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Course Exam
Question 1. Ohm’s Law states that voltage equals current multiplied by resistance. Which formula correctly represents this relationship? A) V = I + R B) V = I × R C) V = I ÷ R D) V = R ÷ I Answer: B Explanation: Ohm’s Law is V = I·R, meaning voltage (V) is the product of current (I) and resistance (R). Question 2. A 150‑W incandescent lamp is connected to a 120‑V source. What is the current drawn by the lamp? A) 0.75 A B) 1.25 A C) 1.80 A D) 2.00 A Answer: B Explanation: I = P/V = 150 W / 120 V = 1.25 A. Question 3. In a series circuit with three resistors of 10 Ω, 20 Ω, and 30 Ω, what is the total resistance? A) 20 Ω
Course Exam
B) 30 Ω
C) 60 Ω
D) 0 Ω
Answer: C Explanation: Series resistances add: 10 + 20 + 30 = 60 Ω. Question 4. Two 100 Ω resistors are connected in parallel. What is the equivalent resistance? A) 200 Ω B) 100 Ω C) 50 Ω D) 25 Ω Answer: C Explanation: 1/Req = 1/100 + 1/100 = 2/100 → Req = 50 Ω. Question 5. Which of the following best describes three‑phase, 208‑V, line‑to‑line, wye‑connected system voltage line‑to‑neutral? A) 120 V B) 208 V C) 240 V D) 277 V
Course Exam
Explanation: Article 250 covers grounding and bonding, including GEC requirements. Question 8. A 3‑wire NM cable (12‑2 with ground) is run in a wall cavity. What is the maximum number of current‑carrying conductors allowed in that cavity before derating is required? A) 1 B) 2 C) 3 D) 4 Answer: C Explanation: Up to 3 current‑carrying conductors may be in a raceway or cavity without derating; the ground is not counted. Question 9. The ampacity of a 4‑AWG THHN copper conductor in a 75 °C column is 85 A. If the conductor is in a raceway with three other current‑carrying conductors, what is the adjusted ampacity? A) 85 A B. 71 A C. 68 A D. 60 A Answer: B
Course Exam
Explanation: For 4–6 conductors, apply 80 % derating: 85 A × 0.80 = 68 A. (Correction: 85 × 0.80 = 68 A, answer C). Question 10. Which type of conduit is permitted for underground installation without a moisture barrier? A) EMT B) RMC C) PVC D) IMC Answer: C Explanation: PVC conduit is non‑metallic and rated for direct burial without additional moisture protection. Question 11. A dwelling unit has a total calculated load of 45 kVA. Applying the NEC residential demand factor of 40 % for the first 10 kVA and 30 % for the remainder, what is the demand load? A) 13.5 kVA B) 15 kVA C) 16.5 kVA D) 18 kVA Answer: C
Course Exam
Answer: A Explanation: Article 210.12 requires AFCI protection for many dwelling unit circuits. Question 14. A feeder supplying a 100 A sub‑panel is run through a metal conduit that also contains two 20‑A branch‑circuit conductors. What is the appropriate conduit fill percentage for this installation? A) 40 % B) 53 % C) 60 % D) 75 % Answer: B Explanation: For more than two conductors in a conduit, the fill limit is 40 % for EMT. However NEC Table 1 allows 53 % for 3–6 conductors in a conduit larger than 1 in. Choose 53 % (option B). Question 15. Which of the following is NOT a permitted grounding electrode according to NEC 250.52? A) Concrete‑encased electrode B) Metal underground water pipe C) Metal roof truss D) Ground rod
Course Exam
Answer: C Explanation: Metal roof trusses are not listed as grounding electrodes; the other three are permitted. Question 16. The voltage drop limit recommended for feeder circuits 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 17. A 240‑V, 30‑A dryer circuit requires a neutral conductor. What size copper neutral is required by NEC Table 310.15(B)(16)? A) 8 AWG B) 10 AWG C) 12 AWG D) 14 AWG Answer: B Explanation: For a 30‑A circuit, 10 AWG copper is the minimum size listed for 60 °C column.
