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RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
Question 1. Which formula correctly represents Ohm’s Law for calculating voltage? A) V = I × R B) V = P ÷ I C) V = I ÷ R D) V = P × R Answer: A Explanation: Voltage equals current multiplied by resistance (V = I·R). Question 2. A 1500 W electric water heater operates at 240 V. What is the current draw? A) 4.2 A B) 6.25 A C) 12.5 A D) 18.75 A Answer: C Explanation: I = P ÷ V = 1500 W ÷ 240 V = 6.25 A (incorrect). Actually correct calculation: 1500 W ÷ 240 V = 6.25 A, so answer B. (Correction: Answer B, Explanation adjusted accordingly.) Question 3. For a continuous load, the NEC requires the branch-circuit rating to be multiplied by what factor? A) 1. B) 1. C) 1. D) 1. Answer: C Explanation: Continuous loads must be sized at 125 % of the actual load.
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
Question 4. In a series circuit of three 2 Ω resistors powered by a 12 V source, what is the total current? A) 0.5 A B) 1 A C) 2 A D) 3 A Answer: B Explanation: Total resistance = 6 Ω; I = V ÷ R = 12 V ÷ 6 Ω = 2 A (incorrect). Actually 12 V ÷ 6 Ω = 2 A, so answer C. (Correction: Answer C, Explanation adjusted.) Question 5. Which conductor size (circular mils) is required for a 30 A residential branch circuit using THHN copper at 75 °C? A) 12 AWG (6,530 CM) B) 10 AWG (10,380 CM) C) 8 AWG (16,510 CM) D) 6 AWG (26,240 CM) Answer: B Explanation: 10 AWG copper THHN is rated for 30 A at 75 °C. Question 6. Which insulation type is permitted for wet locations in residential wiring? A) NM-B B) THHN only C) UF-B D) SE-R Answer: C Explanation: Underground Feeder (UF-B) cable is approved for wet locations.
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
A) Electric range B) Central air-conditioning unit C) Water heater D) Bathroom exhaust fan Answer: B Explanation: The largest motor-driven HVAC equipment determines the HVAC load portion. Question 11. The main service disconnect must be installed within how many feet of the point of entry? A) 3 ft B) 6 ft C) 8 ft D) 10 ft Answer: C Explanation: NEC 230.70 requires the disconnect to be within 8 ft of the service entrance. Question 12. Which grounding electrode is NOT permissible under NEC 250.52? A) Concrete-encased electrode B) Metal underground water pipe C) Aluminum siding D) Ground rod Answer: C Explanation: Aluminum siding is not an approved grounding electrode. Question 13. The minimum size of a grounding electrode conductor (GEC) for a 100 A service fed by copper is: A) 6 AWG
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
B) 8 AWG
C) 10 AWG
D) 12 AWG
Answer: B Explanation: Table 250.66 lists 8 AWG copper for a 100 A service. Question 14. For a residential feeder supplying a 120/240 V single-phase load, what is the minimum neutral conductor size relative to the ungrounded conductors? A) Same size as ungrounded B) One size larger than ungrounded C) One size smaller than ungrounded D) No neutral required Answer: A Explanation: Feeder neutrals must be the same size as the ungrounded conductors unless otherwise calculated. Question 15. When more than three current-carrying conductors are installed in a conduit, what is the NEC derating factor for 4-6 conductors? A) 100 % B) 95 % C) 80 % D) 70 % Answer: C Explanation: NEC Table 310.15(B)(3)(a) requires 80 % derating for 4-6 conductors. Question 16. A 12-AWG THHN conductor is rated 30 A at 75 °C. If installed in a raceway with 5 current-carrying conductors, what is the adjusted ampacity? A) 30 A B) 24 A
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
Explanation: NEC requires a minimum of two receptacles for countertop islands. Question 20. Which area requires GFCI protection? A) Finished basement hallway B) Kitchen countertop C) Bedroom D) Living room Answer: B Explanation: All kitchen countertop receptacles must be GFCI-protected. Question 21. AFCI protection is mandatory in which of the following locations? A) Garage B) Bathroom C) Outdoor patio D) Laundry room Answer: A Explanation: NEC 210.12 requires AFCI protection in garages and accessory buildings. Question 22. Which cable type must be secured within 4 in of each box? A) AC cable B) NM-B cable C) MC cable D) UF-B cable Answer: B Explanation: NM-B must be secured within 4 in of each enclosure per NEC 334.30.
