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Question 1. **Which fundamental relationship defines electric power in a circuit? ** A) P = V ÷ I B) P = I × V C) P = V – I D) P = V + I Answer: B Explanation: Power (P) equals the product of voltage (V) and current (I); P = V × I. Question 2. According to Ohm’s Law, if a resistor has 12 V across it and 3 A flows through it, what is its resistance? A) 4 Ω B) 9 Ω C) 36 Ω D) 0.25 Ω Answer: A Explanation: R = V/I = 12 V ÷ 3 A = 4 Ω. Question 3. Kirchhoff’s Voltage Law (KVL) states that the algebraic sum of voltages around any closed loop is: A) Zero B) Equal to the source voltage C) Equal to the sum of resistances D) Equal to the product of currents Answer: A Explanation: KVL requires the sum of voltage rises and drops in a loop to equal zero. Question 4. In a series circuit with three resistors of 2 Ω, 4 Ω, and 6 Ω, the total resistance is: A) 4 Ω B) 6 Ω C) 12 Ω
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D) 24 Ω
Answer: C Explanation: Series resistances add directly: 2 + 4 + 6 = 12 Ω. Question 5. When two identical resistors are connected in parallel, the equivalent resistance is: A) Half of one resistor B) Equal to one resistor C) Double one resistor D) Zero Answer: A Explanation: For equal resistors R, 1/Req = 1/R + 1/R = 2/R → Req = R/2. Question 6. A residential general-lighting load is calculated using which demand factor for the first 3 kW? A) 100 % B) 80 % C) 70 % D) 50 % Answer: A Explanation: NEC requires the first 3 kW of general-lighting load to be taken at 100 % before applying any demand factor. Question 7. For a dwelling unit, the calculated general-lighting load is 6 kW. What is the demand-factor-adjusted load? A) 5.4 kW B) 4.8 kW C) 6 kW D) 3.6 kW Answer: A Explanation: First 3 kW at 100 % = 3 kW; remaining 3 kW at 80 % = 2.4 kW; total = 5.4 kW.
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C) Metal water pipe D) Aluminum siding Answer: D Explanation: Aluminum siding is not an acceptable grounding electrode; rods, Ufer, and metal water pipes are. Question 12. The purpose of a main bonding jumper (MBJ) is to: A) Connect the neutral to the service-grounding conductor B) Increase the ampacity of the service conductors C) Provide a spare conductor for future circuits D) Isolate the service neutral from the equipment ground Answer: A Explanation: The MBJ bonds the grounded (neutral) conductor to the equipment grounding conductor at the service. Question 13. In a feeder calculation for a commercial building, demand factors are applied to: A) Only lighting loads B) Only motor loads C) All connected loads after a minimum demand is satisfied D) None; all loads are taken at 100 % Answer: C Explanation: NEC permits demand-factor reductions after a base demand is met for the total calculated load. Question 14. A 30 kVA transformer is feeding a building with a 120/240-V secondary. The maximum secondary current is: A) 125 A B) 250 A C) 500 A D) 75 A Answer: A Explanation: I = kVA ÷ V = 30 kVA ÷ 240 V = 125 A.
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Question 15. Which overcurrent protective device size is required for a 15 - ampere branch circuit protected by a standard breaker? A) 15 A B) 20 A C) 25 A D) 30 A Answer: A Explanation: The breaker must not exceed the circuit’s ampacity; a 15 A breaker protects a 15 A circuit. Question 16. When derating conductors for more than three current-carrying conductors in a raceway, the NEC requires a correction factor of at least: A) 100 % B) 80 % C) 70 % D) 60 % Answer: C Explanation: Table 310.15(C)(1) provides a 70 % factor when 4-6 conductors share a raceway. Question 17. The maximum fill for a conduit with three or more conductors of the same size is: A) 40 % B) 31 % C) 53 % D) 60 % Answer: B Explanation: NEC Table 1, Chapter 9 limits conduit fill to 31 % for three or more conductors. Question 18. Which type of cable is permitted for concealed residential wiring in walls and ceilings? A) Type AC (Armored Cable)
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Explanation: Living rooms are not considered damp or wet locations; GFCI is not required there. Question 22. A Class A AFCI is required in which residential area? A) Bedroom outlet B) Hallway lighting circuit C) Kitchen countertop receptacles D) All of the above Answer: D Explanation: NEC 210.12(A) requires AFCI protection for all 120-V, single-phase, 15 - and 20-A circuits supplying outlets in dwelling units, which includes bedrooms, hallways, and kitchens. Question 23. The required clearance between a receptacle and a bathtub edge is: A) 6 in B) 12 in C) 18 in D) 24 in Answer: B Explanation: NEC 210.8(A)(3) mandates a minimum 12-in horizontal distance from the edge of a bathtub or shower stall. Question 24. When installing a luminare in a damp location, the fixture must be rated at least: A) IP 20 B) IP 44 C) IP 65 D) IP 67 Answer: B Explanation: Damp locations require at least a “wet location” rating, commonly IP 44 or higher.
