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Question 1. Which of the following best represents Ohm’s Law? A) V = I + R B) V = I × R C) V = I ÷ R D) V = R ÷ I Answer: B Explanation: Ohm’s Law states that voltage (V) equals current (I) multiplied by resistance (R). Question 2. In a series AC circuit, the total impedance is the: A) Sum of resistances only B) Vector sum of resistance, reactance, and inductance C) Product of individual impedances D) Difference between resistance and reactance Answer: B Explanation: Impedance in AC combines resistance (real) and reactance (imaginary) using vector addition. Question 3. The NEC definition of “continuous load” requires the load to run for at least: A) 2 hours B) 3 hours C) 4 hours D) 6 hours Answer: C Explanation: A continuous load is one expected to operate for three hours or more; NEC requires sizing conductors at 125 % of the load. Question 4. Power factor is the ratio of: A) Real power to apparent power B) Apparent power to reactive power C) Voltage to current D) Resistance to reactance Answer: A Explanation: Power factor = Real Power (W) ÷ Apparent Power (VA), indicating how efficiently electricity is used. Question 5. Which NEC article defines the term “accessible”? A) Article 100 B) Article 210 C) Article 250 D) Article 300
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Answer: A Explanation: Article 100 provides definitions for terms used throughout the NEC, including “accessible”. Question 6. The voltage drop limit commonly recommended for branch circuits is: A) 1 % B) 2 % C) 3 % D) 5 % Answer: C Explanation: NEC recommends a maximum of 3 % voltage drop for branch circuits to maintain performance. Question 7. In a one-line diagram, a solid line with two parallel lines represents: A) Grounding electrode B) Service-entrance conductor C) Neutral conductor D) Equipment grounding conductor Answer: B Explanation: The NEC symbol for a service-entrance conductor is a solid line with two parallel lines. Question 8. The standard color for a grounded (neutral) conductor in NM cable is: A) Black B) Red C) White D) Green Answer: C Explanation: NEC requires neutral conductors to be identified with white or gray insulation. Question 9. According to NEC Article 210, a minimum of how many receptacle outlets must be installed in a kitchen countertop space? A) One B) Two C) Three D) Four Answer: B Explanation: At least two 20-ampere receptacles are required for each countertop space.
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Explanation: THHN, THWN-2, and XHHW-2 are all rated for 90 °C in dry locations (subject to derating). Question 15. The minimum size of a grounding electrode conductor for a 200-A service using copper is: A) #10 AWG B) #8 AWG C) #6 AWG D) #4 AWG Answer: C Explanation: NEC Table 250.66 specifies #6 AWG copper for a 200-A service. Question 16. A “feed-through” conduit is defined as: A) A conduit that passes through a wall without terminations B) A conduit that contains a device housing C) A conduit that is used for grounding only D) A conduit that is buried underground Answer: A Explanation: Feed-through conduit runs through a building element without any electrical connections inside it. Question 17. For a motor rated 7.5 hp, 460 V, three-phase, the minimum ampacity of the branch-circuit conductors (copper) should be: A) 15 A B) 20 A C) 25 A D) 30 A Answer: C Explanation: NEC Table 430.250 indicates 7.5 hp at 460 V requires 25 A conductors (125 % of motor full-load current). Question 18. The required GFCI protection for a receptacle in a residential garage is: A) Not required B) Required only for 15-A receptacles C) Required for all receptacles D) Required only for 20-A receptacles Answer: C Explanation: NEC 210.8(A)(2) requires GFCI protection for all 125-V, 15- and 20-A receptacles in garages.
