NYC ELECTRICAL ENGINEER (DCAS) —
PRACTICE CERTIFICATION EXAM
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Answers) Plus Rationales 2026 Q&A | Instant
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1. A 240V single-phase load draws 18A. What is the power consumption?
A. 2.16 kW
B. 4.32 kW
C. 5.10 kW
D. 3.60 kW
✔ Answer: B (4.32 kW) ✔
Rationale: Using P = V × I, 240 × 18 = 4320W = 4.32 kW.
2. A transformer operates at 95% efficiency. If output is 9.5 kW, what is input?
A. 10.0 kW
B. 10.5 kW
C. 9.0 kW
D. 8.5 kW
✔ Answer: A (10.0 kW) ✔
Rationale: Input = Output / Efficiency = 9..95 = 10 kW.
3. Which device primarily protects circuits from overcurrent?
A. Relay
B. Transformer
C. Circuit breaker
D. Capacitor
✔ Answer: C (Circuit breaker) ✔
Rationale: A circuit breaker interrupts excessive current flow.
4. A three-phase system is preferred mainly because it:
A. Uses less copper than single-phase
B. Produces fluctuating power
C. Requires no grounding
D. Eliminates voltage
✔ Answer: A (Uses less copper than single-phase) ✔
Rationale: Three-phase systems are more efficient in conductor usage.
5. Ohm’s Law is expressed as:
A. P = VI
B. V = IR
C. I = PR
, D. V = PI
✔ Answer: B (V = IR) ✔
Rationale: Ohm’s Law defines voltage, current, and resistance.
6. A 10Ω resistor carries 2A current. Voltage is:
A. 20V
B. 5V
C. 12V
D. 18V
✔ Answer: A (20V) ✔
Rationale: V = I × R = 2 × 10 = 20V.
7. The function of a capacitor is to:
A. Store magnetic energy
B. Store electrical charge
C. Increase resistance
D. Reduce voltage permanently
✔ Answer: B (Store electrical charge) ✔
Rationale: Capacitors store energy in an electric field.
8. Grounding systems are primarily used to:
A. Increase voltage
B. Prevent electrical shock
C. Reduce resistance
D. Store energy
✔ Answer: B (Prevent electrical shock) ✔
Rationale: Grounding ensures safety by directing fault current.
9. In a DC circuit, current flows:
A. Alternating direction
B. Only in one direction
C. Randomly
D. Only in transformers
✔ Answer: B (Only in one direction) ✔
Rationale: DC current is unidirectional.
10. The SI unit of electrical resistance is:
A. Volt
B. Ampere
C. Ohm
D. Watt
✔ Answer: C (Ohm) ✔
Rationale: Resistance is measured in ohms (Ω).
11. A fuse is designed to:
A. Amplify voltage
B. Break circuit under overload
C. Store current
D. Stabilize frequency
✔ Answer: B (Break circuit under overload) ✔
Rationale: A fuse melts under excessive current.
, 12. Power factor represents:
A. Voltage efficiency
B. Current loss
C. Ratio of real power to apparent power
D. Resistance level
✔ Answer: C (Ratio of real power to apparent power) ✔
Rationale: Power factor measures electrical efficiency.
13. A lagging power factor is typically caused by:
A. Capacitive loads
B. Inductive loads
C. Resistive loads
D. Pure DC loads
✔ Answer: B (Inductive loads) ✔
Rationale: Motors and coils cause lagging current.
14. Which material is commonly used as a conductor?
A. Rubber
B. Copper
C. Glass
D. Plastic
✔ Answer: B (Copper) ✔
Rationale: Copper has low resistance and high conductivity.
15. Electrical energy is measured in:
A. Watts
B. Joules
C. Kilowatt-hours
D. Volts
✔ Answer: C (Kilowatt-hours) ✔
Rationale: Utility billing uses kWh.
16. A short circuit results in:
A. Reduced current
B. Infinite resistance
C. Excessive current flow
D. Zero voltage always
✔ Answer: C (Excessive current flow) ✔
Rationale: Short circuits bypass load resistance.
17. The purpose of a relay is to:
A. Store energy
B. Control high power circuits using low power signals
C. Increase resistance
D. Convert AC to DC
✔ Answer: B (Control high power circuits using low power signals) ✔
Rationale: Relays act as electromagnetic switches.
