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2020 Ultimate Exam
Question 1. Which NEC article defines the term “accessible” as used for equipment? A) Article 100 B) Article 110 C) Article 210 D) Article 250 Answer: A Explanation: Article 100 of the NEC provides definitions for terms used throughout the code, including “accessible.” Question 2. Ohm’s Law is expressed as V = I × R. If a circuit has a voltage of 120 V and a resistance of 30 Ω, what is the current? A) 2 A B) 3 A C) 4 A D) 5 A Answer: B Explanation: I = V / R = 120 V / 30 Ω = 4 A. (Correction: 120/30 = 4 A, thus answer C is correct.) Question 3. In a single-family dwelling, the standard calculation for general lighting load uses which value per square foot? A) 2 VA B) 3 VA C) 4 VA D) 5 VA
2020 Ultimate Exam
Answer: C Explanation: The NEC prescribes 3 VA per square foot for general lighting, but the “Standard” residential load calculation uses 3 VA. However, the “Optional” calculation uses 4 VA per square foot for lighting. The question asks for the standard method, thus answer B. Question 4. The minimum number of 20-ampere branch-circuit receptacles required in a kitchen countertop area is: A) Two B) Three C) Four D) Six Answer: A Explanation: NEC 210.52(C)(1) requires at least two 20-A small-appliance circuits serving the countertop receptacles. Question 5. For a 240-V electric dryer, the required minimum conductor size (copper) for a 30-A circuit is: A) 12 AWG B) 10 AWG C) 8 AWG D) 6 AWG Answer: B Explanation: Table 310.16 shows that 10 AWG copper is rated for 30 A at 60 °C, which is the typical rating for dryer circuits.
2020 Ultimate Exam
Answer: D Explanation: A ground-ring alone is not acceptable as the sole grounding electrode unless it meets specific size and placement requirements; typically a ground-ring must be used in conjunction with another electrode. Question 9. The minimum size of equipment grounding conductor for a 60-A circuit protected by a 60-A breaker (copper) is: A) 12 AWG B) 10 AWG C) 8 AWG D) 6 AWG Answer: B Explanation: Table 250.122 specifies that a 60-A circuit requires a 10 AWG copper equipment grounding conductor. Question 10. When more than three current-carrying conductors are installed in a raceway, the ampacity of each conductor must be derated according to which NEC table? A) Table 310. B) Table 310.15(B)(3)(a) C) Table 310.15(B)(2)(a) D) Table 310.15(B)(4) Answer: B Explanation: Table 310.15(B)(3)(a) provides the adjustment factors for more than three current-carrying conductors in a raceway or cable.
2020 Ultimate Exam
Question 11. The correct burial depth for Type UF cable installed under a residential driveway (no concrete protection) is: A) 6 in. B) 12 in. C) 18 in. D) 24 in. Answer: C Explanation: NEC 300.5(D) requires a minimum burial depth of 24 in. for UF cable under a concrete slab, but 12 in. for UF cable under a driveway without concrete. However, the question specifies “no concrete protection,” so the correct answer is B (12 in.). Question 12. Which conduit material is permitted for direct burial without additional raceway protection? A) EMT B) PVC Schedule 40 C) Rigid Metal Conduit (RMC) D) Flexible Metal Conduit (FMC) Answer: B Explanation: PVC Schedule 40 conduit is rated for direct burial per NEC 352.10. Question 13. The maximum number of 14-AWG conductors that may be placed in a 1/2-in. EMT conduit is: A) 5 B) 6 C) 7
2020 Ultimate Exam
Question 16. For a 120/240-V, 30-A dryer circuit, the required neutral conductor size is: A) 12 AWG copper B) 10 AWG copper C) 8 AWG copper D) No neutral required Answer: D Explanation: Electric dryers are typically 240-V only and do not require a neutral conductor. Question 17. The main bonding jumper in a residential service must be sized to protect which of the following? A) Only the service-entrance conductors B) Only the equipment grounding conductors C) Both the service-entrance conductors and the equipment grounding conductors D) Only the neutral conductor Answer: C Explanation: NEC 250.102(C) requires the main bonding jumper to be sized to protect both the service-entrance conductors and the equipment grounding conductor. Question 18. The maximum allowable voltage drop for feeder circuits feeding a single-family dwelling is: A) 2 % B) 3 % C) 5 %
2020 Ultimate Exam
D) 10 %
Answer: B Explanation: NEC 210.19(A)(1) recommends that feeder voltage drop not exceed 3 % of the nominal voltage. Question 19. An AFCI is required in which of the following residential locations? A) Kitchen countertop receptacles B) Bedroom receptacles C) Bathroom receptacles D) Outdoor receptacles Answer: B Explanation: NEC 210.12(A) requires AFCI protection for all 120-V, single-phase, 15- and 20-A receptacle outlets installed in dwelling unit bedrooms. Question 20. The minimum size of a grounding electrode conductor (GEC) for a 100 - A service using a copper grounding electrode is: A) 10 AWG B) 8 AWG C) 6 AWG D) 4 AWG Answer: B Explanation: Table 250.122 shows that a 100-A service requires an 8 AWG copper GEC. Question 21. Which of the following is NOT a permissible method for grounding a metal water pipe that serves as a grounding electrode?
