LADWP Electrical Test Technician
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a digital multimeter when
performing electrical testing?
A. To mechanically tighten electrical connections
B. To generate a high-voltage test signal
C. To measure electrical quantities such as voltage, current, and
resistance
D. To provide mechanical overload protection
Answer: C. To measure electrical quantities such as voltage, current,
and resistance
Rationale: A digital multimeter is a general-purpose electrical test
instrument used to measure quantities such as AC or DC voltage,
current, resistance, continuity, and often frequency or capacitance.
The technician selects the appropriate function, range, and test leads
for the circuit being examined. Proper meter selection and connection
are essential because using an incorrect function or connection can
damage the meter or create a dangerous condition.
2. Which electrical quantity is measured in ohms?
A. Current
B. Resistance
C. Power
D. Capacitance
,Answer: B. Resistance
Rationale: The ohm is the SI unit of electrical resistance. Resistance
describes the opposition a material or component presents to current
flow. Using Ohm's law, resistance can be calculated as voltage divided
by current. Test technicians commonly measure resistance when
checking conductors, coils, heating elements, contacts, and other
electrical components.
3. A technician measures 120 volts across a 24-ohm resistor.
Approximately how much current flows through the resistor?
A. 2 A
B. 5 A
C. 24 A
D. 96 A
Answer: B. 5 A
Rationale: Ohm's law states that current equals voltage divided by
resistance. Dividing 120 volts by 24 ohms gives 5 amperes. This
relationship is fundamental to electrical testing because it allows a
technician to evaluate whether measured voltage, resistance, and
current are consistent with expected circuit behavior.
4. Which instrument is specifically designed to measure insulation
resistance at relatively high test voltages?
A. Clamp ammeter
B. Frequency counter
C. Oscilloscope
D. Megohmmeter
Answer: D. Megohmmeter
,Rationale: A megohmmeter, commonly called a megger, applies a
controlled DC test voltage and measures very high resistance values,
typically in megohms. It is widely used for evaluating insulation in
cables, motors, transformers, and other electrical equipment. The
equipment being tested must be isolated appropriately before the test,
and stored charge must be safely discharged afterward.
5. Before connecting a test instrument to an energized circuit, what
should the technician do first?
A. Increase the meter range to its lowest setting
B. Remove the equipment grounding conductor
C. Verify the instrument, leads, function, and expected voltage are
appropriate
D. Place the instrument in resistance mode
Answer: C. Verify the instrument, leads, function, and expected
voltage are appropriate
Rationale: A test technician must verify that the instrument is rated for
the circuit, that the leads are properly connected, and that the selected
function and range are appropriate. This preliminary check reduces
the possibility of meter damage, incorrect readings, arc flash, or
electric shock. Resistance and continuity functions generally must not
be used on energized circuits.
6. What does an oscilloscope primarily display?
A. Wire insulation thickness
B. Transformer oil level
C. Electrical signal amplitude as a function of time
D. Conductor temperature only
Answer: C. Electrical signal amplitude as a function of time
, Rationale: An oscilloscope displays voltage or another electrical signal
versus time. It allows technicians to observe waveform shape,
frequency, amplitude, distortion, noise, transients, and timing
relationships. In electrical testing, an oscilloscope can reveal
abnormalities that may not be apparent from a simple RMS or DC
voltage measurement.
7. What is the main purpose of a current transformer in an electrical
measurement system?
A. To increase conductor resistance
B. To provide a proportional, isolated current suitable for
measurement or protection
C. To convert DC voltage into mechanical energy
D. To eliminate all harmonics
Answer: B. To provide a proportional, isolated current suitable for
measurement or protection
Rationale: A current transformer, or CT, produces a secondary current
proportional to the primary current. This permits meters and protective
relays to work with manageable currents while maintaining electrical
isolation from the high-current primary circuit. A CT secondary
should never be left improperly open-circuited while its primary is
energized because dangerous voltage can develop.
8. What is the purpose of a potential transformer or voltage
transformer?
A. To measure resistance directly
B. To reduce high system voltage to a proportional level for
measurement and protection
C. To increase motor torque
D. To eliminate the need for grounding
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a digital multimeter when
performing electrical testing?
