LADWP Electrical Craft Helper 2026/2027 | Electrical
Helper Class Code 3799 Exam Study Guide & Practice
Questions | Los Angeles Department of Water and
Power Electrical Craft Helper Test Prep, Electrical
Trade Knowledge, Mathematics, Mechanical Aptitude,
Hand & Power Tools, Electrical Equipment, Safety,
Confined Spaces, Test Equipment, Wiring, Cables,
Motors, Transformers, Circuits & Job Knowledge
Review
Question 1: Which of the following materials is classified as a good
conductor of electricity?
A. Glass
B. Rubber
C. Copper
D. Mica
CORRECT ANSWER: C. Copper
Rationale: Copper is a metallic element with a single free electron in its
outer shell, making it an excellent conductor of electricity. Glass, rubber,
and mica are all considered insulators.
Question 2: What is the primary purpose of a lockout/tagout
(LOTO) procedure in an electrical maintenance setting?
A. To increase the speed of repairs
B. To ensure equipment is properly lubricated
C. To prevent the accidental energization of equipment during servicing
D. To test the efficiency of circuit breakers
CORRECT ANSWER: C. To prevent the accidental energization of
equipment during servicing
Rationale: Lockout/Tagout is a safety procedure used to ensure that
dangerous machines are properly shut off and not started up again prior to
the completion of maintenance or repair work. It is a critical safety standard
to protect workers from unexpected energization.
Question 3: According to Ohm's Law, if resistance is doubled while
voltage remains constant, what happens to current?
,A. It doubles
B. It halves
C. It remains the same
D. It quadruples
CORRECT ANSWER: B. It halves
Rationale: According to Ohm's Law (I = V/R), current is inversely
proportional to resistance. If resistance (R) is doubled and voltage (V) is
constant, the current (I) will be reduced by half.
Question 4: What is the unit of electric current?
A. Volt
B. Ohm
C. Ampere
D. Watt
CORRECT ANSWER: C. Ampere
Rationale: Electric current is measured in amperes (amps). Voltage is
measured in volts, resistance in ohms, and power in watts.
Question 5: Which hand tool is specifically designed for gripping,
twisting, and cutting electrical wire?
A. Ball-peen hammer
B. Adjustable wrench
C. Lineman's pliers
D. Pipe wrench
CORRECT ANSWER: C. Lineman's pliers
Rationale: Lineman's pliers are commonly used by electrical workers for
gripping, twisting, splicing, and cutting conductors.
Question 6: What is the primary function of a ground rod in an
electrical system?
A. To provide a return path for current
B. To serve as a neutral conductor
C. To dissipate electrical faults safely into the earth
D. To increase the voltage of the system
,CORRECT ANSWER: C. To dissipate electrical faults safely into the
earth
Rationale: A ground rod provides a low-impedance path for fault currents to
flow into the earth. This helps to stabilize voltages during transient
conditions and ensure overcurrent protection devices operate correctly.
Question 7: What is the power consumed by a circuit with 120 volts
and 5 amperes?
A. 24 watts
B. 60 watts
C. 600 watts
D. 1,200 watts
CORRECT ANSWER: C. 600 watts
Rationale: Power = Voltage × Current = 120 V × 5 A = 600 watts.
Question 8: What type of electrical drawing shows the physical
layout of equipment and interconnecting wires?
A. Schematic diagram
B. One-line diagram
C. Wiring diagram
D. Block diagram
CORRECT ANSWER: C. Wiring diagram
Rationale: Wiring diagrams show the physical location of components and
the actual wire paths and connections between them. This is contrasted
with schematic diagrams, which focus on the functional relationship of
components.
Question 9: What is the total resistance of two 10-ohm resistors
connected in series?
A. 5 ohms
B. 10 ohms
C. 20 ohms
D. 100 ohms
CORRECT ANSWER: C. 20 ohms
, Rationale: In a series circuit, total resistance is the sum of individual
resistances: R_total = R₁ + R₂ = 10 + 10 = 20 ohms.
Question 10: What is the total resistance of two 10-ohm resistors
connected in parallel?
A. 5 ohms
B. 10 ohms
C. 20 ohms
D. 100 ohms
CORRECT ANSWER: A. 5 ohms
Rationale: In a parallel circuit, 1/R_total = 1/R₁ + 1/R₂ = 1/10 + 1/10 =
2/10, so R_total = 5 ohms. Parallel resistance is less than the smallest
individual resistance.
Question 11: Which electrical quantity represents the pressure that
pushes electrons through a conductor?
A. Current
B. Voltage
C. Resistance
D. Power
CORRECT ANSWER: B. Voltage
Rationale: Voltage is electrical pressure or potential difference that drives
current flow.
Question 12: What color is commonly used to indicate equipment
grounding conductors?
A. Black
B. White
C. Green or bare copper
D. Red
CORRECT ANSWER: C. Green or bare copper
Rationale: The NEC mandates green or bare copper for equipment
grounding conductors.
