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Course Exam
Question 1. Which of the following equations correctly represents Ohm’s Law? A) V = I × R B) P = V ÷ I C) I = V ÷ P D) R = V × I Answer: A Explanation: Ohm’s Law states that voltage (V) equals current (I) multiplied by resistance (R). Question 2. A 120‑V, 10‑A load is connected to a circuit. What is the power consumed by the load? A) 12 W B) 120 W C) 1,200 W D) 12,000 W Answer: C Explanation: Power (P) = V × I = 120 V × 10 A = 1,200 W. Question 3. In a series circuit, the total resistance is 30 Ω and the current is 2 A. What is the total voltage across the circuit? A) 15 V B) 30 V C) 60 V D) 90 V Answer: C Explanation: V = I × R = 2 A × 30 Ω = 60 V. Question 4. Which component stores energy in an electric field? A) Resistor
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B) Inductor C) Capacitor D) Transformer Answer: C Explanation: Capacitors store energy in an electric field between their plates. Question 5. For a three‑phase, 4‑wire wye system, what is the relationship between line voltage (V_L) and phase voltage (V_P)? A) V_L = V_P B) V_L = √2 × V_P C) V_L = √3 × V_P D) V_L = 2 × V_P Answer: C Explanation: In a wye system, line voltage equals √3 times the phase voltage. Question 6. A 150‑ft run of 12‑AWG copper conductors carries 20 A at 120 V. Using a voltage‑drop limit of 3 %, is the conductor size adequate? (Assume 2 % per 100 ft for 12‑AWG.) A) Yes, because drop is <3 % B) No, because drop is >3 % C) Yes, because voltage‑drop is not applicable to branch circuits D) No, because 12‑AWG cannot carry 20 A Answer: A Explanation: Voltage drop = 2 % × (150 ft /100 ft) = 3 %; the limit is met, so the size is acceptable. Question 7. According to NEC Table 310.15(B)(16), what is the ampacity of 4‑AWG copper THHN at 75 °C? A) 55 A B) 70 A C) 85 A
Course Exam
Question 11. What is the minimum size copper grounding electrode conductor (GEC) for a 100‑A service? A) 8 AWG B) 6 AWG C) 4 AWG D) 2 AWG Answer: B Explanation: NEC Table 250.66 requires a minimum of 6 AWG copper for a 100‑A service. Question 12. In a conduit system, the maximum number of 14‑AWG THHN conductors allowed in a ½‑in. EMT without exceeding 40 % fill is: A) 5 B) 9 C) 12 D) 14 Answer: C Explanation: Using Table 1 of Chapter 9, ½‑in. EMT can hold up to 12 conductors of 14‑AWG at 40 % fill. Question 13. Which of the following is NOT a permitted use for NM‑B cable? A) Interior residential wiring B) Exposed in a wet location C) Within a finished wall cavity D) In a concealed attic space Answer: B Explanation: NM‑B is not rated for wet locations; it is limited to dry or damp locations. Question 14. A motor rated 5 hp, 240 V, 3‑phase, 60 Hz requires a full‑load current of 12 A. What is the minimum size of the branch‑circuit breaker protecting this motor, assuming a 125 % multiplier?
Course Exam
A) 12 A
B) 15 A
C) 20 A
D) 25 A
Answer: C Explanation: 12 A × 125 % = 15 A; the next standard breaker size is 20 A. Question 15. Which NEC article governs the installation of AFCI protection for residential branch circuits? A) Article 210 B) Article 210. C) Article 210. D) Article 210. Answer: B Explanation: Article 210.12 specifically requires AFCI protection for certain residential circuits. Question 16. For a 30‑A, 240‑V dryer circuit, what is the minimum size copper conductor required (assuming 75 °C insulation and no adjustment factors)? A) 12 AWG B) 10 AWG C) 8 AWG D) 6 AWG Answer: B Explanation: Table 310.15(B)(16) shows 10 AWG copper THHN rated for 30 A at 75 °C. Question 17. Which of the following best describes the purpose of a service disconnect? A) To protect individual branch circuits B) To provide a means to disconnect all power to the building C) To limit fault current to 15 kA
Course Exam
Answer: C Explanation: Load = 1500 W ÷ 120 V = 12.5 A. Continuous loads require 125 %: 12.5 A × 1.25 = 15.6 A → next standard size is 20 A. Question 21. Which of the following devices is specifically designed to protect against ground‑fault currents of 5 mA in personnel‑safety applications? A) Standard circuit breaker B) GFCI receptacle C) AFCI breaker D) Surge protector Answer: B Explanation: GFCIs detect and interrupt ground‑fault currents as low as 4– 6 mA to protect people. Question 22. When installing a conduit system in a concrete slab, which of the following is required by NEC? A) Use only PVC conduit B) Conduit must be listed for direct burial C) Conduit must be painted black D) No special requirements exist Answer: B Explanation: Conduit in concrete must be listed for direct burial (e.g., RMC, PVC rated for burial). Question 23. A 3‑phase motor has a locked‑rotor current (LRC) of 30 A. Which overcurrent device is appropriate for protecting the motor, assuming the device must be at least 125 % of the LRC? A) 30 A breaker B) 35 A breaker C) 40 A breaker D) 45 A breaker Answer: C
Course Exam
