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Question 1. Which NEC Article defines the term “grounded conductor”? A) Article 100 B) Article 250 C) Article 210 D) Article 430 Answer: A Explanation: Article 100 contains definitions of terms used throughout the NEC, including “grounded conductor.” Question 2. Ohm’s Law states that voltage equals current multiplied by resistance. If a circuit has 12 A flowing through a 5 Ω resistor, what is the voltage? A) 17 V B) 60 V C) 2.4 V D) 0.42 V Answer: B Explanation: V = I × R = 12 A × 5 Ω = 60 V. Question 3. The power formula P = V × I is used to calculate apparent power in VA. If a load draws 3 A at 240 V, what is the apparent power? A) 480 VA B) 720 VA C) 80 VA D) 120 VA Answer: B Explanation: P = 240 V × 3 A = 720 VA. Question 4. In a series circuit, the total resistance is the sum of individual resistances. Three resistors of 2 Ω, 4 Ω, and 6 Ω are connected in series. What is the total resistance? A) 12 Ω
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B) 8 Ω
C) 6 Ω
D) 4 Ω
Answer: A Explanation: R_total = 2 + 4 + 6 = 12 Ω. Question 5. In a parallel circuit, the total current is the sum of branch currents. If three branches carry 2 A, 3 A, and 5 A respectively, what is the total current? A) 10 A B) 8 A C) 5 A D) 2 A Answer: A Explanation: I_total = 2 + 3 + 5 = 10 A. Question 6. Convert 5 HP to watts (1 HP = 746 W). A) 3730 W B) 1492 W C) 7460 W D) 500 W Answer: A Explanation: 5 HP × 746 W/HP = 3730 W. Question 7. A 120 V, 15 A circuit supplies a receptacle run of 100 ft of 12-AWG copper THHN. Using the 3% voltage drop rule, is the voltage drop acceptable? (Assume 2 Ω per 1000 ft for 12-AWG.) A) Yes, because drop is <3% B) No, because drop is >3% C) Yes, because copper eliminates drop D) No, because length exceeds 50 ft limit
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Explanation: For a 20-A circuit, receptacles may be rated 15 A or 20 A; 20 A is permissible. Question 11. Which device provides protection from ground-fault currents on a 120 - V bathroom receptacle? A) AFCI B) GFCI C) Surge protector D) Circuit breaker Answer: B Explanation: Ground-Fault Circuit Interrupters (GFCIs) are required in bathrooms for personnel protection. Question 12. An AFCI is required in which of the following residential locations? A) Kitchen countertop receptacles B) Bedroom outlets C) Outdoor lighting fixtures D) Garage door openers Answer: B Explanation: NEC 210.12(A) mandates AFCI protection for all 120-V, 15- and 20-A branch circuits supplying bedroom outlets. Question 13. A commercial office has a feeder that supplies a load of 120 kVA at 480 V three-phase. What is the full-load current? (Use √3 × V × I = kVA × 1000) A) 144 A B) 200 A C) 100 A D) 173 A Answer: A Explanation: I = (120 kVA × 1000) / (√3 × 480 V) ≈ 144 A.
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Question 14. When sizing a feeder, a demand factor of 0.6 is applied to a calculated load of 80 A. What is the adjusted feeder current? A) 48 A B) 60 A C) 80 A D) 96 A Answer: A Explanation: Adjusted current = 80 A × 0.6 = 48 A. Question 15. For a residential service entrance, the minimum clearance between the service drop and a nearby tree is: A) 3 ft B) 6 ft C) 10 ft D) 12 ft Answer: B Explanation: NEC 230.9 requires a minimum of 6 ft clearance between service conductors and trees or other objects. Question 16. Which of the following is the correct rating for a standard residential main circuit breaker? A) 15 A B) 30 A C) 100 A D) 200 A Answer: C Explanation: Most single-family homes use a 100-A main breaker, though larger services are common.
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Question 20. In a conduit system, the burial depth for PVC (Schedule 40) conduit under a residential driveway is: A) 12 in. B) 18 in. C) 24 in. D) 30 in. Answer: B Explanation: Table 300.5 permits 18 in. burial for PVC conduit under a driveway. Question 21. When more than three current-carrying conductors are placed in a raceway, which correction factor must be applied to the conductor ampacity? A) 0.8 for 4-6 conductors B) 0.7 for 4-6 conductors C) 0.9 for 4-6 conductors D) No correction is required Answer: A Explanation: NEC 310.15(B)(3)(a) provides a 0.8 factor for 4-6 current-carrying conductors. Question 22. The ambient temperature correction factor for a conductor rated at 75 °C placed in a 40 °C environment is: A) 1. B) 0. C) 0. D) 0. Answer: A Explanation: The base temperature is 30 °C; at 40 °C the factor is 1.00 (no derating needed).