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Question 19. In a Class I, Division 2 hazardous location, which type of enclosure is permissible? A) Ex d (dust-tight) B) Ex n (non-explosive) C) Ex p (pressurized) D) All of the above Answer: D Explanation: All listed enclosure types are allowed in Class I, Division 2 areas, provided they meet the appropriate rating. Question 20. The NEC requirement for the working clearance in front of a panelboard is: A) 30 in. minimum B) 36 in. minimum C) 42 in. minimum D) 48 in. minimum Answer: B Explanation: NEC 110.26(A)(1) mandates a minimum of 36 in. of clear space in front of equipment. Question 21. A receptacle installed in a bathroom must have a minimum rating of: A) 15 A B) 20 A C) 30 A D) 40 A Answer: B Explanation: NEC 210.11(C)(3) requires a 20-ampere dedicated circuit for bathroom receptacles. Question 22. The term “equipotential bonding” in swimming pool installations primarily serves to: A) Reduce voltage drop B) Prevent corrosion C) Eliminate stray voltage hazards D) Increase grounding resistance Answer: C Explanation: Equipotential bonding ties all conductive parts together to prevent dangerous voltage differences. Question 23. For a photovoltaic (PV) array with a maximum system voltage of 600 V, the required disconnecting means must be rated for at least:
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Explanation: NEC 680.42 requires a minimum of 8 ft clearance above the water surface. Question 28. A “dedicated circuit” is defined as a circuit that: A) Supplies multiple receptacles B) Supplies lighting only C) Supplies a single appliance or piece of equipment D) Shares a neutral with other circuits Answer: C Explanation: Dedicated circuits serve a single load, such as a refrigerator or HVAC unit. Question 29. The permissible voltage for a Class 3 fire alarm circuit is: A) 30 V B) 50 V C) 100 V D) 300 V Answer: B Explanation: NEC 760.4 defines Class 3 fire alarm circuits as limited to 50 V. Question 30. The NEC requires that a grounding electrode system be bonded to the metal water pipe in service equipment if the pipe is: A) Plastic only B) Exposed for more than 10 ft C) Buried underground D) Uninsulated and within 5 ft of the service drop Answer: D Explanation: NEC 250.52(A)(1) requires bonding to metal water piping that is within 5 ft of the service entrance. Question 31. In a three-phase, 4-wire wye system, the line-to-neutral voltage is: A) Same as line-to-line B) √3 times line-to-line C) 1/√3 of line-to-line D) Not applicable Answer: C Explanation: For wye systems, V_line-to-neutral = V_line-to-line ÷ √3. Question 32. The minimum size of a conduit for pulling three #4 AWG THHN conductors is:
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A) 1/2-in. EMT B) 3/4-in. EMT C) 1-in. EMT D) 1-1/4-in. EMT Answer: B Explanation: Using NEC Chapter 9 Table 5, three #4 AWG THHN (cross-section 0.0211 in² each) total 0.0633 in²; 30 % fill of 3/4-in. EMT (0.307 in²) is 0.092 in², so 3/4-in. is sufficient. Question 33. Which of the following is a permitted method for grounding a metal conduit system? A) Using only the conduit as the equipment ground B) Installing a separate grounding conductor inside the conduit C) Relying on the service-grounded neutral D) None of the above Answer: B Explanation: NEC permits a separate grounding conductor (EGC) to be run inside the conduit to ensure a low-impedance path. Question 34. The required ampere rating for a receptacle serving a countertop appliance requiring 12 A continuous load is: A) 15 A B) 20 A C) 30 A D) 40 A Answer: B Explanation: Continuous loads must be sized at 125 % of the load: 12 A × 1.25 = 15 A, so a 20-A receptacle is required. Question 35. In a commercial lighting load calculation, the NEC “lighting demand factor” for the first 300 ft² is: A) 100 % B) 75 % C) 50 % D) 30 % Answer: A Explanation: NEC Table 220.42 applies 100 % demand for the first 300 ft², then decreasing percentages for additional area. Question 36. A transformer supplying a separately derived system must have its neutral: A) Bonded to ground at the source only B) Unbonded everywhere C) Bonded at the transformer only D) Bonded at both source and transformer
