Page 1 of 170
LADWP ELECTRIC DISTRIBUTION MECHANIC
TRAINEE EXAMINATION QUESTIONS AND VERIFIED
ANSWERS
LADWP ELECTRIC DISTRIBUTION MECHANIC TRAINEE EXAMINATION —
MOST TESTED EXAM COVERAGE AREAS
Electrical theory and principles — voltage, current, resistance, power, AC/DC circuits, transformers,
impedance, grounding, phase relationships, and electrical calculations.
Electric transmission, subtransmission, and distribution systems — overhead and underground
construction, feeders, circuits, conductors, switches, transformers, substations, and distribution
equipment.
Electrical construction, maintenance, and repair — installation methods, connections, splicing,
terminations, troubleshooting, equipment inspection, and preventive maintenance.
Electrical test instruments and measurements — multimeters, clamp meters, insulation testers, voltage
detectors, phase rotation, continuity, resistance, and safe testing practices.
Mechanical equipment, tools, and hydraulic/pneumatic systems — mechanical principles, fasteners,
bearings, torque, hydraulic equipment, pneumatic equipment, hand tools, and power tools.
Rigging, lifting, pulling, and material handling — slings, blocks, tackle, cranes, hoists, load ratings,
signals, balance, inspection, and safe lifting practices.
Electrical safety, CAL/OSHA, and DWP safety procedures — energized work hazards, PPE, approach
boundaries, grounding, arc-flash risks, lockout/tagout, clearances, and safe work practices.
DWP Operating Orders, clearances, “OK To” procedures, and switching — de-energizing, isolating,
tagging, testing, grounding, re-energizing, and communication with system operations.
Plans, schematics, wiring diagrams, specifications, mathematics, and problem solving — symbols, one-
line diagrams, circuit interpretation, measurements, ratios, geometry, metric conversions, and
troubleshooting calculations.
Materials, first aid, emergency response, communication, and work practices — conductor materials,
insulation, hardware, emergency response, crew coordination, documentation, and professional
conduct. (GovernmentJobs)
1.
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A distribution mechanic measures 120 volts across a load drawing 10 amperes during normal operation;
which electrical relationship correctly determines the load's power consumption?
A. 1,200 watts
B. 1,200 watts
C. 12 watts
D. 120 watts
Answer: B
Rationale: Electrical power in a resistive load is calculated using P=VIP=VI. Multiplying 120 volts by 10
amperes produces 1,200 watts. Understanding this relationship is fundamental when evaluating
distribution equipment, estimating loading, checking equipment ratings, and diagnosing abnormal
electrical conditions.
2.
When two resistors are connected in series, which characteristic most directly distinguishes the series
arrangement from a parallel arrangement during circuit analysis?
A. Voltage remains identical across each resistor
B. Branch current divides between components
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C. Total resistance decreases below each resistor
D. The same current passes through each resistor
Answer: D
Rationale: In a series circuit, there is only one current path, so the same current flows through every
component. Voltage divides according to resistance. In parallel circuits, voltage across branches is
generally equal while current divides among available paths.
3.
A mechanic needs to determine the current entering a transformer primary when its apparent power
and primary voltage are known; which relationship should be applied first?
A. Divide apparent power by primary voltage
B. Multiply primary voltage by apparent power
C. Divide primary voltage by apparent power
D. Multiply current by secondary resistance
Answer: A
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Rationale: For a simplified single-phase transformer relationship, apparent power SS equals voltage
multiplied by current, so current can be determined by dividing apparent power by voltage. Correct
calculations help prevent incorrect loading assumptions and unsafe equipment selection.
4.
Why does a transformer normally require alternating current rather than steady direct current to
produce continuous transformer action?
A. Direct current always has excessive frequency
B. Alternating current eliminates magnetic coupling
C. Changing current creates changing magnetic flux
D. Direct current automatically reverses transformer polarity
Answer: C
Rationale: Transformer operation depends on electromagnetic induction. Alternating current
continuously changes the magnetic flux in the core, inducing voltage in the secondary winding. A steady
DC source does not provide continuous changing flux and can cause excessive winding current and
overheating.
5.
