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Question 1. What does the symbol “V” represent in electrical terminology? A) Voltage B) Current C) Resistance D) Power Answer: A Explanation: “V” is the standard abbreviation for voltage, the electrical potential difference between two points. Question 2. According to Ohm’s Law, if a circuit has 12 V applied across a resistor of 4 Ω, what is the current? A) 1 A B) 2 A C) 3 A D) 4 A Answer: B Explanation: I = V / R = 12 V / 4 Ω = 3 A (Oops correction: actually 12/4 = 3 A). The correct answer is C. Answer: C Explanation: Using Ohm’s Law, I = V ÷ R = 12 V ÷ 4 Ω = 3 A. Question 3. Which power formula is appropriate for a purely resistive DC circuit? A) P = V × I B) P = I² × R C) Both A and B D) None of the above
Answer: C Explanation: In a resistive DC circuit, P can be expressed as V × I or I² × R (since V = I R). Question 4. In a series circuit containing three resistors of 2 Ω, 3 Ω, and 5 Ω, the total resistance is: A) 5 Ω B) 7 Ω C) 10 Ω D) 20 Ω Answer: C Explanation: Series resistance adds directly: 2 + 3 + 5 = 10 Ω. Question 5. Two 10 Ω resistors are connected in parallel. What is the equivalent resistance? A) 5 Ω B) 10 Ω C) 20 Ω D) 0 Ω Answer: A Explanation: For parallel resistors, 1/Req = 1/10 + 1/10 = 2/10 → Req = 5 Ω. Question 6. RMS (root‑mean‑square) voltage for a sinusoidal AC source of 120 V peak is: A) 84.9 V B) 120 V C) 169.7 V D) 60 V Answer: A
Explanation: A digital multimeter set to AC voltage measures the magnitude of the alternating voltage. Question 10. A 12‑AWG copper conductor has an ampacity of 20 A at 60 °C. If the ambient temperature is 40 °C, what correction factor should be applied according to NEC Table 310.15(B)(1)? A) 0. B) 0. C) 1. D) 1. Answer: B Explanation: For 40 °C ambient, the correction factor for 60 °C insulation is 0.90; multiply the base ampacity by this factor. Question 11. The minimum burial depth for a non‑metallic raceway (PVC) in residential yards is: A) 6 in. B) 12 in. C) 18 in. D) 24 in. Answer: B Explanation: NEC 300.5 requires a minimum of 12 in. burial for PVC conduit in residential areas unless protected by concrete. Question 12. Which of the following is a permitted use for NM‑B (Romex) cable? A) In wet locations B) Inside metal conduit C) Exposed in a finished ceiling D) Through a fire‑rated wall cavity
Answer: D Explanation: NM‑B can be run through fire‑rated wall cavities as long as it is not exposed to moisture. Question 13. The grounding electrode conductor (GEC) for a 200‑A service with a copper conductor of 4 AWG must be at least what size? A) 8 AWG B) 6 AWG C) 4 AWG D) 2 AWG Answer: B Explanation: NEC 250.66 specifies a minimum of 6 AWG copper for a 200‑A service. Question 14. Which device provides protection against both over‑current and short‑circuit conditions? A) Fuse B) GFCI C) AFCI D) Surge protector Answer: A Explanation: A fuse interrupts the circuit when current exceeds its rating, protecting against both overloads and short circuits. Question 15. A 15‑A circuit breaker must protect a branch circuit that supplies only receptacles. What is the minimum conductor size required? A) 14 AWG copper B) 12 AWG copper
A) 10 A
B) 15 A
C) 20 A
D) 30 A
Answer: B Explanation: NEC 430.22 requires OCPD to be 250 % of the motor’s full‑load current for inverse‑time circuit breakers: 7 A × 2.5 = 17.5 A → next standard size is 20 A. However for non‑inverse‑time, 125 % is used: 7 A × 1.25 = 8.75 A → next standard size 10 A. Since the question does not specify type, the conservative answer is 15 A. (Correct answer: B). Answer: B Explanation: Using the 125 % rule for non‑inverse‑time breakers, 7 A × 1.25 = 8.75 A; the next standard breaker size is 15 A. Question 19. The National Electrical Code requires a GFCI to protect all receptacles in which of the following locations? A) Garages B) Living rooms C) Bedrooms D) Hallways Answer: A Explanation: NEC 210.8(A) mandates GFCI protection for receptacles in garages, among other wet or damp locations. Question 20. An AFCI is required for which type of circuit in a dwelling unit? A) Kitchen countertop receptacles B) Bedroom lighting circuits C) Bathroom vanity outlets
D) Outdoor receptacles Answer: B Explanation: NEC 210.12(A) requires AFCI protection for all 120‑V, single‑phase, 15‑ and 20‑A branch circuits supplying bedroom outlets and lighting. Question 21. The maximum allowable voltage drop for a feeder supplying a continuous load 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 22. When calculating box fill, each internal clamp counts as: A) 1 conductor volume B) 2 conductor volumes C) 0.5 conductor volume D) No volume Answer: A Explanation: NEC 314.16(B) treats each internal clamp as equivalent to one conductor for fill calculations. Question 23. The minimum conduit fill for more than two conductors in a raceway is: A) 40 % B) 31 %
