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Question 1. What is the minimum size copper grounding electrode conductor (GEC) required for a 100‑amp residential service according to the 2020 NEC? A) 6 AWG B) 8 AWG C) 10 AWG D) 12 AWG Answer: B Explanation: Table 250.66 specifies that a 100 A service requires a minimum 8 AWG copper GEC. Question 2. In Kentucky, the maximum height for a receptacle in a habitable room is: A) 48 in. above the floor B) 54 in. above the floor C) 60 in. above the floor D) No specific limit, only accessibility requirements apply Answer: B Explanation: NEC 210.52(A)(3) sets the maximum receptacle height at 48 in. above the floor, but Kentucky amendments allow up to 54 in. for convenience. Question 3. Which of the following is NOT considered a grounding electrode under NEC 250.52? A) Concrete‑encased electrode (Ufer)
B) Ground‑ring electrode C) Metal water pipe not in contact with the earth for 10 ft D) Ground‑rod electrode Answer: C Explanation: A metal water pipe must be in direct contact with the earth for at least 10 ft to qualify as a grounding electrode. Question 4. The required ampacity correction factor for a conduit containing four current‑carrying conductors at 75 °C is: A) 0. B) 0. C) 0. D) 0. Answer: A Explanation: NEC Table 310.15(B)(3)(a) gives a 0.80 factor for 4–6 conductors. Question 5. A 20‑amp branch circuit supplying a bathroom receptacle must be protected by a: A) 20‑amp GFCI breaker only B) 20‑amp GFCI receptacle only C) Either a 20‑amp GFCI breaker or a GFCI receptacle D) No GFCI required if the receptacle is within 6 ft of a sink
Question 8. Which NEC article governs the installation of fire alarm circuits? A) Article 210 B) Article 300 C) Article 760 D) Article 800 Answer: C Explanation: Article 760 covers fire alarm systems, including circuit requirements and wiring methods. Question 9. The maximum allowable voltage drop for a feeder supplying a 5 kW load at 240 V, over 150 ft, is: A) 2 % B) 3 % C) 5 % D) 10 % Answer: B Explanation: NEC recommends a maximum of 3 % voltage drop for feeders to maintain efficiency. Question 10. In Kentucky, the required working clearance in front of a service disconnect is:
A) 30 in. B) 36 in. C) 42 in. D) 48 in. Answer: C Explanation: NEC 110.26 requires a minimum of 42 in. clear working space in front of equipment. Question 11. Which of the following is the correct minimum size for a grounding electrode conductor connected to a 200‑A service using copper? A) 6 AWG B) 4 AWG C) 2 AWG D) 8 AWG Answer: B Explanation: Table 250.66 indicates a 200 A service requires at least 4 AWG copper GEC. Question 12. For a 3‑phase, 4‑wire wye system, the neutral conductor must be: A) Uninsulated B) Identical size to the phase conductors
Answer: B Explanation: NEC 210.8(A)(2) mandates GFCI protection for garage receptacles. Question 15. The minimum height for a light switch in a dwelling unit is: A) 48 in. above the floor B) 42 in. above the floor C) 36 in. above the floor D) No specific minimum height Answer: B Explanation: NEC 210.7(A)(1) requires switches to be installed not less than 42 in. above the floor. Question 16. When installing a feeder in a residential basement, the conduit must be protected from physical damage by: A) Rigid metal conduit only B) PVC conduit with metal plates C) Conduit with a minimum 1‑in. metal cover D) No protection required if conduit is on the surface Answer: C Explanation: NEC 300.4 requires protection of conduit from physical damage, often by a metal plate or other means.
Question 17. A 120‑V receptacle in a swimming pool equipment room must be protected by a: A) 20‑A GFCI breaker only B) 20‑A GFCI receptacle only C) Either a GFCI breaker or receptacle D) No GFCI required if the equipment is listed for wet locations Answer: C Explanation: NEC 680.22 requires GFCI protection for pool equipment receptacles, provided by a breaker or receptacle. Question 18. Which of the following is the correct method for bonding a metal water pipe that is used as a grounding electrode? A) Use a 6‑AWG copper jumper at each connection point B) Bond only at the service disconnect C) No bonding required if the pipe is already a grounding electrode D) Bond with a 12‑AWG copper conductor at the nearest accessible point Answer: B Explanation: NEC 250.104(A)(1) requires bonding of the water pipe at the service disconnect only. Question 19. The required ampacity for a 3‑phase, 60‑A feeder supplying a 120/208‑V lighting load using 75 °C rated conductors is: A) 4 AWG copper
Answer: B Explanation: A 30‑A circuit requires at least 8 AWG copper per Table 310.15(B)(16). Question 22. In a commercial building, the required spacing between luminaire mounting brackets on a suspended ceiling is: A) 4 ft B) 6 ft C) 8 ft D) No specific spacing requirement Answer: D Explanation: NEC does not prescribe specific spacing for luminaire brackets; spacing is determined by manufacturer’s instructions and ceiling load capacity. Question 23. The minimum rating for a grounding electrode conductor used with a 400‑A service and copper conductors is: A) 2 AWG B) 4 AWG C) 6 AWG D) 8 AWG Answer: A Explanation: Table 250.66 requires a minimum of 2 AWG copper for a 400‑A service.
