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Question 1. What is the formula for calculating electrical power in a circuit? A) P = I/R B) P = V × I C) P = V/R D) P = I2 × R Answer: B Explanation: Electrical power (P) is calculated by multiplying voltage (V) by current (I). Question 2. According to Ohm’s Law, what is the current flowing through a 12-ohm resistor connected to a 24V supply? A) 0.5 A B) 2 A C) 12 A D) 36 A Answer: B Explanation: Ohm's Law states I = V/R, so 24V/12Ω = 2A. Question 3. Which of the following is a characteristic of a parallel circuit? A) Current is the same through all components B) Voltage is divided among components C) Voltage is the same across all branches D) Total resistance is the sum of all resistances Answer: C Explanation: In parallel circuits, each branch receives the full supply voltage. Question 4. What type of current do most residential wiring systems use? A) Direct Current (DC) B) Alternating Current (AC) C) Pulsed DC
D) Static Electricity Answer: B Explanation: Residential systems use alternating current (AC) because it is efficiently transmitted and transformed. Question 5. The primary purpose of grounding in residential wiring is to: A) Save energy B) Provide a path for fault current C) Increase voltage D) Reduce current Answer: B Explanation: Grounding ensures a safe path for fault currents to prevent shock hazards. Question 6. Which NEC Article covers Branch Circuits? A) Article 210 B) Article 230 C) Article 250 D) Article 406 Answer: A Explanation: Article 210 of the NEC deals specifically with branch circuits. Question 7. In residential wiring, which cable is commonly referred to as “Romex”? A) NM cable B) EMT C) BX cable D) THHN Answer: A Explanation: Nonmetallic-sheathed cable (NM) is commonly known as Romex.
C) White D) Red Answer: C Explanation: White insulation is standard for neutral conductors. Question 12. According to NEC, what is the minimum burial depth for a direct-buried NM cable? A) 6 inches B) 12 inches C) 18 inches D) 24 inches Answer: C Explanation: Direct-buried NM cable must be at least 18 inches deep per NEC. Question 13. How is the ampacity of a conductor affected as ambient temperature increases? A) Ampacity increases B) Ampacity decreases C) Ampacity is unaffected D) Ampacity doubles Answer: B Explanation: As ambient temperature rises, conductor ampacity decreases. Question 14. What is the maximum allowable voltage drop recommended for branch circuits? A) 1% B) 3% C) 5% D) 10% Answer: B Explanation: The NEC recommends a maximum 3% voltage drop for branch circuits.
Question 15. Which of the following PPE is required when working on energized electrical panels? A) Safety goggles only B) Hard hat only C) Insulated gloves and eye protection D) Steel-toe boots only Answer: C Explanation: Insulated gloves and eye protection are essential PPE for energized electrical work. Question 16. What does GFCI stand for? A) Ground Fault Current Interrupter B) General Fault Circuit Interrupter C) Ground Fault Circuit Interrupter D) General Field Circuit Indicator Answer: C Explanation: GFCI stands for Ground Fault Circuit Interrupter, which protects against shock. Question 17. A 15A circuit breaker is used with which minimum wire size for copper conductors? A) 18 AWG B) 16 AWG C) 14 AWG D) 12 AWG Answer: C Explanation: 14 AWG copper wire is the minimum size for a 15A breaker. Question 18. The NEC requires all 120V, single-phase, 15- and 20-amp outlets in bathrooms to be: A) Weather-resistant B) GFCI-protected C) AFCI-protected D) On a dedicated circuit
B) Ground rod C) Aluminum conductor in contact with earth D) Concrete-encased electrode Answer: C Explanation: Aluminum cannot be used as a grounding electrode in contact with earth due to corrosion. Question 23. When sizing a box for conductors, each ground wire counts as: A) 0 B) 1 C) 2 D) 0. Answer: B Explanation: All ground wires together count as a single conductor when calculating box fill. Question 24. Which conductor color is typically used for equipment grounding? A) Green or bare B) Blue C) Orange D) White Answer: A Explanation: Green or bare wires are standard for equipment grounding. Question 25. Nonmetallic-sheathed cable (NM) is generally NOT permitted in: A) Wood frame residential buildings B) Commercial buildings with metal studs C) Exposed outdoor locations D) Concealed wall spaces Answer: C Explanation: NM cable is not suitable for exposed outdoor use.
