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Question 1. Which NEC article governs the installation of grounding electrode systems? A) Article 210 B) Article 250 C) Article 300 D) Article 430 Answer: B Explanation: Article 250 of the NEC specifically addresses grounding and bonding, including grounding electrode systems. Question 2. For a 120 V, 20-amp branch circuit using copper conductors, what is the minimum size of the grounding-grounded (neutral) conductor? A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: B Explanation: NEC Table 250.122 requires the neutral to be the same size as the ungrounded conductor for 20-amp circuits, which is 12 AWG copper. Question 3. In a three-wire 120/240 V system, which color is typically used for the grounded (neutral) conductor? A) Black B) Red C) White D) Green Answer: C Explanation: The NEC standard color for a grounded (neutral) conductor is white (or gray). Question 4. What is the maximum number of conductors allowed in a 1-in. schedule 40 PVC conduit for 3/4-in. EMT? A) 3 B) 5
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C) 9
D) 12
Answer: C Explanation: Using NEC Chapter 9 Table 1 for conduit fill, a 1-in. PVC can hold up to 9 conductors of 3/4-in. EMT (0.122 in² each) without exceeding 40 % fill. Question 5. Which device provides protection against both ground-fault and arc-fault conditions? A) GFCI B) AFCI C) Dual-function GFCI/AFCI D) Surge protector Answer: C Explanation: A dual-function GFCI/AFCI combines both ground-fault and arc-fault protection in one device. Question 6. According to NEC 2020, receptacles in a dwelling’s kitchen must be installed no farther than how many inches from the countertop edge? A) 12 in. B) 18 in. C) 24 in. D) 30 in. Answer: B Explanation: NEC 210.52(C)(1) requires at least one receptacle outlet in any countertop space wider than 12 in., with the receptacle installed no more than 18 in. from the countertop edge. Question 7. What is the required ampacity of a 4-AWG copper conductor used as a feeder for a 100-amp service, assuming 75 °C insulation? A) 65 A B) 85 A C) 95 A D) 115 A Answer: D
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Question 11. A 20-amp branch circuit supplies a 1,500 W electric water heater. Is the circuit adequate? A) Yes, because 1,500 W ÷ 120 V = 12.5 A < 20 A B) No, because water heaters must be on a 30-amp circuit C) Yes, because the NEC permits 125 % sizing for continuous loads D) No, because the heater requires a dedicated 40-amp breaker Answer: A Explanation: The water heater draws 12.5 A (1,500 W ÷ 120 V), which is well within a 20-amp circuit’s capacity. Question 12. Which type of conduit is permitted for direct burial without a protective cover? A) EMT B) RMC C) PVC (Schedule 40) D) Flexible metal conduit Answer: C Explanation: PVC Schedule 40 conduit is rated for direct burial per NEC 352.10. Question 13. What is the minimum clearance required between a 120/240 V panelboard and a combustible wall? A) 1 in. B) 2 in. C) 3 in. D) 6 in. Answer: B Explanation: NEC 110.26(A)(1) requires a minimum of 2 in. clearance from the front of the panel to any combustible surface. Question 14. In a residential 120/240 V system, which conductor is typically connected to the grounding electrode conductor? A) Ungrounded (hot) conductor B) Grounded (neutral) conductor
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C) Equipment grounding conductor D) All three conductors Answer: B Explanation: The neutral (grounded) conductor is bonded to the grounding electrode system at the service disconnect. Question 15. Which of the following is the correct minimum size for an equipment grounding conductor for a 30-amp circuit using copper? A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: B Explanation: NEC Table 250.122 specifies a 12 AWG copper grounding conductor for a 30-amp circuit. Question 16. What is the purpose of a “dead-front” on a panelboard? A) To prevent accidental contact with live parts B) To provide a mounting surface for breakers C) To improve heat dissipation D) To allow easy access to wiring terminals Answer: A Explanation: A dead-front prevents accidental contact with energized components, enhancing safety. Question 17. Which NEC article addresses the requirements for luminaires (lighting fixtures)? A) Article 410 B) Article 430 C) Article 440 D) Article 460 Answer: A
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but for feeder sizing we use 100 % of load, so the next standard size is 115 A; however, the question expects 85 A based on rounding to the nearest standard size for 75 °C (Table 310.15). Therefore the correct answer is B (85 A) after applying demand factors; this illustrates the need for proper calculation. Question 21. Which NEC article specifically deals with the installation of receptacles in garages? A) Article 210 B) Article 225 C) Article 300 D) Article 408 Answer: A Explanation: Article 210 (Branch Circuits) includes provisions for garage receptacles, particularly 210.11(C)(4). Question 22. For a 120 V, 15-amp circuit, what is the maximum number of receptacle outlets permitted without requiring a dedicated circuit? A) 8 B) 10 C) 12 D) No limit, as long as load does not exceed 80 % of the breaker rating Answer: D Explanation: NEC does not limit the number of receptacles; the total load must not exceed 80 % of the breaker rating for continuous loads. Question 23. Which of the following is the correct designation for a 3-wire, 120/240 V, 4-wire feeder (two hots, one neutral, one ground)? A) 4-wire feeder B) 3-wire feeder C) Multi-wire branch circuit (MWBC) D) Split-phase feeder Answer: D Explanation: A 120/240 V split-phase system uses two hot conductors, a neutral, and an equipment grounding conductor, commonly called a 4-wire feeder.
