationale: NEC 230.70(A)(1) requires service disconnects to be readily
accessible, typically between 4 and 6 feet above finished floor.
9. In a 3-phase, 4-wire wye system, what is the voltage between any two
phases?
A. Phase voltage
B. Line voltage
C. Neutral voltage
D. Ground voltage
B. Line voltage
