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Question 1. Which equation correctly represents Ohm’s Law? A) P = V × I B) V = I × R C) I = V ÷ P D) R = P ÷ I Answer: B Explanation: Ohm’s Law states that voltage (V) equals current (I) multiplied by resistance (R). Question 2. In a single‑phase transformer, the primary voltage is 240 V and the turns ratio is 1:4. What is the secondary voltage? A) 60 V B) 120 V C) 480 V D) 960 V Answer: C Explanation: V₂ = V₁ × (N₂/N₁) = 240 V × 4 = 480 V. Question 3. Which NEC term means “readily accessible without the use of tools”? A) In sight from B) Guarded C) Readily accessible D) Listed Answer: C Explanation: “Readily accessible” is defined as capable of being reached quickly without the use of tools or special equipment. Question 4. On a wiring diagram, the symbol of a circle with a “T” inside represents which device? A) Receptacle B) Switch
C) Transformer D) Thermostat Answer: D Explanation: The “T” inside a circle is the standard symbol for a thermostat. Question 5. According to NEC Article 220, what is the demand factor for the first 10 kW of a continuous load? A) 100 % B) 80 % C) 70 % D) 50 % Answer: A Explanation: The first 10 kW of a continuous load is not derated; the demand factor applies only after the first 10 kW. Question 6. A dwelling unit has a calculated service load of 45 kVA. Using the standard method, what is the minimum service entrance conductor size (copper, 75 °C) required? A) #6 AWG B) #4 AWG C) #2 AWG D) #1/0 AWG Answer: C Explanation: 45 kVA ÷ 240 V ≈ 188 A. #2 AWG copper at 75 °C is rated for 115 A, so we need #1/0 (150 A) actually. Correction: The correct answer should be #1/0 AWG. Therefore answer D. Question 7. What is the minimum clearance required between a service drop conductor and a grounded metal water pipe in a residential installation? A) 6 in. B) 12 in. C) 18 in.
Answer: B Explanation: I = P ÷ (√3 × V × PF). Assuming PF = 0.9, I ≈ 30,000 ÷ (1.732 × 480 × 0.9) ≈ 40 A. The next standard size is 45 A. Question 11. The NEC requires a maximum voltage drop of 3 % for which of the following? A) Feeder circuits only B) Branch circuits only C) Both feeder and branch circuits supplying sensitive equipment D) All circuits, regardless of load Answer: C Explanation: NEC 210.19(A)(1) limits voltage drop to 3 % for branch circuits and 5 % total (including feeder) for sensitive equipment. Question 12. Which conduit type is permitted for direct burial without a raceway? A) EMT B) RMC C) PVC Schedule 40 D) IMC Answer: C Explanation: PVC Schedule 40 conduit is listed for direct burial per NEC 352.10. Question 13. For a 20‑A GFCI receptacle in a bathroom, the required grounding‑type receptacle spacing is: A) Every 6 ft along the wall B) Every 4 ft along the wall C) No more than 3 ft apart D) No specific spacing; only one required per bathroom Answer: D Explanation: NEC 210.52(D) requires at least one receptacle in a bathroom; spacing rules for general areas do not apply.
Question 14. An AFCI is required in which of the following dwelling unit locations? A) Garage B) Bedroom C) Kitchen countertop D) All of the above Answer: D Explanation: NEC 210.12(A) mandates AFCI protection for all 120‑V, 15‑ and 20‑A branch circuits supplying outlets in dwelling unit bedrooms, garages, and kitchen countertops. Question 15. When calculating box fill for a device box, how many “fill units” does a single internal clamp count as? A) 1 B) 2 C) 3 D) 4 Answer: A Explanation: NEC 314.16(B) states that each internal clamp counts as one conductor fill unit. Question 16. The maximum number of #12 AWG conductors allowed in a 1‑in. × ½‑in. EMT conduit (per Table 4 of Chapter 9) is: A) 9 B) 12 C) 15 D) 18 Answer: B Explanation: Table 4 lists a fill limit of 12 #12 AWG conductors for that conduit size. Question 17. Which of the following is NOT a permissible use for flexible metal conduit (FMC)? A) Permanent wiring in exposed ceilings
D) #6 AWG
Answer: B Explanation: Table 250.122 shows that for a 60‑A circuit, the minimum EGC size is #10 AWG copper. Question 21. In a three‑phase, 4‑wire wye system, the line‑to‑neutral voltage is 208 V. What is the line‑to‑line voltage? A) 120 V B) 208 V C) 240 V D) 360 V Answer: D Explanation: V_LL = V_LN × √3 = 208 × 1.732 ≈ 360 V. Question 22. Which of the following devices must be listed and labeled for use in Class I, Division 2 hazardous locations? A) Standard incandescent lamp B) Explosion‑proof motor‑rated enclosure C) Non‑explosion‑proof receptacle D) Standard NM cable Answer: B Explanation: Only explosion‑proof (intrinsically safe) equipment is permitted in Class I, Division 2 areas. Question 23. The minimum height for a receptacle installed in a kitchen countertop area is: A) 12 in. above the countertop B) 15 in. above the countertop C) 18 in. above the countertop D) 20 in. above the countertop Answer: C Explanation: NEC 210.52(C)(1) requires countertop receptacles to be installed no higher than 20 in. above the countertop; the common practice is 18 in. for accessibility.
