Los Angeles Department of Water and Power (LADWP)
Electrical Craft Helper (Class Code 3799) Exam
Section One: Questions 1–100
1. Which of the following best describes the primary purpose of a multimeter in electrical
work?
A) To measure only voltage in high-voltage systems
B) To measure voltage, current, and resistance in a single device
C) To replace the need for lockout/tagout procedures
D) To generate electrical power for testing circuits
Correct Answer: B) To measure voltage, current, and resistance in a single device
Rationale: A multimeter combines multiple measurement functions into one handheld instrument,
allowing electricians to diagnose circuits efficiently. Voltage, current, and resistance are the three
fundamental electrical quantities. Other tools like ammeters or voltmeters perform only single
functions. The multimeter is essential for troubleshooting and verification tasks.
2. In a series circuit, if one component fails open, what happens to the entire circuit?
A) Current continues to flow at reduced voltage
B) The circuit operates normally but with higher resistance
C) Current flow stops completely throughout the circuit
D) Voltage increases across all remaining components
Correct Answer: C) Current flow stops completely throughout the circuit
Rationale: A series circuit provides only one path for current. An open failure breaks that single path,
halting current flow everywhere. This differs from parallel circuits, where other branches continue
operating. Understanding this distinction is critical for troubleshooting electrical systems safely and
efficiently.
3. What is the standard frequency of AC power supplied by utilities in the United States?
A) 25 Hz
B) 50 Hz
C) 60 Hz
D) 100 Hz
Correct Answer: C) 60 Hz
Rationale: U.S. utility grids operate at 60 hertz, while many other countries use 50 Hz. This frequency
affects motor speeds, transformer design, and equipment compatibility. LADWP equipment and
systems are designed around 60 Hz operation, making this a foundational fact for helpers.
4. What electrical quantity represents the pressure that pushes electrons through a conductor?
A) Resistance
B) Voltage
C) Current
D) Power
Correct Answer: B) Voltage
,Rationale: Voltage is the electrical pressure or electromotive force that drives current through a
circuit. It is analogous to water pressure in a pipe. Current is the flow rate of electrons, resistance
opposes that flow, and power is the rate of energy consumption. Understanding these distinctions is
essential.
5. A circuit has a voltage of 120 volts and a resistance of 12 ohms. According to Ohm's Law,
what is the current?
A) 5 amperes
B) 8 amperes
C) 10 amperes
D) 12 amperes
Correct Answer: C) 10 amperes
Rationale: Ohm's Law states I = V/R. Dividing 120 volts by 12 ohms yields 10 amperes. This
calculation is fundamental to electrical work and appears frequently on exams. Mastery of Ohm's
Law allows helpers to verify circuit conditions and assist journey-level workers effectively.
6. Which material is the best conductor of electricity among common wiring materials?
A) Aluminum
B) Copper
C) Steel
D) PVC
Correct Answer: B) Copper
Rationale: Copper has the highest conductivity among common wiring materials, surpassing
aluminum and far exceeding non-conductors like steel or PVC. Copper is the industry standard for
electrical conductors due to its excellent conductivity, corrosion resistance, and workability. This
makes it the preferred choice for most wiring applications.
7. What is the total resistance of two 10-ohm resistors connected in series?
A) 5 ohms
B) 10 ohms
C) 15 ohms
D) 20 ohms
Correct Answer: D) 20 ohms
Rationale: In a series circuit, total resistance equals the sum of individual resistances. Therefore, 10
ohms plus 10 ohms equals 20 ohms. Series resistance adds directly because current must pass
through each resistor sequentially. This principle is essential for circuit analysis and troubleshooting.
8. What is the correct first step when arriving at a job site?
A) Begin working immediately to save time
B) Identify and report hazards before starting work
C) Set up ladders and tools first
D) Check the weather forecast
Correct Answer: B) Identify and report hazards before starting work
,Rationale: Job site safety begins with hazard assessment. Identifying and reporting hazards prevents
injuries before any work begins. Rushing into tasks without assessment violates safety protocols and
endangers workers. This aligns with LADWP safety focus and OSHA requirements.
9. What instrument is used to measure voltage, current, and resistance in a single device?
A) Ammeter
B) Voltmeter
C) Ohmmeter
D) Multimeter
Correct Answer: D) Multimeter
Rationale: A multimeter combines all three measurement functions into one handheld device.
Ammeters measure only current, voltmeters measure only voltage, and ohmmeters measure only
resistance. The multimeter's versatility makes it indispensable for electrical troubleshooting and
verification tasks in the field.
10. What does the term "lockout/tagout" (LOTO) refer to?
A) Securing tools in a locked box at the end of the day
B) Locking the job site entrance to prevent unauthorized access
C) Isolating and tagging energy sources to prevent accidental startup
D) Recording work hours on a tag attached to equipment
Correct Answer: C) Isolating and tagging energy sources to prevent accidental startup
Rationale: LOTO is a safety procedure that ensures equipment is completely de-energized during
maintenance. Workers apply locks and tags to energy isolation devices, preventing accidental re-
energization. This protects personnel from electrical shock, arc flash, and mechanical injury during
service work.