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Question 25. A water-heater rated at 4500 W, 240 V requires a dedicated circuit breaker of what minimum rating? A) 15 A B) 20 A C) 25 A D) 30 A Answer: B Explanation: Current = 4500 W ÷ 240 V = 18.75 A. The next standard breaker size is 20 A. Question 26. Which NEC article governs the installation of electric vehicle (EV) charging equipment? A) 210 B) 625 C) 690 D) 800 Answer: B Explanation: Article 625 specifically addresses EV charging systems and their requirements. Question 27. A 240-V, 30-A dryer circuit must use a minimum conductor size of: A) 12 AWG B) 10 AWG C) 8 AWG D) 6 AWG Answer: B Explanation: Per Table 310.15(B)(16), 30 A requires at least 10 AWG copper for 60 °C rating. Question 28. In a motor control circuit, the “within sight” rule applies to: A) All disconnecting means B) Only motor starters
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Explanation: A thermal overload relay uses a bimetallic strip that bends when heated by excess current, opening the circuit. Question 32. In hazardous location Class I, Division 2, which type of conduit is required? A) Rigid metal conduit (RMC) only B) Non-metallic conduit with flame-retardant coating C) Any conduit listed for hazardous locations D) PVC conduit is prohibited Answer: C Explanation: NEC 500 permits any conduit that is listed for use in Class I, Division 2 areas, including RMC, EMT, and PVC that is listed. Question 33. A health-care facility’s essential electrical system must be supplied by: A) A single-source transformer only B) Two independent sources with automatic transfer switches C) A generator without any transfer equipment D) Battery backup only Answer: B Explanation: NEC 517 requires essential systems to have two independent sources and automatic transfer capabilities. Question 34. Which of the following is NOT a requirement for a swimming-pool lighting fixture? A) Listed for wet locations B) A minimum of 15 ft separation from pool water surface C) Operates at 120 V ± 15 % D) Equipped with a GFCI protection device Answer: B Explanation: There is no NEC requirement for a 15-ft separation; the primary requirements are wet-location rating and GFCI protection.
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Question 35. An emergency exit sign must be illuminated for a minimum of how many minutes after loss of normal power? A) 30 minutes B) 60 minutes C) 90 minutes D) 120 minutes Answer: B Explanation: NEC 700.12 requires emergency illumination to operate for at least 90 minutes, but the sign itself must stay lit for 60 minutes per 700.12(A)(2). (The more stringent requirement is 90 minutes for general emergency lighting; exit signs are 60 minutes.) Question 36. When installing low-voltage Class 2 circuits, the conductors must be separated from power conductors by at least: A) 6 in of air space B) 12 in of air space C) 18 in of air space D) No separation required if in the same raceway Answer: B Explanation: NEC 300.3(C)(1) requires a minimum of 12 in separation between low-voltage and power conductors unless they are in separate raceways or the low-voltage conductors are listed for mixed use. Question 37. The grounding of a coaxial cable used for a TV antenna must be performed at: A) The antenna mast only B) The service panel only C) Both the antenna and the point of entry into the building D) Grounding is not required for coaxial cables Answer: C Explanation: NEC 820.21 requires grounding at both the antenna and the building entry point to prevent voltage surges. Question 38. Which OSHA standard addresses lockout/tagout (LOTO) procedures?
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Answer: C Explanation: A #6 AWG THHN conductor has an area of 0.0305 in². Four conductors: 4 × 0.0305 = 0.122 in². Question 42. NEC requires that a raceway’s fill not exceed 40 % when it contains: A) One conductor B) Two conductors C) Three conductors D) Four or more conductors Answer: B Explanation: Table 1, Chapter 9 states a 40 % fill limit for raceways with one or two conductors. Question 43. A 100-amp service entrance requires a main bonding jumper of at least: A) #6 AWG copper B) #8 AWG copper C) #10 AWG copper D) #12 AWG copper Answer: A Explanation: Table 250.66 requires a minimum of #6 AWG copper for a 100-A service. Question 44. Which type of grounding electrode is permitted to be installed in a concrete slab that is at least 2 ft thick? A) Ground rod only B) Concrete-encased electrode (Ufer) C) Metal water pipe only D) Ground plate only Answer: B Explanation: A concrete-encased electrode (Ufer) is allowed when the concrete is at least 2 ft thick, per NEC 250.52(A)(3).
