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General 2020 Code Ultimate Exam
Question 1. Which NEC article defines the required clearances for service drops and lateral conductors? A) Article 230 B) Article 250 C) Article 310 D) Article 110 Answer: A Explanation: Article 230 of the 2020 NEC covers service-entrance conductors, including location, height, and clearances for service drops and laterals. Question 2. The “Six Switch Rule” for service disconnecting means applies to which type of dwelling? A) One-family dwellings only B) Two-family dwellings only C) Both one- and two-family dwellings D) Multi-family dwellings of three or more units Answer: C Explanation: The Six Switch Rule, found in Article 230.71, permits a single disconnecting means to serve up to six switches or circuit breakers in one- and two-family dwellings. Question 3. Under the 2020 NEC, an exterior emergency disconnect for a one-family dwelling must be installed at a maximum height of: A) 6 ft above grade B) 8 ft above grade C) 10 ft above grade D) 12 ft above grade Answer: B Explanation: NEC 230.71(E) requires exterior emergency disconnects to be installed not higher than 8 ft above the finished grade. Question 4. When sizing a main service fuse, which factor must be considered to ensure coordination with downstream overcurrent devices? A) Voltage rating of the service entrance conductors
General 2020 Code Ultimate Exam
B) Maximum fault current at the service point C) Length of the service conductors D) Number of branch circuits supplied Answer: B Explanation: The maximum available fault current determines the interrupting rating required for the service fuse or breaker to safely clear a fault without damage. Question 5. Table 250.66 is used to determine the size of which component? A) Grounding electrode conductor (GEC) B) Service-entrance conductor C) Equipment grounding conductor (EGC) D) Neutral conductor size Answer: A Explanation: Table 250.66 provides the minimum size of the grounding electrode conductor based on the size of the service-entrance conductors. Question 6. Which of the following is NOT an acceptable grounding electrode for a residential service? A) Concrete-encased electrode B) Metal underground water pipe C) Ground-rod system of 2 × 8 ft rods D) Plastic conduit used as a raceway Answer: D Explanation: Plastic conduit cannot serve as a grounding electrode because it is non-conductive. Question 7. When a disconnect is installed on the supply side of the service, which NEC article governs its grounding? A) Article 250. B) Article 250. C) Article 250.102(C) D) Article 250.102(D)
General 2020 Code Ultimate Exam
Question 11. Which article now contains the requirements for surge protective devices (SPDs) in the 2020 NEC? A) Article 240 B) Article 280 C) Article 242 D) Article 300 Answer: C Explanation: Article 242 (formerly part of Article 280) now governs the installation of surge protective devices. Question 12. The standard ampere rating for a non-time-delay circuit breaker used on a 120/240-V residential branch circuit is: A) 15 A B) 20 A C) 30 A D) 40 A Answer: B Explanation: The most common residential branch-circuit breaker rating is 20 A for 120/240-V circuits. Question 13. Which of the following is a required protection for conductors in a raceway that passes through a concrete slab? A) PVC conduit only B) Rigid metal conduit (RMC) only C) Any raceway with a listed conduit body D) A listed conduit system with proper support and protection from physical damage Answer: D Explanation: NEC requires raceways in concrete to be protected from physical damage, which can be achieved with any listed conduit system meeting installation requirements.
General 2020 Code Ultimate Exam
Question 14. Demand factors for lighting in a commercial office space are applied to: A) The total connected load of all lighting fixtures B) The nameplate rating of each fixture C) The calculated wattage after applying the 3 % lighting factor D) The connected load after applying the occupancy factor Answer: A Explanation: Demand factors are applied to the total connected load of lighting, not to individual fixture ratings. Question 15. An electric vehicle supply equipment (EVSE) is rated for 40 A at 240 V. If two EVSE units are installed on the same feeder, what is the minimum feeder size required, assuming a 125 % demand factor? A) 50 A B) 60 A C) 80 A D) 100 A Answer: C Explanation: Total load = 40 A × 2 = 80 A. Applying 125 % = 100 A. The next standard feeder size is 100 A, but the question asks minimum feeder size; 100 A is required, which corresponds to a 100-A feeder (option C is 80 A, which is insufficient). Correct answer: D. (Note: The correct answer is D; the explanation clarifies the calculation.) Question 16. When calculating neutral load for a 3-phase, 4-wire feeder supplying only single-phase loads, the maximum unbalanced neutral current is: A) Equal to the largest phase load B) 0 A because of balanced loads C) The sum of the phase currents divided by √ D) The vector sum of the phase currents Answer: D Explanation: The neutral carries the vector (phasor) sum of the unbalanced phase currents.
