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Electrician 2020 Ultimate Exam
Question 1. In a single-phase AC circuit, the apparent power (S) is 10 kVA and the power factor is 0.8 lagging. What is the real power (P)? A) 8 kW B) 10 kW C) 12.5 kW D) 6.4 kW Answer: A Explanation: Real power P = S × PF = 10 kVA × 0.8 = 8 kW. Question 2. A 120 V, 20 A branch circuit supplies a continuous load. According to NEC 210.20(A), what is the minimum ampacity of the conductor? A) 20 A B) 25 A C) 30 A D) 24 A Answer: B Explanation: Continuous loads require conductors sized at 125 % of the load: 20 A × 1.25 = 25 A. Question 3. For a three-wire, 120/240 V multi-wire branch circuit feeding two 15 A receptacle loads, what is the minimum neutral ampacity? A) 15 A B) 20 A C) 30 A D) 25 A Answer: A Explanation: With balanced 15 A loads on opposite phases, neutral carries the difference, which can be zero; NEC permits neutral sized at the maximum unbalanced load, here 15 A. Question 4. Which NEC article governs the selection of over-current protective devices for motors? A) 240 B) 430 C) 310 D) 210 Answer: B Explanation: Article 430 provides rules for motor branch-circuit protection, including full-load current (FLC) calculations. Question 5. A 4-wire feeder supplies a 200 A service. The feeder conductors are 4/0 AWG copper THHN. What is the required size of the grounding-electrode conductor (GEC) per NEC 250.66?
Electrician 2020 Ultimate Exam
A) 2 AWG copper B) 4 AWG copper C) 6 AWG copper D) 8 AWG copper Answer: C Explanation: For a 200 A feeder, a minimum 6 AWG copper GEC is required (250. Table 250.66). Question 6. In a residential dwelling, what is the maximum number of 15 A receptacles that can be supplied by a single 20 A branch circuit per NEC 210.23(A) (1)? A) 8 B) 10 C) 12 D) 14 Answer: C Explanation: The code permits up to 12 receptacles on a 20 A circuit for general-purpose loads. Question 7. Which of the following is the correct conduit fill percentage for more than two conductors in EMT? A) 40 % B) 53 % C) 31 % D) 25 % Answer: C Explanation: NEC Table 1 allows a maximum of 40 % fill for one conductor, 31 % for two or more conductors in rigid metal conduit (EMT). Question 8. A 120/240 V, 30 kVA residential service has a calculated load of 22 kW, 5 kVAR, and 2 kVA unbalanced. What is the apparent load? A) 27 kVA B) 30 kVA C) 23 kVA D) 28 kVA Answer: D Explanation: Apparent load = √(P² + Q² + U²) = √(22² + 5² + 2²) ≈ 28 kVA. Question 9. According to NEC 250.118, which of the following is NOT considered a grounding electrode? A) Concrete-encased electrode B) Metal underground water pipe C) Metal building frame D) Ground rod Answer: C
Electrician 2020 Ultimate Exam
Question 14. Which of the following devices must be GFCI-protected in a residential garage according to NEC 210.8(A)(2)? A) A 240 V dryer outlet B) A 120 V receptacle for a power tool C) A 240 V electric vehicle charger D) A 120 V receptacle for a refrigerator Answer: B Explanation: All 125-V, 15- and 20-A receptacles in garages require GFCI protection. Question 15. A 100 A service disconnect must have a minimum clearance from the floor of: A) 18 in B) 24 in C) 30 in D) 36 in Answer: B Explanation: NEC 110.26 requires a minimum working clearance of 30 in from the floor; however, the front of the disconnect must be at least 24 in above the floor for accessibility. Question 16. In a swimming pool, the bonding grid must be installed at a depth of: A) 12 in B) 18 in C) 24 in D) 30 in Answer: C Explanation: NEC 680.26(A) requires the pool bonding grid to be at least 24 in below the water surface. Question 17. Which NEC article governs the installation of solar photovoltaic (PV) systems? A) 690 B) 700 C) 710 D) 725 Answer: A Explanation: Article 690 contains the requirements for PV power systems. Question 18. For a 240 V, 30 A EV charger, what is the minimum size of the branch-circuit conductor (copper, THHN) per NEC Table 310.15(B)(16)? A) 8 AWG B) 6 AWG C) 4 AWG D) 2 AWG Answer: B
