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Question 1. Which of the following best describes the relationship expressed by Ohm’s Law? A) Power equals voltage times current B) Voltage equals current times resistance C) Current equals voltage divided by resistance D) Resistance equals voltage divided by power Answer: B Explanation: Ohm’s Law states V = I × R, meaning voltage equals current multiplied by resistance. Question 2. In a three‑phase, four‑wire wye system, the line‑to‑neutral voltage is 120 V. What is the line‑to‑line voltage? A) 120 V B) 208 V C) 240 V D) 277 V Answer: B Explanation: Line‑to‑line voltage = √ 3 × line‑to‑neutral, so 120 V × 1.732 ≈ 208 V. Question 3. Which NEC article governs the grounding and bonding of electrical systems? A) Article 210 B) Article 250 C) Article 300 D) Article 430 Answer: B Explanation: Article 250 of the NEC covers grounding and bonding requirements. Question 4. A 15‑amp circuit breaker protects a copper conductor sized #14 AWG. What is the maximum allowable ampacity for this conductor per NEC Table 310.15(B)(16)? A) 10 A B) 15 A
C) 20 A
D) 25 A
Answer: B Explanation: #14 copper THHN is rated for 20 A, but the breaker is limited to 15 A for general‑purpose circuits. Question 5. Which device is required to protect a feeder supplying a motor that has a full‑load current of 30 A? A) A standard 30‑A breaker B) A 40‑A breaker with inverse‑time characteristics C) A 35‑A non‑time‑delay fuse D) A 30‑A non‑time‑delay fuse Answer: D Explanation: NEC 430.32 requires non‑time‑delay protection sized at 125 % of the motor FLC; 30 A × 1.25 = 37.5 A, so a 40‑A breaker is typical, but the smallest standard non‑time‑delay fuse ≥ 37.5 A is a 40‑A fuse. However, a 30‑A non‑time‑delay fuse would be undersized, making D incorrect. The correct answer is B. (Correction: Answer B – a 40‑A inverse‑time breaker provides the required 125 % rating.) Question 6. In conduit fill calculations, how many #12 THHN conductors may be placed in a ½‑in. EMT conduit? A) 5 B) 7 C) 9 D) 10 Answer: C Explanation: Per NEC Chapter 9 Table 1, ½‑in. EMT has a cross‑sectional area of 0.304 in². One # THHN occupies 0.0133 in²; 40 % fill allows 0.122 in², permitting 9 conductors. Question 7. Which of the following lighting fixtures is classified as a “wet location” per NEC? A) Recessed downlight in a finished ceiling B) Surface‑mounted fixture in a bathroom vanity area
D) 10 %
Answer: B Explanation: NEC recommends a maximum of 3 % voltage drop for feeders and branch circuits combined. Question 11. A 120/240‑V, single‑phase service requires a neutral conductor. What is the minimum size of the neutral for a 100‑A service? A) #6 AWG copper B) #8 AWG copper C) #10 AWG copper D) #12 AWG copper Answer: A Explanation: For a 100‑A service, the neutral must be sized the same as the ungrounded conductors, which are #6 AWG copper. Question 12. Which NEC article addresses the installation of electric vehicle (EV) charging equipment? A) Article 210 B) Article 625 C) Article 690 D) Article 702 Answer: B Explanation: Article 625 specifically governs EV charging systems. Question 13. In a residential dwelling, what is the required ampacity of the grounding‑electrode conductor for a 150‑A service using aluminum conductors? A) #6 AWG aluminum B) #8 AWG aluminum C) #4 AWG aluminum D) #2 AWG aluminum
Answer: A Explanation: NEC Table 250.66 lists #6 AWG aluminum for a 150‑A service. Question 14. Which of the following is the correct method to calculate the ampacity of a conductor in a raceway that contains more than three current‑carrying conductors? A) Use the base ampacity from Table 310.15(B)(16) without adjustment B) Apply a 80 % derating factor for four to six conductors C) Apply a 70 % derating factor for four to six conductors D) Increase the base ampacity by 25 % Answer: B Explanation: NEC requires a 80 % derating factor when four to six current‑carrying conductors share a raceway. Question 15. A fire alarm system requires a dedicated circuit. What is the minimum rating of the overcurrent protective device (OCPD) for this circuit? A) 15 A B) 20 A C) 30 A D) 40 A Answer: A Explanation: NEC 760.41 allows a 15‑A OCPD for fire alarm circuits, provided the load does not exceed the device rating. Question 16. Which type of conduit is permitted for outdoor installation where it will be exposed to direct sunlight? A) Rigid metal conduit (RMC) only B) PVC conduit only C) EMT conduit only D) Rigid metal conduit (RMC) or PVC conduit Answer: D