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
Question 23. The maximum depth for direct-buried UF cable under a residential driveway is: A) 12 in B) 18 in C) 24 in D) 30 in Answer: B Explanation: NEC 300.5(D) requires a minimum of 18 in cover for UF under driveways. Question 24. When installing a recessed fixture in a combustible ceiling, which rating is required? A) Non-IC B) IC-rated C) Damp-rated D) Outdoor-rated Answer: B Explanation: IC-rated fixtures are permitted in contact with combustible ceilings. Question 25. A 30-amp dryer circuit must use which minimum conductor size? A) 12 AWG copper B) 10 AWG copper C) 8 AWG copper D) 6 AWG copper Answer: B Explanation: 10 AWG copper is the minimum for a 30 A dryer circuit. Question 26. The required disconnect size for a 5-ton residential air-conditioning unit is:
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
A) 6 in B) 12 in C) 18 in D) 24 in Answer: B Explanation: NEC 680.26 requires the grid to be at least 12 in below the finished grade. Question 30. Which statement about rapid-shutdown for residential PV systems is correct? A) Must shut down the entire array within 30 seconds of activation. B) Only required for commercial systems. C) Can be achieved by a manual disconnect only. D) Is not required if the inverter is listed for rapid-shutdown. Answer: A Explanation: NEC 690.12 requires rapid-shutdown of the PV array within 30 seconds. Question 31. A portable generator supplying a home must be connected through a: A) Direct hard-wired connection to the service panel. B) Transfer switch listed for the application. C) Simple extension cord to a receptacle. D) Multi-wire branch circuit. Answer: B Explanation: Transfer switches provide safe isolation between utility and generator power. Question 32. The Florida Building Code requires that lighting fixtures in habitable rooms have a minimum efficacy of:
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
A) 30 lumens/W B) 45 lumens/W C) 60 lumens/W D) 75 lumens/W Answer: C Explanation: FB-2020 mandates at least 60 lumens per watt for general lighting. Question 33. In Brevard County, the “Notice to Proceed” must be submitted to: A) The city mayor. B) The County Building Official. C) The State Fire Marshal. D) The local utility company. Answer: B Explanation: The County Building Official issues the notice after plan approval. Question 34. Which stage of inspection verifies that all conduit, wiring, and grounding are installed before devices are placed? A) Rough-in B) Service C) Final D) Post-construction Answer: A Explanation: Rough-in inspection checks structural electrical work before devices. Question 35. Who must sign off on the final electrical work in a Brevard County residential project? A) The general contractor. B) The owner.
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
D) The manufacturer name. Answer: B Explanation: “Breaker Size” indicates the ampere rating. Question 39. To calculate box fill for a device box, each internal clamp counts as: A) 1 fill unit. B) 2 fill units. C) 3 fill units. D) No fill. Answer: B Explanation: NEC 314.16(B) assigns 2 fill units to each internal clamp. Question 40. A 3-wire NM-B cable (hot-hot-neutral) feeding a 240 V circuit requires how many grounding conductors in the box? A) None, NM-B includes a ground. B) One separate ground wire. C) Two separate grounds. D) Ground is optional. Answer: A Explanation: NM-B contains an equipment grounding conductor. Question 41. Which of the following is the correct method to support a run of MC cable? A) Every 6 ft with staples. B) Every 8 ft with cable ties. C) Every 6 ft with listed clamps or straps. D) No support required for MC. Answer: C
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
Explanation: NEC 330.30 requires MC cable to be supported and secured at intervals not exceeding 6 ft. Question 42. The minimum conduit size required to pull three 4 AWG THHN conductors is: A) ½ in. B) ¾ in. C) 1 in. D) 1¼ in. Answer: B Explanation: Using conduit fill tables, ¾-in. EMT can accommodate three 4 AWG conductors. Question 43. Which of the following is NOT a permissible location for a receptacle in a bathroom? A) Within 3 ft of the basin. B) Directly above the bathtub. C) On the wall opposite the vanity. D) On a freestanding vanity. Answer: B Explanation: NEC 210.52(D) prohibits receptacles within 3 ft of the bathtub rim. Question 44. A 20 A GFCI breaker protects a kitchen countertop circuit. Which additional protection is required? A) AFCI breaker. B) Surge protector. C) No additional protection required. D) Dual-pole breaker. Answer: A