Question 24. Which NEC article governs the installation of swimming pool equipment? A) Article 250 B) Article 680 C) Article 690 D) Article 705 Answer: B Explanation: Article 680 covers swimming pools, fountains, and similar installations. Question 25. For a motor with a full‑load current of 25 A, the NEC requires the overload protection to be set between: A) 100 % and 115 % of FL B) 115 % and 125 % of FL C) 125 % and 150 % of FL D) 150 % and 200 % of FL Answer: B Explanation: NEC 430.32 requires overload protection to be set between 115 % and 125 % of the motor’s full‑load current. Question 26. A generator set rated at 200 kVA, 240/120 V, 3‑phase, is to be connected to a building’s emergency system. Which transfer switch rating is the minimum acceptable? A) 150 A B) 200 A C) 250 A D) 300 A Answer: C Explanation: The transfer switch must be rated at least equal to the generator’s current: 200 kVA ÷ 240 V ≈ 833 A ÷ √3 ≈ 480 A; thus a 250 A switch is insufficient. Actually the correct answer is D (300 A) to handle the load safely.
B) GFCI
C) Surge protector D) Thermal overload Answer: B Explanation: NEC 210.8(A)(2) requires GFCI protection for receptacles in garages. Question 31. When sizing a feeder for a 10‑kW continuous load at 240 V, which correction factor must be applied before selecting conductor size? A) 1.0 (no correction) B) 1.25 (continuous load factor) C) 0.8 (demand factor) D) 1.5 (motor factor) Answer: B Explanation: Continuous loads must be multiplied by 125 % per NEC 210.19(A)(1). Question 32. The minimum conduit fill for a raceway containing three #4 AWG THHN conductors is: A) 30 % B) 40 % C) 45 % D) 53 % Answer: D Explanation: For more than two conductors, the maximum fill is 40 % of the conduit’s cross‑sectional area; however, Table 1 of Chapter 9 shows 53 % for three conductors of a given size. The correct answer is B (40 %). Question 33. Which NEC article addresses the installation of fire alarm systems? A) Article 300 B) Article 700 C) Article 710 D) Article 800
Answer: B Explanation: Article 700 covers the installation of fire alarm and detection systems. Question 34. A lighting fixture rated for 120 V, 600 W is installed in a commercial space. What is the maximum allowable current draw for the branch circuit supplying it? A) 5 A B) 6 A C) 8 A D) 10 A Answer: B Explanation: I = P ÷ V = 600 W ÷ 120 V = 5 A. The next standard circuit size is 15 A, but the maximum continuous load is 80 % of 15 A = 12 A, so the fixture is within limits. The direct answer for the fixture is 5 A, which corresponds to option A. Question 35. For a three‑phase motor rated 15 hp, 460 V, what is the approximate full‑load current (FLA) using the NEC motor tables? A) 15 A B) 20 A C) 25 A D) 30 A Answer: C Explanation: NEC Table 430‑33 shows a 15 hp, 460 V, 3‑phase motor with an FLA of about 25 A. Question 36. Which of the following is the correct minimum burial depth for PVC conduit protecting a feeder in residential yards? A) 12 in. B) 18 in. C) 24 in. D) 30 in. Answer: B
Question 40. Which of the following is the correct definition of “listed” per NEC 100? A) Tested and approved by the AHJ B) Evaluated by a qualified individual and placed on a list by a recognized testing agency C) Installed by a licensed electrician D) Inspected after installation Answer: B Explanation: “Listed” means the product has been evaluated and placed on an approved list by a recognized testing laboratory. Question 41. A 120/240‑V, 3‑wire service requires a grounding electrode conductor (GEC). What is the minimum size of the GEC (copper) for this service? A) #12 AWG B) #10 AWG C) #8 AWG D) #6 AWG Answer: B Explanation: Table 250‑122 indicates a #10 AWG copper GEC is required for a 100 A service; a typical 120/240‑V residential service is 100 A, so #10 AWG is the minimum. Question 42. Which of the following is NOT a permissible grounding electrode material? A) Copper‑clad steel rod B) Galvanized steel pipe C) Aluminum pipe D) Stainless steel rod (minimum ½ in. diameter) Answer: C Explanation: Aluminum is not an acceptable grounding electrode material under NEC 250.52(A)(5). Question 43. The NEC requires that a disconnecting means be provided for each of the following EXCEPT:
A) Motor circuits B) Lighting circuits C) Refrigeration equipment D) Fire alarm circuits Answer: D Explanation: Fire alarm circuits are covered under Article 700 and have separate requirements; a disconnect is not required for the entire fire alarm system. Question 44. Which of the following is the correct minimum size for a feeder overcurrent protective device (OCPD) protecting a 150‑A feeder? A) 100 A B) 125 A C) 150 A D) 175 A Answer: C Explanation: The OCPD must be rated at least equal to the ampacity of the feeder; therefore a 150‑A OCPD is required. Question 45. In a three‑phase, 4‑wire wye system, the neutral is grounded at the service equipment. Which NEC article governs the grounding of the neutral? A) 250.24(A) B) 250.30(B) C) 250.32(C) D) 250. Answer: A Explanation: NEC 250.24(A) specifies that the neutral (grounded conductor) shall be grounded at the service disconnecting means. Question 46. The NEC permits the use of a “tap” for a feeder branch circuit under which condition? A) Tap length not exceeding 10 ft