Course Exam
A) 12 in. above the floor B) 15 in. above the floor C) 18 in. above the floor D) No specific height required Answer: D Explanation: NEC does not prescribe a specific mounting height for garage receptacles. Question 21. Which of the following is the correct method to calculate conduit bend allowance for a 90° bend? A) 0.5 × diameter of conduit B) 1 × diameter of conduit C) 1.5 × diameter of conduit D) 2 × diameter of conduit Answer: B Explanation: Bend allowance for a 90° bend equals the conduit’s nominal diameter. Question 22. An equipment grounding conductor (EGC) of 12 AWG copper is required for a 20‑A branch circuit. Which NEC table provides this requirement? A) Table 250. B) Table 310.15(B)(16)
Course Exam
C) Table 220. D) Table 210.20(A) Answer: A Explanation: Table 250.122 lists minimum EGC sizes based on overcurrent device rating. Question 23. When sizing a feeder for a 30 kW, 480‑V, three‑phase motor, what is the approximate full‑load current (FLA) using the formula I = P/(√ 3 × V × PF) assuming PF = 0.9? A) 30 A B) 36 A C) 40 A D) 45 A Answer: B Explanation: I = 30 kW / (1.732 × 480 V × 0.9) ≈ 30,000 / (746) ≈ 40.2 A. Rounded to nearest standard 40 A (option C). Question 24. Which NEC article addresses the requirements for wiring methods in hazardous (Class I) locations? A) 500 B) 501 C) 502
Course Exam
Explanation: NEC 210.11(C)(3) requires at least one lighting outlet in each hallway; however typical practice is to place one per 12 ft. Since the hallway is 12 ft, at least one is required. Option A. Question 27. Which of the following conduit types is listed as “non‑metallic, rigid” and suitable for outdoor wet locations? A) EMT B) RMC C) PVC D) IMC Answer: C Explanation: PVC conduit is non‑metallic, rigid, and rated for wet locations. Question 28. For a 120‑V, 15‑A branch circuit, the maximum length of NM cable before exceeding a 3 % voltage drop is approximately: A) 30 ft B) 50 ft C) 75 ft D) 100 ft Answer: C Explanation: Using Vdrop = 2 × K × I × L / CM, with K≈12.9 for copper, CM for 14 AWG ≈ 2,500 cm, solving for L gives roughly 75 ft for 3 % drop.
Course Exam
Question 29. Which NEC article governs the installation of receptacle outlets in kitchens? A) 210.52(C) B) 210.52(B) C) 210.52(A) D) 210.52(D) Answer: A Explanation: Article 210.52(C) specifies countertop receptacle placement in kitchens. Question 30. A 250‑kVA transformer has a primary voltage of 13.8 kV and a secondary voltage of 480 V. What is the approximate primary current? A) 10 A B) 12 A C) 14 A D) 16 A Answer: B Explanation: I = kVA / (√3 × V) = 250 kVA / (1.732 × 13.8 kV) ≈ 250,000 / 23,910 ≈ 10.4 A (option A).
Course Exam
A) 210.8(A)(2)
B) 210.8(A)(3)
C) 210.8(B)(2)
D) 210.8(B)(3)
Answer: A Explanation: NEC 210.8(A)(2) covers unfinished basements. Question 34. In a commercial office building, the minimum number of fire alarm notification appliances required per floor is: A) 1 B) 2 C) 3 D) 4 Answer: B Explanation: NEC 760.41 requires at least two notification appliances per floor. Question 35. Which of the following conductor insulation types is rated for 90 °C in dry locations and 75 °C in wet locations? A) THHN B) XHHW- 2 C) NM‑B
Course Exam
D) UF‑B
Answer: B Explanation: XHHW‑2 is rated 90 °C dry, 75 °C wet. Question 36. The maximum number of 1‑in. EMT bends allowed in a single run without a pull box is: A) 3 B) 4 C) 5 D) 6 Answer: B Explanation: NEC 358.30 permits up to four 90° bends between pull points. Question 37. Which NEC article addresses the installation of luminaires in damp or wet locations? A) 410. B) 410. C) 410. D) 410. Answer: B Explanation: Article 410.11 covers damp and wet locations for luminaires.
Course Exam
A) 6 in. B) 12 in. C) 18 in. D) 24 in. Answer: B Explanation: PVC conduit under a driveway requires 12 in. of cover. Question 41. In a three‑wire, 120/240‑V service, what is the purpose of the “bonding jumper” required at the service disconnect? A) To connect the neutral to the grounding electrode system B) To connect the hot conductors together C) To provide a spare conductor for future circuits D) To reduce voltage drop on the neutral Answer: A Explanation: The bonding jumper ties the service neutral to the grounding electrode system. Question 42. Which NEC article governs the installation of temporary wiring for construction sites? A) 590 B) 590.
Course Exam
C) 590.
D) 590.
Answer: A Explanation: Article 590 covers temporary wiring. Question 43. A 20‑A GFCI receptacle is installed on a 12‑AWG branch circuit. What is the maximum allowable length of the branch circuit before a voltage drop exceeds 3 %? A) 50 ft B) 75 ft C) 100 ft D) 125 ft Answer: C Explanation: Using the voltage‑drop formula for 12 AWG (CM≈3,100), 3 % of 120 V = 3.6 V. Solving 2 × K × I × L / CM ≤ 3.6 gives L ≈ 100 ft. Question 44. Which of the following is NOT a permitted method for grounding a metal conduit that is not in direct contact with the earth? A) Bonding with a grounding conductor inside the conduit B) Using a grounding clamp at each outlet box C) Relying on the conduit’s continuity alone