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Question 24. What is the minimum burial depth for a 120 V, 20-amp residential branch circuit using PVC conduit under a driveway? A) 6 in. B) 12 in. C) 18 in. D) 24 in. Answer: B Explanation: NEC 300.5(D) requires a minimum of 12 in. cover for PVC conduit under a driveway. Question 25. Which NEC article governs the installation of fire alarm systems? A) Article 760 B) Article 770 C) Article 800 D) Article 820 Answer: A Explanation: Article 760 covers fire alarm systems, including wiring and equipment requirements. Question 26. A 3-phase, 480 V motor requires a minimum of how many disconnecting means? A) One for each phase B) One per motor C) One per 600 A of motor rating D) No disconnect required if OCPD is present Answer: B Explanation: NEC 430.102 requires a disconnecting means for each motor, regardless of phase count. Question 27. Which of the following is the correct designation for a 12-AWG copper THHN conductor used in a conduit? A) XHHW-
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Explanation: NEC Table 250.66 indicates a #8 AWG copper GEC for a 100-amp service. Question 31. Which NEC article addresses the requirements for emergency systems? A) Article 700 B) Article 710 C) Article 720 D) Article 730 Answer: A Explanation: Article 700 covers emergency wiring and power systems. Question 32. For a 120 V, 20-amp circuit, what is the minimum size of the equipment grounding conductor if aluminum conductors are used? A) 12 AWG copper equivalent B) 10 AWG copper equivalent C) 8 AWG copper equivalent D) 6 AWG copper equivalent Answer: C Explanation: Table 250.122 shows that for a 20-amp circuit with aluminum conductors, the grounding conductor must be sized as #8 AWG copper. Question 33. Which of the following is NOT a permitted location for a receptacle in a dwelling’s laundry room? A) Within 6 ft of a water closet B) At least 12 in. above the floor C) Within 3 ft of a sink D) On a dedicated 20-amp circuit Answer: A Explanation: NEC 210.52(F) does not restrict receptacles near a water closet; however, placement within 6 ft of a water closet is not a specific prohibition, making A the incorrect choice.
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Question 34. In a multi-wire branch circuit (MWBC) supplying two 120 V circuits, what is required at the breaker? A) Two single-pole breakers B) A 2-pole breaker with a common trip C) A GFCI breaker only D) No special requirement Answer: B Explanation: NEC 210.4(B) requires a common-trip or handle-tied 2-pole breaker for MWBCs to ensure simultaneous disconnect. Question 35. Which NEC article governs the installation of electric vehicle (EV) charging equipment? A) Article 625 B) Article 630 C) Article 640 D) Article 690 Answer: A Explanation: Article 625 covers electric vehicle charging systems and their installation requirements. Question 36. What is the minimum ampacity of a feeder supplying a 30-amp, 120 V circuit for a kitchen countertop? A) 30 A B) 40 A C) 50 A D) 60 A Answer: B Explanation: NEC 210.19(A)(1) requires feeder conductors to be sized at least 125 % of the continuous load; 30 A × 1.25 = 37.5 A, rounded up to 40 A. Question 37. Which type of conduit must be used for a conduit system that passes through a fire-rated wall assembly? A) EMT B) RMC
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Explanation: NEC 210.8(A)(10) requires GFCI-protected receptacles installed at least 18 in. from the edge of a bathtub. Question 41. Which NEC article covers the requirements for service-entrance conductors? A) Article 230 B) Article 240 C) Article 250 D) Article 260 Answer: A Explanation: Article 230 addresses service-entrance conductors, including sizing and installation. Question 42. A commercial building uses a 4-wire feeder with 3-phase, 480 V power. How many grounded (neutral) conductors are required? A) 0 B) 1 C) 2 D) 3 Answer: B Explanation: For a 4-wire, 3-phase system, only one neutral conductor is required. Question 43. Which of the following devices must be listed for use in hazardous (Class II) locations? A) Standard receptacle B) Explosion-proof (Ex d) enclosure C) GFCI breaker D) Standard light switch Answer: B Explanation: Hazardous locations require equipment listed for those environments, such as explosion-proof enclosures.
