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Practice Exam
Question 1. Which NEC article establishes the purpose, scope, and arrangement of the Code? A) Article 90 B) Article 110 C) Article 100 D) Article 210 Answer: A Explanation: Article 90 provides the purpose, scope, and organization of the NEC, while Article 110 deals with requirements for equipment. Question 2. In NEC terminology, a “branch circuit” is defined as: A) A circuit that supplies power to a sub‑panel B) A circuit that originates at a service disconnect and supplies only one device C) A circuit that originates at a feeder or service and supplies loads D) A circuit that supplies only lighting loads Answer: C Explanation: A branch circuit starts at a feeder or service and supplies one or more loads; it does not feed other panels. Question 3. Which of the following is NOT a requirement for Lockout/Tagout (LOTO) in residential work? A) Isolating the circuit breaker before work begins B) Verifying the absence of voltage after lockout C) Using a lock that is keyed to the circuit’s breaker handle D) Posting a warning sign on the work area Answer: C
Practice Exam
Explanation: LOTO locks are not required to be keyed to the breaker; any approved lock that prevents re‑energization is acceptable. Question 4. OSHA requires which of the following PPE when working on live circuits up to 600 V? A) Rubber‑soled shoes only B) Insulated gloves rated for the voltage C) Flame‑resistant clothing only D) No PPE if the circuit is de‑energized Answer: B Explanation: Insulated gloves rated for the voltage level are mandatory when there is a risk of electrical shock. Question 5. According to NEC Article 220, the general lighting load for a dwelling unit is calculated as: A) 3 VA per square foot B) 5 VA per square foot C) 10 VA per square foot D) 15 VA per square foot Answer: B Explanation: The NEC requires 3 VA per square foot for general lighting, plus 1.5 VA per square foot for small‑appliance circuits; many practice problems use 5 VA total. Question 6. A 1500 W electric dryer is supplied from a 30 A branch circuit. Which demand factor applies per NEC 220.55? A) 100 %
Practice Exam
Question 9. Which overcurrent protective device rating is NOT permitted for a 20 A branch circuit supplying receptacles? A) 15 A B) 20 A C) 25 A D) 30 A Answer: D Explanation: The OCPD must not exceed the circuit’s ampacity; 30 A would be too large for a 20 A circuit. Question 10. The main bonding jumper in a residential service is required to be sized based on: A) The largest feeder conductor size B) The service‑entrance conductor size C) The smallest grounding electrode conductor size D) The rating of the main breaker Answer: B Explanation: NEC 250.102(C) requires the main bonding jumper to be sized as per Table 250.102(C) based on the service‑entrance conductor. Question 11. Which of the following is considered a grounding electrode? A) A metal water pipe that is not bonded to the GES B) A concrete‑encased electrode (Ufer) C) An isolated steel conduit run D) A copper bonding jumper inside the panel
Practice Exam
Answer: B Explanation: A concrete‑encased electrode is an acceptable grounding electrode per NEC 250.52(A)(3). Question 12. The minimum size of a grounding electrode conductor (GEC) for a 100 A service using copper is: A) #12 AWG B) #10 AWG C) #8 AWG D) #6 AWG Answer: C Explanation: Table 250.66 shows #8 AWG copper is required for a 100 A service. Question 13. Which type of cable is prohibited for installation in a wet location? A) NM‑B (Romex) B) UF‑B C) MC‑C D) THWN‑2 conductors in conduit Answer: A Explanation: NM‑B is rated for dry locations only; UF‑B is approved for wet locations. Question 14. When securing NM cable, the maximum distance between supports is: A) 3 ft B) 4 ft C) 6 ft
Practice Exam
B) 20 %
C) 40 %
D) 53 %
Answer: C Explanation: For three conductors, the conduit fill limit is 40 % of the internal cross‑sectional area (NEC Table 1, Chapter 9). Question 18. A device box must have a minimum interior volume of 20 cu in. for a single 14 AWG conductor with a device. Which box size meets this requirement? A) 18 cu in. B) 20 cu in. C) 22 cu in. D) 30 cu in. Answer: B Explanation: The required volume matches the box’s listed volume; 20 cu in. satisfies the minimum. Question 19. Which of the following receptacle locations is required by NEC 210.52 in a kitchen? A) Only above the countertop B) One receptacle on each wall of the kitchen C) At least one receptacle on each countertop island with a minimum of 12 in. clearance from the edge D) Receptacles are not required in the kitchen Answer: C
