LADWP ELECTRIC DISTRIBUTION
MECHANIC EXAM WITH ACTUAL
QUESTIONS AND VERIFIED ANSWERS,
PLUS EXPLAINED RATIONALES/EXPERT
VERIFIED FOR GUARANTEED 100% PASS
2026/LATEST UPDATE/INSTANT
DOWNLOAD PDF
1. Electrical Safety — De-energization
A crew is assigned to replace a damaged component on a distribution
circuit. The dispatcher states that the circuit has been opened remotely
and that the crew may proceed. Before touching the conductor or
equipment, which action provides the most appropriate additional
protection?
A. Assume the remote opening guarantees that the circuit is de-
energized
B. Verify the absence of voltage using an appropriately rated tester and
establish the required protective grounding procedure
C. Touch the conductor briefly with an insulated tool to determine
whether it is energized
D. Begin work immediately because the circuit breaker has already
operated
Answer: B
Rationale: Proper electrical safety requires positive verification rather
than relying solely on an indication that a device has opened. After
appropriate isolation, qualified personnel verify the absence of voltage
with properly rated equipment and apply protective grounds where
required by the applicable procedure.
1
,2. Ohm's Law
A distribution component has a resistance of 12 ohms and is connected
across a 120-volt source. Assuming the resistance remains constant,
what current should theoretically flow?
A. 0.1 A
B. 1 A
C. 10 A
D. 1,440 A
Answer: C
Rationale: Ohm's law is I = V/R. Therefore, I = 120/12 = 10 amperes.
Understanding this relationship is fundamental when evaluating
electrical loads, conductor capacity, and abnormal circuit conditions.
3. Series Circuit
Three resistors of 4 Ω, 6 Ω, and 10 Ω are connected in series. What is
their total resistance?
A. 20 Ω
B. 2.4 Ω
C. 10 Ω
D. 24 Ω
Answer: A
Rationale: Series resistances add directly: 4 + 6 + 10 = 20 Ω. A series
circuit has the same current through each resistor while the source
voltage is divided among the individual resistances.
4. Parallel Circuits
2
,Two identical 20-ohm resistors are connected in parallel across a voltage
source. What is their equivalent resistance?
A. 40 Ω
B. 20 Ω
C. 10 Ω
D. 5 Ω
Answer: C
Rationale: Two equal resistances in parallel have an equivalent
resistance equal to half the value of either resistor. Thus, 20/2 = 10 Ω.
The parallel combination provides a lower resistance path than either
individual resistor.
5. Transformer Fundamentals
A distribution transformer primarily operates according to which
principle?
A. Chemical conversion
B. Electromagnetic induction
C. Mechanical friction
D. Electrostatic attraction
Answer: B
Rationale: A transformer transfers electrical energy between windings
through electromagnetic induction. Alternating current in the primary
winding establishes a changing magnetic flux, which induces voltage
in the secondary winding.
6. Step-Down Transformer
3
, A transformer has a primary voltage of 7,200 V and a secondary voltage
of 240 V. Its primary winding has 900 turns. Approximately how many
secondary turns are required for the stated voltage ratio?
A. 3 turns
B. 30 turns
C. 300 turns
D. 2,700 turns
Answer: B
Rationale: The ideal transformer relationship is V₁/V₂ = N₁/N₂.
Therefore, 7,200/240 = 30. With 900 primary turns, N₂ = 900/30 = 30
turns.
7. Distribution Transformers
Which statement best describes the purpose of a distribution transformer
in an electrical distribution system?
A. It converts AC power into mechanical power
B. It changes voltage to a level suitable for downstream distribution or
customer utilization
C. It eliminates all electrical losses
D. It automatically corrects every type of power-system fault
Answer: B
Rationale: Distribution transformers change voltage levels to make
electrical power suitable for subsequent distribution or utilization.
They do not eliminate losses or automatically correct every fault.
8. Conductor Identification
4
MECHANIC EXAM WITH ACTUAL
QUESTIONS AND VERIFIED ANSWERS,
PLUS EXPLAINED RATIONALES/EXPERT
VERIFIED FOR GUARANTEED 100% PASS
2026/LATEST UPDATE/INSTANT
DOWNLOAD PDF
1. Electrical Safety — De-energization
A crew is assigned to replace a damaged component on a distribution
circuit. The dispatcher states that the circuit has been opened remotely
and that the crew may proceed. Before touching the conductor or
equipment, which action provides the most appropriate additional
protection?
A. Assume the remote opening guarantees that the circuit is de-
energized
B. Verify the absence of voltage using an appropriately rated tester and
establish the required protective grounding procedure
C. Touch the conductor briefly with an insulated tool to determine
whether it is energized
D. Begin work immediately because the circuit breaker has already
operated
Answer: B
Rationale: Proper electrical safety requires positive verification rather
than relying solely on an indication that a device has opened. After
appropriate isolation, qualified personnel verify the absence of voltage
with properly rated equipment and apply protective grounds where
required by the applicable procedure.
1
,2. Ohm's Law
A distribution component has a resistance of 12 ohms and is connected
across a 120-volt source. Assuming the resistance remains constant,
what current should theoretically flow?
A. 0.1 A
B. 1 A
C. 10 A
D. 1,440 A
Answer: C
Rationale: Ohm's law is I = V/R. Therefore, I = 120/12 = 10 amperes.
Understanding this relationship is fundamental when evaluating
electrical loads, conductor capacity, and abnormal circuit conditions.
3. Series Circuit
Three resistors of 4 Ω, 6 Ω, and 10 Ω are connected in series. What is
their total resistance?
A. 20 Ω
B. 2.4 Ω
C. 10 Ω
D. 24 Ω
Answer: A
Rationale: Series resistances add directly: 4 + 6 + 10 = 20 Ω. A series
circuit has the same current through each resistor while the source
voltage is divided among the individual resistances.
4. Parallel Circuits
2
,Two identical 20-ohm resistors are connected in parallel across a voltage
source. What is their equivalent resistance?
A. 40 Ω
B. 20 Ω
C. 10 Ω
D. 5 Ω
Answer: C
Rationale: Two equal resistances in parallel have an equivalent
resistance equal to half the value of either resistor. Thus, 20/2 = 10 Ω.
The parallel combination provides a lower resistance path than either
individual resistor.
5. Transformer Fundamentals
A distribution transformer primarily operates according to which
principle?
A. Chemical conversion
B. Electromagnetic induction
C. Mechanical friction
D. Electrostatic attraction
Answer: B
Rationale: A transformer transfers electrical energy between windings
through electromagnetic induction. Alternating current in the primary
winding establishes a changing magnetic flux, which induces voltage
in the secondary winding.
6. Step-Down Transformer
3
, A transformer has a primary voltage of 7,200 V and a secondary voltage
of 240 V. Its primary winding has 900 turns. Approximately how many
secondary turns are required for the stated voltage ratio?
A. 3 turns
B. 30 turns
C. 300 turns
D. 2,700 turns
Answer: B
Rationale: The ideal transformer relationship is V₁/V₂ = N₁/N₂.
Therefore, 7,200/240 = 30. With 900 primary turns, N₂ = 900/30 = 30
turns.
7. Distribution Transformers
Which statement best describes the purpose of a distribution transformer
in an electrical distribution system?
A. It converts AC power into mechanical power
B. It changes voltage to a level suitable for downstream distribution or
customer utilization
C. It eliminates all electrical losses
D. It automatically corrects every type of power-system fault
Answer: B
Rationale: Distribution transformers change voltage levels to make
electrical power suitable for subsequent distribution or utilization.
They do not eliminate losses or automatically correct every fault.
8. Conductor Identification
4
