LADWP ELECTRICAL MAINTENANCE EXAM
WITH ACTUAL QUESTIONS AND VERIFIED
ANSWERS, PLUS EXPLAINED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED 100% PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1.
During preventive maintenance on a 480-volt three-phase motor control
center, a maintenance electrician has opened the disconnect and
removed the fuses. Before beginning work, which procedure provides
the most reliable confirmation that the equipment is electrically safe?
A. Check that the disconnect handle is in the OFF position and begin
work.
B. Verify that the control transformer pilot light is extinguished.
C. Perform an approved absence-of-voltage test using properly rated test
equipment after establishing the required isolation and applying the
appropriate safety procedures.
D. Ask another electrician whether the circuit was de-energized.
Answer: C. Perform an approved absence-of-voltage test using
properly rated test equipment after establishing the required
isolation and applying the appropriate safety procedures.
Rationale: Simply opening a disconnect, observing an indicator light,
or relying on another person's statement does not establish an
electrically safe condition. A properly performed absence-of-voltage
test verifies the actual condition of the conductors at the point of work.
1
,2.
A three-phase induction motor is running with excessive vibration. The
motor current readings are 41 A, 40.8 A, and 41.1 A on the three phases,
while the manufacturer's rated full-load current is 41 A. Which condition
is most strongly suggested by these measurements?
A. Severe electrical phase imbalance
B. A significant single-phasing condition
C. An electrical overload caused by excessive current
D. The motor's electrical loading is approximately balanced, so
mechanical causes should be investigated
Answer: D. The motor's electrical loading is approximately
balanced, so mechanical causes should be investigated
Rationale: The three currents are nearly identical and approximately
equal to the rated full-load current. Severe vibration with balanced
current commonly directs troubleshooting toward mechanical
conditions such as misalignment, bearing deterioration, coupling
problems, looseness, or an unbalanced rotor rather than a major
electrical imbalance.
3.
A maintenance electrician measures insulation resistance on a motor
winding and obtains a substantially lower reading than expected. Which
factor should be considered before concluding that the motor winding
insulation has definitively failed?
A. The motor's paint color
B. Temperature, moisture, contamination, test voltage, and the motor's
construction
2
,C. The motor's horsepower alone
D. The number of bolts securing the motor to its base
Answer: B. Temperature, moisture, contamination, test voltage, and
the motor's construction
Rationale: Insulation-resistance measurements are affected by
environmental and equipment conditions. Moisture and contamination
can significantly reduce resistance, while insulation resistance also
varies with temperature. A qualified maintenance procedure should
account for these factors and compare results with appropriate
historical and manufacturer information.
4.
A circuit breaker repeatedly trips shortly after a large motor starts. The
motor has a high inrush current characteristic. Which diagnostic
measurement is most useful for determining whether the trip is
associated with an excessive starting condition?
A. Measure motor starting current and compare its duration and
magnitude with the protection settings and motor characteristics.
B. Measure only the motor's resistance while it is disconnected.
C. Replace the breaker immediately with one having a larger rating.
D. Measure the building's lighting load.
Answer: A. Measure motor starting current and compare its
duration and magnitude with the protection settings and motor
characteristics.
Rationale: Motor starting current can be several times normal
running current. A properly coordinated protective device must
tolerate expected starting current while still providing protection
3
, against abnormal conditions. Measuring actual starting current and
its duration helps distinguish normal inrush from a fault, mechanical
loading problem, or improperly coordinated protection.
5.
A technician discovers that a motor's overload relay has been repeatedly
reset by operating personnel without investigating why it trips. What is
the most appropriate maintenance response?
A. Increase the overload setting immediately.
B. Permanently bypass the overload relay.
C. Treat repeated overload operation as a symptom requiring diagnosis
of the motor, driven load, power supply, and protection system.
D. Install a larger motor without performing additional tests.
Answer: C. Treat repeated overload operation as a symptom
requiring diagnosis of the motor, driven load, power supply, and
protection system.
Rationale: Overload protection is intended to respond to excessive
motor heating or current conditions. Repeated tripping may indicate
mechanical overload, poor ventilation, bearing problems, phase
imbalance, voltage abnormalities, incorrect settings, or other faults.
Raising the setting without determining the cause can create a
dangerous loss of protection.
6.
When inspecting a motor control cabinet, an electrician notices heavy
dust accumulation around ventilation openings and heat-producing
components. Why is this condition particularly important?
