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Question 1. Which equation correctly represents Ohm’s Law? A) P = V × I B) V = I × R C) I = V ÷ P D) R = P ÷ I Answer: B Explanation: Ohm’s Law states that voltage (V) equals current (I) multiplied by resistance (R), V = I·R. Question 2. A 150-W incandescent lamp is connected to a 120-V circuit. What is the current drawn by the lamp? A) 0.75 A B) 1.25 A C) 1.5 A D) 2.0 A Answer: B Explanation: I = P ÷ V = 150 W ÷ 120 V = 1.25 A. Question 3. In a three-phase, four-wire wye system, the line-to-neutral voltage is 208 V. What is the line-to-line voltage? A) 208 V B) 240 V C) 360 V D) 360 × √3 V Answer: C Explanation: V_LL = √3 × V_LN = 1.732 × 208 V ≈ 360 V. Question 4. A branch circuit supplies a continuous load of 18 A. What minimum breaker size must be used according to the 125 % rule? A) 20 A B) 22 A
C) 25 A
D) 30 A
Answer: C Explanation: 18 A × 125 % = 22.5 A; the next standard size is 25 A. Question 5. Which of the following is a correct statement about series circuits? A) Voltage divides proportionally to resistance. B) Current divides proportionally to resistance. C) Total resistance is less than the smallest resistor. D) Power factor is always unity. Answer: A Explanation: In series, the same current flows, and voltage drop across each resistor is proportional to its resistance. Question 6. Two 10-Ω resistors are connected in parallel. What is the equivalent resistance? A) 5 Ω B) 10 Ω C) 20 Ω D) 0 Ω Answer: A Explanation: 1/R_eq = 1/10 + 1/10 = 2/10 → R_eq = 10/2 = 5 Ω. Question 7. A 120-V circuit has a total load of 12 A. What is the real power consumed, assuming a power factor of 0.9? A) 1080 W B) 1200 W C) 972 W D) 1440 W Answer: C Explanation: P = V·I·PF = 120 V × 12 A × 0.9 = 972 W.
B) 2.00 in³ C) 1.00 in³ D) 3.00 in³ Answer: A Explanation: NEC Table 314.16(A) gives 2.25 in³ for each #12 conductor. Question 12. A metal conduit run contains three #6 THHN conductors and one #12 grounding conductor. What is the minimum conduit fill percentage? A) 40 % B) 53 % C) 33 % D) 25 % Answer: C Explanation: For more than two conductors, max fill is 40 %; however, the required fill is 3×(0.050 in²) + 0.013 in² = 0.163 in². A ½-in. EMT has 0.304 in² (40 % of 0.304 in² = 0.122 in²) which is insufficient, so a ¾-in. EMT (0.533 in²) at 40 % = 0.213 in² meets the requirement. The fill percentage used is 0.163 ÷ 0.533 ≈ 30 % (under 40 %). Thus the answer reflects that the fill is below the 40 % limit, i.e., 33 % is the closest. Question 13. Which of the following is the correct ampacity of a 3-conductor # AWG copper cable rated for 75 °C in a raceway with three current-carrying conductors? A) 55 A B) 70 A C) 85 A D) 95 A Answer: B Explanation: Table 310.15(B)(16) shows #4 Cu at 75 °C = 85 A. With three current-carrying conductors, apply a 80 % derating factor: 85 A × 0.80 = 68 A, rounded to the next standard size 70 A.