Practice Exam
Explanation: NEC 210.52(C) requires at least one receptacle on each countertop island or peninsula, placed no more than 12 in. from the edge. Question 20. Ground‑Fault Circuit‑Interrupter (GFCI) protection is mandatory for which of the following areas? A) Living room outlets B) Outdoor receptacles C) Bedroom ceiling fans D) Kitchen under‑cabinet lighting Answer: B Explanation: NEC 210.8(A)(3) requires GFCI protection for all outdoor receptacles. Question 21. Arc‑Fault Circuit‑Interrupter (AFCI) protection is required in which dwelling‑unit area? A) Garages only B) Bedrooms and living rooms C) Bathrooms only D) Outdoor decks Answer: B Explanation: NEC 210.12(A) mandates AFCI protection for all 120‑V, 15‑ and 20‑A branch circuits supplying outlets in bedrooms, living rooms, and other dwelling areas. Question 22. The maximum height for a standard receptacle box in a residential kitchen is: A) 18 in. above the floor B) 30 in. above the floor C) 48 in. above the floor
Practice Exam
B) Central air‑conditioning unit C) Electric water heater D) Electric dryer Answer: B Explanation: Central air‑conditioning units are typically cord‑and‑plug connected; they can share a branch circuit if the load permits. Question 26. For a fixed electric baseboard heater rated at 2500 W, the required branch‑circuit breaker size is: A) 15 A B) 20 A C) 25 A D) 30 A Answer: B Explanation: 2500 W ÷ 240 V = 10.4 A; applying the 125 % rule for continuous loads yields 13 A, so a 20 A breaker is the next standard size. Question 27. Which NEC article governs the installation of swimming pools and hot tubs? A) Article 210 B) Article 250 C) Article 680 D) Article 690 Answer: C Explanation: Article 680 specifically addresses swimming pools, fountains, and similar installations.
Practice Exam
Question 28. All pool pump motors must be protected by a GFCI device located: A) At the nearest convenient outlet B) On the pump motor itself C) At the feeder disconnect within 6 ft of the pool water’s edge D) No GFCI is required for pool pumps Answer: C Explanation: NEC 680.22(A) requires GFCI protection for pool pump motors, located at the feeder disconnect not more than 6 ft from the water’s edge. Question 29. The minimum clearance for overhead conductors serving a pool within the pool’s “clearance zone” is: A) 6 ft above the water surface B) 8 ft above the water surface C) 10 ft above the water surface D) 12 ft above the water surface Answer: C Explanation: NEC 680.24 requires a minimum of 10 ft clearance for overhead conductors over the pool water. Question 30. In a detached garage, the minimum number of 120‑V 20‑A branch circuits required by NEC 210.11(C)(4) is: A) One B) Two C) Three D) Four Answer: B
Practice Exam
B) 1 in. C) 2 in. D) 4 in. Answer: B Explanation: NEC 800.133(A) requires at least 1 in. separation between power conductors and communications cables unless the cables are listed for the purpose. Question 34. The permissible ampacity for a 12 AWG copper conductor with 75 °C insulation in a raceway with an ambient temperature of 35 °C is: A) 20 A B) 25 A C) 30 A D) 35 A Answer: B Explanation: Table 310.15(B)(16) lists 25 A for 12 AWG at 75 °C; the ambient temperature correction factor (0.94 for 35 °C) still yields a value above 20 A, so 25 A is permitted. Question 35. Which of the following is the correct method for grounding a metal conduit that serves as the equipment grounding conductor? A) Connect a separate grounding wire to the conduit every 10 ft B) Use a bonding jumper to the grounding electrode system at each end C) Bond the conduit to the panel’s grounding bus bar at the source only D) No bonding is required if the conduit is continuous Answer: C Explanation: NEC 250.118 allows the metal conduit to serve as an EGC when it is bonded to the grounding bus at the panel; additional bonds are not required if the conduit is continuous.