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Question 45. The NEC defines a “wet location” as: A) Any location exposed to weather B) Only outdoor areas C) Any location with a relative humidity over 90 % D) Only locations below grade Answer: A Explanation: A wet location is any area subject to moisture, including outdoors, bathrooms, and other areas where water may be present. Question 46. For a 3-phase, 480 V motor with a full-load current of 35 A, the minimum size of the overload protection device is: A) 30 A B) 35 A C) 40 A D) 45 A Answer: C Explanation: Overload devices must be set between 115 % and 125 % of FLC. 115 % of 35 A = 40.25 A → the next standard size is 40 A. Question 47. A transformer’s primary overcurrent protection must be sized to protect the transformer against: A) Only short-circuit currents B) Only overload currents C) Both short-circuit and overload currents D) Only ground-fault currents Answer: C Explanation: NEC 450.3 requires the primary protection to safeguard against both overload and short-circuit conditions. Question 48. In a Class II hazardous location, equipment must be: A) Explosion-proof B) Intrinsically safe C) Both A and B are acceptable methods
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Question 52. A 30-A, 240-V dryer circuit may be protected by a 30-A two-pole breaker. Which type of conduit is permissible for this installation in a residential attic? A) Rigid steel conduit (RSC) only B) Non-metallic raceway (PVC) only C) Either EMT or PVC, provided it is listed for the application D) Flexible metal conduit only Answer: C Explanation: Both EMT and PVC are acceptable for dryer circuits in attics if they meet the NEC listing requirements. Question 53. Which NEC article addresses the requirements for grounding and bonding of photovoltaic (PV) systems? A) 690 B) 705 C) 710 D) 720 Answer: A Explanation: Article 690 covers the installation, grounding, and bonding of solar photovoltaic systems. Question 54. A 3-phase, 208 V motor has a name-plate FLC of 12 A. The conductor size selected must be based on: A) Name-plate current only B) NEC Table 310.15(B)(16) with a 125 % multiplier C) NEC Table 430.250 (FLC) and the appropriate ampacity table D) The voltage rating alone Answer: C Explanation: Motor conductors are sized using Table 430.250 (FLC) and the applicable ampacity tables, not the name-plate current directly. Question 55. When a grounding electrode conductor (GEC) is installed in a raceway that also contains other conductors, the GEC must be:
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A) Labeled with green insulation B) Larger than the largest current-carrying conductor C) Identified by green with a yellow stripe or bare copper D) Installed in a separate conduit only Answer: C Explanation: NEC 250.118 requires the GEC to be either bare copper, green, or green with a yellow stripe. Question 56. Which of the following is a required feature of a fire-rated (UL-94) cable used in a commercial building? A) Halogen-free jacket B) Low smoke emission rating C) Self-extinguishing property when exposed to flame D) All of the above Answer: C Explanation: UL-94 fire-rated cables must self-extinguish after the flame source is removed. Question 57. A 20-amp branch circuit feeding a kitchen must have a minimum of how many receptacle outlets? A) Two B) Three C) Four D) No minimum; depends on layout Answer: C Explanation: NEC 210.52(C)(1) requires at least two receptacles for each countertop space, resulting in a minimum of four receptacles on a 20-A circuit. Question 58. What is the minimum size of an equipment grounding conductor (EGC) for a 60-A circuit using 10 AWG copper conductors? A) #10 AWG B) #12 AWG C) #8 AWG
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Explanation: NEC 210.12(A) mandates AFCI protection for all such circuits in dwellings. Question 62. A feeder supplying a 30-kW office load at 208 V (3-phase) will have a calculated current of: A) 42 A B) 52 A C) 70 A D) 84 A Answer: B Explanation: I = P ÷ (√3 × V) = 30 kW ÷ (1.732 × 208 V) ≈ 83.6 A. Wait, mis-calc. Actually 30 kW ÷ (1.732 × 208) = 30,000 ÷ 360.256 ≈ 83.3 A. None of the choices match; correct answer should be 84 A (rounded). Therefore choose D. Answer: D Explanation: Using three-phase power formula, I ≈ 84 A, which matches choice D. Question 63. A 12-AWG copper conductor is used for a 20-A branch circuit. If the ambient temperature is 40 °C, the ampacity must be derated to: A) 100 % (no derating) B) 90 % C) 80 % D) 70 % Answer: B Explanation: Table 310.15(B)(2)(a) provides a 90 % factor for 30 °C- 40 °C ambient temperature. Question 64. Which type of conduit is required for a direct-buried underground feeder? A) EMT B) PVC Schedule 40 C) Flexible metal conduit (FMC) D) Rigid metal conduit (RMC) only Answer: B
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Explanation: PVC Schedule 40 (or Schedule 80) is permitted for underground direct-buried installations per NEC 352.10. Question 65. In a commercial building, the maximum number of receptacles allowed on a single 120-V, 20-A branch circuit is: A) 8 B) 10 C) 12 D) No explicit limit; dictated by load calculation Answer: D Explanation: NEC 210.23 permits more than 10 receptacles on a 20-A branch circuit provided the calculated load does not exceed 80 % of the circuit rating. Question 66. A fire alarm system must be powered by a dedicated circuit that is: A) Protected by a GFCI breaker only B) Supplied from the emergency power system with an automatic transfer switch C) Connected to any general-purpose circuit D) Powered by a battery only, no utility power required Answer: B Explanation: NEC 760 requires fire alarm circuits to be supplied by an emergency power source with an automatic transfer switch. Question 67. When installing a receptacle in a wet location (e.g., outdoors), the enclosure must be rated at least: A) IP 20 B) IP 44 C) IP 65 D) IP 67 Answer: C Explanation: Outdoor wet locations require at least a weather-resistant (WR) enclosure, commonly rated IP 65.
