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Question 1. Which of the following equations correctly represents Ohm’s Law? A) V = I × R B) I = V × R C) R = V ÷ I² D) P = V × I Answer: A Explanation: Ohm’s Law states that voltage (V) equals current (I) multiplied by resistance (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 series circuit, the total resistance is 30 Ω and the supply voltage is 90 V. What is the circuit current? A) 1 A B) 2 A C) 3 A D) 4 A Answer: C Explanation: I = V / R = 90 V / 30 Ω = 3 A. Question 4. Which statement about parallel circuits is correct? A) Voltage is the same across each branch. B) Current is the same through each branch.
C) Total resistance equals the sum of branch resistances. D) Power is independent of voltage. Answer: A Explanation: In parallel, each branch experiences the full source voltage. Question 5. A transformer has a primary voltage of 240 V and a turns ratio of 10:1. What is the secondary voltage? A) 24 V B) 48 V C) 240 V D) 2,400 V Answer: A Explanation: V₂ = V₁ × (N₂/N₁) = 240 V × (1/10) = 24 V. Question 6. Which unit is used to measure electrical energy consumption? A) Volt‑ampere (VA) B) Watt (W) C) Kilowatt‑hour (kWh) D) Ohm (Ω) Answer: C Explanation: Energy consumption is expressed in kilowatt‑hours. Question 7. In a three‑phase, four‑wire wye system, the line‑to‑neutral voltage is 120 V. What is the line‑to‑line voltage? A) 120 V B) 208 V C) 240 V D) 277 V Answer: B
Question 11. When tracing a circuit from the service entrance to a lighting fixture, which diagram is most useful? A) Riser diagram B) Floor plan C) Elevation view D) Detail drawing Answer: A Explanation: A riser diagram shows vertical circuit paths from the service to equipment. Question 12. According to NEC Table 310.15(B)(16), a 75 °C copper conductor with 3 current‑carrying conductors in a raceway has an ampacity of: A) 20 A B) 25 A C) 30 A D) 35 A Answer: C Explanation: For 75 °C, #12 AWG copper is rated 30 A; adjustment for more than 3 conductors is not required until >3. Question 13. Which insulation type is permitted for wet locations? A) THHN in conduit only B) NM‑B cable C) UF‑B cable D) Romex® Answer: C Explanation: UF‑B (underground feeder) is rated for direct burial and wet locations. Question 14. The maximum allowable voltage drop for branch‑circuit conductors feeding sensitive electronic equipment is: A) 1 %
B) 2 %
C) 3 %
D) 5 %
Answer: B Explanation: NEC recommends ≤ 2 % voltage drop for branch circuits serving sensitive loads. Question 15. A 20‑A circuit breaker protects a 12‑AWG copper branch circuit. What is the minimum size of the equipment grounding conductor (EGC) required? A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: A Explanation: Per NEC Table 250.122, a 20‑A circuit requires a minimum 14 AWG copper EGC. Question 16. Which of the following devices provides protection against both ground‑fault and arc‑fault conditions? A) GFCI B) AFCI C) Dual‑function AFCI/GFCI D) Standard circuit breaker Answer: C Explanation: Dual‑function devices combine AFCI and GFCI protection. Question 17. The service entrance conductors for a single‑family dwelling are sized to carry 200 A. Which conductor size is appropriate for copper, 75 °C? A) #4 AWG B) #2 AWG C) #0 AWG D) #3/0 AWG
Question 21. The conduit fill for a 3/4‑in. EMT with three #12 AWG THHN conductors is: A) 20 % B) 31 % C) 40 % D) 53 % Answer: B Explanation: The allowable fill for three conductors is 40 % of the conduit’s cross‑sectional area; three #12 THHN occupy about 31 % of a 3/4‑in. EMT. Question 22. Which cable type is permitted for use in a residential attic without a fire‑rated barrier? A) NM‑B B) AC cable C) MC cable with a metal sheath D) UF‑B Answer: A Explanation: NM‑B may be installed in attics if protected from physical damage; a fire‑rated barrier is not required. Question 23. The minimum depth for a buried UF‑B cable under a residential driveway is: A) 6 in. B) 12 in. C) 18 in. D) 24 in. Answer: B Explanation: NEC 300.5(D) requires a minimum of 12 in. cover for UF‑B beneath a driveway. Question 24. A device box must be sized to accommodate how many #14 AWG conductors for a standard duplex receptacle? A) 2
B) 3
C) 4
D) 5
Answer: C Explanation: A duplex receptacle requires two conductors for the hot and neutral, plus a grounding conductor; each conductor counts as one fill unit, totaling three, but code requires a minimum of four fill units for a device box, so a box sized for four #14 AWG conductors is used. Question 25. The maximum number of 90‑degree bends permitted in a single run of flexible metal conduit (FMC) without a pull box is: A) 4 B) 6 C) 8 D) 10 Answer: B Explanation: NEC 376.30 limits FMC to six 90‑degree bends between pull points. Question 26. Which flexible cord is rated for a maximum of 15 A in a residential setting? A) SJT B) SJTW C) SEOW D) TFFN Answer: A Explanation: SJT (Service Junior Thermoplastic) is rated 15 A for general use. Question 27. According to NEC 110.26, the minimum headroom for working space about a piece of equipment is: A) 6 ft B) 6 ft ½ in. C) 7 ft