General 2020 Code Ultimate Exam
C) One unit of “fill” equal to the volume of a #6 AWG conductor D) No additional fill if the clamp is external Answer: A Explanation: NEC 314.16(B) requires each internal clamp to be counted as one conductor of the largest gauge present in the box. Question 21. A pull box used for an angle pull of three 6 AWG conductors must have a minimum interior width of: A) 6 in. B) 8 in. C) 10 in. D) 12 in. Answer: B Explanation: NEC 314.28 requires pull boxes for angle pulls to have an interior width at least equal to the largest conductor diameter plus 6 in.; for 6 AWG, 8 in. is the minimum. Question 22. Which cable type must be supported within 4½ ft of every outlet box, per NEC 334.30? A) NM-B (Romex) B) MC cable C) AC cable D) All of the above Answer: D Explanation: All listed non-metallic and metal-clad cable types must be supported within 4½ ft of each box. Question 23. For a luminaire installed in a damp location, the enclosure must be listed for at least which NEMA rating? A) NEMA 1 B) NEMA 2 C) NEMA 3R D) NEMA 4 Answer: C
General 2020 Code Ultimate Exam
Explanation: Damp locations require at least NEMA 3R rated enclosures. Question 24. A commercial dryer requires a disconnecting means within sight of the appliance. The disconnect must be located: A) No more than 6 ft from the dryer B) Within the same equipment room C) Within 50 ft of the dryer D) Inside the dryer’s cabinet Answer: B Explanation: NEC 430.102 requires the disconnect to be “within sight” and in the same room as the appliance. Question 25. An air-conditioning unit rated at 5 kW, 208 V, 3-phase requires a branch-circuit breaker of what minimum rating, assuming a 125 % sizing rule? A) 15 A B) 20 A C) 25 A D) 30 A Answer: B Explanation: Full-load current = 5 kW / (√ 3 × 208 V) ≈ 14 A. Applying 125 % = 17.5 A → next standard size is 20 A. Question 26. In a nursing home, patient sleeping areas must have which type of arc-fault protection? A) GFCI only B) AFCI only C) Both AFCI and GFCI D) No arc-fault protection required Answer: B Explanation: NEC 210.12(A) requires AFCI protection for sleeping areas in health-care facilities. Question 27. The Full Load Current (FLC) for a 3-phase, 15 hp motor at 460 V is found in which NEC table?
General 2020 Code Ultimate Exam
Answer: B Explanation: NEC 702.12 requires a listed transfer switch or interlock device for generator connections. Question 31. For a transformer with a primary voltage of 240 V and secondary voltage of 120 V, which article governs grounding of the secondary (separately derived) system? A) Article 250.30(B) B) Article 250.92(A) C) Article 250.102(C) D) Article 250.130(C) Answer: A Explanation: Article 250.30(B) requires grounding of separately derived systems, such as transformer secondary circuits. Question 32. Class I, Division 1 hazardous locations require equipment to be: A) Explosion-proof (Ex d) B) Dust-tight (Ex e) C) Intrinsically safe (Ex i) D) Non-hazardous rated (Ex n) Answer: A Explanation: Class I, Division 1 locations contain flammable gases or vapors; equipment must be explosion-proof (Ex d) to contain any ignition. Question 33. “Type P” cable is specifically designed for use in which type of hazardous location? A) Class II, Division 2 B) Class I, Division 2 C) Class III, Division 1 D) Non-hazardous areas only Answer: B Explanation: Type P cable is approved for use in Class I, Division 2 areas where flammable gases may be present but are not normally present.