Explanation: NEC 110.26(A)(1) mandates a minimum 36‑in. clear working space in front of equipment. Question 20. Which NEC article governs the installation of photovoltaic (PV) systems? A) Article 690 B) Article 705 C) Article 710 D) Article 720 Answer: A Explanation: Article 690 contains the requirements for PV power systems. Question 21. A 250‑V, 3‑phase motor has a full‑load current of 45 A. According to NEC 430.32, what is the minimum size of the OCPD protecting this motor? A) 45 A B) 56 A C) 60 A D) 70 A Answer: C Explanation: 125 % of 45 A = 56.25 A; the next standard breaker size is 60 A. Question 22. Which of the following is the correct method for grounding a metal conduit that serves as the equipment grounding conductor? A) Use a separate grounding wire in addition to the conduit B) Bond the conduit to the grounding electrode at each end C) Bond the conduit to the grounding electrode at one location only D) No bonding is required if the conduit is continuous Answer: C Explanation: NEC 250.118 permits the metal conduit to serve as the grounding conductor if it is bonded to the grounding electrode system at one point.
Question 23. When installing a receptacle in a bathroom, what is the minimum amp rating required for the circuit that supplies the receptacle? A) 15 A B) 20 A C) 30 A D) 40 A Answer: B Explanation: NEC 210.11(C)(3) requires a dedicated 20‑A branch circuit for bathroom receptacles. Question 24. Which type of cable is permitted for use in a wet location without additional protection? A) NM‑B (Romex) B) UF‑B C) AC cable D) MC cable with PVC coating Answer: B Explanation: UF‑B (underground feeder) is rated for wet locations. Question 25. A conduit system contains six current‑carrying conductors. According to NEC Table 310.15(C)(1), what derating factor must be applied? A) 100 % B) 80 % C) 70 % D) 60 % Answer: B Explanation: For 4‑6 conductors, the derating factor is 80 %. Question 26. In a commercial building, what is the minimum height for a receptacle outlet installed in a workplane? A) 12 in. above the floor
C) Fluorescent fixture with a regular ballast D) Any fixture with a metal housing Answer: B Explanation: Only fixtures listed for hazardous locations are permitted in Class I, Division 2 areas. Question 30. A 120‑V, 15‑A receptacle is installed on a branch circuit protected by a 20‑A breaker. Is this installation compliant with NEC? A) Yes, because the receptacle rating is lower than the breaker B) No, because the receptacle must match the breaker rating C) Yes, if the circuit supplies only one receptacle D) No, because a 15‑A receptacle requires a 15‑A breaker Answer: A Explanation: NEC 210.21(B)(3) allows a 15‑A receptacle on a 20‑A branch circuit provided the circuit supplies only that receptacle. Question 31. Which of the following is the correct method for sizing a feeder to a 30‑kW, 240‑V, three‑phase load with a demand factor of 80 %? A) 100 A B) 125 A C) 150 A D) 175 A Answer: B Explanation: Load = 30 kW / 240 V = 125 A. Applying 80 % demand factor: 125 A × 0.8 = 100 A. The next standard size is 125 A. Question 32. In a residential dwelling, how many 20‑A branch circuits are required for kitchen countertop receptacles according to NEC? A) One B) Two C) Three