Explanation: NEC Table 220.54 lists a 30‑A dryer as 5 kW (5,000 VA), but the demand factor for a single dryer is 100 %, so 5,000 VA; however, for the purpose of a typical residential load calculation, the dryer is counted as 5 kW, which equals 5,000 VA. (The answer reflects the standard 5 kW rating.) Question 31. Which conduit material is required to be listed for use in hazardous (Class I, Division 2) locations? A) PVC B) EMT C) Rigid steel conduit (RMC) with appropriate fittings D) Flexible non‑metallic conduit (FNC) Answer: C Explanation: RMC is a metal conduit suitable for hazardous locations when listed accordingly. Question 32. In a three‑phase, four‑wire wye system, a 120‑V, 20‑A receptacle is supplied from which conductors? A) Two line conductors only B) One line and neutral only C) One line, neutral, and ground D) Two lines and neutral Answer: B Explanation: 120‑V receptacles in a wye system are fed from a single line (phase) conductor and the neutral. Question 33. Which article of the NEC governs the installation of swimming pool equipment? A) Article 680 B) Article 690 C) Article 700 D) Article 710 Answer: A Explanation: Article 680 addresses swimming pools, fountains, and similar installations.
Question 34. A fire alarm system requires a dedicated power source with a minimum of: A) 12 V DC battery backup B) 120 V AC uninterruptible power supply (UPS) C) 24 V DC battery backup with 10 % of load capacity D) 120 V AC battery backup with 100 % of load capacity for 24 h Answer: D Explanation: NEC 760.41 requires fire alarm circuits to have a battery backup capable of 100 % of the load for at least 24 hours. Question 35. Which type of grounding electrode is NOT permitted as a primary grounding electrode? A) Ground rod B) Metal underground water pipe C) Concrete‑encased electrode (Ufer) D) Aluminum conduit in a raceway Answer: D Explanation: Aluminum conduit is not an approved grounding electrode under NEC. Question 36. When installing a motor disconnect, the disconnecting means must be located within how many feet of the motor? A) 25 ft B) 50 ft C) 75 ft D) No distance limitation, but must be readily accessible Answer: D Explanation: NEC 430.102 requires the disconnect to be readily accessible; no specific distance limit is set.
A) #10 AWG
B) #8 AWG
C) #6 AWG
D) #4 AWG
Answer: B Explanation: Table 250.122 specifies #8 AWG copper for a 100‑A service. Question 41. Which of the following devices must be installed in a commercial garage to protect against electric shock? A) GFCI receptacles for all 125‑V outlets B) AFCI breakers for lighting circuits only C) Surge protectors on all equipment D) Standard circuit breakers only Answer: A Explanation: NEC 210.8(A)(2) requires GFCI protection for all 125‑V, single‑phase receptacles in garages. Question 42. In a data communications room, the separation distance between a CAT‑6 cable and a power cable of 120 V is required to be at least: A) 1 in. B) 6 in. C) 12 in. D) 24 in. Answer: B Explanation: NEC 800.133 requires a minimum of 6 in. separation for low‑voltage data cables from power conductors. Question 43. Which NEC article governs the installation of emergency lighting systems? A) Article 700 B) Article 710 C) Article 720
D) Article 730 Answer: A Explanation: Article 700 addresses emergency systems, including lighting. Question 44. A 30‑amp, 240‑V dryer requires a neutral conductor. What is the minimum size of that neutral? A) #14 AWG B) #12 AWG C) #10 AWG D) #8 AWG Answer: B Explanation: The neutral must be sized the same as the ungrounded conductors for a 30‑A circuit, which is #12 AWG copper. Question 45. Which of the following statements about a “dedicated” circuit is correct? A) It can serve multiple appliances of the same type. B) It must supply only one specific load or equipment. C) It must be protected by a GFCI. D) It must be a 120‑V circuit only. Answer: B Explanation: A dedicated circuit supplies a single piece of equipment or load. Question 46. When installing a metal‑clad (MC) cable in a residential attic, the cable must be secured within how many inches of a non‑metallic box? A) 4 in. B) 6 in. C) 8 in. D) 12 in. Answer: B Explanation: NEC 334.30 requires MC cable to be secured within 6 in. of a box.
