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Question 1. According to Ohm’s Law, if the voltage across a resistor is doubled, what happens to the current through the resistor (assuming resistance is constant)? A) It is halved B) It doubles C) It remains the same D) It decreases by a factor of four Answer: B Explanation: Ohm’s Law states I = V/R. If V is doubled and R is constant, I also doubles. Question 2. What is the unit of electrical power? A) Ampere B) Ohm C) Watt D) Volt Answer: C Explanation: The unit of power is the watt (W), which is equal to one joule per second. Question 3. In a series circuit with three resistors, if one resistor fails open, what happens? A) Only that resistor stops working B) The whole circuit opens and current stops C) The voltage increases D) The current increases Answer: B Explanation: In a series circuit, if any component opens, the entire circuit is interrupted and current stops. Question 4. Which of the following is the formula for calculating total resistance in parallel? A) R_total = R1 + R2 + R B) R_total = (R1 × R2 × R3)
C) 1/R_total = 1/R1 + 1/R2 + 1/R D) R_total = (R1 + R2 + R3)/ Answer: C Explanation: For parallel circuits, the reciprocals of the resistances add to yield the reciprocal of total resistance. Question 5. What is the primary function of a transformer? A) Convert AC to DC B) Change voltage levels C) Increase resistance D) Provide overload protection Answer: B Explanation: A transformer transfers electrical energy between circuits and can step voltage up or down. Question 6. Which electrical quantity is measured in farads? A) Resistance B) Capacitance C) Inductance D) Power Answer: B Explanation: Capacitance is measured in farads. Question 7. What is the phase difference between voltage and current in a pure inductor? A) 0° B) 90° (current leads) C) 90° (current lags) D) 180° Answer: C Explanation: In a pure inductor, current lags voltage by 90 degrees.
D) Professional Power Engineering Answer: B Explanation: PPE stands for Personal Protective Equipment. Question 12. Which instrument would be best to check insulation resistance on a motor winding? A) Voltmeter B) Clamp-on ammeter C) Megohmmeter D) Wattmeter Answer: C Explanation: Megohmmeters are used for insulation resistance testing. Question 13. What is the minimum required clearance in front of an electrical panel (up to 600V) per NEC 110.26? A) 18 inches B) 24 inches C) 30 inches D) 36 inches Answer: D Explanation: NEC requires 36 inches of clear working space in front of panels up to 600V. Question 14. Which of the following is a mandatory rule in the NEC? A) Any statement using “shall” B) Any statement using “should” C) Recommendations in the annexes D) Informational notes Answer: A Explanation: “Shall” indicates a mandatory rule per the NEC.
Question 15. What is the purpose of the National Electrical Code? A) To specify manufacturer’s product standards B) To ensure safe electrical installations C) To limit electrical use D) To regulate energy consumption Answer: B Explanation: The NEC’s primary purpose is the practical safeguarding of persons and property from electrical hazards. Question 16. According to NEC Article 100, what does “Ampacity” refer to? A) Resistance of a conductor B) Maximum current a conductor can carry continuously C) Voltage rating D) Impedance of a circuit Answer: B Explanation: Ampacity is the maximum current a conductor can carry without exceeding temperature rating. Question 17. Which of the following is required for approval of electrical equipment? A) Equipment must be listed or labeled B) Equipment must be painted red C) Equipment must be made in the USA D) Equipment must be purchased from the utility Answer: A Explanation: NEC requires equipment to be listed, labeled, or otherwise approved. Question 18. In residential wiring, what is the minimum ampacity of a branch circuit supplying a kitchen countertop receptacle? A) 10 amps B) 15 amps
Question 22. What is the maximum allowable fill for a single conduit according to NEC Table 1, Chapter 9 (for more than 2 conductors)? A) 25% B) 30% C) 40% D) 60% Answer: C Explanation: For more than two conductors, the maximum fill is 40%. Question 23. Which type of raceway is suitable for direct burial? A) EMT B) IMC C) RMC D) Flexible metallic conduit Answer: C Explanation: Rigid Metal Conduit (RMC) is approved for direct burial. Question 24. Which of these is a nonmetallic-sheathed cable? A) NM B) MC C) AC D) MI Answer: A Explanation: NM (Nonmetallic-Sheathed) cable is commonly used in residential wiring. Question 25. Flexible cords and cables are NOT permitted to be used as: A) Extension cords B) Permanent wiring for fixed equipment