Question 13: What is the correct formula for Ohm's Law?
Helper Class Code 3799 Exam Study Guide & Practice
Questions | Los Angeles Department of Water and
Power Electrical Craft Helper Test Prep, Electrical
Trade Knowledge, Mathematics, Mechanical Aptitude,
Hand & Power Tools, Electrical Equipment, Safety,
Confined Spaces, Test Equipment, Wiring, Cables,
Motors, Transformers, Circuits & Job Knowledge
Review
Question 1: Which of the following materials is classified as a good
conductor of electricity?
A. Glass
B. Rubber
C. Copper
D. Mica
CORRECT ANSWER: C. Copper
Rationale: Copper is a metallic element with a single free electron in its
outer shell, making it an excellent conductor of electricity. Glass, rubber,
and mica are all considered insulators.
Question 2: What is the primary purpose of a lockout/tagout
(LOTO) procedure in an electrical maintenance setting?
A. To increase the speed of repairs
B. To ensure equipment is properly lubricated
C. To prevent the accidental energization of equipment during servicing
D. To test the efficiency of circuit breakers
CORRECT ANSWER: C. To prevent the accidental energization of
equipment during servicing
Rationale: Lockout/Tagout is a safety procedure used to ensure that
dangerous machines are properly shut off and not started up again prior to
the completion of maintenance or repair work. It is a critical safety standard
to protect workers from unexpected energization.
Question 3: According to Ohm's Law, if resistance is doubled while
voltage remains constant, what happens to current?
,A. It doubles
B. It halves
C. It remains the same
D. It quadruples
CORRECT ANSWER: B. It halves
Rationale: According to Ohm's Law (I = V/R), current is inversely
proportional to resistance. If resistance (R) is doubled and voltage (V) is
constant, the current (I) will be reduced by half.
Question 4: What is the unit of electric current?
A. Volt
B. Ohm
C. Ampere
D. Watt
CORRECT ANSWER: C. Ampere
Rationale: Electric current is measured in amperes (amps). Voltage is
measured in volts, resistance in ohms, and power in watts.
Question 5: Which hand tool is specifically designed for gripping,
twisting, and cutting electrical wire?
A. Ball-peen hammer
B. Adjustable wrench
C. Lineman's pliers
D. Pipe wrench
CORRECT ANSWER: C. Lineman's pliers
Rationale: Lineman's pliers are commonly used by electrical workers for
gripping, twisting, splicing, and cutting conductors.
Question 6: What is the primary function of a ground rod in an
electrical system?
A. To provide a return path for current
B. To serve as a neutral conductor
C. To dissipate electrical faults safely into the earth
D. To increase the voltage of the system
,CORRECT ANSWER: C. To dissipate electrical faults safely into the
earth
Rationale: A ground rod provides a low-impedance path for fault currents to
flow into the earth. This helps to stabilize voltages during transient
conditions and ensure overcurrent protection devices operate correctly.
Question 7: What is the power consumed by a circuit with 120 volts
and 5 amperes?
A. 24 watts
B. 60 watts
C. 600 watts
D. 1,200 watts
CORRECT ANSWER: C. 600 watts
Rationale: Power = Voltage × Current = 120 V × 5 A = 600 watts.
Question 8: What type of electrical drawing shows the physical
layout of equipment and interconnecting wires?
A. Schematic diagram
B. One-line diagram
C. Wiring diagram
D. Block diagram
CORRECT ANSWER: C. Wiring diagram
Rationale: Wiring diagrams show the physical location of components and
the actual wire paths and connections between them. This is contrasted
with schematic diagrams, which focus on the functional relationship of
components.
Question 9: What is the total resistance of two 10-ohm resistors
connected in series?
A. 5 ohms
B. 10 ohms
C. 20 ohms
D. 100 ohms
CORRECT ANSWER: C. 20 ohms
, Rationale: In a series circuit, total resistance is the sum of individual
resistances: R_total = R₁ + R₂ = 10 + 10 = 20 ohms.
Question 10: What is the total resistance of two 10-ohm resistors
connected in parallel?
A. 5 ohms
B. 10 ohms
C. 20 ohms
D. 100 ohms
CORRECT ANSWER: A. 5 ohms
Rationale: In a parallel circuit, 1/R_total = 1/R₁ + 1/R₂ = 1/10 + 1/10 =
2/10, so R_total = 5 ohms. Parallel resistance is less than the smallest
individual resistance.
Question 11: Which electrical quantity represents the pressure that
pushes electrons through a conductor?
A. Current
B. Voltage
C. Resistance
D. Power
CORRECT ANSWER: B. Voltage
Rationale: Voltage is electrical pressure or potential difference that drives
current flow.
Question 12: What color is commonly used to indicate equipment
grounding conductors?
A. Black
B. White
C. Green or bare copper
D. Red
CORRECT ANSWER: C. Green or bare copper
Rationale: The NEC mandates green or bare copper for equipment
grounding conductors.
Question 13: What is the correct formula for Ohm's Law?