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Explanation: EMT must be supported and secured within 8 ft of each outlet box and at intervals not exceeding 10 ft; the maximum spacing is 8 ft between supports. Question 41. Which of the following is the correct procedure for calculating box fill for a device with three conductors, a grounding conductor, and a yoke? A) Count each conductor once, add one for the grounding conductor, add one for the yoke B) Count each conductor twice, add one for the grounding conductor, add two for the yoke C) Count each conductor once, add two for the grounding conductor, add one for the yoke D) Count each conductor twice, add one for the grounding conductor, add one for the yoke Answer: A Explanation: NEC 314.16(B) requires one fill unit per insulated conductor, one for the equipment grounding conductor, and one for each internal yoke. Question 42. The minimum size of a grounding electrode conductor for a 400-A service using copper is: A) #4 AWG B) #2 AWG C) #1/0 AWG D) #3/0 AWG Answer: D Explanation: NEC Table 250.66 indicates #3/0 AWG copper for a 400-A service; however, the next larger size #4/0 AWG is sometimes used. The correct answer based on the table is D (#3/0 AWG). Question 43. In a fire alarm system, the “initiating device” is typically: A) A control panel B) A smoke detector C) A power supply D) A notification appliance Answer: B Explanation: Initiating devices such as smoke or heat detectors sense a fire condition and send a signal to the control panel. Question 44. A “raceway” is defined by the NEC as: A) Any conduit, tubing, cable tray, or other enclosure that physically protects conductors B) Only metal conduit C) Only PVC conduit D) Only flexible metal conduit Answer: A
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Explanation: NEC 300.1 defines raceway broadly to include conduit, tubing, cable trays, and other protective enclosures. Question 45. The short-circuit rating of a circuit breaker must be at least: A) 50 % of the prospective fault current B) 75 % C) Equal to the prospective fault current D) 125 % of the prospective fault current Answer: C Explanation: NEC 240.81 requires the breaker’s interrupting rating to be equal to or greater than the available fault current. Question 46. The maximum number of 12-AWG THHN conductors that can be placed in a 1-in. PVC conduit (schedule 40) is: A) 15 B) 20 C) 25 D) 30 Answer: B Explanation: Using NEC Chapter 9 Table 5, the area of #12 THHN is 0.0133 in². 30 % of 1-in. PVC conduit (0.864 in²) is 0.259 in². 0.259 ÷ 0.0133 ≈ 19.5, so 20 conductors is the maximum. Question 47. Which of the following is considered a “continuous load” in a commercial kitchen? A) A range oven operating 30 min per day B) A dishwasher that runs 8 hours continuously C) A lighting fixture on a timer D) A walk-in cooler that cycles on/off Answer: B Explanation: Loads that run for three hours or more are continuous; a dishwasher operating 8 hours meets that definition. Question 48. The NEC permits the use of a “single-pole” breaker to protect a 240 - V circuit only if: A) The circuit is for a dryer B) The breaker is a “dual-pole” type C) The breaker has a handle-tie D) The breaker is listed for 240 V single-pole use Answer: D
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Question 53. The permissible voltage for a “low-voltage lighting” system under NEC is: A) 30 V B) 50 V C) 100 V D) 150 V Answer: C Explanation: NEC defines low-voltage lighting as 100 V or less (Article 725). Question 54. The required minimum ampacity of a feeder supplying a 400-sq ft kitchen with a 3-kW range, 2-kW dishwasher, and 4-kW microwave is: A) 20 A B) 30 A C) 40 A D) 50 A Answer: C Explanation: Total load = 3 kW + 2 kW + 4 kW = 9 kW. At 120 V, I = 9 kW ÷ 120 V = 75 A. Applying the 125 % factor for continuous loads (range considered continuous) = 94 A. The nearest standard feeder size is 100 A, but the question asks for minimum ampacity; the correct answer based on typical calculations would be 100 A, which is not listed. Therefore, the closest answer is D (50 A) if the calculation were based on a 240-V system: 9 kW ÷ 240 V = 37.5 A × 1.25 = 46.9 A → 50 A. Hence, answer C (40 A) is not sufficient; answer D (50 A) is correct. Question 55. According to NEC 210.52(A)(1), the minimum number of receptacle outlets required in a habitable room of 200 ft² is: A) One per 30 ft² B) One per 50 ft² C) One per 75 ft² D) One per 100 ft² Answer: A Explanation: NEC requires at least one receptacle outlet for each 30 ft² of floor area. Question 56. Which of the following devices must be listed for “in-use” protection in a damp location? A) Standard duplex receptacle B) GFCI receptacle C) Weather-proof in-use receptacle D) Toggle switch Answer: C Explanation: Only weather-proof in-use receptacles are listed for protection while a plug is inserted in damp or wet locations.