Question 26. A 20 amp circuit supplying a kitchen receptacle should use what minimum wire size (copper)? A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: B Explanation: 12 AWG copper is required for 20 amp circuits. Question 27. The main bonding jumper is installed between the: A) Neutral bar and ground bar in the main panel B) Hot and neutral bus bars C) Ground rod and water pipe D) Panel enclosure and black wire Answer: A Explanation: The main bonding jumper connects the neutral and ground bars in the main service panel. Question 28. Which of the following is considered a continuous load? A) A load operated for 1 hour B) A load operated for 2 hours C) A load operated for 3 hours or more D) A load operated for 30 minutes Answer: C Explanation: A continuous load is one that operates for 3 hours or more. Question 29. What is the minimum size of a grounding electrode conductor for a 100-amp residential service using copper? A) 10 AWG
Question 33. Service entrance conductors must be: A) Buried at least 24 inches deep B) Sized for the calculated load and protected from physical damage C) Spliced inside walls D) Always installed in metallic conduit Answer: B Explanation: Service entrance conductors should be sized for load and protected from damage. Question 34. Which of the following is a requirement for a receptacle installed outdoors? A) Must be GFCI protected B) Must be 30 inches above grade C) Must be switched D) Cannot be used for holiday lighting Answer: A Explanation: Outdoor receptacles must have GFCI protection. Question 35. What is the NEC minimum height for a service mast above a residential roof? A) 12 inches B) 24 inches C) 30 inches D) 36 inches Answer: B Explanation: Minimum clearance above roof is typically 24 inches unless within 6 feet of the edge. Question 36. Which NEC article covers receptacles, cord connectors, and attachment plugs? A) Article 210 B) Article 240 C) Article 406
D) Article 410 Answer: C Explanation: Article 406 covers receptacles, cord connectors, and plugs. Question 37. When using EMT (Electrical Metallic Tubing), the proper method for connecting two pieces is: A) Electrical tape B) Threaded couplings C) Compression or set-screw connectors D) Welding Answer: C Explanation: EMT is joined using compression or set-screw connectors. Question 38. What is the maximum number of 12 AWG conductors permitted in a 4” x 2-1/8” device box? A) 4 B) 6 C) 9 D) 11 Answer: B Explanation: A standard 4” x 2-1/8” device box can accommodate up to 6 12 AWG conductors. Question 39. What is the minimum clearance height for overhead service conductors above a residential driveway? A) 8 feet B) 10 feet C) 12 feet D) 18 feet Answer: D Explanation: Overhead service drops must be at least 18 feet above driveways.
D) Gray Answer: C Explanation: Black or red are used for hot conductors. Question 44. Which of the following is a requirement for installing NM cable in an attic? A) Must be stapled every 10 feet B) Must be protected from physical damage within 6 feet of the attic access C) Must be painted D) Must be run in conduit Answer: B Explanation: NM cable must be protected near attic access where it is subject to damage. Question 45. Which of the following must be installed in a bathroom containing a shower or tub? A) Dedicated 30A circuit B) GFCI-protected receptacle C) Outdoor-rated receptacle D) Metal conduit Answer: B Explanation: GFCI protection is required for receptacles in bathrooms. Question 46. What is the purpose of a lockout/tagout procedure? A) To increase voltage B) To prevent accidental energization during maintenance C) To ground the wiring system D) To adjust breaker size Answer: B Explanation: Lockout/tagout ensures equipment remains de-energized during work. Question 47. For a 240V dryer circuit, how many conductors are required?