C) Temporary wiring D) Portable tools Answer: B Explanation: Flexible cords are not to be used as a substitute for permanent wiring. Question 26. Which of the following is required for a kitchen countertop receptacle circuit? A) GFCI protection B) AFCI protection C) Dedicated 30A circuit D) Only switched outlets Answer: A Explanation: GFCI protection is required for kitchen countertop circuits per NEC 210.8. Question 27. When sizing a motor branch-circuit conductor, which value is used from NEC Table 430.250? A) Horsepower rating B) Full-load current C) Locked rotor current D) Service factor Answer: B Explanation: Full-load current is used to size conductors for motors. Question 28. Which of the following appliances is required to have a dedicated circuit in a dwelling? A) Garbage disposal B) Microwave C) Electric range D) Ceiling fan Answer: C Explanation: An electric range requires a dedicated branch circuit.
B) Lighting in commercial buildings C) Electric range D) Garbage disposal Answer: B Explanation: Commercial building lighting is considered a continuous load (operates for 3 hours or more). Question 33. What is the minimum required depth for direct burial of a rigid metal conduit? A) 6 inches B) 12 inches C) 18 inches D) 24 inches Answer: C Explanation: NEC Table 300.5 requires a minimum of 18 inches for RMC direct burial. Question 34. What is the minimum size copper grounding electrode conductor for a 200-amp residential service? A) 4 AWG B) 6 AWG C) 8 AWG D) 10 AWG Answer: B Explanation: NEC 250.66 requires a minimum of 6 AWG copper for up to 200A. Question 35. Which NEC article covers requirements for Ground Fault Circuit Interrupters (GFCIs)? A) Article 210 B) Article 250 C) Article 240 D) Article 430
Answer: A Explanation: Article 210 covers GFCI requirements. Question 36. Which of the following is a requirement for disconnecting means for motors? A) Must be within sight of the motor B) Must be more than 100 feet from the motor C) May be located in another building D) Is not required Answer: A Explanation: NEC requires disconnecting means within sight of the motor. Question 37. What does a “demand factor” do in load calculations? A) Increases the calculated load B) Decreases the calculated load C) Has no effect D) Multiplies the load by 2 Answer: B Explanation: Demand factors allow for reduction in calculated loads based on usage diversity. Question 38. What is the maximum voltage drop recommended for branch circuits? A) 1% B) 3% C) 5% D) 10% Answer: B Explanation: NEC recommends no more than 3% voltage drop in branch circuits. Question 39. To increase the power factor of an inductive load, which device is commonly used? A) Transformer
Explanation: Time-delay fuses permit short-term surges (like motor starting) without blowing. Question 43. Which of the following is NOT a function of a circuit breaker? A) Interrupt overcurrent B) Interrupt short-circuit current C) Provide GFCI protection D) Allow manual circuit switching Answer: C Explanation: Standard circuit breakers do not provide GFCI protection. Question 44. In a blueprint, what does a circle with a capital “S” inside usually indicate? A) Receptacle B) Switch C) Smoke detector D) Sensor Answer: B Explanation: The symbol typically represents a switch. Question 45. Which tool is best for identifying an open circuit? A) Clamp-on ammeter B) Megohmmeter C) Continuity tester D) Wattmeter Answer: C Explanation: A continuity tester checks for open circuits. Question 46. What is the minimum working clearance width required in front of electrical equipment? A) 18 inches B) 24 inches
C) 30 inches D) 36 inches Answer: C Explanation: NEC 110.26 requires a minimum width of 30 inches. Question 47. Which NEC chapter covers wiring methods and materials? A) Chapter 1 B) Chapter 2 C) Chapter 3 D) Chapter 4 Answer: C Explanation: Chapter 3 covers wiring methods and materials. Question 48. What is the maximum continuous load permitted on a 20A branch circuit? A) 12A B) 16A C) 20A D) 24A Answer: B Explanation: NEC 210.20(A) limits continuous loads to 80% of the circuit rating. Question 49. Which of the following is a typical use for a Type MC cable? A) Direct burial B) Exposed or concealed work in dry or wet locations C) Overhead service drop D) Temporary wiring Answer: B Explanation: MC cable is suitable for exposed or concealed work, dry or wet locations.