Question 14. What is the required clearance between a service entrance conductors and a grounded metal water pipe in a residential garage? A) 3 in. B) 6 in. C) 12 in. D) No clearance required Answer: B Explanation: NEC 300.3(C)(1) requires a minimum 6-in. separation from grounded metal water pipes. Question 15. Which type of overcurrent device is permitted for protecting a 30-A branch circuit supplying a receptacle outlet? A) 30-A fuse only B) 30-A circuit breaker only C) Either a 30-A fuse or a 30-A circuit breaker D) 25-A breaker with 125 % adjustment Answer: C Explanation: Article 240 allows either fuses or circuit breakers of the same rating as the circuit. Question 16. In a motor circuit, what is the purpose of an overload relay? A) To protect against short circuits B) To protect against ground faults C) To protect the motor from overheating due to excessive current D) To provide a disconnecting means Answer: C Explanation: An overload relay trips when motor current exceeds a preset value, preventing overheating. Question 17. A 240-V, 30-A single-phase motor requires a branch-circuit conductor size of: A) #10 Cu
D) #6 Cu Answer: B Explanation: NEC 210.11(C)(2) calls for #10 Cu for a 30-A dryer circuit. Question 21. Which of the following is the correct method for grounding a metal conduit that serves as an equipment grounding conductor? A) Use a separate grounding wire inside the conduit. B) Rely on the conduit’s metal surface alone. C) Bond each conduit body and fitting with a grounding screw. D) No grounding required if the conduit is PVC. Answer: C Explanation: NEC 250.118 requires bonding each conduit body and fitting with a grounding screw or clamp. Question 22. When installing a receptacle in a bathroom, which protection is mandatory? A) AFCI only B) GFCI only C) Both AFCI and GFCI D) Neither AFCI nor GFCI if the circuit is 20 A Answer: B Explanation: NEC 210.8(A)(1) requires GFCI protection for bathroom receptacles. Question 23. A hazardous location is classified as Class I, Division 2. Which of the following best describes this environment? A) Flammable gases or vapors present continuously in the air. B) Flammable gases or vapors may be present under abnormal conditions. C) Combustible dust in the air. D) Ignitable fibers or flyings. Answer: B
Explanation: Class I, Division 2 denotes areas where flammable gases/vapors are not normally present but may appear under abnormal conditions. Question 24. For a swimming pool pump motor, which grounding requirement is mandatory? A) Only a ground rod is needed. B) Equipotential bonding grid around the pool. C) No grounding required if the motor is double-insulated. D) Grounding only at the service panel. Answer: B Explanation: NEC 680.26 requires an equipotential bonding grid for pools to reduce shock hazard. Question 25. Which OSHA standard addresses the use of personal protective equipment (PPE) for electrical work? A) 1910. B) 1926. C) 1910. D) 1910. Answer: D Explanation: OSHA 1910.269 covers electrical safety-related work practices and PPE. Question 26. A conduit run is installed in a concrete wall. What is the minimum cover required for EMT in this situation? A) 1 in. B) 1½ in. C) 2 in. D) 2½ in. Answer: C Explanation: NEC 300.5(A)(1) requires 2 in. cover for EMT in concrete.
B) #4 AWG
C) #2 AWG
D) #1/0 AWG
Answer: C Explanation: Table 250.122 lists #2 AWG copper for a 200-A service. Question 31. A 120-V, 15-A receptacle is to be installed in a garage. Which protection is required? A) GFCI only B) AFCI only C) Both GFCI and AFCI D) Neither, if the circuit is dedicated Answer: A Explanation: NEC 210.8(A)(2) requires GFCI protection for receptacles in garages. Question 32. What is the minimum ampacity of a feeder conductor supplying a 60 - A branch circuit, assuming the feeder carries only that circuit? A) 60 A B) 70 A C) 80 A D) 100 A Answer: A Explanation: The feeder must be sized for the load it serves; 60 A is sufficient when no derating applies. Question 33. Which NEC article governs the installation of raceways in outdoor locations? A) 300. B) 300. C) 300. D) 300.
Answer: C Explanation: Article 300.22 addresses protection of raceways and cables in outdoor locations. Question 34. In a three-wire 120/240-V circuit, what is the purpose of the neutral conductor? A) Carry unbalanced load current back to the source. B) Provide a grounding path. C) Act as a protective earth. D) Supply 240-V loads directly. Answer: A Explanation: The neutral carries the difference between the two hot conductors (unbalanced current) back to the source. Question 35. Which of the following devices is specifically required for a residential laundry area? A) AFCI for the dryer circuit. B) GFCI for the washing machine receptacle. C) Surge protector for the dryer. D) No special device required. Answer: B Explanation: NEC 210.8(A)(7) requires GFCI protection for receptacles in laundry areas. Question 36. A commercial building uses a 480-V three-phase, four-wire wye service. What is the phase voltage? A) 120 V B) 208 V C) 277 V D) 480 V Answer: B
Answer: A Explanation: The neutral is a grounded conductor that returns current to the source and is bonded to ground at the service. Question 40. For a 30-A, 240-V air-conditioning unit, what minimum size copper branch-circuit conductor is required? A) #12 Cu B) #10 Cu C) #8 Cu D) #6 Cu Answer: C Explanation: NEC 210.23(A)(2) requires #8 Cu for a 30-A, 240-V AC unit (considering 125 % of the rated load). Question 41. Which article addresses the requirements for emergency power systems and transfer switches? A) 700 B) 701 C) 702 D) 710 Answer: A Explanation: Article 700 covers emergency systems, including transfer equipment. Question 42. A conduit run contains four current-carrying conductors. What derating factor must be applied to the conductor ampacity according to NEC Table 310.15(B)(3)(a)? A) 100 % B) 80 % C) 70 % D) 60 % Answer: B Explanation: For 4–6 conductors, the derating factor is 80 %.
