Stationary Engineer
Electric Exam
1. What is the primary purpose of a circuit breaker in an electrical system?
A. To regulate voltage
B. To convert AC to DC
C. To protect the circuit from overload and short circuit
D. To increase power factor
Answer: C. To protect the circuit from overload and short circuit
2. A motor rated at 240 V draws 30 A. What is its power in kilowatts (kW) if the
power factor is 0.85?
A. 6.12 kW
B. 7.20 kW
C. 8.50 kW
D. 5.44 kW
Answer: A. 6.12 kW
(Formula: P = V × I × PF / 1000 → 240 × 30 × 0.85 ÷ 1000 = 6.12 kW)
,3. Which of the following electrical instruments is used to measure resistance?
A. Ammeter
B. Voltmeter
C. Ohmmeter
D. Wattmeter
Answer: C. Ohmmeter
4. According to OSHA lockout/tagout procedures, before working on electrical
equipment, an engineer must:
A. Wear rubber gloves only
B. Tag the equipment with their initials only
C. Disconnect, lock, and verify zero energy before servicing
D. Notify a supervisor but continue working
Answer: C. Disconnect, lock, and verify zero energy before servicing
5. In a three-phase electrical system, the voltage between two phases is called:
A. Line-to-line voltage
B. Neutral voltage
C. Ground fault voltage
,D. Phase-to-ground voltage
Answer: A. Line-to-line voltage
6. A transformer steps down voltage from 480 V to 120 V. If the primary current is 10
A, what is the approximate secondary current (ignoring losses)?
A. 2.5 A
B. 10 A
C. 20 A
D. 40 A
Answer: D. 40 A
(Formula: V₁ × I₁ = V₂ × I₂ → 480 × 10 = 120 × I₂ → I₂ = 40 A)
7. What device is commonly used to start large motors gradually to reduce inrush
current?
A. Circuit breaker
B. Soft starter
C. Relay
D. Transformer
Answer: B. Soft starter
8. Which type of fire extinguisher should be used on an electrical fire?
A. Class A
, B. Class B
C. Class C
D. Class D
Answer: C. Class C
9. The National Electrical Code (NEC) requires grounding of electrical systems
primarily to:
A. Improve efficiency
B. Reduce harmonics
C. Provide a path for fault current and enhance safety
D. Save energy costs
Answer: C. Provide a path for fault current and enhance safety
10. A synchronous motor runs at 1800 RPM at 60 Hz. What is the number of poles in
the motor?
A. 2 poles
B. 4 poles
C. 6 poles
D. 8 poles
Answer: B. 4 poles
Electric Exam
1. What is the primary purpose of a circuit breaker in an electrical system?
A. To regulate voltage
B. To convert AC to DC
C. To protect the circuit from overload and short circuit
D. To increase power factor
Answer: C. To protect the circuit from overload and short circuit
2. A motor rated at 240 V draws 30 A. What is its power in kilowatts (kW) if the
power factor is 0.85?
A. 6.12 kW
B. 7.20 kW
C. 8.50 kW
D. 5.44 kW
Answer: A. 6.12 kW
(Formula: P = V × I × PF / 1000 → 240 × 30 × 0.85 ÷ 1000 = 6.12 kW)
,3. Which of the following electrical instruments is used to measure resistance?
A. Ammeter
B. Voltmeter
C. Ohmmeter
D. Wattmeter
Answer: C. Ohmmeter
4. According to OSHA lockout/tagout procedures, before working on electrical
equipment, an engineer must:
A. Wear rubber gloves only
B. Tag the equipment with their initials only
C. Disconnect, lock, and verify zero energy before servicing
D. Notify a supervisor but continue working
Answer: C. Disconnect, lock, and verify zero energy before servicing
5. In a three-phase electrical system, the voltage between two phases is called:
A. Line-to-line voltage
B. Neutral voltage
C. Ground fault voltage
,D. Phase-to-ground voltage
Answer: A. Line-to-line voltage
6. A transformer steps down voltage from 480 V to 120 V. If the primary current is 10
A, what is the approximate secondary current (ignoring losses)?
A. 2.5 A
B. 10 A
C. 20 A
D. 40 A
Answer: D. 40 A
(Formula: V₁ × I₁ = V₂ × I₂ → 480 × 10 = 120 × I₂ → I₂ = 40 A)
7. What device is commonly used to start large motors gradually to reduce inrush
current?
A. Circuit breaker
B. Soft starter
C. Relay
D. Transformer
Answer: B. Soft starter
8. Which type of fire extinguisher should be used on an electrical fire?
A. Class A
, B. Class B
C. Class C
D. Class D
Answer: C. Class C
9. The National Electrical Code (NEC) requires grounding of electrical systems
primarily to:
A. Improve efficiency
B. Reduce harmonics
C. Provide a path for fault current and enhance safety
D. Save energy costs
Answer: C. Provide a path for fault current and enhance safety
10. A synchronous motor runs at 1800 RPM at 60 Hz. What is the number of poles in
the motor?
A. 2 poles
B. 4 poles
C. 6 poles
D. 8 poles
Answer: B. 4 poles