Explanation: 30 A × 125 % = 37.5 A; the next standard size is 40 A. Question 24. Which of the following is the correct NEC reference for the minimum height of a receptacle outlet in a garage? A) 210.52(D) B) 210.52(G) C) 210.7(C) D) 210.8(A) Answer: A Explanation: NEC 210.52(D) addresses receptacle placement in garages, specifying a minimum height of 18 in. above the floor. Question 25. In a residential dwelling, how many 20‑A small‑appliance branch circuits are required by NEC? A) One B) Two C) Three D) Four Answer: B Explanation: NEC 210.11(C)(1) requires at least two 20‑A small‑appliance circuits for the kitchen, pantry, and dining areas. Question 26. Which of the following is the proper method for grounding a metal conduit that serves as the equipment grounding conductor? A) No grounding needed if the conduit is continuous B) Install a separate grounding wire inside the conduit C) Use a grounding clamp at each box and a grounding electrode conductor at the service entrance D) Only bond the conduit at the panel Answer: C
Course Exam
Question 30. Which of the following is the correct NEC definition of “identified” conductors? A) Conductors that are labeled with a manufacturer’s name B) Conductors that have a colored insulation or marking indicating their purpose C) Conductors that are larger than 4 AWG D) Conductors that are listed for outdoor use only Answer: B Explanation: “Identified” means the conductor’s insulation or markings indicate its function (e.g., grounded, equipment grounding). Question 31. For a commercial building with a 400‑A service, what is the minimum size copper service‑entrance conductor (based on NEC Table 310.15(B)(16) and 75 °C rating)? A) 250 kcmil B) 300 kcmil C) 350 kcmil D) 400 kcmil Answer: B Explanation: 300 kcmil copper THHN is rated for 350 A at 75 °C; the next larger standard size that meets or exceeds 400 A is 350 kcmil, but 300 kcmil is insufficient, so 350 kcmil is required. However, the answer list does not include 350 kcmil, indicating the correct choice is C (350 kcmil). Question 32. Which of the following statements about AFCI protection is true? A) AFCIs protect only against ground‑fault currents. B) AFCIs are required for all 15‑A and 20‑A circuits in a dwelling. C) AFCIs detect arcing conditions that could cause fire. D) AFCIs can replace all GFCI devices. Answer: C Explanation: AFCIs are designed to detect dangerous arcing conditions that may lead to fire.
Course Exam
Question 33. In a residential panel, a 240‑V, 30‑A double‑pole breaker is used to feed a 4500‑W electric range. Is the breaker appropriately sized? A) Yes, because the range draws less than 30 A. B) No, because the range requires a 40‑A breaker. C) Yes, because the range is a non‑continuous load. D) No, because the breaker must be sized at 125 % of the load. Answer: A Explanation: Load = 4500 W ÷ 240 V = 18.75 A. A 30‑A breaker is sufficient for this non‑continuous load. Question 34. Which NEC article addresses the requirements for temporary wiring used on construction sites? A) Article 590 B) Article 300 C) Article 210 D) Article 430 Answer: A Explanation: Article 590 covers temporary installations, including wiring on construction sites. Question 35. When installing a grounding electrode system for a new residential building, which of the following is acceptable as a grounding electrode? A) A 4‑AWG copper conductor buried 12 in. deep B) A metal water pipe in direct contact with the earth for at least 10 ft C) A concrete‑encased electrode (Ufer) with at least 20 ft of #4 rebar D) All of the above Answer: D Explanation: NEC permits any of the listed methods as a grounding electrode. Question 36. A 3‑phase, 480‑V feeder supplies a motor load of 30 kW with a power factor of 0. lagging. What is the apparent power (kVA) of the feeder?
Course Exam
Question 39. A 120‑V, 20‑A receptacle is to be installed in a garage. Which protection is required by NEC? A) No special protection needed B) GFCI protection only C) AFCI protection only D) Both GFCI and AFCI protection Answer: B Explanation: NEC 210.8(A)(2) requires GFCI protection for garage receptacles. Question 40. In a fire alarm system, which of the following is the correct minimum conductor size for the power‑limiting circuit? A) 14 AWG copper B) 12 AWG copper C) 10 AWG copper D) 8 AWG copper Answer: B Explanation: NFPA 72 requires a minimum of 12 AWG copper for the power‑limiting circuit. Question 41. Which of the following is the correct definition of “continuous load” per NEC? A) Any load that operates for more than 1 hour per day B) A load that operates for three hours or more continuously C) Any load that exceeds 80 % of the circuit rating D) A load that is always on, regardless of duration Answer: B Explanation: NEC defines a continuous load as one that runs for three hours or more without interruption. Question 42. When installing a receptacle in a wet location, which of the following enclosure types is required?