Practice Exam
Question 36. Which box fill calculation is correct for a single‑gang device box containing one 14 AWG switch and two 14 AWG conductors? A) 2 cu in. (device) + 2 cu in. (each conductor) = 6 cu in. B) 2 cu in. (device) + 1 cu in. (each conductor) = 4 cu in. C) 2 cu in. (device) + 2 cu in. (each conductor) = 8 cu in. D) 2 cu in. (device) + 2 cu in. (each conductor) = 4 cu in. Answer: B Explanation: Each insulated conductor counts as 1 cu in. (for 14 AWG), the device counts as 2 cu in.; total = 2 + 1 + 1 = 4 cu in. Question 37. According to NEC, a receptacle installed in a bathroom must be GFCI protected and located: A) Within 3 ft of the sink B) No more than 6 ft from the bathtub edge C) At any height as long as it is GFCI protected D) Directly above the vanity mirror Answer: C Explanation: NEC 210.8(A)(1) requires all bathroom receptacles to be GFCI protected, but does not prescribe a specific location. Question 38. Which of the following is true regarding the use of “dual‑rated” (15 A/20 A) receptacles? A) They can be installed on any 15 A circuit B) They must be installed only on 20 A circuits C) They are permitted on both 15 A and 20 A circuits
Practice Exam
A) Using only tape at each end B) Installing a support strap every 3 ft C) Securing the conduit to the building structure every 10 ft D) No support is required for rigid metal conduit Answer: C Explanation: NEC 358.30 requires RMC to be supported and secured within 3 ft of each termination and at intervals not exceeding 10 ft. Question 42. In a residential kitchen, the countertop receptacle spacing requirement is: A) No more than 2 ft apart B) No more than 4 ft apart C) No more than 6 ft apart D) No more than 8 ft apart Answer: B Explanation: NEC 210.52(C)(1) mandates receptacles on countertops be placed so that no point along the countertop is more than 24 in. (2 ft) from a receptacle; this translates to a maximum spacing of 4 ft between receptacles. Question 43. Which device is required to protect a 120/240‑V, 30‑A dryer circuit from ground faults? A) A standard 30‑A circuit breaker B) A GFCI breaker sized for 30 A C) A 15‑A GFCI receptacle D) No GFCI protection is required for dryers Answer: B
Practice Exam
Explanation: NEC 210.8(A)(2) requires GFCI protection for dryer circuits if the dryer is located in a garage or unfinished basement; a 30‑A GFCI breaker provides the necessary protection. Question 44. When installing a new service entrance, the service disconnect must be located: A) Inside the building only B) Outside the building only C) Either inside or outside, but within sight of the service entrance D) At any location convenient to the homeowner Answer: C Explanation: NEC 230.71 requires the service disconnect to be installed either inside or outside the building but within sight and not more than 6 ft from the service entrance. Question 45. The maximum number of conductors allowed in a 1‑in. PVC conduit for 12 AWG THHN is: A) 6 B) 8 C) 10 D) 12 Answer: C Explanation: Using the 40 % fill rule and the conduit’s internal area, a 1‑in. PVC conduit can accommodate up to 10 12 AWG THHN conductors. Question 46. Which of the following statements about “readily accessible” equipment is correct? A) The equipment must be operable without the use of tools
Practice Exam
A) 30 in. B) 48 in. C) 56 in. D) 72 in. Answer: B Explanation: NEC 210.52(B) requires garage receptacles to be installed not higher than 48 in. above the floor. Question 50. In a residential basement, a dedicated 20‑A circuit is required for: A) All lighting fixtures B) All receptacles C) A bathroom vanity outlet D) A single 120‑V receptacle for a workstation Answer: C Explanation: NEC 210.11(C)(1) mandates a dedicated 20‑A branch circuit for bathroom vanity outlets. Question 51. The NEC permits the use of “flexible metal conduit” (FMC) for which of the following applications? A) Underground burial deeper than 24 in. B) Direct burial in concrete C) Installation in wet locations with proper fittings D) As a permanent raceway for high‑temperature conductors Answer: C Explanation: FMC is allowed in wet locations when equipped with listed fittings and proper corrosion protection.
Practice Exam
Question 52. Which of the following is the correct method to calculate the required box volume for a device box containing three 12 AWG conductors and one duplex receptacle? A) 2 cu in. (receptacle) + 2 cu in. (each conductor) = 8 cu in. B) 2 cu in. (receptacle) + 1 cu in. (each conductor) = 5 cu in. C) 2 cu in. (receptacle) + 1 cu in. (each conductor) = 4 cu in. D) 2 cu in. (receptacle) + 2 cu in. (each conductor) = 6 cu in. Answer: B Explanation: Each 12 AWG conductor counts as 1 cu in.; the duplex receptacle counts as 2 cu in.; total = 2 + 1 + 1 + 1 = 5 cu in. Question 53. The required minimum clearance between a residential service disconnect and a water pipe that serves as a grounding electrode is: A) 0 in. (they may touch) B) 1 in. C) 2 in. D) 4 in. Answer: A Explanation: NEC 250.68(A) allows the grounding electrode conductor to be connected to a water pipe without a required clearance. Question 54. When a circuit is required to be “listed” for a specific use, it means: A) The manufacturer has approved the product for that use after testing B) The product is inexpensive and readily available C) The product is made of copper only D) The product can be installed by an unqualified person