Explanation: According to NEC Table 250.66, a 100‑A service requires a minimum of 8 AWG copper grounding electrode conductor. Question 26. A 30‑A, 2‑pole circuit breaker is installed to protect a 240‑V feeder. What is the maximum allowable ampacity for the feeder conductors? A) 30 A B) 35 A C) 40 A D) 45 A Answer: A Explanation: Conductors must be rated at least equal to the overcurrent device; thus, 30 A is the maximum permissible ampacity. Question 27. The NEC definition of “grounded conductor” refers to: A) The neutral conductor B) The equipment grounding conductor C) The protective earth conductor D) Any conductor connected to ground Answer: A Explanation: “Grounded conductor” is the term used for the neutral wire that is intentionally bonded to earth at the service disconnect. Question 28. Which of the following is NOT a permitted method for grounding a metal conduit system? A) Bonding every conduit joint with a bonding jumper B) Using a continuous metal raceway that is electrically continuous C) Installing a separate grounding electrode conductor in the conduit
D) Relying on the conduit’s connection to the service equipment only Answer: D Explanation: The conduit must be bonded at each joint or have a grounding conductor; relying solely on a single connection is not sufficient. Question 29. The minimum size of a receptacle outlet box for a single 15‑A duplex receptacle is: A) 2 in. × 2 in. × 2 in. B) 2 in. × 3 in. × 2 in. C) 2 in. × 2 in. × 3 in. D) 3 in. × 3 in. × 3 in. Answer: C Explanation: NEC 314.16 requires a minimum volume of 18 cu in.; a 2 × 2 × 3 in. box provides 12 cu in., which is insufficient. Actually the correct minimum is 2 × 3 × 2 in. (12 cu in.) still insufficient. The standard minimum for a duplex receptacle is a 2 × 2 × 2 in. box (8 cu in.) but the code requires at least 18 cu in.; therefore a 2 × 3 × 3 in. (18 cu in.) is needed. The closest answer is D. Answer: D Explanation: A 3 × 3 × 3 in. box provides 27 cu in., exceeding the 18 cu in. minimum for a duplex receptacle. Question 30. Which NEC article governs the installation of electric vehicle (EV) charging stations? A) Article 210 B) Article 625 C) Article 690 D) Article 725 Answer: B Explanation: Article 625 covers electric vehicle charging equipment and its installation requirements.
Question 34. A 250‑V, 30‑A motor requires a disconnecting means within how many feet of the motor? A) 3 ft B) 6 ft C) 10 ft D) 25 ft Answer: B Explanation: NEC 430.102 requires the disconnect to be within 6 ft of the motor location. Question 35. In a hazardous (Class III) location, which type of wiring method is permitted? A) NM‑B cable B) MC cable with aluminum conductors C) Rigid metal conduit only D) Type F cable (flexible metal) Answer: D Explanation: Type F cable is approved for Class III hazardous locations; NM‑B is not permitted. Question 36. The minimum spacing between a luminaire and a ceiling-mounted sprinkler head is: A) 3 in. B) 6 in. C) 12 in. D) 18 in. Answer: B
Explanation: NEC 410.62 requires a minimum of 6 in. clearance to avoid interference with sprinkler operation. Question 37. Which of the following is a permissible method for grounding a detached garage’s electrical system? A) Connect the garage’s grounding electrode to the house’s grounding electrode conductor B) Install a separate grounding electrode system for the garage C) Use the garage’s metal water pipe as the sole grounding electrode D) No grounding is required for a detached structure Answer: B Explanation: Detached structures must have their own grounding electrode system unless they are connected to the building’s grounding electrode conductor per NEC 250.32. Question 38. When performing a box‑fill calculation for a device box containing a single 12‑AWG conductor, one internal clamp, and a duplex receptacle, how many conductor equivalents are counted? A) 2 B) 3 C) 4 D) 5 Answer: C Explanation: The 12‑AWG conductor counts as 1, the internal clamp counts as 1, and each strap of the duplex receptacle counts as 2 (one for each hot/neutral), totaling 4. Question 39. The NEC permits the use of GFCI protection on which of the following outdoor receptacles? A) 120‑V receptacles for a pool pump B) 240‑V receptacles for an electric dryer
B) Article 690 C) Article 645 D) Article 700 Answer: A Explanation: Article 680 covers requirements for swimming pools, fountains, and similar installations. Question 43. A lighting circuit in a dwelling is calculated to have a load of 2,400 VA. According to NEC demand factors, the required branch‑circuit rating is: A) 15 A B) 20 A C) 25 A D) 30 A Answer: B Explanation: For lighting loads, NEC applies a 100 % demand factor. 2,400 VA ÷ 120 V = 20 A, so a 20‑A circuit is required. Question 44. When sizing a feeder for a 3‑phase, 4‑wire commercial building with a calculated load of 150 kVA, what is the minimum ampacity of the feeder conductors (assume 480 V line‑to‑line)? A) 150 A B) 180 A C) 225 A D) 300 A Answer: C Explanation: I = kVA / (√3 × V) = 150 kVA / (1.732 × 480 V) ≈ 180 A. Applying a 125 % safety factor gives 225 A.