Course Exam
A) Standard dry‑location box B) Weatherproof (in‑use) cover C) Plastic box with a standard cover D) No cover required if the box is metal Answer: B Explanation: Wet locations require a weatherproof (in‑use) cover to protect the receptacle. Question 43. A 250‑V, 30 A feeder supplies a 3‑phase motor. Which conductor size (copper, THHN, 75 °C) is the minimum required, assuming no adjustment factors? A) 8 AWG B) 6 AWG C) 4 AWG D) 2 AWG Answer: B Explanation: Table 310.15(B)(16) shows 6 AWG copper THHN rated for 55 A at 75 °C, which exceeds the 30 A requirement. Question 44. Which NEC article addresses the requirements for emergency and standby power systems? A) Article 700 B) Article 702 C) Article 705 D) Article 710 Answer: A Explanation: Article 700 covers emergency systems, while Article 702 covers legally required standby systems. Question 45. For a commercial lighting circuit that serves 12 fixtures each rated at 150 W, what is the minimum ampere rating of the branch‑circuit breaker, assuming a 125 % continuous load factor? A) 15 A
Course Exam
C) Surge protector D) None of the above Answer: B Explanation: NEC 210.8(A)(10) requires GFCI protection for laundry receptacles. Question 49. A conduit run contains three current‑carrying conductors and one equipment grounding conductor. What is the required conduit fill percentage for this installation? A) 20 % B) 31 % C) 40 % D) 53 % Answer: C Explanation: For more than two conductors, NEC permits up to 40 % fill in a conduit. Question 50. Which NEC article governs the installation of low‑voltage fire‑alarm wiring? A) Article 300 B) Article 720 C) Article 760 D) Article 800 Answer: C Explanation: Article 760 covers fire alarm systems and their wiring. Question 51. When using a multimeter to verify the presence of voltage on a 120‑V circuit, which of the following safety practices is required by OSHA? A) Touch the probe tips together before testing B) Use a multimeter rated for at least 600 V C) Test the circuit with the multimeter set to the lowest voltage range D) No safety precautions are needed for low‑voltage circuits Answer: B
Course Exam
Explanation: OSHA requires that test equipment be rated for the voltage being measured; a 600‑V rated meter is appropriate for 120‑V circuits. Question 52. A transformer secondary is 240 V, 10 kVA. What is the maximum continuous current that can be drawn from the secondary? A) 25 A B) 30 A C) 35 A D) 40 A Answer: B Explanation: I = kVA ÷ V = 10 kVA ÷ 240 V = 41.7 A. However, NEC requires 125 % for continuous loads, so the maximum continuous current is 10 kVA ÷ 240 V ÷ 1.25 = 33.3 A, which is closest to 30 A as the next standard rating. Question 53. Which of the following is the correct minimum clearance between a live part and a grounded metal surface in a dry location for a 120‑V circuit? A) 0.5 in. B) 1 in. C) 1.5 in. D) 2 in. Answer: B Explanation: NEC 210.21(B)(1) requires a minimum of 1 in. clearance in dry locations. Question 54. In a residential garage, a 20‑A circuit supplies a portable electric heater. Which protection is required? A) AFCI only B) GFCI only C) Both AFCI and GFCI D) No special protection Answer: B
Course Exam
Explanation: Article 300 covers general requirements for wiring methods, including raceways and enclosures. Question 58. A 120‑V, 15‑A circuit supplies a kitchen countertop receptacle. According to NEC, what is the maximum distance a countertop point can be from a receptacle? A) 12 ft B) 18 ft C) 24 ft D) 30 ft Answer: A Explanation: NEC 210.52(C)(1) limits the spacing so that no point along the countertop is more than 12 ft from a receptacle. Question 59. Which of the following is the correct NEC requirement for the minimum size of a grounding electrode conductor for a 200‑A service using copper? A) 8 AWG B) 6 AWG C) 4 AWG D) 2 AWG Answer: C Explanation: NEC Table 250.66 specifies 4 AWG copper for a 200‑A service. Question 60. In a commercial office building, a 15‑A branch circuit supplies multiple receptacles. Which device must be installed at the panel to provide AFCI protection for this circuit? A) A standard 15‑A breaker B) A 15‑A GFCI breaker C) A 15‑A AFCI breaker D) No device is required Answer: C
Course Exam
Explanation: AFCI protection is required for many residential‑type circuits in commercial occupancies; a 15 ‑A AFCI breaker satisfies the requirement. Question 61. Which of the following is the correct NEC definition of “qualified person”? A) Anyone who has completed an apprenticeship B) A person who has the knowledge and skills to perform a task safely C) Only a licensed electrician D) Any employee of a utility company Answer: B Explanation: NEC defines a qualified person as one who possesses the required knowledge, training, and experience to safely perform the work. Question 62. A 240‑V, 30‑A dryer circuit is installed using NM‑B cable. Which of the following is the correct conductor size? A) 12 AWG B) 10 AWG C) 8 AWG D) 6 AWG Answer: B Explanation: For a 30‑A dryer circuit, 10 AWG copper NM‑B is the minimum size per NEC Table 310.15(B)(16). Question 63. Which NEC article governs the installation of communications cables (telephone, data, video)? A) Article 800 B) Article 810 C) Article 820 D) Article 830 Answer: A Explanation: Article 800 covers communications circuits.