LADWP ELECTRIC DISTRIBUTION MECHANIC
TRAINEE EXAMINATION QUESTIONS AND VERIFIED
ANSWERS
LADWP ELECTRIC DISTRIBUTION MECHANIC TRAINEE EXAMINATION —
MOST TESTED EXAM COVERAGE AREAS
Electrical theory and principles — voltage, current, resistance, power, AC/DC circuits, transformers,
impedance, grounding, phase relationships, and electrical calculations.
Electric transmission, subtransmission, and distribution systems — overhead and underground
construction, feeders, circuits, conductors, switches, transformers, substations, and distribution
equipment.
Electrical construction, maintenance, and repair — installation methods, connections, splicing,
terminations, troubleshooting, equipment inspection, and preventive maintenance.
Electrical test instruments and measurements — multimeters, clamp meters, insulation testers, voltage
detectors, phase rotation, continuity, resistance, and safe testing practices.
Mechanical equipment, tools, and hydraulic/pneumatic systems — mechanical principles, fasteners,
bearings, torque, hydraulic equipment, pneumatic equipment, hand tools, and power tools.
Rigging, lifting, pulling, and material handling — slings, blocks, tackle, cranes, hoists, load ratings,
signals, balance, inspection, and safe lifting practices.
Electrical safety, CAL/OSHA, and DWP safety procedures — energized work hazards, PPE, approach
boundaries, grounding, arc-flash risks, lockout/tagout, clearances, and safe work practices.
DWP Operating Orders, clearances, “OK To” procedures, and switching — de-energizing, isolating,
tagging, testing, grounding, re-energizing, and communication with system operations.
Plans, schematics, wiring diagrams, specifications, mathematics, and problem solving — symbols, one-
line diagrams, circuit interpretation, measurements, ratios, geometry, metric conversions, and
troubleshooting calculations.
Materials, first aid, emergency response, communication, and work practices — conductor materials,
insulation, hardware, emergency response, crew coordination, documentation, and professional
conduct. (GovernmentJobs)
1.
, Page 2 of 170
A distribution mechanic measures 120 volts across a load drawing 10 amperes during normal operation;
which electrical relationship correctly determines the load's power consumption?
A. 1,200 watts
B. 1,200 watts
C. 12 watts
D. 120 watts
Answer: B
Rationale: Electrical power in a resistive load is calculated using P=VIP=VI. Multiplying 120 volts by 10
amperes produces 1,200 watts. Understanding this relationship is fundamental when evaluating
distribution equipment, estimating loading, checking equipment ratings, and diagnosing abnormal
electrical conditions.
2.
When two resistors are connected in series, which characteristic most directly distinguishes the series
arrangement from a parallel arrangement during circuit analysis?
A. Voltage remains identical across each resistor
B. Branch current divides between components
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C. Total resistance decreases below each resistor
D. The same current passes through each resistor
Answer: D
Rationale: In a series circuit, there is only one current path, so the same current flows through every
component. Voltage divides according to resistance. In parallel circuits, voltage across branches is
generally equal while current divides among available paths.
3.
A mechanic needs to determine the current entering a transformer primary when its apparent power
and primary voltage are known; which relationship should be applied first?
A. Divide apparent power by primary voltage
B. Multiply primary voltage by apparent power
C. Divide primary voltage by apparent power
D. Multiply current by secondary resistance
Answer: A
, Page 4 of 170
Rationale: For a simplified single-phase transformer relationship, apparent power SS equals voltage
multiplied by current, so current can be determined by dividing apparent power by voltage. Correct
calculations help prevent incorrect loading assumptions and unsafe equipment selection.
4.
Why does a transformer normally require alternating current rather than steady direct current to
produce continuous transformer action?
A. Direct current always has excessive frequency
B. Alternating current eliminates magnetic coupling
C. Changing current creates changing magnetic flux
D. Direct current automatically reverses transformer polarity
Answer: C
Rationale: Transformer operation depends on electromagnetic induction. Alternating current
continuously changes the magnetic flux in the core, inducing voltage in the secondary winding. A steady
DC source does not provide continuous changing flux and can cause excessive winding current and
overheating.
5.
