LADWP Electrical Craft Helper (Class 3799) & Electrician (Class 3863) Practice Examination 2026
LADWP Electrical Craft Helper (Class 3799) – Section 1: Electrical Fundamentals
1. What is the fundamental purpose of a conductor in an electrical circuit?
A) To oppose the flow of current
B) To provide a path for current flow
C) To store electrical energy
D) To convert electrical energy to heat
Answer: B
Rationale: A conductor provides a low-resistance path for current to flow between components in a circuit.
2. What is the standard unit of measurement for electrical resistance?
A) Volt
B) Ampere
C) Watt
D) Ohm
Answer: D
Rationale: Resistance is measured in ohms (Ω), representing the opposition to current flow.
3. What is the unit of measurement for electrical current?
A) Volt
B) Ampere
C) Ohm
D) Watt
Answer: B
Rationale: Electric current is measured in amperes (A), representing the rate of electron flow.
4. What is the unit of measurement for electrical potential difference?
A) Ampere
B) Volt
C) Ohm
D) Watt
,Answer: B
Rationale: Voltage is measured in volts (V), representing the electrical potential difference between two
points.
5. What is the unit of measurement for electrical power?
A) Volt
B) Ampere
C) Watt
D) Ohm
Answer: C
Rationale: Electrical power is measured in watts (W), representing the rate of energy transfer.
6. In a DC circuit, current flows:
A) Back and forth periodically
B) In one direction only
C) Only when there is a load
D) Randomly
Answer: B
Rationale: Direct current (DC) flows in one direction only, unlike alternating current which reverses
direction.
7. In an AC circuit, current:
A) Flows in one direction only
B) Reverses direction periodically
C) Never changes direction
D) Flows only through resistors
Answer: B
Rationale: Alternating current (AC) periodically reverses direction, typically at 60 Hz in the United States.
8. What is the formula for Ohm's Law?
A) V = I × R
B) V = I ÷ R
2
,C) V = R ÷ I
D) V = I² × R
Answer: A
Rationale: Ohm's Law states that voltage equals current multiplied by resistance.
9. A circuit has a voltage of 120 V and a resistance of 20 ohms. What is the current?
A) 4 A
B) 6 A
C) 8 A
D) 10 A
Answer: B
Rationale: I = V ÷ R = 120 ÷ 20 = 6 amperes.
10. A 240-volt circuit draws 15 amperes. What is the resistance?
A) 12 ohms
B) 16 ohms
C) 20 ohms
D) 24 ohms
Answer: B
Rationale: R = V ÷ I = 240 ÷ 15 = 16 ohms.
11. What is the formula for electrical power in a DC circuit?
A) P = V × I
B) P = V ÷ I
C) P = I ÷ V
D) P = V × R
Answer: A
Rationale: Power in a DC circuit equals voltage multiplied by current.
12. A 120-volt circuit draws 10 amperes. What is the power consumed?
A) 1,200 W
B) 120 W
3
, C) 12 W
D) 1,000 W
Answer: A
Rationale: P = V × I = 120 × 10 = 1,200 watts.
13. What does the term "ampacity" refer to?
A) The maximum number of amps in a circuit
B) The maximum current a conductor can carry continuously without exceeding its insulation temperature
rating
C) The capacity of a transformer
D) The electrical capacity of a battery
Answer: B
Rationale: Ampacity is the maximum current a conductor can carry continuously under conditions of use
without exceeding its insulation temperature rating.
14. Which of the following is a good conductor of electricity?
A) Rubber
B) Glass
C) Copper
D) Plastic
Answer: C
Rationale: Copper is an excellent conductor of electricity, commonly used in electrical wiring.
15. Which of the following is an insulator?
A) Copper
B) Aluminum
C) Silver
D) Rubber
Answer: D
Rationale: Rubber is an insulator, used to cover conductors to prevent electrical shock.
# Section 2: Electrical Safety
4
LADWP Electrical Craft Helper (Class 3799) – Section 1: Electrical Fundamentals
1. What is the fundamental purpose of a conductor in an electrical circuit?
A) To oppose the flow of current
B) To provide a path for current flow
C) To store electrical energy
D) To convert electrical energy to heat
Answer: B
Rationale: A conductor provides a low-resistance path for current to flow between components in a circuit.
2. What is the standard unit of measurement for electrical resistance?
A) Volt
B) Ampere
C) Watt
D) Ohm
Answer: D
Rationale: Resistance is measured in ohms (Ω), representing the opposition to current flow.
3. What is the unit of measurement for electrical current?
A) Volt
B) Ampere
C) Ohm
D) Watt
Answer: B
Rationale: Electric current is measured in amperes (A), representing the rate of electron flow.
4. What is the unit of measurement for electrical potential difference?
A) Ampere
B) Volt
C) Ohm
D) Watt
,Answer: B
Rationale: Voltage is measured in volts (V), representing the electrical potential difference between two
points.
5. What is the unit of measurement for electrical power?
A) Volt
B) Ampere
C) Watt
D) Ohm
Answer: C
Rationale: Electrical power is measured in watts (W), representing the rate of energy transfer.
6. In a DC circuit, current flows:
A) Back and forth periodically
B) In one direction only
C) Only when there is a load
D) Randomly
Answer: B
Rationale: Direct current (DC) flows in one direction only, unlike alternating current which reverses
direction.
7. In an AC circuit, current:
A) Flows in one direction only
B) Reverses direction periodically
C) Never changes direction
D) Flows only through resistors
Answer: B
Rationale: Alternating current (AC) periodically reverses direction, typically at 60 Hz in the United States.
8. What is the formula for Ohm's Law?
A) V = I × R
B) V = I ÷ R
2
,C) V = R ÷ I
D) V = I² × R
Answer: A
Rationale: Ohm's Law states that voltage equals current multiplied by resistance.
9. A circuit has a voltage of 120 V and a resistance of 20 ohms. What is the current?
A) 4 A
B) 6 A
C) 8 A
D) 10 A
Answer: B
Rationale: I = V ÷ R = 120 ÷ 20 = 6 amperes.
10. A 240-volt circuit draws 15 amperes. What is the resistance?
A) 12 ohms
B) 16 ohms
C) 20 ohms
D) 24 ohms
Answer: B
Rationale: R = V ÷ I = 240 ÷ 15 = 16 ohms.
11. What is the formula for electrical power in a DC circuit?
A) P = V × I
B) P = V ÷ I
C) P = I ÷ V
D) P = V × R
Answer: A
Rationale: Power in a DC circuit equals voltage multiplied by current.
12. A 120-volt circuit draws 10 amperes. What is the power consumed?
A) 1,200 W
B) 120 W
3
, C) 12 W
D) 1,000 W
Answer: A
Rationale: P = V × I = 120 × 10 = 1,200 watts.
13. What does the term "ampacity" refer to?
A) The maximum number of amps in a circuit
B) The maximum current a conductor can carry continuously without exceeding its insulation temperature
rating
C) The capacity of a transformer
D) The electrical capacity of a battery
Answer: B
Rationale: Ampacity is the maximum current a conductor can carry continuously under conditions of use
without exceeding its insulation temperature rating.
14. Which of the following is a good conductor of electricity?
A) Rubber
B) Glass
C) Copper
D) Plastic
Answer: C
Rationale: Copper is an excellent conductor of electricity, commonly used in electrical wiring.
15. Which of the following is an insulator?
A) Copper
B) Aluminum
C) Silver
D) Rubber
Answer: D
Rationale: Rubber is an insulator, used to cover conductors to prevent electrical shock.
# Section 2: Electrical Safety
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