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Question 1. What does the NEC term “accessible” mean? A) Able to be reached without using tools B) Capable of being removed without damaging the building C) Reachable only with a ladder D) Visible from the exterior of the building Answer: A Explanation: “Accessible” means that a component can be reached without the use of tools or removing any part of the building structure. Question 2. According to Ohm’s Law, if a circuit has a voltage of 120 V and a resistance of 30 Ω, what is the current? A) 2 A B) 3 A C) 4 A D) 5 A Answer: B Explanation: I = V / R = 120 V / 30 Ω = 4 A (Oops, correct answer is 4 A). Actually the correct calculation yields 4 A, so the correct answer is C. Question 3. Which formula correctly represents electrical power? A) P = V ÷ I
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B) P = V × I
C) P = I ÷ V
D) P = V – I
Answer: B Explanation: Power (watts) equals voltage multiplied by current (P = V × I). Question 4. In a series circuit, the total resistance is: A) The sum of individual resistances B) The reciprocal of the sum of reciprocals C) Always less than the smallest resistor D) Independent of the number of resistors Answer: A Explanation: Series resistances add directly: R_total = R1 + R2 + …. Question 5. In a parallel circuit, the total current is: A) The sum of the branch currents B) The average of the branch currents C) The product of branch currents D) Equal to the smallest branch current Answer: A
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A) Article 100 B) Article 110 C) Article 210 D) Article 250 Answer: A Explanation: Article 100 provides definitions, including “grounded conductor”. Question 9. For a 20‑amp branch circuit feeding a bathroom vanity light, the minimum wire size is: A) 14 AWG copper B) 12 AWG copper C) 10 AWG copper D) 8 AWG copper Answer: B Explanation: 20‑A circuits require at least 12 AWG copper conductors per NEC Table 310.15(B)(16). Question 10. When calculating box fill, a device (e.g., a switch) counts as: A) One conductor volume B) Two conductor volumes C) Three conductor volumes
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D) Four conductor volumes Answer: B Explanation: Each yoke-mounted device counts as the volume of two conductors. Question 11. The maximum recommended voltage drop for a feeder supplying a dwelling unit is: A) 1 % B) 2 % C) 3 % D) 5 % Answer: C Explanation: NEC recommends a maximum of 3 % voltage drop for feeders and branch circuits combined. Question 12. Which conduit material is permitted for wet locations without a moisture barrier? A) Rigid metal conduit (RMC) B) PVC conduit C) Flexible metal conduit (FMC) D) All of the above Answer: D
Course Exam
Question 15. Which article governs the installation of tamper‑resistant receptacles? A) Article 210 B) Article 406 C) Article 408 D) Article 410 Answer: B Explanation: Article 406 covers receptacle, cord connector, and attachment plug installation, including tamper‑resistant requirements. Question 16. The required working clearance in front of a panelboard is: A) 24 in. wide and 30 in. deep B) 30 in. wide and 36 in. deep C) 36 in. wide and 30 in. deep D) 42 in. wide and 48 in. deep Answer: C Explanation: NEC 110.26 requires a minimum of 30 in. deep and 36 in. wide working space in front of equipment. Question 17. Which of the following is NOT a permitted use for Type NM cable? A) Inside walls of a residential dwelling
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B) In wet locations C) In attics without protection from physical damage D) In concealed ceilings Answer: B Explanation: Type NM (non‑metallic sheathed) cable is not allowed in wet locations. Question 18. The grounding electrode conductor (GEC) for a single‑family home is typically sized: A) 14 AWG copper for 100 A service B) 12 AWG copper for 100 A service C) 10 AWG copper for 100 A service D) 8 AWG copper for 100 A service Answer: C Explanation: NEC Table 250.66 allows 10 AWG copper for a 100 A service grounding electrode conductor. Question 19. Which NEC article addresses the requirements for AFCI protection? A) Article 210 B) Article 210. C) Article 240
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Explanation: NEC 430.22 requires conductors sized for at least 125 % of the motor’s full‑load current, but the overcurrent device is typically 150 % for single‑phase motors. Question 22. Which of the following is the correct method for supporting NM cable in a residential attic? A) Every 4 ft B) Every 6 ft C) Every 8 ft D) Every 12 ft Answer: C Explanation: NEC 334.30 requires NM cable to be supported at intervals not exceeding 4.5 ft (≈ 54 in.) and within 12 in. of boxes; 8 ft is a common practice but the code limits to 4.5 ft. Therefore the correct answer is B (every 6 ft). Question 23. A 120‑V, 15‑A circuit feeding a kitchen countertop must be protected by a GFCI. Which device can provide this protection? A) Standard circuit breaker only B) GFCI circuit breaker or GFCI receptacle C) AFCI breaker only D) No protection required Answer: B
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Explanation: Either a GFCI breaker at the panel or a GFCI receptacle at the outlet can satisfy the requirement. Question 24. The NEC permits the use of metal‑clad (MC) cable in which of the following situations? A) Direct burial without conduit B) Exposed in a garage without protection C) In a wet location with appropriate jacket D) Inside a non‑metallic raceway only Answer: C Explanation: MC cable is listed for wet locations when it has a suitable jacket (e.g., MC‑WH). Question 25. For a 100‑A residential service, the minimum size of the service‑entrance conductors (copper) is: A) 8 AWG B) 6 AWG C) 4 AWG D) 2 AWG Answer: C Explanation: NEC Table 310.15(B)(16) indicates 4 AWG copper is required for a 100 ‑A service.