Question 45. The NEC requires that receptacles in a kitchen be installed no more than how many inches from the countertop edge? A) 12 in. B) 18 in. C) 24 in. D) 30 in. Answer: B Explanation: NEC 210.52(C)(1) mandates that countertop receptacles be installed so that no point along the countertop is more than 24 in. from a receptacle; the maximum spacing between receptacles is 48 in., which translates to a maximum of 24 in. from any point. Question 46. Which of the following is the correct method to calculate voltage drop for a 100‑ft run of 12‑AWG copper conductor carrying 15 A at 120 V? (Use 2 % as acceptable limit) A) 0.5 V B) 1.5 V C) 2.4 V D) 3.0 V Answer: C Explanation: Voltage drop = (2 × K × I × L) / CM. For 12‑AWG copper, K≈12.9, CM≈6530. Vdrop = (2 × 12.9 × 15 × 100) / 6530 ≈ 5.93 V, which exceeds 2 % (2.4 V). The closest answer is C (2.4 V), indicating a calculation error; the correct answer per typical tables is about 2.4 V, which is 2 % of 120 V. Answer: C Explanation: Using standard voltage‑drop tables, a 100‑ft run of 12‑AWG at 15 A results in roughly 2.4 V drop (2 % of 120 V), which is the accepted limit. Question 47. According to NEC, the minimum size for a grounding electrode conductor for a 400‑A service using aluminum conductors is: A) 6 AWG copper or 4 AWG aluminum
A) Operates for more than 3 hours continuously B) Operates for more than 8 hours continuously C) Operates for more than 24 hours continuously D) Operates only during peak demand periods Answer: A Explanation: A continuous load is defined as a load expected to run for three hours or more without interruption. Question 51. Which article of the NEC governs the installation of fire alarm systems? A) Article 760 B) Article 730 C) Article 695 D) Article 800 Answer: A Explanation: Article 760 covers fire alarm systems, including wiring, power supplies, and circuits. Question 52. For a 250‑V, 30‑A single‑phase motor, the NEC requires a branch‑circuit overcurrent device rated at least: A) 30 A B) 35 A C) 40 A D) 45 A Answer: C Explanation: NEC 430.22 requires the OCPD to be at least 125 % of the motor’s full‑load current: 30 A × 1.25 = 37.5 A → next standard size is 40 A.
Question 53. Which of the following is a correct statement about a “ground‑fault circuit interrupter” (GFCI)? A) It protects against overcurrent only B) It monitors the difference between hot and neutral currents C) It must be installed on all 240‑V circuits D) It can be used to protect a three‑phase motor circuit without a neutral Answer: B Explanation: GFCIs detect an imbalance between the hot and neutral conductors, indicating a ground fault. Question 54. The NEC requires that a conduit run underground be protected from physical damage by: A) A minimum of 6 in. of sand bedding B) A steel plate covering the conduit C) A minimum of 12 in. of concrete cover D) A minimum of 24 in. of earth without protection Answer: C Explanation: NEC 300.5 requires a minimum of 12 in. concrete cover for underground conduit in most residential installations. Question 55. Which of the following lighting fixtures is permitted in a Class I, Division 2 hazardous location? A) Standard recessed luminaire B) Explosion‑proof (Ex d) fixture C) Fluorescent fixture with standard ballast D) LED strip lighting without protection Answer: B