2020 Ultimate Exam
Explanation: NEC 210.52(G) requires at least one receptacle for each 30 ft² of floor area in garages. Question 24. The minimum conduit fill for a raceway containing three 12-AWG THHN conductors is: A) 10 % B) 20 % C) 30 % D) 40 % Answer: B Explanation: NEC Chapter 9 permits up to 40 % fill for raceways with three or fewer conductors, but the standard practice is to keep fill at or below 40 % of the conduit’s internal cross-sectional area. The correct answer is C (30 %). Question 25. Which of the following devices provides protection against both ground-fault and arc-fault conditions? A) GFCI B) AFCI C) Dual-function AFCI/GFCI D) Surge protector Answer: C Explanation: Dual-function devices combine both GFCI and AFCI protection in a single unit. Question 26. The required size of a grounding electrode conductor for a 200-A service using aluminum conductors is: A) 6 AWG copper
2020 Ultimate Exam
B) 4 AWG copper C) 2 AWG copper D) 1/0 AWG copper Answer: C Explanation: Table 250.122 indicates that a 200-A service using aluminum conductors requires a 2 AWG copper GEC. Question 27. The NEC permits the use of a 20-ampere branch-circuit breaker on a 12-AWG copper conductor when the conductor is rated for 90 °C. This is allowed because: A) The breaker size is limited to 15 A for 12-AWG B) The 90 °C rating can be used for equipment-rated conductors only C) The 90 °C rating can be applied if the termination is also rated for 90 °C D) It is never allowed; 12-AWG is limited to 20 A regardless of temperature rating Answer: C Explanation: NEC 110.14(C) allows use of the 90 °C ampacity for conductors when both the conductor and the termination are rated for 90 °C. Question 28. For a residential lighting circuit using 14-AWG THHN in a conduit, the maximum number of conductors allowed in a 3/4-in. EMT without exceeding the 40 % fill limit is: A) 5 B) 7 C) 9 D) 11 Answer: D
2020 Ultimate Exam
B) Non-IC-rated only C) Both IC-rated and listed for insulation contact D) No special rating required Answer: C Explanation: NEC 410.116 requires recessed fixtures installed in contact with insulation to be IC-rated. Question 32. The minimum size of a grounding electrode conductor for a 150-A service using a concrete-encased electrode (Ufer) is: A) 10 AWG copper B) 8 AWG copper C) 6 AWG copper D) 4 AWG copper Answer: B Explanation: Table 250.122 lists 8 AWG copper for a 150-A service. Question 33. For a 30-amp, 240-V electric water heater, the required branch-circuit conductor size (copper) is: A) 12 AWG B) 10 AWG C) 8 AWG D) 6 AWG Answer: B Explanation: A 30-A circuit requires at least 10 AWG copper per Table 310.16.
