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Question 1. Which formula correctly expresses 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. If a circuit has 120 V and draws 10 A, what is the power consumption? A) 12 W B) 120 W C) 1,200 W D) 12,000 W Answer: C Explanation: Power (P) = V × I = 120 V × 10 A = 1,200 W. Question 3. In a series circuit with three resistors of 4 Ω, 6 Ω, and 10 Ω, the total resistance is: A) 20 Ω B) 10 Ω C) 0 Ω D) 24 Ω Answer: A Explanation: Series resistance adds: 4 Ω + 6 Ω + 10 Ω = 20 Ω.
Contractor Ultimate Exam
Question 4. Two 8 Ω resistors are connected in parallel. What is the equivalent resistance? A) 4 Ω B) 16 Ω C) 8 Ω D) 2 Ω Answer: A Explanation: 1/R_eq = 1/8 + 1/8 = 1/4 → R_eq = 4 Ω. Question 5. According to NEC Article 110, equipment must be identified by: A) Color-coded tape only B) Permanent markings readable after installation C) Temporary stickers that can be removed D) Hand-written labels that are replaced yearly Answer: B Explanation: NEC requires permanent, legible identification that remains readable after installation. Question 6. Which of the following is the correct method for splicing conductors in a raceway? A) Twist the wires together and tape them B) Use a listed splice connector and secure it within the raceway C) Solder the wires and leave them exposed D) Wrap with electrical tape only Answer: B Explanation: NEC permits only listed splice devices that are secured and listed for the environment.
Contractor Ultimate Exam
Explanation: Table 250.66 allows a 4 AWG copper GEC for a 4/0 AL service conductor. Question 10. Which of the following is NOT a permissible location for a service disconnect? A) Inside a detached garage of a single-family home B) In a utility room of the same building C) In a separate outbuilding without a feeder from the main service D) In the same building as the service entrance Answer: C Explanation: A service disconnect must be installed on the same building as the service entrance; a separate outbuilding requires a feeder and a subpanel, not a service disconnect. Question 11. The minimum clearance between a service drop and a roof edge is: A) 6 ft B) 10 ft C) 12 ft D) 2 ft Answer: A Explanation: NEC 230.9 requires a minimum of 6 ft clearance between a service drop and any roof edge. Question 12. Which conductor is used to bond metal water piping to the grounding system? A) Equipment Grounding Conductor (EGC) B) Grounding Electrode Conductor (GEC) C) Service-entrance conductor
Contractor Ultimate Exam
D) Neutral conductor Answer: A Explanation: The EGC is used to bond metal water piping per NEC 250.104(A). Question 13. For a 200 A service, the minimum size of the grounding electrode conductor (copper) is: A) 6 AWG B) 4 AWG C) 2 AWG D) 1/0 AWG Answer: B Explanation: Table 250.66 specifies 4 AWG copper for a 200 A service. Question 14. The demand factor for the first 3,000 VA of a dwelling’s general lighting load is: A) 100 % B) 80 % C) 70 % D) 50 % Answer: A Explanation: NEC Table 220.42 requires 100 % for the first 3 kVA of general lighting load. Question 15. A 1500 sq ft single-family home requires how many 20-A branch circuits for kitchen countertop receptacles? A) 1 B) 2
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B) All 120-V, 15- and 20-A branch circuits supplying living areas C) Outdoor receptacles only D) Kitchen countertop circuits only Answer: B Explanation: NEC 210.12(A) mandates AFCI protection for all 120-V, 15- and 20-A branch circuits supplying dwelling unit living areas. Question 19. The “6-foot rule” for receptacle placement in a dwelling states that: A) No point along a wall can be more than 6 ft from a receptacle B) Receptacles must be installed every 6 ft horizontally C) Receptacles must be placed 6 ft above the floor D) Receptacles must be within 6 ft of a light switch Answer: A Explanation: NEC 210.52(A) requires that no point along a wall line be more than 6 ft from a receptacle. Question 20. THHN conductors are rated for a maximum temperature of: A) 60 °C B) 75 °C C) 90 °C D) 105 °C Answer: C Explanation: THHN is rated for 90 °C in dry locations. Question 21. When bundling more than three conductors in a conduit, the ampacity must be adjusted by:
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A) 0 % (no adjustment) B) 80 % of the listed value C) 70 % of the listed value D) 50 % of the listed value Answer: C Explanation: NEC 310.15(B)(3)(a) requires a 70 % derating factor for more than three current-carrying conductors in a raceway. Question 22. Which cable type is prohibited in a wet location? A) NM-B (Romex) B) UF-B C) MC-C D) SE-U Answer: A Explanation: NM-B cable is not permitted in wet locations; UF-B, MC-C, and SE-U are rated for wet conditions. Question 23. The maximum fill for a conduit containing only one conductor is: A) 53 % B) 31 % C) 40 % D) 60 % Answer: A Explanation: NEC Table 1, Chapter 9 allows 53 % fill for a single conductor in a conduit.
