LADWP ELECTRICAL MECHANIC TEST
TECHNICIAN EXAM 130 QUESTIONS WITH
ANSWERS & DETAILED RATIONALES |
2026/2027 EDITION
Core Domains
• Electrical Theory & Mathematics: Ohm's Law, AC/DC Circuits, Power
Calculations, 3-Phase Systems
• Substation Equipment: Transformers, CTs/PTs, Circuit Breakers,
Switchgear, Relays
• Testing & Diagnostic Equipment: Megger, Ductor, Doble, TTR,
Primary/Secondary Injection
• Motor Theory & Control: AC/DC Motors, Motor Starters, Overload Relays,
VFDs
• Safety & Codes: LOTO, Approach Boundaries, PPE, Los Angeles City
Electrical Code
• Mechanical Aptitude: Gears, Levers, Pulleys, Bolts, Rigging
• Power Systems: 3-Phase Wye/Delta Configurations, Power Factor,
Synchronous Condensers
• Batteries & DC Systems: Lead-Acid Batteries, Charging Systems, Specific
Gravity
This comprehensive examination guide is designed for candidates preparing for
the LADWP Electrical Mechanic and Test Technician exam for the 2026/2027
testing cycle. The exam evaluates foundational electrical theory, practical
knowledge of utility substation equipment, testing procedures, safety protocols,
and mechanical aptitude required for working at the Los Angeles Department of
Water and Power . This resource features 130 practice questions with verified
answers and detailed rationales to ensure exam readiness.
,SECTION 1: ELECTRICAL THEORY & MATHEMATICS (Questions 1-30)
Question 1
A 120V circuit draws 15A. What is the resistance?
A. 4Ω
B. 8Ω
C. 12Ω
D. 16Ω
Correct answer: B
RATIONALE: Ohm's Law states R = V/I = 120/15 = 8Ω. This fundamental
relationship is essential for electrical troubleshooting .
Question 2
What is the formula for electrical power in watts?
A. P = I² / R
B. P = V × I
C. P = V / I
D. P = R × I
Correct answer: B
RATIONALE: The formula for electrical power is P = V × I. It can also be
expressed as P = I² × R or P = V² / R. Power is measured in watts and represents
the rate at which electrical energy is converted to another form of energy .
Question 3
Total resistance in a series circuit is calculated as:
A. R_T = R1 + R2 + R3
B. R_T = 1/R1 + 1/R2 + 1/R3
,C. R_T = R1 × R2 / (R1 + R2)
D. R_T = R1 - R2 - R3
Correct answer: A
RATIONALE: In a series circuit, total resistance equals the sum of all
individual resistances. This is a fundamental law of series circuits .
Question 4
In a purely inductive AC circuit, how does current relate to voltage?
A. Current leads voltage by 90°
B. Current lags voltage by 90°
C. Current is in phase with voltage
D. Current is 180° out of phase with voltage
Correct answer: B
RATIONALE: In a purely inductive circuit, current lags voltage by 90°
because the inductor opposes changes in current. This phase relationship is
represented by the mnemonic "ELI" (E leads I) .
Question 5
In a purely capacitive AC circuit, how does current relate to voltage?
A. Current leads voltage by 90°
B. Current lags voltage by 90°
C. Current is in phase with voltage
D. Current is 180° out of phase with voltage
Correct answer: A
RATIONALE: In a purely capacitive circuit, current leads voltage by 90°. This
is represented by the mnemonic "ICE" (I leads E). The capacitor opposes changes
in voltage, causing current to lead .
Question 6
, What is the SI unit of electrical charge, equal to the quantity of electricity
conveyed in one second by a current of one ampere?
A. Ohm
B. Coulomb
C. Watt
D. Henry
Correct answer: B
RATIONALE: 1 ampere = 1 coulomb per second. The coulomb is the
fundamental unit of electric charge .
Question 7
What is the standard frequency of AC power in the United States?
A. 50 Hz
B. 60 Hz
C. 120 Hz
D. 400 Hz
Correct answer: B
RATIONALE: The standard frequency for AC power in the United States is 60
Hz. Most of the world uses 50 Hz .
Question 8
What is the standard RMS voltage for U.S. household power?
A. 110V
B. 120V
C. 208V
D. 240V
Correct answer: B
RATIONALE: The standard RMS voltage for U.S. household power is 120V.