Answer: D Explanation: NEC 408.4 requires that each circuit be legibly identified on the panelboard directory. Question 50. In a commercial office building, a lighting circuit is supplied by a 20‑A breaker. According to NEC, the maximum continuous load on this circuit may not exceed: A) 12 A B) 14 A C) 16 A D) 18 A Answer: C Explanation: Continuous loads must not exceed 80 % of the breaker rating: 0.8 × 20 A = 16 A. Question 51. Which of the following is the correct definition of “guarded” as used in NEC 100? A) Protected by a lockable cover B) Protected by a non‑removable barrier that prevents accidental contact C) Mounted at a height greater than 6 ft D) Located within a locked room Answer: B Explanation: “Guarded” means a protective barrier that prevents accidental contact with live parts. Question 52. A 30‑kW, 208‑V three‑phase motor requires a starter. What is the minimum size of the overload protection device? A) 115 % of FLA B) 125 % of FLA C) 150 % of FLA D) 200 % of FLA Answer: B Explanation: NEC 430.32 requires overload protection set between 115 % and 125 % of the motor’s full‑load current.
Question 53. Which of the following conduit fittings must be threaded with pipe‑thread sealant? A – EMT compression fitting B – RMC threaded coupling C – PVC solvent‑weld fitting D – IMC slip‑on coupling Answer: B Explanation: Rigid Metal Conduit (RMC) threaded couplings require pipe‑thread sealant or Teflon tape per NEC 358.12. Question 54. For a residential kitchen countertop, the maximum spacing between receptacles is: A) 3 ft B) 4 ft C) 6 ft D) 8 ft Answer: B Explanation: NEC 210.52(C)(1) requires receptacles installed so that no point along the countertop is more than 24 in. from a receptacle, which translates to a maximum spacing of 4 ft. Question 55. Which of the following is the correct minimum size for a grounding electrode conductor (GEC) attached to a 200‑A service? A) #8 AWG copper B) #6 AWG copper C) #4 AWG copper D) #2 AWG copper Answer: C Explanation: Table 250‑122 specifies #4 AWG copper for a 200‑A service. Question 56. The NEC permits the use of a “multi‑wire branch circuit” (MWBC) provided that: A) All ungrounded conductors are of the same size B) The circuit supplies only lighting loads
Explanation: Either a two‑pole breaker or a fused disconnect rated for the service amperage is acceptable per NEC 230.71. Question 60. Which of the following is the correct minimum spacing between outlets on a wall in a commercial office space (excluding kitchens and bathrooms)? A) 6 ft B) 8 ft C) 10 ft D) 12 ft Answer: B Explanation: NEC 210.52(B) requires receptacles placed so that the distance between them does not exceed 8 ft. Question 61. The NEC defines “listed” equipment as having been: A) Inspected by the AHJ after installation B) Tested and approved by a nationally recognized testing laboratory C) Approved by the manufacturer’s sales department D) Installed by a licensed electrician Answer: B Explanation: “Listed” means evaluated and approved by a recognized testing agency, such as UL. Question 62. Which of the following is the correct minimum size for a feeder conductor supplying a 60 ‑A load, using copper conductors with a 75 °C rating? A) #6 AWG B) #4 AWG C) #2 AWG D) #1/0 AWG Answer: B Explanation: #4 AWG copper at 75 °C is rated for 85 A, which exceeds the 60‑A requirement.
Question 63. In a residential dwelling, the minimum number of dedicated 20‑A circuits required for kitchen countertop appliances is: A) 1 B) 2 C) 3 D) 4 Answer: B Explanation: NEC 210.11(C)(1) requires at least two 20‑A small‑appliance circuits for kitchen countertops. Question 64. Which NEC article governs the installation of emergency (standby) power systems? A) Article 700 B) Article 710 C) Article 725 D) Article 740 Answer: A Explanation: Article 700 covers emergency systems, including standby generators and transfer switches. Question 65. A 120/240‑V, 3‑wire service has a grounding electrode system consisting of two 8‑ft copper rods spaced 6 ft apart. What is the minimum size of the grounding electrode conductor (GEC) for this service? A) #12 AWG B) #10 AWG C) #8 AWG D) #6 AWG Answer: B Explanation: For a 100‑A service, the GEC must be #10 AWG copper per Table 250 ‑122. Question 66. Which of the following is a required feature for a listed panelboard in a hazardous (Class I) location?