General 2020 Code Ultimate Exam
Question 34. In a health-care facility, the “Patient Care Vicinity” is defined as: A) The area within 6 ft of a patient bed B) The space within 10 ft of any medical equipment C) The area inside a patient room only D) The entire floor where patients are located Answer: A Explanation: NEC 517.2 defines the Patient Care Vicinity as the 6-ft radius around a patient’s bed. Question 35. Equipotential bonding of a swimming pool shell must be connected to the building’s grounding electrode system using a bonding jumper of minimum size: A) #12 copper B) #8 copper C) #6 copper D) #4 copper Answer: C Explanation: NEC 680.26(A) requires a #6 copper bonding jumper for pools. Question 36. Re-inspection of a newly installed pool must be performed within how many days after the initial inspection? A) 30 days B) 60 days C) 90 days D) 120 days Answer: C Explanation: NEC 680.27 requires re-inspection within 90 days to verify compliance. Question 37. Which article now distinguishes between battery storage systems and energy-storage systems (ESS) for solar PV installations? A) Article 690 B) Article 706
General 2020 Code Ultimate Exam
Explanation: Arc-flash labels must contain incident energy, PPE, and boundary data; warranty information is not required. Question 41. New Jersey adopts the NEC with amendments found in which code? A) N.J.A.C. 5:23-3. B) N.J.S.A. 27:1- 10 C) N.J.A.C. 4:12-2. D) N.J.S.A. 33:5- 2 Answer: A Explanation: The New Jersey Uniform Construction Code (N.J.A.C. 5:23-3.16) adopts the NEC with state-specific amendments. Question 42. The maximum number of conductors permitted in a 1-in. Schedule 80 PVC conduit without exceeding 40 % fill is: A) 3 B) 4 C) 5 D) 6 Answer: B Explanation: Table 1 in Chapter 9 shows that 4 #12 conductors fill 40 % of a 1-in. Schedule 80 PVC conduit. Question 43. A “housekeeping pad” must provide a minimum clearance of how many inches from the top of the equipment to the nearest obstruction? A) 18 in. B) 24 in. C) 30 in. D) 36 in. Answer: B Explanation: NEC 110.26(A)(2) requires a minimum of 24 in. of headroom above equipment.
General 2020 Code Ultimate Exam
Question 44. When performing a box-fill calculation for a device box containing a single-pole receptacle, the receptacle counts as: A) One conductor B) Two conductors C) Three conductors D) Four conductors Answer: B Explanation: NEC 314.16(B) counts each yoke-connected device (e.g., receptacle) as two conductors. Question 45. For a conduit body (C) used for a 90-degree pull, the interior volume must be at least: A) 1 in³ per conductor B) 2 in³ per conductor C) 3 in³ per conductor D) 4 in³ per conductor Answer: C Explanation: NEC 314.28 requires a minimum of 3 in³ per conductor for conduit bodies. Question 46. Which of the following cable types is permitted to be installed in a plenum space? A) NM-B B) UF C) MC with plenum-rated insulation (MC-PR) D) AC cable Answer: C Explanation: Only plenum-rated cables, such as MC-PR, are allowed in air-handling spaces. Question 47. A lighting fixture installed in a clothes closet must be listed for which environment? A) Damp B) Wet
General 2020 Code Ultimate Exam
Explanation: Class II, Division 2 locations contain combustible dust; intrinsically safe (Ex i) wiring is permitted. Question 51. The minimum size of the equipment grounding conductor for a 100 - A feeder using 3 AWG copper conductors is: A) #12 AWG B) #10 AWG C) #8 AWG D) #6 AWG Answer: C Explanation: Table 250.122 specifies a #8 AWG copper EGC for a 100-A circuit. Question 52. When installing a panelboard in a commercial building, the minimum clear working space in front of the panel must be: A) 30 in. wide and 36 in. deep B) 36 in. wide and 30 in. deep C) 30 in. wide and 30 in. deep D) 36 in. wide and 36 in. deep Answer: A Explanation: NEC 110.26(A)(1) requires at least 30 in. width and 36 in. depth of working space. Question 53. A surge protective device installed at the service entrance must be listed under which NEC article? A) Article 240 B) Article 242 C) Article 280 D) Article 300 Answer: B Explanation: Article 242 governs the installation of SPDs at the service entrance. Question 54. In a commercial office, the demand factor for receptacles is: A) 100 % of the total connected load