11. What is the unit of electrical resistance?
A) Ampere
B) Volt
C) Ohm
D) Watt
Correct Answer: C) Ohm
Rationale: The ohm (Ω) is the standard unit for measuring resistance to current flow. Amperes
measure current, volts measure voltage, and watts measure power. Understanding these units and
their relationships through Ohm's Law is fundamental to all electrical work and testing.
12. Which of the following is an insulator?
A) Aluminum
B) Silver
C) Rubber
D) Gold
Correct Answer: C) Rubber
Rationale: Rubber has high electrical resistance and is used to insulate wires, preventing current from
flowing where it should not. Aluminum, silver, and gold are all conductors. Insulators protect workers
from shock and prevent short circuits by containing current within intended paths.
, 13. What type of current flows in one direction only?
A) Alternating current (AC)
B) Direct current (DC)
C) Pulsating current
D) Inductive current
Correct Answer: B) Direct current (DC)
Rationale: DC flows in a single, constant direction, unlike AC which reverses periodically. Batteries and
electronic devices typically use DC, while utility power distribution uses AC. Understanding this
distinction is important for working with different electrical systems and equipment.
14. What is a short circuit?
A) A circuit with too much resistance
B) An unintended low-resistance path between conductors
C) A circuit that is turned off at the breaker
D) A circuit with no voltage present
Correct Answer: B) An unintended low-resistance path between conductors
Rationale: A short circuit bypasses the normal load, allowing excessive current to flow. This can
damage equipment, cause fires, or create shock hazards. Protective devices like fuses and circuit
breakers interrupt short circuits to prevent damage. Recognizing short circuit conditions is essential
for safe troubleshooting.
15. In a parallel circuit, if one branch fails open, what happens to the other branches?
A) All branches stop working
B) Other branches continue to operate normally
C) Voltage increases in other branches
D) Current decreases in all branches
Correct Answer: B) Other branches continue to operate normally
Rationale: Parallel circuits provide multiple independent paths for current. If one branch fails, other
branches remain energized and functional. This is why homes are wired in parallel—lighting and
appliances continue working when one fails. This principle is fundamental to understanding
distribution systems.
16. What is 35% of 200?
A) 50
B) 60
C) 70
D) 80
Correct Answer: C) 70
Rationale: To find 35% of 200, multiply 0.35 by 200, which equals 70. Basic arithmetic skills are
essential for electrical work involving load calculations, material estimates, and measurements.
Accurate calculations prevent errors that could compromise safety or project timelines.
17. What type of circuit has two or more paths for current to flow?
A) Series
B) Parallel
Electrical Craft Helper (Class Code 3799) Exam
Section One: Questions 1–100
1. Which of the following best describes the primary purpose of a multimeter in electrical
work?
A) To measure only voltage in high-voltage systems
B) To measure voltage, current, and resistance in a single device
C) To replace the need for lockout/tagout procedures
D) To generate electrical power for testing circuits
Correct Answer: B) To measure voltage, current, and resistance in a single device
Rationale: A multimeter combines multiple measurement functions into one handheld instrument,
allowing electricians to diagnose circuits efficiently. Voltage, current, and resistance are the three
fundamental electrical quantities. Other tools like ammeters or voltmeters perform only single
functions. The multimeter is essential for troubleshooting and verification tasks.
2. In a series circuit, if one component fails open, what happens to the entire circuit?
A) Current continues to flow at reduced voltage
B) The circuit operates normally but with higher resistance
C) Current flow stops completely throughout the circuit
D) Voltage increases across all remaining components
Correct Answer: C) Current flow stops completely throughout the circuit
Rationale: A series circuit provides only one path for current. An open failure breaks that single path,
halting current flow everywhere. This differs from parallel circuits, where other branches continue
operating. Understanding this distinction is critical for troubleshooting electrical systems safely and
efficiently.
3. What is the standard frequency of AC power supplied by utilities in the United States?
A) 25 Hz
B) 50 Hz
C) 60 Hz
D) 100 Hz
Correct Answer: C) 60 Hz
Rationale: U.S. utility grids operate at 60 hertz, while many other countries use 50 Hz. This frequency
affects motor speeds, transformer design, and equipment compatibility. LADWP equipment and
systems are designed around 60 Hz operation, making this a foundational fact for helpers.
4. What electrical quantity represents the pressure that pushes electrons through a conductor?
A) Resistance
B) Voltage
C) Current
D) Power
Correct Answer: B) Voltage
,Rationale: Voltage is the electrical pressure or electromotive force that drives current through a
circuit. It is analogous to water pressure in a pipe. Current is the flow rate of electrons, resistance
opposes that flow, and power is the rate of energy consumption. Understanding these distinctions is
essential.
5. A circuit has a voltage of 120 volts and a resistance of 12 ohms. According to Ohm's Law,
what is the current?
A) 5 amperes
B) 8 amperes
C) 10 amperes
D) 12 amperes
Correct Answer: C) 10 amperes
Rationale: Ohm's Law states I = V/R. Dividing 120 volts by 12 ohms yields 10 amperes. This
calculation is fundamental to electrical work and appears frequently on exams. Mastery of Ohm's
Law allows helpers to verify circuit conditions and assist journey-level workers effectively.