A. To mechanically tighten electrical connections
B. To generate a high-voltage test signal
C. To measure electrical quantities such as voltage, current, and
resistance
D. To provide mechanical overload protection
Answer: C. To measure electrical quantities such as voltage, current,
and resistance
Rationale: A digital multimeter is a general-purpose electrical test
instrument used to measure quantities such as AC or DC voltage,
current, resistance, continuity, and often frequency or capacitance.
The technician selects the appropriate function, range, and test leads
for the circuit being examined. Proper meter selection and connection
are essential because using an incorrect function or connection can
damage the meter or create a dangerous condition.
2. Which electrical quantity is measured in ohms?
A. Current
B. Resistance
C. Power
D. Capacitance
,Answer: B. Resistance
Rationale: The ohm is the SI unit of electrical resistance. Resistance
describes the opposition a material or component presents to current
flow. Using Ohm's law, resistance can be calculated as voltage divided
by current. Test technicians commonly measure resistance when
checking conductors, coils, heating elements, contacts, and other
electrical components.
3. A technician measures 120 volts across a 24-ohm resistor.
Approximately how much current flows through the resistor?
A. 2 A
B. 5 A
C. 24 A
D. 96 A
Answer: B. 5 A
Rationale: Ohm's law states that current equals voltage divided by
resistance. Dividing 120 volts by 24 ohms gives 5 amperes. This
relationship is fundamental to electrical testing because it allows a
technician to evaluate whether measured voltage, resistance, and
current are consistent with expected circuit behavior.
4. Which instrument is specifically designed to measure insulation
resistance at relatively high test voltages?
A. Clamp ammeter
B. Frequency counter
C. Oscilloscope
D. Megohmmeter
Answer: D. Megohmmeter
,Rationale: A megohmmeter, commonly called a megger, applies a
controlled DC test voltage and measures very high resistance values,
typically in megohms. It is widely used for evaluating insulation in
cables, motors, transformers, and other electrical equipment. The
equipment being tested must be isolated appropriately before the test,
and stored charge must be safely discharged afterward.
5. Before connecting a test instrument to an energized circuit, what
should the technician do first?
A. Increase the meter range to its lowest setting
B. Remove the equipment grounding conductor
C. Verify the instrument, leads, function, and expected voltage are
appropriate
D. Place the instrument in resistance mode
Answer: C. Verify the instrument, leads, function, and expected
voltage are appropriate
Rationale: A test technician must verify that the instrument is rated for
the circuit, that the leads are properly connected, and that the selected
function and range are appropriate. This preliminary check reduces
the possibility of meter damage, incorrect readings, arc flash, or
electric shock. Resistance and continuity functions generally must not
be used on energized circuits.
6. What does an oscilloscope primarily display?
A. Wire insulation thickness
B. Transformer oil level
C. Electrical signal amplitude as a function of time
D. Conductor temperature only
Answer: C. Electrical signal amplitude as a function of time
, Rationale: An oscilloscope displays voltage or another electrical signal
versus time. It allows technicians to observe waveform shape,
frequency, amplitude, distortion, noise, transients, and timing
relationships. In electrical testing, an oscilloscope can reveal
abnormalities that may not be apparent from a simple RMS or DC
voltage measurement.
7. What is the main purpose of a current transformer in an electrical
measurement system?
A. To increase conductor resistance
B. To provide a proportional, isolated current suitable for
measurement or protection
C. To convert DC voltage into mechanical energy
D. To eliminate all harmonics
Answer: B. To provide a proportional, isolated current suitable for
measurement or protection
Rationale: A current transformer, or CT, produces a secondary current
proportional to the primary current. This permits meters and protective
relays to work with manageable currents while maintaining electrical
isolation from the high-current primary circuit. A CT secondary
should never be left improperly open-circuited while its primary is
energized because dangerous voltage can develop.
8. What is the purpose of a potential transformer or voltage
transformer?
A. To measure resistance directly
B. To reduce high system voltage to a proportional level for
measurement and protection
C. To increase motor torque
D. To eliminate the need for grounding