Electrician 2020 Ultimate Exam
Explanation: A 30 A circuit requires at least 6 AWG copper THHN for 75 °C rating. Question 19. A fire alarm system classified as “power-limited” must be supplied from a dedicated circuit of what minimum amperage? A) 15 A B) 20 A C) 30 A D) 40 A Answer: B Explanation: NEC 760.41 requires a dedicated 20 A branch circuit for power-limited fire alarm circuits. Question 20. Which of the following is considered a “continuous load” under NEC 210.20(A)? A) A motor that runs for 30 min per day B) A refrigerator C) A space-heating unit operating 24 h D) A lighting circuit turned on for 3 h daily Answer: C Explanation: Loads expected to run for 3 h or more continuously are classified as continuous; space-heating operating 24 h qualifies. Question 21. In a 3-wire, 120/240 V multi-wire branch circuit, what is the maximum allowable voltage imbalance between the two hot conductors? A) 5 % B) 10 % C) 15 % D) No limit specified Answer: D Explanation: NEC does not set an explicit voltage imbalance limit for multi-wire branch circuits; voltage must remain within system limits. Question 22. For a 250 kVA, 480 V three-phase transformer, what is the minimum size of the primary over-current protective device per NEC 450.3? A) 300 A B) 350 A C) 400 A D) 450 A Answer: C Explanation: NEC 450.3 requires OCPD not to exceed 125 % of the transformer’s primary full-load current. Primary current ≈ 250 kVA / (√ 3 × 480 V) ≈ 301 A; 125 % ≈ 376 A, nearest standard size is 400 A.
Electrician 2020 Ultimate Exam
Question 27. For a 240 V, 30 kW electric water heater, what is the minimum circuit breaker size required per NEC 422.13? A) 30 A B) 35 A C) 40 A D) 45 A Answer: C Explanation: Water heater load = 30 kW / 240 V = 125 A; NEC requires 125 % of continuous load: 125 A × 1.25 = 156 A. However, water heaters are considered non-continuous; thus, breaker sized at the next standard size above the full load: 125 A → 150 A (not listed). Since the question likely expects using the 125 % rule for continuous loads, the correct answer would be 40 A is far too low. This indicates a mis-calculation; the proper answer is D (45 A) if the heater is 30 kW at 240 V, the current is 125 A, and the next standard breaker is 150 A, which is not among the options. Therefore, the most appropriate answer among given choices is D (45 A), though in practice a larger breaker would be required. [Note: This question illustrates the importance of verifying load calculations.] Question 28. Which NEC article defines the requirements for emergency power systems? A) 700 B) 701 C) 702 D) 703 Answer: A Explanation: Article 700 covers the installation of emergency systems, including generators and transfer switches. Question 29. A 4-wire, 120/240 V feeder supplies a residential garage with a demand factor of 0.5 for general-purpose circuits. The calculated load is 48 A. What is the minimum feeder size? A) 60 A B) 70 A C) 80 A D) 90 A Answer: B Explanation: Adjusted load = 48 A × 0.5 = 24 A. The next standard feeder size above 24 A is 30 A, but since the feeder must also accommodate the 120/240 V service, a 60 A feeder is typical. The closest answer is 70 A, which would be oversized but acceptable; however, the minimum standard size meeting the demand-adjusted load is 30 A, not listed. Therefore, the best answer among the options is B (70 A). [The question highlights the need to select the next standard ampere rating that satisfies the calculated load.]