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Question 57. The required grounding conductor size for a 60-A feeder using copper is: A) #10 AWG B) #8 AWG C) #6 AWG D) #4 AWG Answer: B Explanation: NEC Table 250.66 shows #8 AWG copper for a 60-A feeder. Question 58. In a three-wire 120/240-V circuit, the neutral conductor is required to be: A) Same size as the hot conductors B) One size larger than the hot conductors C) Half the size of the hot conductors D) Not required if the load is balanced Answer: A Explanation: NEC requires the neutral to be the same ampacity as the ungrounded conductors unless specific allowances apply. Question 59. The maximum allowable temperature rise for a conductor protected by a 20-A breaker in a 30 °C ambient environment is: A) 30 °C B) 60 °C C) 75 °C D) 90 °C Answer: B Explanation: Conductors must not exceed their temperature rating; a 20-A breaker typically protects 60 °C rated conductors in 30 °C ambient (allowing 30 °C rise). Question 60. Which of the following is a required feature of a commercial panelboard’s labeling? A) Color-coding only B) Circuit directory with circuit numbers and loads C) Manufacturer’s logo only D) No labeling required if the panel is in a locked room Answer: B Explanation: NEC 408.4 requires a clear circuit directory indicating circuit numbers and associated loads. Question 61. The NEC permits the use of “metal-clad” (MC) cable in which of the following applications?
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A) 1-in. EMT B) 1-1/4-in. EMT C) 1-1/2-in. EMT D) 2-in. EMT Answer: B Explanation: Total cross-sectional area = 3 × 0.0201 in² (for #3 AWG) + 0.0366 in² (for #8 AWG) ≈ 0.097 in². 30 % fill of 1-1/4-in. EMT (0.307 in²) = 0.092 in², which is just under the required area, so 1-1/4-in. EMT is sufficient. Question 66. In a commercial office building, the demand factor for the first 3000 ft² of floor area for general lighting is: A) 100 % B) 80 % C) 60 % D) 40 % Answer: B Explanation: NEC Table 220.42 applies a 80 % demand factor for the first 3000 ft² of general lighting load. Question 67. Which of the following is NOT a permitted method for installing a grounding electrode? A) Ground rod B) Metal water pipe not bonded within 5 ft of service C) Concrete-encased electrode D) Ground ring Answer: B Explanation: A metal water pipe must be bonded within 5 ft of the service; otherwise, it cannot serve as a grounding electrode. Question 68. The NEC requires that a disconnecting means for a PV array be located: A) At the inverter only B) Within sight of the array C) At the service panel only D) Anywhere within the building Answer: B Explanation: NEC 690.13 requires the disconnect to be readily accessible and within sight of the PV array. Question 69. For a 3-phase, 4-wire feeder supplying a 30-kVA motor, the minimum size of the feeder breaker is: A) 30 A B) 40 A C) 50 A D) 60 A
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Answer: C Explanation: Motor full-load current for 30 kVA at 460 V is about 37 A; applying 125 % gives 46 A, so a 50-A breaker is the next standard size. Question 70. The NEC definition of “equipment grounding conductor” is: A) A conductor that carries normal return current B) A conductor that provides a low-impedance path to ground for fault current C) The neutral conductor D) The insulated hot conductor Answer: B Explanation: An equipment grounding conductor (EGC) is intended to carry fault current safely to ground. Question 71. A “GFCI breaker” provides protection for: A) Only the hot conductor B) Both hot and neutral conductors C) Only the neutral conductor D) Only the equipment grounding conductor Answer: B Explanation: A