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Question 1. What is the mathematical expression of Ohm’s Law? A) V = I × R B) P = I × V C) V = P × R D) I = V × R Answer: A Explanation: Ohm’s Law states that voltage (V) equals current (I) multiplied by resistance (R). Question 2. Which type of current periodically reverses direction? A) Direct Current (DC) B) Alternating Current (AC) C) Pulsating DC D) Static Current Answer: B Explanation: AC alternates its direction and magnitude, unlike DC which flows in one direction. Question 3. What is the unit of electrical resistance? A) Volt B) Ampere C) Ohm D) Watt Answer: C Explanation: The ohm is the standard unit for measuring electrical resistance. Question 4. What device is used to protect a circuit from overcurrent? A) Transformer B) Fuse C) Resistor D) Capacitor
Answer: B Explanation: A fuse interrupts the circuit if the current exceeds a safe level, preventing damage. Question 5. The total resistance of two 10-ohm resistors in series is: A) 5 ohms B) 10 ohms C) 20 ohms D) 0.5 ohms Answer: C Explanation: In series, you sum the resistances: 10 + 10 = 20 ohms. Question 6. In a parallel circuit, the voltage across each branch is: A) Zero B) The same C) Divided equally D) Double the supply Answer: B Explanation: Each branch in a parallel circuit receives the full supply voltage. Question 7. Which unit measures electrical power? A) Joule B) Ampere C) Watt D) Coulomb Answer: C Explanation: Electrical power is measured in watts. Question 8. What does the term “RMS” stand for in AC circuits? A) Real Mean Square
Question 12. Which device changes the voltage level in an AC circuit? A) Rectifier B) Transformer C) Capacitor D) Inductor Answer: B Explanation: Transformers are used to increase or decrease AC voltage levels. Question 13. What is the full-load current of a 10 HP, 230V, single-phase motor (use 1 HP = 746 W)? A) 10.5A B) 32.4A C) 48.5A D) 3.2A Answer: B Explanation: (10 × 746 W) / 230V ≈ 32.4A (ignoring efficiency for simplicity). Question 14. Which conductor color is typically used for a grounded (neutral) conductor in the US? A) Black B) Red C) White D) Green Answer: C Explanation: White or gray is used for grounded (neutral) conductors. Question 15. According to NEC, what is required for disconnecting means for service equipment? A) Must be accessible B) Must be locked C) Must be in a separate room
D) Must be underground Answer: A Explanation: Disconnecting means must be readily accessible to allow for quick shutoff. Question 16. Article 100 of the NEC primarily deals with: A) Overcurrent protection B) Definitions C) Service entrance requirements D) Motor calculations Answer: B Explanation: Article 100 provides definitions for terms used throughout the NEC. Question 17. What is the minimum working clearance in front of electrical panels (up to 600V) required by NEC? A) 18 inches B) 24 inches C) 36 inches D) 48 inches Answer: C Explanation: NEC requires at least 36 inches of clearance in front of panels up to 600V. Question 18. Which of the following is NOT a method for identifying ungrounded conductors? A) Red insulation B) Black insulation C) White insulation D) Blue insulation Answer: C Explanation: White is reserved for grounded (neutral) conductors.
Answer: A Explanation: Overcurrent protection is required at service entrances. Question 23. What is the purpose of Article 250 in the NEC? A) Lighting requirements B) Grounding and bonding C) Motor wiring D) Conduit fill Answer: B Explanation: Article 250 covers requirements for grounding and bonding. Question 24. What is the standard unit for capacitance? A) Ohm B) Farad C) Henry D) Volt Answer: B Explanation: Capacitance is measured in farads. Question 25. Which of the following is a requirement for temporary wiring? A) Must be underground B) Must not exceed 90 days C) Must be inspected daily D) Must not exceed 600V Answer: B Explanation: Temporary wiring is typically limited to 90 days. Question 26. What is the minimum burial depth for nonmetallic raceways under a driveway? A) 6 inches
B) 12 inches C) 18 inches D) 24 inches Answer: D Explanation: Nonmetallic raceways under driveways usually require a 24-inch burial depth. Question 27. What color is used for equipment grounding conductors? A) Black B) White C) Green D) Blue Answer: C Explanation: Green or bare copper is used for equipment grounding. Question 28. The ampacity of a wire is determined by: A) Wire color B) Insulation type and conductor size C) Length only D) Voltage only Answer: B Explanation: Ampacity depends on insulation type, conductor size, and ambient temperature. Question 29. What is the maximum number of 12 AWG conductors permitted in a standard 4-inch square box (21 cubic inches)? A) 4 B) 6 C) 8 D) 10 Answer: C
C) 12 feet D) 16 feet Answer: B Explanation: Receptacles must be placed so that no point along the floor line is more than 6 feet from a receptacle. Question 34. What is the minimum height for mounting switches in a dwelling? A) 36 inches B) 42 inches C) 48 inches D) 60 inches Answer: C Explanation: The maximum switch mounting height is typically 48 inches above the finished floor. Question 35. What is the minimum rating for a service disconnect in a single-family dwelling? A) 60A B) 100A C) 150A D) 200A Answer: B Explanation: NEC requires a minimum 100A service disconnect for single-family dwellings. Question 36. Which type of raceway is suitable for direct burial without additional protection? A) EMT B) PVC Schedule 40 C) RMC D) FMC Answer: C Explanation: Rigid Metal Conduit (RMC) is approved for direct burial.