D) Four Answer: B Explanation: NEC 210.52(B)(1) requires at least two 20‑A circuits for kitchen countertop receptacles. Question 33. Which of the following is the correct minimum size of a disconnecting means for a 75 ‑kVA transformer? A) 100 A B) 125 A C) 150 A D) 200 A Answer: C Explanation: NEC 450.3 requires the disconnect to be rated at not less than 125 % of the transformer’s full‑load current. 75 kVA at 240 V = 312.5 A; 125 % = 390.6 A, thus a 400‑A disconnect is required. (Correction: The correct answer is D – 200 A is insufficient; a 400‑A disconnect is needed.) Question 34. Which NEC article covers the requirements for emergency lighting systems? A) Article 700 B) Article 701 C) Article 702 D) Article 703 Answer: A Explanation: Article 700 deals with emergency systems, including emergency lighting. Question 35. A metal raceway is used as an equipment grounding conductor. Where must the bonding jumper be installed? A) At each outlet box B) At the service entrance only C) At the panelboard only D) At one point in the raceway system
Explanation: NEC 680.22 requires GFCI protection for pool pump circuits. Question 39. In a commercial office building, what is the minimum number of receptacle outlets required per 100 ft² of floor area? A) One B) Two C) Three D) Four Answer: B Explanation: NEC 210.52(A)(1) requires at least one receptacle per 30 ft² of floor area; this equates to roughly three per 100 ft², but the minimum is two. Question 40. Which type of cable is permitted for use in a ceiling void that is not fire‑rated? A) NM‑B (Romex) B) MC cable with steel armor C) AC cable D) None; fire‑rated cable is required Answer: D Explanation: NEC requires fire‑rated (e.g., MC with fire‑resistive rating) cable for concealed spaces. Question 41. A 240 ‑V, 30‑A dryer circuit must be protected by a breaker. What is the minimum size of the breaker? A) 20 A B) 30 A C) 35 A D) 40 A Answer: B Explanation: The breaker must be sized to protect the circuit; a 30‑A breaker matches the dryer’s rating.
Question 42. Which NEC article addresses the installation of communication circuits, such as data and telephone wiring? A) Article 300 B) Article 800 C) Article 820 D) Article 830 Answer: B Explanation: Article 800 governs communications circuits. Question 43. What is the required clearance in front of a service disconnecting means? A) 30 in. B) 36 in. C) 42 in. D) 48 in. Answer: B Explanation: NEC 110.26(A)(1) specifies a minimum 36‑in. clearance. Question 44. Which of the following is the correct method for calculating the ampacity of a conductor in a raceway that contains a neutral that carries only unbalanced current? A) Include the neutral in the count of current‑carrying conductors B) Exclude the neutral from the count if it carries only unbalanced current C) Always apply a 80 % derating factor regardless of neutral D) Increase the ampacity by 10 % for the neutral Answer: B Explanation: NEC 310.15(B)(5) allows the neutral to be excluded from the current‑carrying count when it only carries unbalanced current. Question 45. A 120‑V, 20‑A receptacle is installed in a garage. Which protection is required? A) AFCI protection only B) GFCI protection only
Explanation: #6 AWG copper THHN is rated for 65 A at 75 °C, but with a 125 % multiplier for feeder applications, a larger size is required; #6 AWG is the next standard size that meets the 100‑A requirement. Question 49. Which NEC article governs the installation of fire alarm wiring? A) Article 760 B) Article 770 C) Article 780 D) Article 790 Answer: A Explanation: Article 760 covers fire alarm systems. Question 50. A 120/240‑V single‑phase service requires a neutral. What is the minimum size of the neutral for a 60‑A service using aluminum conductors? A) #6 AWG B) #8 AWG C) #10 AWG D) #12 AWG Answer: B Explanation: NEC Table 310.15(B)(16) indicates #8 AWG aluminum is suitable for a 60‑A service. Question 51. Which of the following is the correct minimum conduit size for three 4/0 AWG aluminum conductors? A) 1‑in. EMT B) 1‑¼‑in. EMT C) 1‑½‑in. EMT D) 2‑in. EMT Answer: C Explanation: The cross‑sectional area of three 4/0 AWG aluminum conductors exceeds the capacity of 1‑¼‑in. EMT; 1‑½‑in. EMT provides sufficient space.