6. Which material is the best conductor of electricity among common wiring materials?
A) Aluminum
B) Copper
C) Steel
D) PVC
Correct Answer: B) Copper
Rationale: Copper has the highest conductivity among common wiring materials, surpassing
aluminum and far exceeding non-conductors like steel or PVC. Copper is the industry standard for
electrical conductors due to its excellent conductivity, corrosion resistance, and workability. This
makes it the preferred choice for most wiring applications.
7. What is the total resistance of two 10-ohm resistors connected in series?
A) 5 ohms
B) 10 ohms
C) 15 ohms
D) 20 ohms
Correct Answer: D) 20 ohms
Rationale: In a series circuit, total resistance equals the sum of individual resistances. Therefore, 10
ohms plus 10 ohms equals 20 ohms. Series resistance adds directly because current must pass
through each resistor sequentially. This principle is essential for circuit analysis and troubleshooting.
8. What is the correct first step when arriving at a job site?
A) Begin working immediately to save time
B) Identify and report hazards before starting work
C) Set up ladders and tools first
D) Check the weather forecast
Correct Answer: B) Identify and report hazards before starting work
,Rationale: Job site safety begins with hazard assessment. Identifying and reporting hazards prevents
injuries before any work begins. Rushing into tasks without assessment violates safety protocols and
endangers workers. This aligns with LADWP safety focus and OSHA requirements.
9. What instrument is used to measure voltage, current, and resistance in a single device?
A) Ammeter
B) Voltmeter
C) Ohmmeter
D) Multimeter
Correct Answer: D) Multimeter
Rationale: A multimeter combines all three measurement functions into one handheld device.
Ammeters measure only current, voltmeters measure only voltage, and ohmmeters measure only
resistance. The multimeter's versatility makes it indispensable for electrical troubleshooting and
verification tasks in the field.
10. What does the term "lockout/tagout" (LOTO) refer to?
A) Securing tools in a locked box at the end of the day
B) Locking the job site entrance to prevent unauthorized access
C) Isolating and tagging energy sources to prevent accidental startup
D) Recording work hours on a tag attached to equipment
Correct Answer: C) Isolating and tagging energy sources to prevent accidental startup
Rationale: LOTO is a safety procedure that ensures equipment is completely de-energized during
maintenance. Workers apply locks and tags to energy isolation devices, preventing accidental re-
energization. This protects personnel from electrical shock, arc flash, and mechanical injury during
service work.
11. What is the unit of electrical resistance?
A) Ampere
B) Volt
C) Ohm
D) Watt
Correct Answer: C) Ohm
Rationale: The ohm (Ω) is the standard unit for measuring resistance to current flow. Amperes
measure current, volts measure voltage, and watts measure power. Understanding these units and
their relationships through Ohm's Law is fundamental to all electrical work and testing.
12. Which of the following is an insulator?
A) Aluminum
B) Silver
C) Rubber
D) Gold
Correct Answer: C) Rubber
Rationale: Rubber has high electrical resistance and is used to insulate wires, preventing current from
flowing where it should not. Aluminum, silver, and gold are all conductors. Insulators protect workers
from shock and prevent short circuits by containing current within intended paths.
, 13. What type of current flows in one direction only?
A) Alternating current (AC)
B) Direct current (DC)
C) Pulsating current
D) Inductive current
Correct Answer: B) Direct current (DC)
Rationale: DC flows in a single, constant direction, unlike AC which reverses periodically. Batteries and
electronic devices typically use DC, while utility power distribution uses AC. Understanding this
distinction is important for working with different electrical systems and equipment.
14. What is a short circuit?
A) A circuit with too much resistance
B) An unintended low-resistance path between conductors
C) A circuit that is turned off at the breaker
D) A circuit with no voltage present
Correct Answer: B) An unintended low-resistance path between conductors
Rationale: A short circuit bypasses the normal load, allowing excessive current to flow. This can
damage equipment, cause fires, or create shock hazards. Protective devices like fuses and circuit
breakers interrupt short circuits to prevent damage. Recognizing short circuit conditions is essential
for safe troubleshooting.
15. In a parallel circuit, if one branch fails open, what happens to the other branches?
A) All branches stop working
B) Other branches continue to operate normally
C) Voltage increases in other branches
D) Current decreases in all branches
Correct Answer: B) Other branches continue to operate normally
Rationale: Parallel circuits provide multiple independent paths for current. If one branch fails, other
branches remain energized and functional. This is why homes are wired in parallel—lighting and
appliances continue working when one fails. This principle is fundamental to understanding
distribution systems.
16. What is 35% of 200?
A) 50
B) 60
C) 70
D) 80
Correct Answer: C) 70
Rationale: To find 35% of 200, multiply 0.35 by 200, which equals 70. Basic arithmetic skills are
essential for electrical work involving load calculations, material estimates, and measurements.
Accurate calculations prevent errors that could compromise safety or project timelines.
17. What type of circuit has two or more paths for current to flow?
A) Series
B) Parallel