Contractor Ultimate Exam
Answer: B Explanation: NEC permits metal straps or clamps listed for the raceway type; plastic zip ties and adhesives are not approved for permanent support. Question 27. A luminaire installed in a closet must be rated for which environment? A) Damp B) Wet C) Dry D) Explosion-proof Answer: C Explanation: Closets are considered dry locations; therefore a dry-rated luminaire is acceptable (NEC 410.10). Question 28. Which article governs the installation of receptacles in a wet location such as a bathroom? A) Article 210 B) Article 300 C) Article 410 D) Article 422 Answer: A Explanation: NEC Article 210 addresses requirements for receptacles, including wet locations like bathrooms. Question 29. The required disconnecting means for a water heater rated at 4500 W, 240 V is: A) A 15-A circuit breaker B) A 20-A circuit breaker C) A 30-A circuit breaker
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D) A fused disconnect Answer: B Explanation: 4500 W ÷ 240 V = 18.75 A; the next standard size is a 20-A breaker, meeting Article 422.13. Question 30. For a 3-phase, 4-wire motor rated 10 HP, 460 V, the minimum size of the branch-circuit conductor (copper) is: A) 10 AWG B) 8 AWG C) 6 AWG D) 4 AWG Answer: C Explanation: NEC Table 430.250 indicates a 10 HP 3-phase motor requires at least 6 AWG copper for the branch circuit. Question 31. Motor overload protection must be set at what percentage of the full-load current? A) 80 % B) 100 % C) 115 % to 125 % D) 150 % Answer: C Explanation: NEC 430.32 requires overload protection set between 115 % and 125 % of the motor’s full-load current. Question 32. The “within sight” requirement for a motor disconnect means the disconnect must be: A) Within 50 ft of the motor
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C) At every panel downstream D) It does not require grounding Answer: B Explanation: NEC 250.30 requires the neutral of a separately derived system to be grounded at the source (the transformer or generator). Question 35. Which of the following is the correct minimum size for a grounding electrode conductor (copper) for a 100 kVA, 480 V three-phase service? A) 6 AWG B) 4 AWG C) 2 AWG D) 1/0 AWG Answer: C Explanation: Service-entrance conductor size is roughly 3/0 AL; per Table 250.66, a 2 AWG copper GEC is required for that size. Question 36. In a hazardous (Class I, Division 2) location, which type of conduit is permitted for wiring? A) PVC conduit only B) Rigid metal conduit (RMC) only C) Both PVC and RMC, provided they are listed for the division D) Flexible metal conduit (FMC) only Answer: C Explanation: NEC 500.10 permits any conduit type listed for the specific hazardous classification, including PVC and RMC. Question 37. The minimum clearance between a pool pump and the nearest edge of the pool deck is:
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A) 3 ft B) 5 ft C) 6 ft D) 10 ft Answer: C Explanation: NEC 680.26 requires a minimum of 6 ft clearance between pool equipment and the pool deck. Question 38. A swimming pool’s equipotential bonding grid must be installed using which conductor size at minimum? A) 12 AWG copper B) 10 AWG copper C) 8 AWG copper D) 6 AWG copper Answer: C Explanation: NEC 680.26(A)(1) requires a minimum of 8 AWG copper for the bonding grid. Question 39. Which NEC article governs the installation of electric signs? A) Article 410 B) Article 590 C) Article 700 D) Article 720 Answer: B Explanation: NEC Article 590 covers electric signs and outline lighting.
