NCCER Electrical Level 4 Certification Exam Study Guide
and Practice Test Bank Latest 2025–2026 Update | 150
Actual Exam-Style Questions and 100% Verified Answers
| Complete Review with Rationales | Based on NCCER
Electrical Level 4 Modules | Already Graded A+ | Instant
Download PDF
1. A three-phase motor is drawing unbalanced currents across its phases.
What is the MOST likely cause?
A. Low supply voltage
B. Open winding in one phase
C. Incorrect grounding
D. Overlubrication
✔ B. Open winding in one phase
An open winding interrupts current flow in one phase, causing imbalance
and uneven current distribution across remaining phases.
2. What is the primary function of a Variable Frequency Drive (VFD)?
A. Increase voltage
B. Control motor speed
C. Convert AC to DC permanently
D. Store electrical energy
✔ B. Control motor speed
A VFD adjusts frequency and voltage supplied to a motor, thereby
controlling its speed efficiently.
3. In a power distribution system, what does the term “fault current” refer to?
A. Normal operating current
B. Leakage current
C. Current during a short circuit
, D. Induced current
✔ C. Current during a short circuit
Fault current is the excessive current that flows when a short circuit or
fault condition occurs.
4. Which device provides overcurrent protection for branch circuits?
A. Transformer
B. Circuit breaker
C. Capacitor
D. Relay
✔ B. Circuit breaker
Circuit breakers automatically interrupt current flow when excessive
current is detected.
5. What is the purpose of bonding in electrical systems?
A. Increase resistance
B. Ensure conductivity between metal parts
C. Reduce voltage
D. Store energy
✔ B. Ensure conductivity between metal parts
Bonding connects conductive parts to maintain equal potential and
prevent shock hazards.
6. A step-down transformer reduces voltage from 480V to 120V. What
happens to current?
A. Decreases proportionally
B. Remains constant
C. Increases proportionally
D. Drops to zero
✔ C. Increases proportionally
In transformers, when voltage decreases, current increases to maintain
power balance (ignoring losses).
,7. What NEC article covers grounding and bonding?
A. Article 110
B. Article 250
C. Article 300
D. Article 430
✔ B. Article 250
NEC Article 250 specifically addresses grounding and bonding
requirements.
8. Which instrument measures insulation resistance?
A. Ammeter
B. Voltmeter
C. Megohmmeter
D. Wattmeter
✔ C. Megohmmeter
A megohmmeter measures high resistance values, typically insulation
resistance.
9. What is the typical efficiency range of a large power transformer?
A. 50–60%
B. 60–70%
C. 80–90%
D. 95–99%
✔ D. 95–99%
Power transformers are highly efficient, often exceeding 95% efficiency.
10.A motor starter includes which of the following components?
A. Fuse only
B. Contactor and overload relay
C. Capacitor
D. Transformer
✔ B. Contactor and overload relay
Motor starters combine a contactor for control and overload protection
for safety.
, 11.What is the purpose of a relay in control circuits?
A. Store energy
B. Amplify voltage
C. Electrically operate a switch
D. Measure current
✔ C. Electrically operate a switch
Relays use an electrical signal to control another circuit.
12.Which type of conduit is most resistant to corrosion?
A. EMT
B. RMC
C. PVC
D. FMC
✔ C. PVC
PVC conduit is non-metallic and highly resistant to corrosion.
13.What is the main function of a capacitor in a motor circuit?
A. Increase resistance
B. Improve power factor
C. Reduce voltage
D. Stop current
✔ B. Improve power factor
Capacitors help correct lagging power factor in inductive loads like
motors.
14.What does “lockout/tagout” ensure?
A. Faster repairs
B. Equipment identification
C. Worker safety during maintenance
D. Voltage regulation
✔ C. Worker safety during maintenance
Lockout/tagout prevents accidental energization of equipment during
servicing.
and Practice Test Bank Latest 2025–2026 Update | 150
Actual Exam-Style Questions and 100% Verified Answers
| Complete Review with Rationales | Based on NCCER
Electrical Level 4 Modules | Already Graded A+ | Instant
Download PDF
1. A three-phase motor is drawing unbalanced currents across its phases.
What is the MOST likely cause?
A. Low supply voltage
B. Open winding in one phase
C. Incorrect grounding
D. Overlubrication
✔ B. Open winding in one phase
An open winding interrupts current flow in one phase, causing imbalance
and uneven current distribution across remaining phases.
2. What is the primary function of a Variable Frequency Drive (VFD)?
A. Increase voltage
B. Control motor speed
C. Convert AC to DC permanently
D. Store electrical energy
✔ B. Control motor speed
A VFD adjusts frequency and voltage supplied to a motor, thereby
controlling its speed efficiently.
3. In a power distribution system, what does the term “fault current” refer to?
A. Normal operating current
B. Leakage current
C. Current during a short circuit
, D. Induced current
✔ C. Current during a short circuit
Fault current is the excessive current that flows when a short circuit or
fault condition occurs.
4. Which device provides overcurrent protection for branch circuits?
A. Transformer
B. Circuit breaker
C. Capacitor
D. Relay
✔ B. Circuit breaker
Circuit breakers automatically interrupt current flow when excessive
current is detected.
5. What is the purpose of bonding in electrical systems?
A. Increase resistance
B. Ensure conductivity between metal parts
C. Reduce voltage
D. Store energy
✔ B. Ensure conductivity between metal parts
Bonding connects conductive parts to maintain equal potential and
prevent shock hazards.
6. A step-down transformer reduces voltage from 480V to 120V. What
happens to current?
A. Decreases proportionally
B. Remains constant
C. Increases proportionally
D. Drops to zero
✔ C. Increases proportionally
In transformers, when voltage decreases, current increases to maintain
power balance (ignoring losses).
,7. What NEC article covers grounding and bonding?
A. Article 110
B. Article 250
C. Article 300
D. Article 430
✔ B. Article 250
NEC Article 250 specifically addresses grounding and bonding
requirements.
8. Which instrument measures insulation resistance?
A. Ammeter
B. Voltmeter
C. Megohmmeter
D. Wattmeter
✔ C. Megohmmeter
A megohmmeter measures high resistance values, typically insulation
resistance.
9. What is the typical efficiency range of a large power transformer?
A. 50–60%
B. 60–70%
C. 80–90%
D. 95–99%
✔ D. 95–99%
Power transformers are highly efficient, often exceeding 95% efficiency.
10.A motor starter includes which of the following components?
A. Fuse only
B. Contactor and overload relay
C. Capacitor
D. Transformer
✔ B. Contactor and overload relay
Motor starters combine a contactor for control and overload protection
for safety.
, 11.What is the purpose of a relay in control circuits?
A. Store energy
B. Amplify voltage
C. Electrically operate a switch
D. Measure current
✔ C. Electrically operate a switch
Relays use an electrical signal to control another circuit.
12.Which type of conduit is most resistant to corrosion?
A. EMT
B. RMC
C. PVC
D. FMC
✔ C. PVC
PVC conduit is non-metallic and highly resistant to corrosion.
13.What is the main function of a capacitor in a motor circuit?
A. Increase resistance
B. Improve power factor
C. Reduce voltage
D. Stop current
✔ B. Improve power factor
Capacitors help correct lagging power factor in inductive loads like
motors.
14.What does “lockout/tagout” ensure?
A. Faster repairs
B. Equipment identification
C. Worker safety during maintenance
D. Voltage regulation
✔ C. Worker safety during maintenance
Lockout/tagout prevents accidental energization of equipment during
servicing.