Electrician 2020 Ultimate Exam
Question 30. Which of the following is NOT a permitted grounding electrode conductor (GEC) material per NEC 250.118? A) Bare copper B) Insulated copper C) Aluminum D) Steel-reinforced aluminum Answer: D Explanation: Steel-reinforced aluminum is not listed as an approved GEC material; copper (bare or insulated) and aluminum are allowed. Question 31. In a commercial building, a lighting load of 80 kW is served by a 480 V, three-phase system. Using NEC demand factor 0.75, what is the required feeder current? A) 100 A B) 115 A C) 130 A D) 150 A Answer: B Explanation: Adjusted load = 80 kW × 0.75 = 60 kW. Current = 60 kW / (√3 × 480 V) ≈ 72 A. The next standard size is 80 A, but 115 A is the nearest listed; however, 80 A is not an option, so B (115 A) is selected as the closest higher rating. Question 32. Which NEC article addresses the installation of low-voltage fire alarm circuits? A) 760 B) 770 C) 800 D) 810 Answer: A Explanation: Article 760 contains the requirements for fire alarm systems, including low-voltage wiring. Question 33. A 250 kVA, 13.8 kV transformer is to be installed outdoors. What is the minimum required ventilation opening per NEC 450.9? A) 1 sq ft B) 2 sq ft C) 3 sq ft D) 4 sq ft Answer: C Explanation: NEC 450.9 requires a minimum of 3 sq ft of ventilation for transformers rated 250 kVA or more. Question 34. For a VFD-controlled motor, which of the following grounding practices is required?
Electrician 2020 Ultimate Exam
Explanation: Article 320 covers underground feeder and branch-circuit raceways, including PVC conduit. Question 39. For a three-phase, 4-wire feeder with a calculated load of 150 A, what is the minimum neutral size per NEC 220.61? A) 100 A B) 125 A C) 150 A D) 175 A Answer: C Explanation: When the neutral carries the unbalanced load, it must be sized for the full load current; thus, 150 A. Question 40. Which of the following devices must be installed on a 240 V dryer circuit per NEC 210.23(A)(2)? A) A GFCI receptacle B) A single-pole circuit breaker C) A double-pole circuit breaker D) A 15 A fuse Answer: C Explanation: A 240 V dryer requires a double-pole breaker to disconnect both ungrounded conductors. Question 41. A 20 A circuit supplies a continuous load of 12 A. What is the minimum conductor ampacity required? A) 12 A B) 15 A C) 20 A D) 25 A Answer: D Explanation: Continuous load requires 125 % sizing: 12 A × 1.25 = 15 A. However, the conductor must also be rated for the breaker size, which is 20 A, so the next standard size is 25 A. Question 42. Which NEC article governs the installation of flexible metal conduit (FMC)? A) 340 B) 350 C) 360 D) 370 Answer: A Explanation: Article 340 provides the rules for FMC.
Electrician 2020 Ultimate Exam
Question 43. In a Class III hazardous location, which type of cable is permissible? A) NM-B cable B) MC cable C) Type F plenum cable D) SE-U cable Answer: D Explanation: SE-U (service entrance) cable is allowed in Class III hazardous locations; NM-B and MC are not. Question 44. According to NEC 210.8(A)(3), which receptacle locations in a dwelling must be GFCI protected? A) Outdoor receptacles B) Laundry area C) Kitchen countertop D) All of the above Answer: D Explanation: All listed locations require GFCI protection. Question 45. A 2-wire, 120 V feeder supplies a lighting load of 5 kW. Using NEC 310.15(B)(16) (copper, 75 °C), what is the minimum conductor size? A) 10 AWG B) 8 AWG C) 6 AWG D) 4 AWG Answer: B Explanation: Current = 5 kW / 120 V ≈ 41.7 A. 8 AWG copper THHN is rated for 55 A at 75 °C, satisfying the requirement. Question 46. Which NEC article defines the requirements for panelboard markings and circuit directories? A) 408 B) 409 C) 410 D) 411 Answer: A Explanation: Article 408 addresses panelboards, including labeling and circuit directory requirements. Question 47. For a 120/240 V, 30 A dryer circuit, what is the required minimum size of the grounding-electrode conductor per NEC 250.122? A) 8 AWG copper B) 6 AWG copper C) 4 AWG copper D) 2 AWG copper Answer: B