GFCI breaker monitors the current balance between hot and neutral and trips if an imbalance occurs. Question 72. In a residential dwelling, the minimum ampacity of the feeder supplying a 20-A kitchen branch circuit is: A) 20 A B) 25 A C) 30 A D) 40 A Answer: C Explanation: The feeder must be sized to handle the branch-circuit load plus any additional demand; the standard practice is to use a 30-A feeder for a 20-A kitchen circuit. Question 73. The NEC requires that a metal conduit used as an equipment grounding conductor be: A) Continuous from source to equipment B) Installed with a separate grounding wire C) Only grounded at each outlet box D) Not used as a grounding path Answer: A
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Question 78. The minimum spacing between a receptacle and a permanent water pipe (e.g., a faucet) is: A) 6 in. B) 12 in. C) 18 in. D) No minimum, as long as the receptacle is GFCI protected Answer: B Explanation: NEC 210.52(C)(1) requires receptacles to be at least 12 in. above countertop surfaces, which includes the area above a faucet. Question 79. The NEC permits the use of “flexible metal conduit” (FMC) for which of the following? A) Direct burial B) Outdoor wet locations without protection C) Installation in cabinets and panels D) As a primary feeder in commercial buildings Answer: C Explanation: FMC is allowed for short runs in cabinets, panels, and equipment enclosures. Question 80. The required size of a grounding electrode conductor for a 250-A service using aluminum is: A) #4 AWG B) #2 AWG C) #1/0 AWG D) #2/0 AWG Answer: C Explanation: NEC Table 250.66 lists #1/0 AWG aluminum for a 250-A service. Question 81. Which of the following is the correct method for calculating the required ampacity of a feeder supplying a 1500-W electric range? A) Divide the wattage by 120 V B) Divide the wattage by 240 V C) Multiply the wattage by 1.25 D) Add 10 A to the calculated current Answer: B Explanation: A range typically operates on 240 V; current = 1500 W ÷ 240 V = 6.25 A; then apply the 125 % factor for a continuous load → 7.8 A, rounded up to a 15 - A breaker. Question 82. The NEC requires that a metal raceway serving a residential kitchen be secured within:
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A) 2 ft of the first outlet box B) 3 ft C) 6 ft D) 8 ft Answer: D Explanation: NEC 300.11 requires raceways to be supported and secured within 8 ft of each outlet box. Question 83. In a three-wire 120/240-V system, the neutral conductor is required to be bonded to ground at the: A) Service disconnect only B) First point of use only C) Both service and each subpanel D) Never, it must remain isolated Answer: A Explanation: NEC 250.24(A) requires the neutral and ground to be bonded at the service disconnect only. Question 84. The NEC defines a “locked-in-place” conduit as one that: A) Is bolted to a structural member B) Uses a compression fitting that cannot be removed without tools C) Is glued with PVC cement D) Is secured with a zip tie Answer: B Explanation: A locked-in-place fitting is a compression or set-screw type that cannot be removed without a tool. Question 85. The minimum size of a breaker required to protect a 12-AWG copper branch circuit supplying a 15-A receptacle is: A) 10 A B) 15 A C) 20 A D) 25 A Answer: B Explanation: The breaker must be rated equal to or higher than the circuit’s ampacity; 15 A is the appropriate size. Question 86. Which of the following is a required feature of a “listed” panelboard? A) Color-coded wires only B) Manufacturer’s warranty C) A label indicating the maximum number of over-current devices D) No labeling required if installed in a locked room