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A) Using only the service neutral as a ground B) Installing a separate grounding electrode system C) Connecting to the main building’s equipment grounding conductor only D) No grounding required if the garage is unoccupied Answer: B Explanation: Detached structures must have their own grounding electrode system per NEC 250.32. Question 29. In a residential solar photovoltaic (PV) system, the inverter must be equipped with: A) A built‑in GFCI B) A built‑in AFCI C) A disconnecting means within sight of the inverter D) No disconnecting means if the system is < 5 kW Answer: C Explanation: NEC 690.13 requires a means to disconnect the PV source within sight of the inverter. Question 30. The NEC defines “service‑disconnecting means” as: A) Any circuit breaker in the panel B) The main breaker or fused disconnect that isolates the entire service
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C) Only a fuse located at the meter base D) The first GFCI device downstream of the service entrance Answer: B Explanation: The service‑disconnecting means is the device that can disconnect all ungrounded conductors feeding the building. Question 31. Which of the following is the correct conduit fill limit for a single 3/4‑in. EMT conduit containing three #12 AWG THHN conductors? A) 40 % B) 53 % C) 60 % D) 70 % Answer: B Explanation: For more than two conductors, the fill limit is 40 % of the conduit’s internal cross‑sectional area; however, Table 1 in Chapter 9 of the NEC gives 53 % for a single conduit with three conductors. The correct answer is B. Question 32. A homeowner wants to install a receptacle in a garage that will be used for a portable air‑compressor. Which protection is required? A) GFCI only B) AFCI only C) Both GFCI and AFCI
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Explanation: NEC 210.52(D) requires bathroom receptacles to be installed not less than 15 in. and not more than 48 in. above the floor; the typical vanity height is 18 in. above the countertop. Question 35. For a 240‑V, 30‑A dryer circuit, which type of overcurrent protection is acceptable? A) 20‑A breaker B) 30‑A two‑pole breaker C) 40‑A single‑pole breaker D) 50‑A two‑pole breaker with a 30‑A fuse downstream Answer: B Explanation: The circuit must be protected by a 30‑A two‑pole breaker matching the branch‑circuit rating. Question 36. Which NEC article addresses the installation of fire alarm wiring? A) Article 300 B) Article 725 C) Article 800 D) Article 820 Answer: D Explanation: Article 820 covers the installation of fire alarm systems.
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Question 37. A residential circuit supplying a bathroom lighting fixture must be protected by an AFCI. This requirement is found in: A) Article 210.12(A) B) Article 210.8(A)(1) C) Article 210.11(C)(1) D) Article 210.52(B) Answer: A Explanation: Article 210.12(A) requires AFCI protection for all 120‑V, single‑phase, 15 ‑ and 20‑A branch circuits supplying outlets or lighting in dwelling units. Question 38. When installing a recessed lighting fixture in a ceiling that is also a fire‑rated assembly, which of the following is required? A) No special requirements if the fixture is listed for the ceiling type B) Use of a fire‑rated box and sealing with firestop mortar C) Installation of a metal conduit to the fixture D) Only a GFCI breaker at the panel Answer: B Explanation: Fire‑rated assemblies require a fire‑rated box and proper firestopping to maintain the rating.
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Question 41. In a residential installation, a flexible metal conduit (FMC) is used to protect a branch‑circuit conductor that runs through a wall. The maximum length of FMC without a support is: A) 3 ft B) 4 ft C) 6 ft D) 8 ft Answer: B Explanation: NEC 376.30 requires FMC to be supported within 4 ft of each outlet box and at intervals not exceeding 6 ft; the maximum unsupported length is 4 ft. Question 42. Which of the following devices is specifically designed to protect against ground‑fault currents in a swimming pool pump motor? A) GFCI breaker B) AFCI breaker C) Surge protective device (SPD) D) Thermal overload relay Answer: A Explanation: GFCI devices protect pool pump motors from ground‑fault currents that could cause shock. Question 43. The NEC requires that a receptacle installed outdoors be:
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A) Weather‑proof only when the cover is in place B) Tamper‑resistant only if within 6 ft of a sink C) GFCI protected and have a weather‑proof enclosure D) Rated for 240 V only Answer: C Explanation: Outdoor receptacles must be GFCI protected and installed in a weather‑proof enclosure (NEC 210.8(A)(3)). Question 44. When installing a 12‑/ 2 NM cable in a stud cavity, the cable must be protected from nails within how many inches of the nearest edge of the stud? A) 1 in. B) 1½ in. C) 2 in. D) 2½ in. Answer: B Explanation: NEC 300.4(D) requires a minimum of 1½ in. protection from nails or screws. Question 45. Which of the following is the correct ampacity for a 75 °C rated 3 ‑conductor, 4‑wire 6 AWG copper cable in a raceway with three current‑carrying conductors?
