LADWP ELECTRICAL HELPER EXAM
PREP 150 MULTI CRAFT PRACTICE
QUESTIONS WITH EXPERT ANSWERS
and DETAILED RATIONALES VERIFIED
2026
LADWP Electrical Helper Practice Exam
1. When working around high-voltage equipment, what is
the primary reason an Electrical Helper must maintain the
Minimum Approach Distance (MAD) specified by OSHA
and LADWP safety rules?
A) To ensure there is enough physical space to store tools
and ladders safely
B) To prevent an electrical arc-flash or sparkover through
the air to the worker’s body or conductive tools
C) To allow cooling air currents to circulate freely around
active circuit breakers
D) To reduce the physical wear and tear on insulated
rubber gloves and blankets
Correct Answer: B
Rationale: High voltage can arc through the air to a
grounded object or person even without direct physical
contact. Maintaining the Minimum Approach Distance
(MAD) protects workers from lethal arc-flash burns and
electrocution by providing a safe air barrier.
2. An Electrical Helper needs to measure the electrical
current flowing through a live operational single-
conductor cable without breaking the circuit. Which
diagnostic test tool must be selected?
A) An in-line digital Megohmmeter
, B) A clamp-on Ammeter (Current Clamp)
C) A three-lead Phase Rotation Meter
D) A high-impedance Analog Voltmeter
Correct Answer: B
Rationale: A clamp-on ammeter measures the
magnetic field surrounding a conductor to calculate the
active AC current flow. This allows the helper to safely
gather amperage readings without disconnecting cables
or interrupting utility service.
3. According to standard electrical safe work practices, what
must a worker do immediately before relying on a digital
multimeter to verify a circuit is de-energised?
A) Calibrate the meter's internal resistance settings by
touching the leads to a known resistor
B) Verify the meter functions correctly by testing it on a
known live power source, checking the dead circuit, and
then re-testing on the live source
C) Clean the metallic test lead tips with an abrasive wire
brush to remove oxidisation
D) Replace the internal AA alkaline batteries to guarantee
accurate display backlight illumination
Correct Answer: B
Rationale: This is known as the "Live-Dead-Live" test
method. It ensures that the multimeter did not fail or
blow an internal fuse right before checking the target
circuit, preventing a false "zero voltage" reading on a
lethal live line.
4. Which standard electrical formula correctly represents
Ohm’s Law for calculating the total resistance of a direct
current (DC) circuit?
A) Resistance (R) = Voltage (E) multiplied by Current (I)
B) Resistance (R) = Voltage (E) divided by Current (I)
C) Resistance (R) = Current (I) divided by Voltage (E)
, D) Resistance (R) = Watts (P) multiplied by Voltage (E)
Correct Answer: B
Rationale: Ohm’s Law states that Resistance (R) equals
Voltage (E or V) divided by Current (I). Mathematically,
this is expressed as R = E / I.
5. What is the total equivalent resistance of a series circuit
containing three field resistors valued at 10 ohms, 20
ohms, and 30 ohms respectively?
A) 60 ohms
B) 5.45 ohms
C) 20 ohms
D) 15 ohms
Correct Answer: A
Rationale: In a series circuit, total resistance is
calculated by simply adding the individual resistances
together (\(R_t = R_1 + R_2 + R_3\)). Therefore, 10 + 20
+ 30 = 60 ohms.
6. While inspecting a substation yard, an Electrical Helper
notices a co-worker has made contact with a live overhead
line and is being actively shocked. What is the first, most
urgent action the helper must take?
A) Grab the co-worker's leather tool belt and pull them
away from the electrical line immediately
B) De-energise the circuit at the main disconnect switch or
use a certified, non-conductive rescue hook to pull the
victim clear
C) Call emergency services and wait quietly at the
substation entry gate for paramedics to arrive
D) Throw a clean, wet cotton rope over the live wire to
trigger a short circuit and trip the breaker
Correct Answer: B
Rationale: Touching an actively electrocuted person
will cause the current to pass into your body, creating a
, second victim. The power source must be isolated first, or
a non-conductive tool (like a fiberglass hot stick) must be
used to safely break the contact.
7. What type of fire extinguisher is specifically rated and
designed to safely put out an active electrical fire occurring
inside a generator control panel?
A) Class A water-pressurised extinguisher
B) Class B synthetic foam-producer extinguisher
C) Class C dry chemical or Carbon Dioxide (CO₂)
extinguisher
D) Class D combustible sodium-metal powder
extinguisher
Correct Answer: C
Rationale: Class C extinguishers utilize non-conductive
extinguishing agents, such as CO₂ or dry chemicals, to
suppress fires involving energized electrical equipment
without exposing the operator to shock hazards.
8. When routing electrical conductors through rigid metal
conduit (RMC), what tool must be used on the cut ends of
the conduit before pulling the wires?
A) A high-speed pneumatic impact wrench
B) A conduit reamer to remove sharp internal burrs
C) A hydraulic pipe bender with a deep-channel shoe
D) A heavy-duty canvas wire-pulling mesh grip
Correct Answer: B
Rationale: Cutting conduit leaves a sharp internal edge
(burr). Reaming the inside edge smooth prevents these
burrs from slicing through the insulation of the wires
during the pulling process, preventing short circuits.
9. If a circuit has an operational voltage of 120 volts and a
total measured resistance of 15 ohms, what is the active
current flowing through the circuit?