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Question 23. Box fill is calculated based on the volume of the box. How many cubic inches are required per conductor that occupies more than 6 AWG? A) 2 in³ B) 2.5 in³ C) 3 in³ D) 4 in³ Answer: C Explanation: NEC 314.16(B) assigns 3 in³ per conductor larger than 6 AWG. Question 24. A pull box used for a 90-degree bend of three 4-AWG conductors must be sized at least: A) 2 in. × 2 in. × 2 in. B) 4 in. × 4 in. × 4 in. C) 6 in. × 6 in. × 6 in. D) 8 in. × 8 in. × 8 in. Answer: C Explanation: For a 90-degree pull of 4-AWG conductors, NEC 314.28 requires a minimum interior dimension of 6 in. in each direction. Question 25. Which raceway type is permitted for direct burial without a protective conduit in residential applications? A) EMT B) RMC C) PVC conduit D) Direct-buried UF cable Answer: D Explanation: UF (Underground Feeder) cable is listed for direct burial without additional conduit. Question 26. The minimum conduit size for a 3-phase, 200-A feeder using 4/0 AWG copper conductors is:
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B) 54 in. above the floor C) 60 in. above the floor D) No limit as long as it is accessible Answer: B Explanation: NEC 210.52(A)(3) requires receptacles to be installed so the outlet box is not more than 54 in. above the floor. Question 30. In a kitchen, the minimum spacing between countertop receptacles is: A) 12 in. B) 18 in. C) 24 in. D) 30 in. Answer: C Explanation: NEC 210.52(C)(1) mandates receptacles at intervals not exceeding 24 in. along the countertop. Question 31. Which type of luminaire is required in a bathtub’s “zone 0” (inside the tub)? A) Damp-rated fixture B) Wet-rated fixture C) Explosion-proof fixture D) No fixture is permitted Answer: D Explanation: NEC 410.10(D) prohibits any luminaire in “zone 0” of a bathtub. Question 32. A bathroom vanity light installed above a mirror is considered which type of location? A) Damp location B) Wet location C) Dry location
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D) Hazardous location Answer: A Explanation: The area above a bathroom mirror is classified as a damp location; fixtures must be listed for damp use. Question 33. For a 30-A electric water heater, the required disconnecting means must be rated at least: A) 30 A B) 40 A C) 45 A D) 50 A Answer: B Explanation: NEC 422.31 requires a disconnecting means rated not less than the branch-circuit rating; a 30-A heater typically uses a 40-A breaker. Question 34. A dryer circuit in a dwelling must be protected by a breaker of what minimum rating? A) 15 A B) 20 A C) 30 A D) 40 A Answer: C Explanation: NEC 210.23(A)(2) requires at least a 30-A breaker for a dryer branch circuit. Question 35. When calculating motor branch-circuit conductors, the NEC permits using 125 % of the motor’s full-load current for sizing. A motor has a full-load current of 20 A. What is the minimum conductor ampacity? A) 20 A B) 25 A C) 30 A
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D) Class III, Division 1 Answer: B Explanation: Class I, Division 2 locations contain flammable gases/vapors only under abnormal conditions. Question 39. In a Class II, Division 1 hazardous area, which type of conduit is required? A) Rigid Metal Conduit (RMC) only B) EMT with a flame-proof cover C) Any listed conduit that is sealed and rated for the division D) PVC conduit is prohibited Answer: C Explanation: NEC 501.10 allows any conduit that is listed for the specific hazardous classification and is properly sealed. Question 40. For patient care areas in a hospital, the grounding electrode system must be: A) Separate from the building grounding system B) Integrated with the building grounding system C) Not required because equipment is isolated D) Only required for MRI rooms Answer: B Explanation: NEC 517.12 requires patient care areas to be grounded to the building grounding electrode system. Question 41. In an assembly occupancy, the minimum number of exit doors required for a space with an occupant load of 300 persons is: A) 1 B) 2 C) 3 D) 4
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Answer: B Explanation: According to NFPA 101 (Life Safety Code) and referenced by NEC, an occupant load of 300 requires at least two exits. Question 42. Agricultural buildings often use which type of conduit to protect against corrosion? A) EMT B) RMC with zinc coating C) PVC conduit D) Flexible Metal Conduit (FMC) Answer: C Explanation: PVC conduit is non-conductive and resistant to corrosion, making it suitable for agricultural environments. Question 43. An electric sign that is illuminated by low-voltage lighting must be installed in accordance with which NEC article? A) 410 B) 720 C) 730 D) 740 Answer: C Explanation: NEC Article 730 covers electric signs and outline lighting. Question 44. For an elevator machine room, the minimum size of the grounding electrode conductor is: A) #12 AWG copper B) #10 AWG copper C) #8 AWG copper D) #6 AWG copper Answer: C