Question 43. Which type of cable is permitted for interior wiring of a residential dwelling in dry locations? A) NM-B (Romex) B) MC-H C) UF-B D) AC-B Answer: A Explanation: NM-B is the standard non-metallic sheathed cable allowed in dry interior locations. Question 44. In a commercial building, a lighting circuit is required to have AFCI protection. Which NEC article provides this requirement? A) 210. B) 210. C) 210. D) 210. Answer: A Explanation: Article 210.12 mandates AFCI protection for certain branch circuits, including lighting in dwellings; commercial requirements are covered in 210.12(A). Question 45. What is the minimum distance required between a service drop and a window opening in a dwelling unit? A) 3 ft B) 6 ft C) 10 ft D) 12 ft Answer: B Explanation: NEC 230.24 requires a minimum 6-ft clearance from the service drop to windows, doors, or similar openings.
Question 49. What is the permissible voltage drop for a feeder supplying a 100 A load over a 150-ft run, assuming 3 % is acceptable? A) 2.4 V B) 3.6 V C) 4.5 V D) 6.0 V Answer: B Explanation: 3 % of 120 V (typical single-phase) = 3.6 V. For 240 V systems, 3 % = 7.2 V; the question likely assumes 120 V, so 3.6 V is correct. Question 50. Which of the following is the correct NEC reference for the calculation of box fill for devices? A) 314.16(A) B) 300.22(B) C) 310.15(B)(3) D) 250. Answer: A Explanation: NEC 314.16(A) provides the box-fill calculation rules. Question 51. A conduit is installed in a wall that will be painted. Which type of conduit is most appropriate? A) EMT B) RMC C) PVC D) FMC Answer: A Explanation: EMT (electrical metallic tubing) is commonly used in interior walls and can be painted to match finish. Question 52. Which NEC article deals with the installation of fire alarm systems? A) 760
B) 770
C) 770.
D) 770.
Answer: A Explanation: Article 760 covers fire alarm systems. Question 53. For a 120-V, 20-A circuit feeding a receptacle in a utility room, which protection is required? A) GFCI only B) AFCI only C) Both GFCI and AFCI D) No special protection required Answer: A Explanation: NEC 210.8(A)(2) mandates GFCI protection for receptacles in utility rooms. Question 54. What is the minimum size of a copper grounding electrode conductor for a 400-A service? A) #6 AWG B) #4 AWG C) #2 AWG D) #1/0 AWG Answer: D Explanation: Table 250.122 lists #1/0 AWG copper for a 400-A service. Question 55. Which of the following is the correct method for calculating the required conduit size for three #4 AWG THHN conductors? A) Use the largest conductor’s cross-sectional area multiplied by 3, then apply 40 % fill. B) Sum the individual areas, then ensure total does not exceed 40 % of conduit’s internal area. C) Multiply the conduit’s nominal size by the number of conductors.
Explanation: NEC 210.23(A)(2) requires the branch-circuit rating to be at least 125 % of the continuous load; 15 A × 125 % = 18.75 A, so the next standard size is 20 A. Question 59. Which of the following is the appropriate method to protect a feeder supplying a detached garage? A) Install a GFCI breaker at the service panel. B) Install a separate sub-panel with a disconnect in the garage. C) Use a fused disconnect at the garage entrance only. D) No special protection is needed if the feeder is 12-AWG. Answer: B Explanation: NEC 225.30 requires a disconnecting means in or at the detached structure; a sub-panel with a local disconnect satisfies this. Question 60. What is the minimum distance required between a receptacle and a bathtub rim? A) 6 in. B) 12 in. C) 18 in. D) 24 in. Answer: B Explanation: NEC 210.8(A)(10) requires GFCI protection for receptacles within 12 in. of a bathtub rim; the distance for placement is also 12 in. Question 61. Which NEC article addresses the requirements for wiring methods in health-care facilities? A) 517 B) 518 C) 519 D) 520 Answer: D Explanation: Article 520 covers health-care facilities.
Question 62. A 30-A circuit supplies a receptacle in a garage. Which type of receptacle is required? A) Standard 15-A receptacle B) 20-A receptacle C) 30-A receptacle D) GFCI receptacle only Answer: B Explanation: NEC 210.21(B)(3) allows a 20-A receptacle on a 30-A branch circuit if the circuit supplies only receptacles. Question 63. Which of the following is the correct NEC reference for the calculation of conduit fill for PVC conduit? A) Table C.2, Annex C B) Table 4, Chapter 9 C) Table 5, Chapter 9 D) Table 1, Chapter 9 Answer: A Explanation: Annex C, Table C.2 provides fill capacities for PVC and other raceways. Question 64. For a 120-V, 15-A receptacle in a dwelling, what is the required minimum wire gauge for the branch circuit? A) #14 Cu B) #12 Cu C) #10 Cu D) #8 Cu Answer: A Explanation: NEC 210.19(A)(1) permits #14 Cu for a 15-A circuit. Question 65. Which article specifies the requirements for installing luminaires in hazardous (Class I) locations?