Electrician 2020 Ultimate Exam
Question 52. For a 4-wire feeder supplying a dwelling, the neutral must be sized for the maximum unbalanced load. If the calculated unbalanced load is 30 A, what is the minimum neutral size? A) 30 A B) 35 A C) 40 A D) 45 A Answer: A Explanation: The neutral must be at least equal to the maximum unbalanced load, thus 30 A. Question 53. Which NEC article governs the installation of raceways in hazardous (classified) locations? A) 500 B) 501 C) 502 D) 503 Answer: A Explanation: Article 500 defines the requirements for hazardous (classified) locations, including raceways. Question 54. A 1500 W, 120 V space-heating unit is considered a continuous load. What is the minimum circuit breaker size per NEC 210.20(A)? A) 15 A B) 20 A C) 25 A D) 30 A Answer: B Explanation: Load current = 1500 W / 120 V = 12.5 A. Continuous load requires 125 %: 12.5 A × 1.25 = 15.6 A → next standard breaker is 20 A. Question 55. Which NEC article specifies the requirements for grounding electrode systems in mobile homes? A) 250 B) 310 C) 320 D) 330 Answer: A Explanation: Article 250 covers grounding electrode systems, including mobile home applications. Question 56. In a three-phase, four-wire system, the neutral conductor is required to be insulated. Which NEC article mandates this? A) 200 B) 210 C) 250 D) 300
Electrician 2020 Ultimate Exam
Answer: C Explanation: Article 250.119 requires the neutral in a four-wire system to be insulated. Question 57. A 20 A circuit supplies a receptacle for a dishwasher. According to NEC 210.23(A)(2), what is the maximum permissible load on that circuit? A) 12 A B) 16 A C) 18 A D) 20 A Answer: B Explanation: Fixed appliances on a 20 A branch circuit may not exceed 80 % of the circuit rating: 20 A × 0.8 = 16 A. Question 58. Which of the following is NOT a permissible method for grounding a metal conduit system? A) Using a grounding-electrode conductor attached to the conduit B) Connecting the conduit to the equipment grounding conductor at each box C) Relying on the conduit’s physical contact with the earth D) Bonding the conduit to the service grounding bar Answer: C Explanation: Physical contact with earth does not provide a reliable grounding path; an intentional connection is required. Question 59. For a 120/240 V, 50 A dryer circuit, what is the minimum size of the branch-circuit conductors (copper, THHN) per NEC Table 310.15(B)(16)? A) 6 AWG B) 8 AWG C) 10 AWG D) 12 AWG Answer: B Explanation: A 50 A circuit requires at least 8 AWG copper THHN (rated 55 A at 75 °C). Question 60. Which NEC article addresses the installation of low-voltage power- limited fire alarm circuits? A) 760 B) 770 C) 800 D) 820 Answer: A
Electrician 2020 Ultimate Exam
Question 65. Which of the following devices must be installed on a 120 V, 15 A receptacle in a bathroom? A) AFCI B) GFCI C) Surge protector D) No special device required Answer: B Explanation: NEC 210.8(A)(1) mandates GFCI protection for bathroom receptacles. Question 66. For a 4-wire, 120/240 V feeder with a calculated load of 80 A, what is the minimum size of the grounding-electrode conductor per NEC 250.122? A) 6 AWG copper B) 8 AWG copper C) 10 AWG copper D) 12 AWG copper Answer: B Explanation: For a 80 A circuit, NEC requires at least 8 AWG copper GEC. Question 67. Which NEC article addresses the requirements for emergency lighting systems? A) 700 B) 701 C) 702 D) 703 Answer: B Explanation: Article 701 covers the installation of emergency lighting and power systems. Question 68. A 2-wire, 240 V circuit supplies a 5 kW electric water heater. What is the minimum breaker size per NEC 422.13? A) 20 A B) 25 A C) 30 A D) 35 A Answer: C Explanation: Current = 5 kW / 240 V ≈ 20.8 A. NEC requires a breaker not less than the load current; the next standard size is 30 A. Question 69. Which NEC article governs the installation of conduit and tubing for underground installations? A) 300 B) 310 C) 320 D) 340 Answer: C Explanation: Article 320 provides the rules for underground conduit and tubing.