Question 37. What is the minimum size copper grounding electrode conductor for a 200A residential service? A) #10 AWG B) #8 AWG C) #6 AWG D) #4 AWG Answer: D Explanation: #4 AWG copper is the minimum required for a 200A service. Question 38. What is the requirement for GFCI protection in residential bathrooms? A) Not required B) Only for showers C) For all receptacles D) Only for whirlpool tubs Answer: C Explanation: All bathroom receptacles must have GFCI protection. Question 39. Which code article covers hazardous (classified) locations? A) 210 B) 250 C) 500 D) 600 Answer: C Explanation: Articles 500–516 cover hazardous locations. Question 40. What is the standard supply voltage to most residential homes in the US? A) 120V B) 208V
Question 44. What is the minimum size service entrance conductor allowed for a 100A service (copper)? A) #6 AWG B) #4 AWG C) #2 AWG D) #1 AWG Answer: B Explanation: #4 AWG copper is the minimum for a 100A service entrance. Question 45. When are tamper-resistant receptacles required? A) In commercial kitchens B) In all garage outlets C) In dwelling unit areas accessible to children D) Only in bathrooms Answer: C Explanation: Tamper-resistant receptacles are required in areas accessible to children in dwellings. Question 46. Which of the following is NOT considered a continuous load? A) Lighting in a retail store B) Electric water heater C) Air conditioner D) Residential refrigerator Answer: D Explanation: Residential refrigerators are not considered continuous loads. Question 47. What is the minimum clearance above a roof for overhead service conductors? A) 1 foot B) 2 feet C) 3 feet D) 4 feet
Answer: C Explanation: Overhead conductors must be at least 3 feet above the roof. Question 48. What is a feeder in an electrical system? A) The main service conductor B) A branch circuit conductor C) A conductor from the service to a distribution panel D) A ground wire Answer: C Explanation: Feeders run from service equipment to distribution panels. Question 49. What is the required ampacity correction factor for more than three current-carrying conductors in a raceway? A) 70% B) 80% C) 85% D) 100% Answer: B Explanation: For 4–6 conductors, ampacity is reduced to 80% per NEC Table 310.15(B)(3)(a). Question 50. What must be done before working on energized equipment? A) Notify the building owner B) Put on gloves C) De-energize and lockout/tagout D) Take a photo Answer: C Explanation: Lockout/tagout ensures equipment cannot be accidentally energized. Question 51. Which of the following would be considered a special occupancy under NEC?
Explanation: Flexible cord is not a permanent wiring method. Question 55. What is the minimum required illumination for working spaces about service equipment? A) None B) 1 foot-candle C) 5 foot-candles D) 10 foot-candles Answer: B Explanation: At least one foot-candle of illumination is required. Question 56. Which of the following is a function of a transformer? A) Provides overcurrent protection B) Changes frequency C) Steps voltage up or down D) Converts AC to DC Answer: C Explanation: Transformers step voltages up or down. Question 57. What is the maximum cord-and-plug connected load for a 15A branch circuit? A) 10A B) 12A C) 15A D) 20A Answer: B Explanation: NEC limits cord-and-plug connected loads to 80% of branch circuit rating. Question 58. Overcurrent protection for conductors is covered in which NEC Article? A) 100 B) 210
C) 240
D) 300
Answer: C Explanation: Article 240 covers overcurrent protection. Question 59. What is the minimum burial depth for UF cable (residential) without conduit? A) 6 inches B) 12 inches C) 18 inches D) 24 inches Answer: C Explanation: UF cable must be buried at least 18 inches. Question 60. Which type of transformer connection is used for three-phase loads? A) Delta-Delta B) Wye-Wye C) Delta-Wye D) All of the above Answer: D Explanation: All of these can be used for three-phase transformer connections. Question 61. What is the purpose of bonding in an electrical system? A) Increase resistance B) Create a short circuit C) Provide a low impedance path for fault current D) Decrease voltage Answer: C Explanation: Bonding ensures a low-impedance path for clearing faults.
Answer: C Explanation: Minimum length is 8 times the conduit size: 8 × 2" = 16 inches. Question 66. What type of circuit must be provided for central heating equipment? A) Multiwire branch circuit B) Dedicated branch circuit C) Shared with lighting D) Shared with kitchen appliances Answer: B Explanation: Central heating must be on its own dedicated branch circuit. Question 67. What is the minimum ampacity for service entrance conductors for a 200A service? A) 100A B) 150A C) 200A D) 250A Answer: C Explanation: Conductors must be rated at least the service rating. Question 68. What is the minimum conductor size for a 30A circuit using copper wire? A) #14 AWG B) #12 AWG C) #10 AWG D) #8 AWG Answer: C Explanation: #10 AWG copper is the minimum for 30A circuits. Question 69. What type of protection is required for receptacles installed near a kitchen sink? A) Tamper-resistant
B) GFCI
C) AFCI
D) Isolated ground Answer: B Explanation: GFCI protection is required near sinks. Question 70. What is the minimum required working space width in front of electrical equipment? A) 24 inches B) 30 inches C) 36 inches D) 48 inches Answer: B Explanation: NEC requires at least 30 inches in width. Question 71. What is the minimum required clearance for service drops above public streets? A) 10 feet B) 12 feet C) 15 feet D) 18 feet Answer: D Explanation: Service drops must be at least 18 feet above public streets. Question 72. What is required for the connection of an EV charging system? A) GFCI protection B) Separate meter C) Dedicated branch circuit D) Isolated ground Answer: C Explanation: EV charging systems require a dedicated branch circuit.