This is the effective voltage that powers most residential circuits .
TECHNICIAN EXAM 130 QUESTIONS WITH
ANSWERS & DETAILED RATIONALES |
2026/2027 EDITION
Core Domains
• Electrical Theory & Mathematics: Ohm's Law, AC/DC Circuits, Power
Calculations, 3-Phase Systems
• Substation Equipment: Transformers, CTs/PTs, Circuit Breakers,
Switchgear, Relays
• Testing & Diagnostic Equipment: Megger, Ductor, Doble, TTR,
Primary/Secondary Injection
• Motor Theory & Control: AC/DC Motors, Motor Starters, Overload Relays,
VFDs
• Safety & Codes: LOTO, Approach Boundaries, PPE, Los Angeles City
Electrical Code
• Mechanical Aptitude: Gears, Levers, Pulleys, Bolts, Rigging
• Power Systems: 3-Phase Wye/Delta Configurations, Power Factor,
Synchronous Condensers
• Batteries & DC Systems: Lead-Acid Batteries, Charging Systems, Specific
Gravity
This comprehensive examination guide is designed for candidates preparing for
the LADWP Electrical Mechanic and Test Technician exam for the 2026/2027
testing cycle. The exam evaluates foundational electrical theory, practical
knowledge of utility substation equipment, testing procedures, safety protocols,
and mechanical aptitude required for working at the Los Angeles Department of
Water and Power . This resource features 130 practice questions with verified
answers and detailed rationales to ensure exam readiness.
,SECTION 1: ELECTRICAL THEORY & MATHEMATICS (Questions 1-30)
Question 1
A 120V circuit draws 15A. What is the resistance?
A. 4Ω
B. 8Ω
C. 12Ω
D. 16Ω
Correct answer: B
RATIONALE: Ohm's Law states R = V/I = 120/15 = 8Ω. This fundamental
relationship is essential for electrical troubleshooting .
Question 2
What is the formula for electrical power in watts?
A. P = I² / R
B. P = V × I
C. P = V / I
D. P = R × I
Correct answer: B
RATIONALE: The formula for electrical power is P = V × I. It can also be
expressed as P = I² × R or P = V² / R. Power is measured in watts and represents
the rate at which electrical energy is converted to another form of energy .
Question 3
Total resistance in a series circuit is calculated as:
A. R_T = R1 + R2 + R3
B. R_T = 1/R1 + 1/R2 + 1/R3
,C. R_T = R1 × R2 / (R1 + R2)
D. R_T = R1 - R2 - R3
Correct answer: A
RATIONALE: In a series circuit, total resistance equals the sum of all
individual resistances. This is a fundamental law of series circuits .
Question 4
In a purely inductive AC circuit, how does current relate to voltage?
A. Current leads voltage by 90°
B. Current lags voltage by 90°
C. Current is in phase with voltage
D. Current is 180° out of phase with voltage
Correct answer: B
RATIONALE: In a purely inductive circuit, current lags voltage by 90°
because the inductor opposes changes in current. This phase relationship is
represented by the mnemonic "ELI" (E leads I) .
Question 5
In a purely capacitive AC circuit, how does current relate to voltage?
A. Current leads voltage by 90°
B. Current lags voltage by 90°
C. Current is in phase with voltage
D. Current is 180° out of phase with voltage
Correct answer: A
RATIONALE: In a purely capacitive circuit, current leads voltage by 90°. This
is represented by the mnemonic "ICE" (I leads E). The capacitor opposes changes
in voltage, causing current to lead .
Question 6
, What is the SI unit of electrical charge, equal to the quantity of electricity
conveyed in one second by a current of one ampere?
A. Ohm
B. Coulomb
C. Watt
D. Henry
Correct answer: B
RATIONALE: 1 ampere = 1 coulomb per second. The coulomb is the
fundamental unit of electric charge .
Question 7
What is the standard frequency of AC power in the United States?
A. 50 Hz
B. 60 Hz
C. 120 Hz
D. 400 Hz
Correct answer: B
RATIONALE: The standard frequency for AC power in the United States is 60
Hz. Most of the world uses 50 Hz .
Question 8
What is the standard RMS voltage for U.S. household power?
A. 110V
B. 120V
C. 208V
D. 240V
Correct answer: B
RATIONALE: The standard RMS voltage for U.S. household power is 120V.
This is the effective voltage that powers most residential circuits .