A) 1,800 amperes
PREP 150 MULTI CRAFT PRACTICE
QUESTIONS WITH EXPERT ANSWERS
and DETAILED RATIONALES VERIFIED
2026
LADWP Electrical Helper Practice Exam
1. When working around high-voltage equipment, what is
the primary reason an Electrical Helper must maintain the
Minimum Approach Distance (MAD) specified by OSHA
and LADWP safety rules?
A) To ensure there is enough physical space to store tools
and ladders safely
B) To prevent an electrical arc-flash or sparkover through
the air to the worker’s body or conductive tools
C) To allow cooling air currents to circulate freely around
active circuit breakers
D) To reduce the physical wear and tear on insulated
rubber gloves and blankets
Correct Answer: B
Rationale: High voltage can arc through the air to a
grounded object or person even without direct physical
contact. Maintaining the Minimum Approach Distance
(MAD) protects workers from lethal arc-flash burns and
electrocution by providing a safe air barrier.
2. An Electrical Helper needs to measure the electrical
current flowing through a live operational single-
conductor cable without breaking the circuit. Which
diagnostic test tool must be selected?
A) An in-line digital Megohmmeter
, B) A clamp-on Ammeter (Current Clamp)
C) A three-lead Phase Rotation Meter
D) A high-impedance Analog Voltmeter
Correct Answer: B
Rationale: A clamp-on ammeter measures the
magnetic field surrounding a conductor to calculate the
active AC current flow. This allows the helper to safely
gather amperage readings without disconnecting cables
or interrupting utility service.
3. According to standard electrical safe work practices, what
must a worker do immediately before relying on a digital
multimeter to verify a circuit is de-energised?
A) Calibrate the meter's internal resistance settings by
touching the leads to a known resistor
B) Verify the meter functions correctly by testing it on a
known live power source, checking the dead circuit, and
then re-testing on the live source
C) Clean the metallic test lead tips with an abrasive wire
brush to remove oxidisation
D) Replace the internal AA alkaline batteries to guarantee
accurate display backlight illumination
Correct Answer: B
Rationale: This is known as the "Live-Dead-Live" test
method. It ensures that the multimeter did not fail or
blow an internal fuse right before checking the target
circuit, preventing a false "zero voltage" reading on a
lethal live line.
4. Which standard electrical formula correctly represents
Ohm’s Law for calculating the total resistance of a direct
current (DC) circuit?
A) Resistance (R) = Voltage (E) multiplied by Current (I)
B) Resistance (R) = Voltage (E) divided by Current (I)
C) Resistance (R) = Current (I) divided by Voltage (E)
, D) Resistance (R) = Watts (P) multiplied by Voltage (E)
Correct Answer: B
Rationale: Ohm’s Law states that Resistance (R) equals
Voltage (E or V) divided by Current (I). Mathematically,
this is expressed as R = E / I.
5. What is the total equivalent resistance of a series circuit
containing three field resistors valued at 10 ohms, 20
ohms, and 30 ohms respectively?
A) 60 ohms
B) 5.45 ohms
C) 20 ohms
D) 15 ohms
Correct Answer: A
Rationale: In a series circuit, total resistance is
calculated by simply adding the individual resistances
together (\(R_t = R_1 + R_2 + R_3\)). Therefore, 10 + 20
+ 30 = 60 ohms.
6. While inspecting a substation yard, an Electrical Helper
notices a co-worker has made contact with a live overhead
line and is being actively shocked. What is the first, most
urgent action the helper must take?
A) Grab the co-worker's leather tool belt and pull them
away from the electrical line immediately
B) De-energise the circuit at the main disconnect switch or
use a certified, non-conductive rescue hook to pull the
victim clear
C) Call emergency services and wait quietly at the
substation entry gate for paramedics to arrive
D) Throw a clean, wet cotton rope over the live wire to
trigger a short circuit and trip the breaker
Correct Answer: B
Rationale: Touching an actively electrocuted person
will cause the current to pass into your body, creating a
, second victim. The power source must be isolated first, or
a non-conductive tool (like a fiberglass hot stick) must be
used to safely break the contact.
7. What type of fire extinguisher is specifically rated and
designed to safely put out an active electrical fire occurring
inside a generator control panel?
A) Class A water-pressurised extinguisher
B) Class B synthetic foam-producer extinguisher
C) Class C dry chemical or Carbon Dioxide (CO₂)
extinguisher
D) Class D combustible sodium-metal powder
extinguisher
Correct Answer: C
Rationale: Class C extinguishers utilize non-conductive
extinguishing agents, such as CO₂ or dry chemicals, to
suppress fires involving energized electrical equipment
without exposing the operator to shock hazards.
8. When routing electrical conductors through rigid metal
conduit (RMC), what tool must be used on the cut ends of
the conduit before pulling the wires?
A) A high-speed pneumatic impact wrench
B) A conduit reamer to remove sharp internal burrs
C) A hydraulic pipe bender with a deep-channel shoe
D) A heavy-duty canvas wire-pulling mesh grip
Correct Answer: B
Rationale: Cutting conduit leaves a sharp internal edge
(burr). Reaming the inside edge smooth prevents these
burrs from slicing through the insulation of the wires
during the pulling process, preventing short circuits.
9. If a circuit has an operational voltage of 120 volts and a
total measured resistance of 15 ohms, what is the active
current flowing through the circuit?
A) 1,800 amperes