4
WITH ACTUAL QUESTIONS AND VERIFIED
ANSWERS, PLUS EXPLAINED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED 100% PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1.
During preventive maintenance on a 480-volt three-phase motor control
center, a maintenance electrician has opened the disconnect and
removed the fuses. Before beginning work, which procedure provides
the most reliable confirmation that the equipment is electrically safe?
A. Check that the disconnect handle is in the OFF position and begin
work.
B. Verify that the control transformer pilot light is extinguished.
C. Perform an approved absence-of-voltage test using properly rated test
equipment after establishing the required isolation and applying the
appropriate safety procedures.
D. Ask another electrician whether the circuit was de-energized.
Answer: C. Perform an approved absence-of-voltage test using
properly rated test equipment after establishing the required
isolation and applying the appropriate safety procedures.
Rationale: Simply opening a disconnect, observing an indicator light,
or relying on another person's statement does not establish an
electrically safe condition. A properly performed absence-of-voltage
test verifies the actual condition of the conductors at the point of work.
1
,2.
A three-phase induction motor is running with excessive vibration. The
motor current readings are 41 A, 40.8 A, and 41.1 A on the three phases,
while the manufacturer's rated full-load current is 41 A. Which condition
is most strongly suggested by these measurements?
A. Severe electrical phase imbalance
B. A significant single-phasing condition
C. An electrical overload caused by excessive current
D. The motor's electrical loading is approximately balanced, so
mechanical causes should be investigated
Answer: D. The motor's electrical loading is approximately
balanced, so mechanical causes should be investigated
Rationale: The three currents are nearly identical and approximately
equal to the rated full-load current. Severe vibration with balanced
current commonly directs troubleshooting toward mechanical
conditions such as misalignment, bearing deterioration, coupling
problems, looseness, or an unbalanced rotor rather than a major
electrical imbalance.
3.
A maintenance electrician measures insulation resistance on a motor
winding and obtains a substantially lower reading than expected. Which
factor should be considered before concluding that the motor winding
insulation has definitively failed?
A. The motor's paint color
B. Temperature, moisture, contamination, test voltage, and the motor's
construction
2
,C. The motor's horsepower alone
D. The number of bolts securing the motor to its base
Answer: B. Temperature, moisture, contamination, test voltage, and
the motor's construction
Rationale: Insulation-resistance measurements are affected by
environmental and equipment conditions. Moisture and contamination
can significantly reduce resistance, while insulation resistance also
varies with temperature. A qualified maintenance procedure should
account for these factors and compare results with appropriate
historical and manufacturer information.
4.
A circuit breaker repeatedly trips shortly after a large motor starts. The
motor has a high inrush current characteristic. Which diagnostic
measurement is most useful for determining whether the trip is
associated with an excessive starting condition?
A. Measure motor starting current and compare its duration and
magnitude with the protection settings and motor characteristics.
B. Measure only the motor's resistance while it is disconnected.
C. Replace the breaker immediately with one having a larger rating.
D. Measure the building's lighting load.
Answer: A. Measure motor starting current and compare its
duration and magnitude with the protection settings and motor
characteristics.
Rationale: Motor starting current can be several times normal
running current. A properly coordinated protective device must
tolerate expected starting current while still providing protection
3
, against abnormal conditions. Measuring actual starting current and
its duration helps distinguish normal inrush from a fault, mechanical
loading problem, or improperly coordinated protection.
5.
A technician discovers that a motor's overload relay has been repeatedly
reset by operating personnel without investigating why it trips. What is
the most appropriate maintenance response?
A. Increase the overload setting immediately.
B. Permanently bypass the overload relay.
C. Treat repeated overload operation as a symptom requiring diagnosis
of the motor, driven load, power supply, and protection system.
D. Install a larger motor without performing additional tests.
Answer: C. Treat repeated overload operation as a symptom
requiring diagnosis of the motor, driven load, power supply, and
protection system.
Rationale: Overload protection is intended to respond to excessive
motor heating or current conditions. Repeated tripping may indicate
mechanical overload, poor ventilation, bearing problems, phase
imbalance, voltage abnormalities, incorrect settings, or other faults.
Raising the setting without determining the cause can create a
dangerous loss of protection.
6.
When inspecting a motor control cabinet, an electrician notices heavy
dust accumulation around ventilation openings and heat-producing
components. Why is this condition particularly important?
4