Answer: D Explanation: AFCI protection is required for all bedroom outlets. Question 54. What is the minimum size THHN copper conductor allowed for a 30A branch circuit? A) 10 AWG B) 12 AWG C) 8 AWG D) 14 AWG Answer: A Explanation: 10 AWG copper is the minimum for a 30A branch circuit. Question 55. Which of these is NOT considered a “continuous load” under the NEC? A) Commercial lighting B) Electric water heater C) Electric range D) Fire alarm circuit Answer: C Explanation: Electric ranges are not typically classified as continuous loads. Question 56. Which of the following is used to protect against arc faults? A) GFCI B) AFCI C) Circuit breaker D) Fuse Answer: B Explanation: Arc-Fault Circuit Interrupters (AFCIs) protect against arc faults. Question 57. What is the maximum allowable voltage drop from the service entrance to the most remote outlet?
A) 1%
B) 3%
C) 5%
D) 10%
Answer: C Explanation: Total voltage drop should not exceed 5% from service to end-use equipment. Question 58. What is the minimum burial depth for direct-buried UF cable under a residential driveway? A) 6 inches B) 12 inches C) 18 inches D) 24 inches Answer: D Explanation: Minimum is 24 inches under driveways per NEC Table 300.5. Question 59. The “immediate vicinity” for disconnecting means is defined as: A) Within 5 feet B) Within 10 feet C) Within sight (and not more than 50 feet) D) In the same room Answer: C Explanation: “Within sight” means visible and not more than 50 feet from the equipment. Question 60. Which type of test instrument can be used to measure both voltage and resistance? A) Clamp-on ammeter B) Continuity tester C) Megohmmeter D) Multimeter Answer: D
B) 4 feet C) 6 feet D) 8 feet Answer: C Explanation: NEC 400.7 limits the length to 6 feet for pendant fixtures. Question 65. When calculating box fill, how many conductors does a device yoke count as? A) 0 B) 1 C) 2 D) 4 Answer: C Explanation: Each yoke counts as two conductors. Question 66. For a 3-phase, 4-wire wye system, what is the relationship between line and phase voltages? A) Equal B) Line voltage is √3 times phase voltage C) Line voltage is half phase voltage D) Line voltage is double phase voltage Answer: B Explanation: Line voltage = phase voltage × √3 in a wye system. Question 67. What is the minimum rating for service equipment in a single-family dwelling? A) 60A B) 100A C) 150A D) 200A Answer: B
Explanation: NEC 230.79(C) requires at least 100A for single-family dwellings. Question 68. Which NEC Article covers grounding and bonding? A) Article 200 B) Article 210 C) Article 250 D) Article 310 Answer: C Explanation: Article 250 covers grounding and bonding. Question 69. What is the maximum number of 12 AWG conductors allowed in a 4-inch square box, 2-1/ inches deep (21 in³)? A) 8 B) 9 C) 10 D) 12 Answer: B Explanation: Each 12 AWG conductor requires 2.25 in³; 21/2.25 = 9. Question 70. Which conductor insulation is suitable for wet locations? A) THHN B) THWN C) NM D) TFFN Answer: B Explanation: THWN is rated for wet locations. Question 71. For a feeder tap over 10 feet but not over 25 feet, what is the maximum ampacity allowed for the tap conductors?