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Question 48. Low-voltage communication cables must be grounded at the point of entrance to a building according to: A) Article 300 B) Article 250 C) Article 800 D) Article 820 Answer: C Explanation: NEC Article 800 deals with communication circuits and requires grounding at the entrance point. Question 49. The NEC index is most useful for quickly locating which of the following? A) Definitions only B) Illustrations and diagrams C) Table numbers and article headings D) Manufacturer warranty information Answer: C Explanation: The index lists keywords with corresponding article and table numbers, enabling rapid code lookup. Question 50. A 250-kVA, three-phase transformer serving a commercial building must have its primary overcurrent protective device sized at a minimum of: A) 250 A B) 300 A C) 350 A D) 400 A Answer: B Explanation: Primary current = 250 kVA / (√3 × 480 V) ≈ 301 A; the next standard breaker size is 300 A, but NEC 450.3 requires the OCPD not exceed 125 % of the transformer rating, so 300 A is acceptable.
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Question 51. Which of the following conduit materials is permitted for use in a wet location without additional protection? A) EMT B) RMC C) PVC D) Flexible Metal Conduit Answer: C Explanation: PVC conduit is listed for wet locations and does not require additional protection. Question 52. The minimum size for a grounding electrode conductor serving a 400 - A service is: A) #8 AWG copper B) #6 AWG copper C) #4 AWG copper D) #2 AWG copper Answer: C Explanation: Table 250.66 specifies #4 AWG copper for a 400-A service. Question 53. When installing a receptacle box in a wall that contains two 12 - AWG conductors, one equipment grounding conductor, and a device, what is the required box volume? (Assume 2 in³ per conductor, 2 in³ for the device, and 2 in³ for the ground.) A) 8 in³ B) 12 in³ C) 16 in³ D) 20 in³ Answer: B Explanation: Two conductors = 2 × 2 = 4 in³, ground = 2 in³, device = 2 in³; total = 8 in³. NEC adds one conductor volume for the device, so 8 + 2 = 10 in³; the next standard box size is 12 in³.
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B) 20 A
C) 30 A
D) 40 A
Answer: B Explanation: The GFCI must be rated at least equal to the upstream overcurrent protection, which is 20 A. Question 58. The NEC requires that a disconnecting means for a motor be located within: A) 6 ft of the motor B) 10 ft of the motor C) 25 ft of the motor D) No specific distance, only accessible Answer: A Explanation: NEC 430.102 requires the disconnect to be within sight of the motor, generally interpreted as within 6 ft. Question 59. A 3-phase, 4-wire feeder uses 4/0 AWG aluminum conductors. What is the minimum conduit size for this installation? A) 2-in. EMT B) 2-1/2-in. EMT C) 3-in. EMT D) 4-in. EMT Answer: B Explanation: 4/0 AWG Al requires at least 2-1/2-in. EMT per Table 358.30 for four conductors plus a ground. Question 60. In a commercial kitchen, the minimum ampacity of branch-circuit conductors for a 30-A dishwasher is: A) 30 A B) 35 A
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C) 40 A
D) 45 A
Answer: C Explanation: NEC 210.23(A)(2) requires conductors sized at least 125 % of the continuous load; 30 A × 1.25 = 37.5 A, next standard size is 40 A. Question 61. Which of the following is a requirement for a receptacle installed in a wet location? A) Must be a GFCI receptacle only B) Must be listed for wet locations C) Must be installed at least 6 ft above grade D) Must be on a dedicated circuit Answer: B Explanation: NEC 406.7 requires receptacles in wet locations to be listed for wet use. Question 62. The maximum length of a flexible cord used as a power supply for a portable tool without a listed extension cord is: A) 25 ft B) 50 ft C) 75 ft D) 100 ft Answer: B Explanation: NEC 400.8(A)(1) limits flexible cord use for portable tools to 50 ft unless otherwise listed. Question 63. A 120 V, 15-A receptacle in a dwelling must be installed at a height not exceeding: A) 48 in. above the floor B) 54 in. above the floor C) 60 in. above the floor