2020 Ultimate Exam
Question 34. Which of the following statements about tamper-resistant receptacles (TR) is correct? A) They are required only in kitchens. B) They are required in all 125-V, 15- and 20-A receptacles in dwelling units. C) They are optional for all residential installations. D) They are required only for outdoor receptacles. Answer: B Explanation: NEC 406.12 requires TR receptacles in all 125-V, 15- and 20-A receptacles in dwelling units. Question 35. The maximum number of disconnecting means permitted on a single feeder panel serving a detached garage is: A) One B) Two C) Three D) No limit Answer: A Explanation: NEC 225.31 requires a single disconnecting means for each separate building. Question 36. The required clearance between a pool pump motor and the edge of the pool is: A) 3 ft. B) 5 ft. C) 10 ft. D) No specific clearance required
2020 Ultimate Exam
Question 39. The required AFCI protection for a 20-A, 120-V receptacle circuit in a living room is: A) Not required B) Required only if the circuit feeds a TV C) Required for all 120-V, 15- and 20-A circuits in dwelling unit living areas D) Required only for circuits over 30 A Answer: C Explanation: NEC 210.12(A) requires AFCI protection for all 120-V, 15- and 20-A circuits supplying outlets in dwelling unit living areas, including living rooms. Question 40. Which of the following is a permissible method for protecting a 12 - AWG branch-circuit conductor that runs through a metal conduit exposed to a corrosive environment? A) Use of a larger conductor size B) Application of a corrosion-resistant coating to the conductor C) Use of a listed corrosion-resistant conduit material D) No protection is required Answer: C Explanation: NEC 300.8 requires that metal raceways in corrosive environments be of a corrosion-resistant material (e.g., stainless steel or PVC). Question 41. The minimum required number of receptacles in a bedroom of a single-family dwelling is: A) One B) Two
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C) Three D) Four Answer: A Explanation: NEC 210.52(E)(1) requires at least one receptacle outlet in each bedroom. Question 42. A residential dryer circuit that includes a 120-V control circuit must have a neutral conductor of at least what size? A) 14 AWG copper B) 12 AWG copper C) 10 AWG copper D) No neutral required Answer: B Explanation: If a dryer requires a 120-V control circuit, a neutral is needed and must be sized to handle the control load, typically 12 AWG copper for a 30-A circuit. Question 43. The required minimum burial depth for a PVC conduit containing a feeder to a detached garage is: A) 6 in. B) 12 in. C) 18 in. D) 24 in. Answer: B Explanation: NEC 300.5(D) requires a minimum of 12 in. burial for PVC conduit under a residential driveway or similar area.
2020 Ultimate Exam
Answer: B Explanation: NEC 406.9(A) requires outdoor receptacle enclosures in wet locations to be at least NEMA 3R rated. Question 47. The minimum size of a grounding electrode conductor for a 400-A service using copper conductors is: A) 2 AWG B) 1/0 AWG C) 2/0 AWG D) 4/0 AWG Answer: C Explanation: Table 250.122 specifies 2/0 AWG copper for a 400-A service. Question 48. A 20-amp GFCI breaker installed in a residential panel provides protection for which of the following? A) Only ground-faults B) Only arc-faults C) Both ground-fault and arc-fault protection D) Neither ground-fault nor arc-fault protection Answer: A Explanation: A standard GFCI breaker provides only ground-fault protection; AFCI protection requires a separate AFCI device. Question 49. The NEC requires that a disconnecting means for a residential solar PV system be located: A) Inside the dwelling only
2020 Ultimate Exam
B) Outside the dwelling only C) Either inside or outside, within sight of the inverter D) At the service panel only Answer: C Explanation: NEC 690.13 requires the PV disconnect to be installed within sight of the inverter or listed as remote. Question 50. The minimum ampacity of a feeder conductor supplying a 20-A, 120 - V kitchen small-appliance branch circuit is: A) 15 A B) 20 A C) 25 A D) 30 A Answer: B Explanation: The feeder must be sized to carry the full load of the branch circuit; thus a 20-A conductor is the minimum. Question 51. The NEC permits the use of aluminum conductors for branch-circuit wiring in residential dwellings provided that: A) They are used only for 240-V circuits B) They are marked with “AL” and have proper terminations rated for aluminum C) They are larger than copper conductors by one size D) They are only used in conduit Answer: B Explanation: NEC 310.15(B)(16) allows aluminum conductors if they are identified as “AL” and are terminated in equipment rated for aluminum.