Contractor Ultimate Exam
Explanation: NEC Table 310.15(B)(2)(a) indicates that PVC conduit must be derated for ambient temperatures above 40 °C. Question 43. The NEC requires a minimum of how many disconnecting means for a single-family dwelling with a 200 A service? A) One B) Two C) Three D) Four Answer: A Explanation: NEC 230.71 requires at least one service disconnecting means for a dwelling. Question 44. When installing a receptacle in a garage, the receptacle must be GFCI protected if the garage is: A) Unfinished only B) Finished only C) Either finished or unfinished D) Only if it is a detached garage Answer: C Explanation: NEC 210.8(A)(2) requires GFCI protection for all 125-V, 15- and 20-A receptacles in garages, regardless of finish. Question 45. The minimum size of a grounding electrode conductor (copper) for a 350 kVA, 13.8 kV feeder is: A) 4/0 AWG B) 250 kcmil C) 500 kcmil D) 1 /0 AWG
Contractor Ultimate Exam
Answer: C Explanation: For a 350 kVA, 13.8 kV feeder, the feeder conductor size is about 250 kcmil. Table 250.66 indicates a 500 kcmil copper GEC is required. Question 46. Which of the following is the correct definition of a “branch circuit” per NEC? A) A circuit that supplies power to the main service panel B) A circuit that originates at the service disconnect and supplies loads directly C) A circuit that runs from a feeder to the load devices D) A circuit that only supplies lighting fixtures Answer: C Explanation: NEC defines a branch circuit as a circuit that originates from a feeder or panel and supplies the loads. Question 47. The required ampacity for a 12-AWG copper conductor in a 30 °C ambient temperature, with three current-carrying conductors in a conduit, is: A) 20 A B) 25 A C) 30 A D) 35 A Answer: B Explanation: 12-AWG copper is rated 30 A at 60 °C (Table 310.16). With three conductors, derating is 80 %, giving 24 A; the next standard size is 25 A. Question 48. Which of the following devices is NOT permitted in a wet location? A) A weather-proof GFCI receptacle B) A listed metal box with a gasketed cover C) A standard non-metallic (NM) cable splice box
Contractor Ultimate Exam
B) 6 ft C) 12 in. D) 18 in. Answer: D Explanation: NEC 110.26(A)(2) requires a minimum of 18 in. clearance from combustible material. Question 52. For a three-wire, 120/240 V dryer circuit, the required neutral conductor size (copper) is: A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: B Explanation: Dryer circuits are 30 A; per Table 310.16, 12 AWG copper is the minimum for the neutral. Question 53. Which of the following is NOT a requirement for a listed panelboard cover? A) Must be securely fastened B) Must be made of metal only C) Must provide protection against accidental contact with live parts D) Must be marked with the panelboard rating Answer: B Explanation: Panelboard covers may be metal or non-metallic as long as they meet the listed protection criteria.
Contractor Ultimate Exam
Question 54. In a commercial building, the minimum size of a feeder conductor supplying a 100 A panelboard is: A) 8 AWG copper B) 6 AWG copper C) 4 AWG copper D) 2 AWG copper Answer: C Explanation: Per NEC Table 310.15(B)(16), 4 AWG copper is rated for 85 A at 75 °C; with 125 % factor, it can serve a 100 A feeder. Question 55. The required ampacity for a 3-phase, 4-wire motor branch circuit supplying a 5 HP motor at 460 V is: A) 12 A B) 15 A C) 18 A D) 20 A Answer: B Explanation: NEC Table 430.250 shows a 5 HP, 460 V 3-phase motor requires a 15 A branch-circuit conductor. Question 56. For a 250 V, 30 A receptacle in a commercial kitchen, the required grounding conductor size (copper) is: A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: C