A) 2
B) 3
C) 4
D) 5
Answer: C Explanation: Modern 240V dryers require four conductors: two hots, a neutral, and a ground. Question 48. What is the standard voltage for general purpose residential receptacles in the U.S.? A) 120V B) 208V C) 240V D) 277V Answer: A Explanation: General purpose receptacles are 120V. Question 49. Which of the following is true for a multi-wire branch circuit? A) Uses a single neutral for two or more ungrounded conductors B) Each conductor must have its own neutral C) Does not require a ground D) Only used in commercial installations Answer: A Explanation: Multi-wire branch circuits share a neutral between two hots. Question 50. Which device is used to join NM cables in a wall? A) EMT coupling B) Junction box C) Split bolt D) Surface raceway Answer: B
Question 54. What is the maximum number of 20A duplex receptacles allowed on a single 20A branch circuit in a dwelling? A) 6 B) 10 C) 13 D) Unlimited (per NEC, based on load calculation) Answer: D Explanation: The NEC does not set a strict number; it's based on load calculations. Question 55. Which conductor is identified by a white or gray color in residential wiring? A) Hot B) Neutral C) Ground D) Switched hot Answer: B Explanation: White or gray indicates the neutral conductor. Question 56. What is the function of a bonding jumper? A) Carry normal current B) Connect non-current-carrying metal parts to the grounding system C) Increase voltage D) Isolate equipment Answer: B Explanation: Bonding jumpers ensure metal parts are connected to the grounding system. Question 57. Which NEC article covers conductors for general wiring? A) Article 210 B) Article 250 C) Article 310
D) Article 334 Answer: C Explanation: Article 310 covers conductors for general wiring. Question 58. What is the minimum size of a service disconnect for a single-family dwelling? A) 30A B) 50A C) 60A D) 100A Answer: D Explanation: The minimum size for a service disconnect is 100A. Question 59. A 120V circuit draws 10A. How much power does it consume? A) 120W B) 1,200W C) 12W D) 10W Answer: B Explanation: Power = Voltage × Current = 120V × 10A = 1,200W. Question 60. Which of the following is true about GFCIs? A) They protect against fire only B) They trip when a ground fault is detected C) They replace circuit breakers D) They are only used outdoors Answer: B Explanation: GFCIs trip when a ground fault is detected.
C) 60A
D) 100A
Answer: D Explanation: Main disconnects must be rated at least 100A. Question 65. What is the maximum number of 12 AWG wires permitted in a 4" x 1-1/2" square box? A) 4 B) 6 C) 8 D) 10 Answer: A Explanation: This box size allows for 4 12 AWG wires. Question 66. Which code article covers luminaires, lampholders, and lamps? A) Article 406 B) Article 410 C) Article 422 D) Article 334 Answer: B Explanation: Article 410 covers luminaires, lampholders, and lamps. Question 67. In a residential panel, where should the neutral and ground bars be bonded together? A) Only in the main service panel B) In every subpanel C) In every junction box D) Never Answer: A Explanation: Neutral and ground are bonded only in the main service panel.
Question 68. Where must a receptacle be installed in a hallway that is more than 10 feet long? A) Every 2 feet B) At each end C) At least one receptacle per hallway over 10 feet D) Not required Answer: C Explanation: NEC requires one receptacle in hallways longer than 10 feet. Question 69. Which of the following is the correct method to splice two NM cables in a wall cavity? A) Electrical tape only B) Wire nuts inside a junction box C) Twisted together without a box D) Soldered together inside the wall Answer: B Explanation: All splices must be made inside a junction box. Question 70. What is the minimum box fill volume for one 12 AWG conductor? A) 1.5 cubic inches B) 2.25 cubic inches C) 2.5 cubic inches D) 3 cubic inches Answer: B Explanation: Each 12 AWG conductor requires 2.25 cubic inches of box volume. Question 71. Which of the following is not a permitted method for grounding a receptacle box? A) Ground screw and wire B) Bonding jumper C) Metallic conduit D) Electrical tape