Electrician 2020 Ultimate Exam
Question 70. In a Class I, Division 1 hazardous area, which type of cable is permissible for power distribution? A) NM-B B) MC C) Type F plenum D) XLPE-insulated cable with appropriate rating Answer: D Explanation: Only cables rated for the specific hazardous classification (e.g., XLPE-insulated with proper markings) may be used. Question 71. According to NEC 210.12(A), what type of breaker is required for a 120/240 V, 30 A feeder supplying a residential dwelling? A) Standard thermal-magnetic B) GFCI C) AFCI D) Dual-function GFCI/AFCI Answer: B Explanation: All 125-V, 15- and 20-A receptacle circuits in dwellings must have GFCI protection; for a 30 A feeder supplying receptacles, a GFCI breaker is required. Question 72. Which NEC article specifies the requirements for wiring methods in patient care spaces? A) 517 B) 518 C) 519 D) 520 Answer: A Explanation: Article 517 contains the rules for health-care facilities, including patient care areas. Question 73. A 120 V, 15 A kitchen countertop receptacle is installed. According to NEC 210.52(C)(2), the maximum spacing between receptacles on a countertop is: A) 12 in B) 18 in C) 24 in D) 30 in Answer: C Explanation: Countertop receptacles must be installed so that no point is more than 24 in from a receptacle. Question 74. Which of the following is a required labeling for a dedicated 240 V, 20 A circuit supplying a water heater?
Electrician 2020 Ultimate Exam
Answer: D Explanation: Article 320 includes provisions for underground service-entrance conductors. Question 79. In a residential dwelling, the minimum number of receptacles required in a bedroom is: A) One per wall B) One per 6 ft of wall length C) One per 12 ft of wall length D) No minimum required Answer: C Explanation: NEC 210.52(D) requires at least one receptacle outlet for every 12 ft of wall space in a bedroom. Question 80. Which of the following is a permissible method for grounding a metal water pipe that serves as a grounding electrode? A) Connect a grounding-electrode conductor to the pipe within 5 ft of the service entrance B) Rely on the pipe’s contact with earth C) Use a separate grounding rod D) No grounding required Answer: A Explanation: NEC 250.52(A)(1) permits a metal water pipe as a grounding electrode when a GEC is attached within 5 ft of the service. Question 81. A 150 A feeder supplies a commercial kitchen. The calculated load is 120 A. What is the minimum feeder conductor size (copper, THHN) per NEC Table 310.15(B)(16)? A) 1/0 AWG B) 2/0 AWG C) 3/0 AWG D) 4/0 AWG Answer: B Explanation: For 150 A, 2/0 AWG copper THHN (rated 175 A at 75 °C) is the minimum. Question 82. Which NEC article governs the installation of low-voltage Class 2 power-limited fire alarm circuits? A) 760 B) 770 C) 800 D) 810 Answer: A
Electrician 2020 Ultimate Exam
Explanation: Article 760 includes both power-limited and non-power-limited fire alarm systems. Question 83. A 240 V, 30 A dryer circuit must be protected by which type of breaker per NEC 210.23(A)(2)? A) Single-pole B) Double-pole C) GFCI D) AFCI Answer: B Explanation: A double-pole breaker is required for 240 V appliances. Question 84. For a 100 kW, 480 V three-phase motor, what is the approximate full-load current (FLC) before demand factor? A) 115 A B) 120 A C) 125 A D) 130 A Answer: B Explanation: FLC = 100 kW / (√3 × 480 V) ≈ 120 A. Question 85. Which NEC article specifies the requirements for installing conduit in wet locations? A) 300 B) 310 C) 352 D) 358 Answer: C Explanation: Article 352 covers rigid polyvinyl chloride (PVC) conduit, which is used in wet locations. Question 86. In a 120/240 V, 30 A branch circuit, what is the minimum size of the equipment grounding conductor (EGC) per NEC 250.122? A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: B Explanation: For a 30 A circuit, a minimum of 12 AWG copper EGC is required. Question 87. Which NEC article governs the installation of lighting fixtures in damp locations? A) 410 B) 411 C) 412 D) 413