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
Explanation: NEC 300.5(D) requires 24 in of cover for PVC conduit under a driveway. Question 48. When installing a ceiling fan in a closet, the fan must be: A) Rated for damp locations. B) Listed for use in a closet. C) Mounted at least 6 ft from the floor. D) Connected to a dedicated 20 A circuit. Answer: B Explanation: NEC 410.117 requires fans installed in closets to be listed for that use. Question 49. A 15-amp GFCI receptacle installed in a garage must be protected by a: A) 15-amp breaker only. B) 20-amp breaker only. C) 15- or 20-amp breaker, as long as the receptacle is rated for the breaker size. D) No breaker is required. Answer: C Explanation: NEC permits a 15-amp GFCI on a 20-amp circuit if the receptacle is marked “ 20 A max”. Question 50. Which of the following devices must be listed for use in a hazardous (Class II) location? A) Standard receptacle. B) Explosion-proof motor starter. C) Plastic outlet box. D) Non-metallic conduit. Answer: B Explanation: Only explosion-proof devices are permitted in Class II hazardous areas.
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
Question 51. The NEC requires that a receptacle in a laundry room be GFCI-protected if the receptacle is: A) Within 6 ft of the washing machine. B) Located on a dedicated circuit. C) Any receptacle in a laundry room. D) Only the one serving the dryer. Answer: C Explanation: All receptacles in laundry areas must be GFCI-protected. Question 52. A 100-amp service entrance requires a minimum conductor size of: A) 2 AWG copper. B) 4 AWG copper. C) 6 AWG copper. D) 8 AWG copper. Answer: B Explanation: 4 AWG copper THHN is rated for 100 A at 75 °C. Question 53. Which of the following is the correct method to calculate the ampacity of a conductor buried in the earth? A) Use the same table as for conduit-run conductors. B) Apply a 20 % derating factor. C) Use NEC Table 310.15(B)(4). D) No correction needed. Answer: C Explanation: Table 310.15(B)(4) provides ampacity adjustments for direct burial. Question 54. In a residential panel, a 2-pole 240 V breaker is used for a: A) 120 V lighting circuit.
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
B) 30-amp breaker. C) 40-amp breaker. D) No breaker required. Answer: B Explanation: NEC 210.23(A)(2) requires the branch-circuit rating not less than the load; a 30-A breaker is appropriate. Question 58. The NEC defines a “continuous load” as a load that: A) Operates for more than 3 hours continuously. B) Operates for more than 6 hours continuously. C) Is a motor load. D) Is a lighting load only. Answer: B Explanation: Continuous loads run for 3 hours or more; the NEC uses a 125 % factor for such loads. Question 59. Which of the following is the correct minimum distance between a receptacle and a swimming pool water line? A) 6 in. B) 12 in. C) 18 in. D) 24 in. Answer: B Explanation: NEC 680.22 requires receptacles to be at least 12 in. away from pool water lines. Question 60. For a residential solar PV array, the required signage must include: A) Manufacturer name only. B) DC voltage and maximum current.
RESIDENTIAL ELECTRICAL 2014
Ultimate Exam
C) Inverter model number. D) No signage required. Answer: B Explanation: NEC 690.12(A) requires labeling of system voltage and maximum current. Question 61. Which type of grounding electrode is typically installed to a depth of 8 ft? A) Concrete-encased electrode. B) Ground rod. C) Metal water pipe. D) Ground plate. Answer: B Explanation: Ground rods are driven a minimum of 8 ft into the earth. Question 62. The NEC permits the use of a single-pole breaker to protect a 240 V circuit under which condition? A) The circuit supplies only lighting. B) The breaker is listed for 240 V on a single pole. C) The circuit is fed from a 120/240 V panel. D) This is never permitted. Answer: D Explanation: 240 V circuits require a 2-pole breaker. Question 63. The required minimum size of a copper grounding electrode conductor for a 200 A service is: A) 8 AWG B) 6 AWG C) 4 AWG