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Question 44. What is the minimum size of a conduit that can be used to pull a single 4/0 AWG copper grounding electrode conductor? A) 1-in. EMT B) 1-in. PVC C) 1-1/2-in. EMT D) 2-in. PVC Answer: B Explanation: According to NEC Chapter 9 Table 1, a 1-in. PVC conduit can accommodate a 4/0 AWG conductor (area 0.213 in²) within the 40 % fill limit. Question 45. Which NEC article governs the installation of low-voltage (Class 2) power-limited circuits? A) Article 210 B) Article 725 C) Article 770 D) Article 800 Answer: B Explanation: Article 725 covers Class 2 and Class 3 power-limited circuits. Question 46. In a residential dwelling, what is the minimum number of dedicated 20-amp circuits required for kitchen countertop receptacles? A) 1 B) 2 C) 3 D) 4 Answer: B Explanation: NEC 210.52(C)(1) requires at least two 20-amp small-appliance circuits for countertop receptacles. Question 47. Which of the following is the correct method to identify a 3 - phase, 4-wire feeder in the field? A) Red, black, white, green B) Black, red, blue, white (or gray)
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D) No special protection required Answer: C Explanation: NEC 210.4(B) requires a common-trip breaker for MWBCs, which this bathroom circuit is. Question 51. Which of the following is the correct minimum size for a non-metallic sheathed cable (NM-B) used for a 30-amp, 120 V circuit? A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: B Explanation: NM-B cable must have conductors sized to the breaker; 12 AWG copper is rated for 20 A, but for 30 A a 10 AWG is required. However, the question asks minimum size; thus answer C (10 AWG). (Correct answer: C) Question 52. Which NEC article governs the installation of receptacles in swimming pools? A) Article 680 B) Article 690 C) Article 700 D) Article 710 Answer: A Explanation: Article 680 covers swimming pools, fountains, and similar installations, including receptacle requirements. Question 53. What is the required minimum clearance between a service disconnect and the nearest combustible material? A) 6 in. B) 12 in. C) 18 in. D) 24 in. Answer: B
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Explanation: NEC 230.70(A)(1) requires at least 12 in. of clearance from the service disconnect to any combustible material. Question 54. Which of the following is NOT a permitted grounding electrode? A) Metal underground water pipe B) Concrete-encased electrode (Ufer) C) Grounding electrode conductor only D) Ground rod Answer: C Explanation: A grounding electrode conductor is not an electrode; it connects the system to an actual electrode such as a water pipe, ground rod, or Ufer. Question 55. For a 120/240 V, 3-wire feeder, what is the maximum allowable voltage drop for a 100-ft run supplying a 10-amp continuous load? A) 0.5 % B) 1 % C) 2 % D) 3 % Answer: C Explanation: NEC recommends a maximum of 3 % total voltage drop (2 % feeder, 1 % branch). For a feeder only, 2 % is acceptable. Question 56. Which NEC article addresses the requirements for signage and identification of electrical equipment? A) Article 110 B) Article 210 C) Article 250 D) Article 300 Answer: A Explanation: Article 110 includes requirements for equipment identification and labeling. Question 57. In a residential dwelling, what is the minimum number of dedicated 20-amp circuits required for a laundry area?
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Answer: C Explanation: Article 770 addresses low-voltage lighting systems. Question 61. A 20-amp, 120 V circuit supplies a bathroom vanity light and a fan. What type of breaker is required? A) Standard 20-amp single-pole breaker B) 20-amp GFCI breaker C) 20-amp AFCI breaker D) 20-amp dual-function GFCI/AFCI breaker Answer: B Explanation: NEC 210.8(A)(10) requires GFCI protection for bathroom receptacles; however, for lighting and fan circuits, GFCI is not required unless a receptacle is present. Since the circuit only supplies a light and fan, a standard breaker suffices. Thus answer A is correct. Question 62. Which NEC article deals with the requirements for temporary wiring? A) Article 590 B) Article 600 C) Article 610 D) Article 620 Answer: A Explanation: Article 590 covers temporary installations, including wiring for construction sites. Question 63. What is the minimum size of a copper conductor used as a feeder to a 120 V, 20-amp kitchen appliance circuit, assuming a 125 % load factor? A) 12 AWG B) 10 AWG C) 8 AWG D) 6 AWG Answer: B
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Explanation: 20 A × 1.25 = 25 A. The next standard size for copper conductors is 10 AWG (rated 30 A at 75 °C). Question 64. Which type of conduit is required for a fire-rated wall penetration for a 4-wire feeder? A) EMT only B) RMC only C) Any conduit with a listed firestop seal D) No conduit needed if the feeder is in a raceway Answer: C Explanation: NEC 300.21 requires a firestop seal, regardless of conduit type. Question 65. For a 240 V, 30-amp dryer circuit, which of the following is the correct breaker type? A) Single-pole 30-A breaker B) Two-pole 30-A breaker with common trip C) Two-pole 30-A breaker without common trip D) GFCI 30-A breaker Answer: B Explanation: A 240 V dryer requires a two-pole breaker with a common trip to disconnect both hots simultaneously. Question 66. Which NEC article specifies the requirements for photovoltaic (PV) systems? A) Article 690 B) Article 705 C) Article 710 D) Article 720 Answer: A Explanation: Article 690 covers the installation of solar photovoltaic systems. Question 67. In a residential dwelling, how many GFCI-protected receptacles are required in a finished basement?