Question 52. In a residential dwelling, how many 15‑A branch circuits are required for bathroom lighting? A) One per bathroom B) One for the entire dwelling C) Two per bathroom D) No specific requirement Answer: A Explanation: NEC 210.11(C)(3) requires at least one 20‑A circuit for bathroom receptacles, but lighting can be on a separate 15‑A circuit; the minimum is one per bathroom. Question 53. Which of the following devices must be installed on a circuit supplying a spa heater? A) AFCI breaker B) GFCI breaker C) Surge protector D) No special device required Answer: B Explanation: NEC 680.23 requires GFCI protection for spa heater circuits. Question 54. Which NEC article addresses the installation of emergency power systems (E‑P‑S)? A) Article 700 B) Article 701 C) Article 702 D) Article 703 Answer: A Explanation: Article 700 covers emergency systems, including emergency power. Question 55. A 120‑V, 20‑A receptacle is installed in a kitchen countertop. Which of the following is required by NEC?
B) 55‑A non‑time‑delay fuse C) 50‑A breaker with instantaneous trip only D) 45‑A breaker with time‑delay Answer: A Explanation: NEC 430.32 requires OCPD sized at 125 % of motor FLC; 50 A × 1.25 = 62.5 A, so a 65‑A or 70‑A breaker is typical. The closest standard size is a 70‑A inverse‑time breaker; a 60‑A breaker would be undersized. (Correction: The correct answer is A – a 70‑A breaker, but the listed option is 60 ‑A; therefore the correct answer should be “A 70‑A breaker with inverse‑time characteristic.”) Question 59. Which of the following is the correct minimum size of a feeder conductor for a 200 ‑A service using aluminum conductors? A) #4 AWG B) #2 AWG C) #1/0 AWG D) #2/0 AWG Answer: C Explanation: #1/0 AWG aluminum is rated for 150 A; with a 125 % multiplier for feeders, a larger size is needed. #2/0 AWG aluminum is the appropriate size for a 200‑A service. (Correction: The correct answer is D – #2/0 AWG aluminum.) Question 60. A 120‑V, 15‑A receptacle is installed in a wet location outdoors. Which protection is required? A) AFCI only B) GFCI only C) Both AFCI and GFCI D) No special protection Answer: B Explanation: NEC 210.8(A)(3) requires GFCI protection for outdoor receptacles. Question 61. Which NEC article governs the installation of electric vehicle supply equipment (EVSE)? A) Article 210
B) Article 625 C) Article 690 D) Article 702 Answer: B Explanation: Article 625 covers electric vehicle charging systems. Question 62. In a residential dwelling, how many 20‑A circuits are required for the kitchen countertop receptacles? A) One B) Two C) Three D) Four Answer: B Explanation: NEC 210.52(C)(1) requires at least two 20‑A circuits for kitchen countertop receptacles. Question 63. Which of the following is the correct minimum clearance in front of a transformer? A) 30 in. B) 36 in. C) 42 in. D) 48 in. Answer: C Explanation: NEC 110.26(A)(2) requires a minimum 42‑in. front clearance for transformers. Question 64. What is the minimum size of a grounding‑electrode conductor for a 100‑A service using copper? A) #8 AWG B) #6 AWG C) #4 AWG D) #2 AWG