Question 50. Which of the following is the correct method for grounding a metal‑clad (MC) cable at a service panel? A) Connect the armor to the neutral bus B) Attach a grounding clamp to the metal armor and connect to the grounding bus C) No grounding is required for MC cable D) Use a separate grounding wire only if the armor is non‑conductive Answer: B Explanation: NEC 250.118 requires bonding the metal armor to the grounding bus with a listed grounding clamp. Question 51. The minimum size of a grounding electrode conductor for a 400‑A service using aluminum is: A) #4 AWG B) #2 AWG C) #1/0 AWG D) #4/0 AWG Answer: C Explanation: Table 250.122 lists #1/0 AWG aluminum for a 400‑A service. Question 52. Which of the following devices must be installed on all 125‑V, single‑phase receptacles in a bathroom? A) AFCI breaker B) GFCI protection C) Surge protector D) Arc‑fault detector Answer: B Explanation: NEC 210.8(A)(1) requires GFCI protection for bathroom receptacles. Question 53. A 120‑V, 15‑A receptacle is installed in a hallway. According to NEC, the receptacle spacing must not exceed:
A) 8 ft B) 10 ft C) 12 ft D) 14 ft Answer: C Explanation: NEC 210.52(B) requires receptacles in hallways to be spaced no more than 12 ft apart. Question 54. Which of the following is a permissible use for a 12‑AWG NM‑B cable? A) Direct burial underground B) In a wet location above ground C) Within a finished wall in a residential dwelling D) As a feeder to a motor in a commercial building Answer: C Explanation: NM‑B is permitted for interior, dry, finished-wall installations in residences. Question 55. The NEC requires a minimum of how many disconnecting means for a single‑phase, 3 ‑wire service? A) One B) Two C) Three D) Four Answer: A Explanation: One disconnecting means is required for a single‑phase service (NEC 230.71). Question 56. Which of the following is the correct formula for calculating three‑phase apparent power (VA) in a balanced wye system? A) √3 × V_LL × I_L B) V_LL × I_L C) √3 × V_LN × I_L
Question 60. Which of the following is the correct method to size the equipment grounding conductor (EGC) for a 60‑A branch circuit using copper conductors? A) #10 AWG B) #12 AWG C) #14 AWG D) #8 AWG Answer: B Explanation: Table 250.122 specifies #12 AWG copper for a 60‑A circuit. Question 61. A motor rated 5 hp, 230 V, 3‑phase requires a full‑load current of 12 A. What is the minimum size of the branch‑circuit conductor (copper) for continuous operation? A) #12 AWG B) #10 AWG C) #8 AWG D) #6 AWG Answer: B Explanation: For continuous loads, conductors must be sized at 125 % of the load: 12 A × 1.25 = 15 A. #10 AWG copper is rated 30 A, which satisfies the requirement. Question 62. Which type of grounding electrode is required for a metal‑clad (MC) cable that is installed in a metal conduit? A) No additional electrode is needed B) A separate grounding electrode conductor to the grounding electrode system C) Only the conduit armor provides grounding D) A grounding rod at each outlet box Answer: B Explanation: The metal conduit provides equipment grounding, but the MC cable’s armor must be bonded to the grounding electrode system via a grounding jumper. Question 63. In a commercial office building, the lighting load is calculated using 3 VA per square foot. For a 10,000 ft² floor, what is the total lighting VA?
A) 20,000 VA
B) 30,000 VA
C) 40,000 VA
D) 50,000 VA
Answer: B Explanation: 10,000 ft² × 3 VA/ft² = 30,000 VA. Question 64. Which of the following is NOT a permitted method for protecting a conduit that passes through a fire‑rated wall assembly? A) Using fire‑stop mortar B) Installing a listed fire‑rated conduit assembly C) Leaving the conduit unprotected if it is metal D) Using a fire‑rated sleeve with intumescent material Answer: C Explanation: Metal conduit must still be fire‑stopped when passing through fire‑rated assemblies. Question 65. A 120‑V, 20‑A receptacle is installed in a garage. Which of the following is required by NEC? A) AFCI protection only B) GFCI protection only C) Both AFCI and GFCI protection D) No special protection required Answer: B Explanation: NEC 210.8(A)(2) mandates GFCI protection for garage receptacles. Question 66. When using a conduit body (C‑type), the maximum number of conductors that may be installed without exceeding 40 % fill is: A) 2 B) 4 C) 6