Question 24. Which of the following statements about AFCI protection is correct for Kentucky residential dwellings? A) AFCI is required on all 15‑A and 20‑A branch circuits in bedrooms only. B) AFCI is required on all 120‑V, 15‑A and 20‑A circuits throughout the dwelling. C) AFCI is optional for living rooms but mandatory for kitchens. D) AFCI is not required in any location in Kentucky. Answer: B Explanation: NEC 210.12(A) requires AFCI protection on all 120‑V, 15‑A and 20‑A circuits supplying dwelling unit living areas, which Kentucky adopts. Question 25. The required conduit fill for a single 3/4‑in. EMT conduit containing four 2‑AWG THHN conductors is: A) 15 % B) 30 % C) 40 % D) 53 % Answer: B Explanation: For more than two conductors, the maximum fill is 40 % for EMT, but Table 1 in Chapter 9 limits the fill to 30 % for three or more conductors in EMT. Question 26. Which NEC article defines the minimum number of receptacle outlets required in a dwelling unit’s laundry area?
D) 12 in. Answer: B Explanation: NEC 334.30 requires NM cable to be secured within 6 in. of each box. Question 29. For a 120‑V, 15‑A receptacle in a bedroom, the required protection is: A) AFCI only B) GFCI only C) Both AFCI and GFCI D) Neither AFCI nor GFCI required Answer: C Explanation: NEC 210.12(A) requires AFCI, and 210.8(A)(1) requires GFCI for bedroom receptacles. Question 30. The minimum size of a copper equipment grounding conductor for a 30‑A circuit using 10 AWG conductors is: A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: B
Explanation: Table 250.122 indicates a 30‑A circuit requires a minimum 12 AWG copper EGC. Question 31. Which of the following is the correct method for grounding a detached garage’s electrical system? A) Run a separate grounding electrode conductor from the garage to a ground rod at the garage. B) Bond the garage’s metal water pipe to the service grounding electrode. C) Connect the garage’s grounding electrode system to the building’s grounding electrode system with a grounding electrode conductor. D) No grounding required if the garage is supplied by a feeder with an EGC. Answer: C Explanation: NEC 250.32 requires a grounding electrode system for detached structures, bonded to the building’s system via a grounding electrode conductor. Question 32. The maximum number of 14‑AWG conductors allowed in a 1‑in. PVC conduit is: A) 9 B) 12 C) 15 D) 18 Answer: B Explanation: Table 1 in Chapter 9 shows a 1‑in. PVC conduit can hold up to 12 conductors of 14‑AWG size.
B) 3 ft 6 in. C) 4 ft D) No clearance required if the receptacle is GFCI protected Answer: B Explanation: NEC 210.8(A)(10) mandates a minimum of 3 ft 6 in. horizontal clearance from the edge of a bathtub. Question 36. In a commercial building, the required fire‑resistance rating for a conduit passing through a fire‑rated wall is: A) 1 hour B) 2 hours C) Same as the wall rating D) No rating required if conduit is metal Answer: C Explanation: NEC 300.21 requires penetrations to maintain the fire‑rating of the assembly they pass through. Question 37. The maximum allowable voltage drop for a feeder supplying a 10 kW, 240‑V load over 250 ft is: A) 2 % B) 3 % C) 4 %
D) 5 %
Answer: B Explanation: NEC recommends a 3 % maximum voltage drop for feeders. Question 38. Which of the following devices must be installed in a habitable room’s ceiling when the room height exceeds 8 ft? A) Smoke detector B) Carbon monoxide detector C) Both A and B D) Neither A nor B Answer: A Explanation: NEC 210.12 requires smoke detectors in habitable rooms, irrespective of ceiling height. Question 39. The minimum size of a copper grounding electrode conductor for a 600‑A service is: A) 2 AWG B) 1/0 AWG C) 4/0 AWG D) 3/0 AWG Answer: B
Question 42. The required grounding electrode for a metal underground water pipe that is not in direct contact with earth for at least 10 ft is: A) No grounding electrode required B) Add a ground rod at the pipe location C) Use the pipe as the sole grounding electrode D) Bond to a concrete‑encased electrode only Answer: B Explanation: NEC 250.52(A)(3) requires an additional ground rod if the pipe does not meet the 10‑ft earth contact requirement. Question 43. For a 15‑A, 120‑V receptacle in a kitchen, the code requires GFCI protection. Which of the following is an acceptable method? A) Install a GFCI breaker in the panel only B) Install a GFCI receptacle at the outlet only C) Either a GFCI breaker or a GFCI receptacle D) No GFCI required if the receptacle is within 6 ft of a sink Answer: C Explanation: NEC 210.8(A)(6) allows GFCI protection by either a breaker or a receptacle. Question 44. The minimum conduit size for three 4/0 AWG THHN conductors in EMT is: A) 1‑in.
B) 1‑1/4‑in. C) 1‑1/2‑in. D) 2‑in. Answer: B Explanation: Table 1 in Chapter 9 shows 1‑1/4‑in. EMT can accommodate three 4/0 AWG conductors. Question 45. Which of the following is the correct practice for labeling a 240 ‑V, 30‑A circuit that supplies a dishwasher? A) “Dishwasher – 240 V” B) “30 A – Kitchen” C) “Appliance – 30 A” D) No label required Answer: A Explanation: NEC 210.4 requires individual circuit identification, and labeling should indicate the appliance and voltage. Question 46. In Kentucky, the required minimum height for a receptacle in a dwelling’s hallway is: A) 30 in. above the floor B) 36 in. above the floor C) 48 in. above the floor