General 2020 Code Ultimate Exam
B) 80 % of the total connected load C) 55 % of the first 3 kVA plus 35 % of the remainder D) 30 % of the total connected load Answer: C Explanation: NEC 220.42 applies a demand factor of 55 % for the first 3 kVA and 35 % for the remainder of receptacle loads. Question 55. When sizing a feeder for an EVSE that can operate at 16 A, 20 A, or 32 A, the NEC requires the feeder to be sized for: A) The lowest setting (16 A) B) The average of the three settings C) The highest setting (32 A) D) The sum of all settings Answer: C Explanation: NEC 625.31 requires feeders to be sized for the maximum continuous load the EVSE can draw. Question 56. The neutral conductor for a 120/240-V single-phase feeder supplying only 120-V loads may be: A) Omitted if a 4-wire feeder is used B) Shared with another feeder C) Sized at 75 % of the ungrounded conductor size D) Sized per Table 250.122 based on the ungrounded conductor rating Answer: D Explanation: Neutral size follows Table 250.122 relative to the rating of the ungrounded conductors. Question 57. The maximum allowable voltage drop for feeder conductors supplying sensitive electronic equipment is: A) 1 % B) 2 % C) 3 % D) 5 %
General 2020 Code Ultimate Exam
Question 61. A 1500-sq-ft commercial building has a lighting load of 12 W/ft². Applying the NEC demand factor for lighting, the calculated demand is: A) 12 kW B) 15 kW C) 18 kW D) 20 kW Answer: B Explanation: Total lighting load = 12 W/ft² × 1500 ft² = 18 kW. NEC Table 220. applies a 100 % demand for the first 3 kVA and 80 % thereafter: 3 kW + (15 kW × 0.8) = 3 kW + 12 kW = 15 kW. Question 62. For a motor-protected circuit using an inverse-time circuit breaker, the breaker must be sized at least: A) 125 % of the motor FLC B) 150 % of the motor FLC C) 175 % of the motor FLC D) 200 % of the motor FLC Answer: C Explanation: NEC 430.32 permits an inverse-time breaker sized up to 175 % of the motor’s full-load current. Question 63. When installing a conduit body (LB) for a 45-degree pull of three #10 AWG conductors, the minimum interior volume required is: A) 45 in³ B) 60 in³ C) 75 in³ D) 90 in³ Answer: B Explanation: NEC 314.28 requires 3 in³ per conductor for a conduit body, so 3 × 3 = 9 in³; however, for a 45-degree pull the minimum is 20 in³ per conductor, giving 60 in³ total. Question 64. The required clearance between a service disconnect and a swimming pool deck is:
General 2020 Code Ultimate Exam
A) 3 ft B) 4 ft C) 5 ft D) 6 ft Answer: B Explanation: NEC 680.26 requires a minimum of 4 ft clearance between the disconnect and the pool deck. Question 65. In a building with an Energy Storage System (ESS) rated at 25 kWh, the ESS must be protected by a circuit breaker rated at least: A) 125 % of the maximum continuous current B) 150 % of the maximum continuous current C) 200 % of the maximum continuous current D) 250 % of the maximum continuous current Answer: A Explanation: NEC 706.4 requires overcurrent protection sized at a minimum of 125 % of the ESS’s maximum continuous current. Question 66. A conduit system that contains both power and data cables must be installed with: A) Separate conduits for each type B) A single conduit with a separator bar C) A conduit listed for mixed-use applications D) No special requirements as long as the conduit is metal Answer: C Explanation: NEC 800.24 allows mixed-use conduits if the conduit is listed for both power and communications. Question 67. The minimum size of a grounding electrode conductor for a grounding rod system consisting of four 5/8-in. rods is: A) #12 copper B) #10 copper C) #8 copper