18. Alternating current (AC) changes direction:
A. Never
B. Once per hour
C. Periodically
PRACTICE CERTIFICATION EXAM
Questions With Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf A+ Grade Guarantee Verified By
Professionals
1. A 240V single-phase load draws 18A. What is the power consumption?
A. 2.16 kW
B. 4.32 kW
C. 5.10 kW
D. 3.60 kW
✔ Answer: B (4.32 kW) ✔
Rationale: Using P = V × I, 240 × 18 = 4320W = 4.32 kW.
2. A transformer operates at 95% efficiency. If output is 9.5 kW, what is input?
A. 10.0 kW
B. 10.5 kW
C. 9.0 kW
D. 8.5 kW
✔ Answer: A (10.0 kW) ✔
Rationale: Input = Output / Efficiency = 9..95 = 10 kW.
3. Which device primarily protects circuits from overcurrent?
A. Relay
B. Transformer
C. Circuit breaker
D. Capacitor
✔ Answer: C (Circuit breaker) ✔
Rationale: A circuit breaker interrupts excessive current flow.
4. A three-phase system is preferred mainly because it:
A. Uses less copper than single-phase
B. Produces fluctuating power
C. Requires no grounding
D. Eliminates voltage
✔ Answer: A (Uses less copper than single-phase) ✔
Rationale: Three-phase systems are more efficient in conductor usage.
5. Ohm’s Law is expressed as:
A. P = VI
B. V = IR
C. I = PR
, D. V = PI
✔ Answer: B (V = IR) ✔
Rationale: Ohm’s Law defines voltage, current, and resistance.
6. A 10Ω resistor carries 2A current. Voltage is:
A. 20V
B. 5V
C. 12V
D. 18V
✔ Answer: A (20V) ✔
Rationale: V = I × R = 2 × 10 = 20V.
7. The function of a capacitor is to:
A. Store magnetic energy
B. Store electrical charge
C. Increase resistance
D. Reduce voltage permanently
✔ Answer: B (Store electrical charge) ✔
Rationale: Capacitors store energy in an electric field.
8. Grounding systems are primarily used to:
A. Increase voltage
B. Prevent electrical shock
C. Reduce resistance
D. Store energy
✔ Answer: B (Prevent electrical shock) ✔
Rationale: Grounding ensures safety by directing fault current.
9. In a DC circuit, current flows:
A. Alternating direction
B. Only in one direction
C. Randomly
D. Only in transformers
✔ Answer: B (Only in one direction) ✔
Rationale: DC current is unidirectional.
10. The SI unit of electrical resistance is:
A. Volt
B. Ampere
C. Ohm
D. Watt
✔ Answer: C (Ohm) ✔
Rationale: Resistance is measured in ohms (Ω).
11. A fuse is designed to:
A. Amplify voltage
B. Break circuit under overload
C. Store current
D. Stabilize frequency
✔ Answer: B (Break circuit under overload) ✔
Rationale: A fuse melts under excessive current.
, 12. Power factor represents:
A. Voltage efficiency
B. Current loss
C. Ratio of real power to apparent power
D. Resistance level
✔ Answer: C (Ratio of real power to apparent power) ✔
Rationale: Power factor measures electrical efficiency.
13. A lagging power factor is typically caused by:
A. Capacitive loads
B. Inductive loads
C. Resistive loads
D. Pure DC loads
✔ Answer: B (Inductive loads) ✔
Rationale: Motors and coils cause lagging current.
14. Which material is commonly used as a conductor?
A. Rubber
B. Copper
C. Glass
D. Plastic
✔ Answer: B (Copper) ✔
Rationale: Copper has low resistance and high conductivity.
15. Electrical energy is measured in:
A. Watts
B. Joules
C. Kilowatt-hours
D. Volts
✔ Answer: C (Kilowatt-hours) ✔
Rationale: Utility billing uses kWh.
16. A short circuit results in:
A. Reduced current
B. Infinite resistance
C. Excessive current flow
D. Zero voltage always
✔ Answer: C (Excessive current flow) ✔
Rationale: Short circuits bypass load resistance.
17. The purpose of a relay is to:
A. Store energy
B. Control high power circuits using low power signals
C. Increase resistance
D. Convert AC to DC
✔ Answer: B (Control high power circuits using low power signals) ✔
Rationale: Relays act as electromagnetic switches.
18. Alternating current (AC) changes direction:
A. Never
B. Once per hour
C. Periodically
