Ohio Electrical Contractor Exam Practice
Questions & [Verified Answers], Plus
Explained Rationales|2026 Latest Update|
Instant Download PDF
1. In an electrical installation, what is the primary purpose of a
circuit breaker?
A. To increase circuit voltage
B. To regulate power-factor correction
C. To interrupt current when an overcurrent condition occurs
D. To provide a continuous grounding path
Answer: C
Rationale: A circuit breaker is an overcurrent protective device
designed to open a circuit when current exceeds the permitted level
for the circuit conductors or equipment. This helps prevent conductor
overheating, insulation damage, equipment failure, and fire hazards.
2. Which conductor is normally identified as the equipment
grounding conductor in a typical branch circuit?
A. White
B. Gray
C. Red
D. Green or bare
Answer: D
1|Page
,Rationale: Equipment grounding conductors are generally identified
by green insulation, green with yellow stripes in certain applications,
or by being bare. Their purpose is to provide a low-impedance path for
fault current so that overcurrent protection can operate promptly.
3. What is the main purpose of a grounding electrode system?
A. To increase available circuit voltage
B. To connect the electrical system to earth and provide a reference
for the electrical system
C. To replace equipment grounding conductors
D. To eliminate the need for overcurrent protection
Answer: B
Rationale: A grounding electrode system connects the electrical
system to earth through grounding electrodes. It helps stabilize
system voltage with respect to earth and provides a path for certain
transient and fault conditions. It does not replace the equipment
grounding conductor or overcurrent protection.
4. A 120-volt branch circuit supplies a 12-ampere continuous load.
Assuming no other loads are present, what minimum circuit
ampacity should be considered for the continuous portion of the
load?
A. 12 A
B. 13 A
C. 15 A
D. 20 A
Answer: C
2|Page
,Rationale: Continuous loads are generally calculated at 125% of their
value for conductor and overcurrent protection sizing. Therefore, 12 A
× 125% = 15 A. The resulting calculated load must be compatible with
the applicable circuit and equipment ratings.
5. What is the primary purpose of a disconnecting means for
electrical equipment?
A. To increase the equipment's efficiency
B. To provide additional grounding electrodes
C. To allow the equipment to be disconnected from its source of
supply
D. To reduce conductor resistance
Answer: C
Rationale: A disconnecting means allows electrical equipment to be
isolated from its supply. This provides a means for servicing,
maintenance, and emergency shutdown when required by the
applicable electrical requirements.
6. Which device is specifically designed to provide protection against
ground-fault current to personnel?
A. Standard fuse
B. Thermal overload relay
C. Ground-fault circuit interrupter (GFCI)
D. Surge protective device
Answer: C
Rationale: A GFCI monitors current leaving and returning through the
circuit conductors. When it detects an imbalance indicating current
3|Page
, may be flowing through an unintended path, it opens the circuit
rapidly.
7. What is the purpose of an AFCI?
A. Protect against excessive voltage
B. Detect and interrupt certain hazardous arcing conditions
C. Measure grounding electrode resistance
D. Replace a service disconnect
Answer: B
Rationale: Arc-fault circuit interrupters are intended to reduce the risk
of fires caused by hazardous electrical arcing. They detect
characteristic arcing conditions and interrupt the circuit when
appropriate.
8. When calculating voltage drop, which three factors have the
greatest direct effect?
A. Conduit color, box size, and insulation type
B. Current, conductor impedance, and conductor length
C. Panel color, breaker brand, and raceway type
D. Ground rod length, box size, and transformer rating
Answer: B
Rationale: Voltage drop increases as current and circuit length
increase and as conductor impedance increases. Proper conductor
sizing helps maintain acceptable voltage at the utilization equipment.
9. What is the primary function of a transformer?
4|Page
Questions & [Verified Answers], Plus
Explained Rationales|2026 Latest Update|
Instant Download PDF
1. In an electrical installation, what is the primary purpose of a
circuit breaker?
A. To increase circuit voltage
B. To regulate power-factor correction
C. To interrupt current when an overcurrent condition occurs
D. To provide a continuous grounding path
Answer: C
Rationale: A circuit breaker is an overcurrent protective device
designed to open a circuit when current exceeds the permitted level
for the circuit conductors or equipment. This helps prevent conductor
overheating, insulation damage, equipment failure, and fire hazards.
2. Which conductor is normally identified as the equipment
grounding conductor in a typical branch circuit?
A. White
B. Gray
C. Red
D. Green or bare
Answer: D
1|Page
,Rationale: Equipment grounding conductors are generally identified
by green insulation, green with yellow stripes in certain applications,
or by being bare. Their purpose is to provide a low-impedance path for
fault current so that overcurrent protection can operate promptly.
3. What is the main purpose of a grounding electrode system?
A. To increase available circuit voltage
B. To connect the electrical system to earth and provide a reference
for the electrical system
C. To replace equipment grounding conductors
D. To eliminate the need for overcurrent protection
Answer: B
Rationale: A grounding electrode system connects the electrical
system to earth through grounding electrodes. It helps stabilize
system voltage with respect to earth and provides a path for certain
transient and fault conditions. It does not replace the equipment
grounding conductor or overcurrent protection.
4. A 120-volt branch circuit supplies a 12-ampere continuous load.
Assuming no other loads are present, what minimum circuit
ampacity should be considered for the continuous portion of the
load?
A. 12 A
B. 13 A
C. 15 A
D. 20 A
Answer: C
2|Page
,Rationale: Continuous loads are generally calculated at 125% of their
value for conductor and overcurrent protection sizing. Therefore, 12 A
× 125% = 15 A. The resulting calculated load must be compatible with
the applicable circuit and equipment ratings.
5. What is the primary purpose of a disconnecting means for
electrical equipment?
A. To increase the equipment's efficiency
B. To provide additional grounding electrodes
C. To allow the equipment to be disconnected from its source of
supply
D. To reduce conductor resistance
Answer: C
Rationale: A disconnecting means allows electrical equipment to be
isolated from its supply. This provides a means for servicing,
maintenance, and emergency shutdown when required by the
applicable electrical requirements.
6. Which device is specifically designed to provide protection against
ground-fault current to personnel?
A. Standard fuse
B. Thermal overload relay
C. Ground-fault circuit interrupter (GFCI)
D. Surge protective device
Answer: C
Rationale: A GFCI monitors current leaving and returning through the
circuit conductors. When it detects an imbalance indicating current
3|Page
, may be flowing through an unintended path, it opens the circuit
rapidly.
7. What is the purpose of an AFCI?
A. Protect against excessive voltage
B. Detect and interrupt certain hazardous arcing conditions
C. Measure grounding electrode resistance
D. Replace a service disconnect
Answer: B
Rationale: Arc-fault circuit interrupters are intended to reduce the risk
of fires caused by hazardous electrical arcing. They detect
characteristic arcing conditions and interrupt the circuit when
appropriate.
8. When calculating voltage drop, which three factors have the
greatest direct effect?
A. Conduit color, box size, and insulation type
B. Current, conductor impedance, and conductor length
C. Panel color, breaker brand, and raceway type
D. Ground rod length, box size, and transformer rating
Answer: B
Rationale: Voltage drop increases as current and circuit length
increase and as conductor impedance increases. Proper conductor
sizing helps maintain acceptable voltage at the utilization equipment.
9. What is the primary function of a transformer?
4|Page
