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Ultimate Exam
Question 1. Which of the following best describes the relationship defined by Ohm’s Law? A) Power equals voltage times current B) Voltage equals current times resistance C) Current equals voltage divided by power D) Resistance equals power divided by voltage Answer: B Explanation: Ohm’s Law states V = I × R, meaning voltage equals current multiplied by resistance. Question 2. In a three-phase wye system, the line-to-neutral voltage is ___ the line-to-line voltage. A) Equal to B) √2 times larger than C) √3 times larger than D) √3 times smaller than Answer: D Explanation: In a wye connection, V_line = √3 × V_phase, so the phase (line-to-neutral) voltage is √3 times smaller than the line-to-line voltage. Question 3. A multimeter set to measure resistance should display an infinite reading when its probes are: A) Connected to a shorted circuit B) Connected to an open circuit C) Connected across a live conductor D) Connected to a diode in forward bias Answer: B
Ultimate Exam
Explanation: An open circuit has no conductive path, so the resistance is infinite. Question 4. Which NEC article defines the term “equipment grounding conductor”? A) Article 100 B) Article 250 C) Article 300 D) Article 210 Answer: A Explanation: Article 100 provides definitions for NEC terminology, including “equipment grounding conductor.” Question 5. The maximum number of 90-degree bends allowed between pull points in a conduit run is: A) 2 B) 4 C) 6 D) 8 Answer: B Explanation: NEC permits up to four 90-degree bends (or equivalent) between conduit pull points. Question 6. For a continuous load, the branch-circuit breaker must be rated at least: A) 80 % of the load B) 100 % of the load C) 125 % of the load
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B) Must be supported at intervals not exceeding 6 ft C) Must be removed when the permanent wiring is in place D) Must be protected by a GFCI receptacle Answer: C Explanation: Temporary wiring is required to be removed when the permanent wiring is installed (NEC 590). Question 10. The purpose of a main bonding jumper (MBJ) is to: A) Carry normal load current to the service equipment B) Connect the neutral to the grounding electrode system C) Provide a path for fault current from equipment grounding conductors D) Isolate the neutral from the ground in a separately derived system Answer: B Explanation: The MBJ ties the service neutral to the grounding electrode system, establishing a reference to earth. Question 11. Which conduit material is permitted for use in damp locations without additional corrosion protection? A) Rigid Metal Conduit (RMC) B) Electrical Metallic Tubing (EMT) C) Flexible Metal Conduit (FMC) D) All of the above Answer: D Explanation: All listed metal conduit types are rated for damp locations. Question 12. The ampacity adjustment factor for conductors bundled in a raceway with more than three current-carrying conductors is:
Ultimate Exam
A) 0.80 for 4–6 conductors B) 0.70 for 4–6 conductors C) 0.80 for 7–9 conductors D) 0.70 for 7–9 conductors Answer: A Explanation: NEC Table 310.15(B)(3)(a) provides a 0.80 factor for 4– conductors in a raceway. Question 13. A motor with a full-load current (FLC) of 30 A is to be protected by a circuit breaker. The minimum breaker size, per NEC, should be: A) 30 A B) 35 A C) 40 A D) 45 A Answer: C Explanation: NEC 430.32 requires the breaker to be 115 % of FLC: 30 A × 1.15 = 34.5 A; the next standard size is 40 A. Question 14. Which class of hazardous location is defined for the presence of flammable gases or vapors? A) Class I B) Class II C) Class III D) Class IV Answer: A Explanation: Class I locations involve flammable gases, vapors, or liquids.
Ultimate Exam
Explanation: NM cable must be supported or secured; simply hanging it is not allowed. Question 18. The required GFCI protection for a receptacle that supplies a residential bathroom vanity outlet is: A) None required B) Only for 125-V, 15-A receptacles C) Required for all receptacles in the bathroom D) Required only if the receptacle is within 6 ft of a sink Answer: C Explanation: NEC 210.8(A)(1) mandates GFCI protection for all receptacles in bathrooms. Question 19. In a three-phase delta-connected transformer, the line voltage is equal to the phase voltage. This is true because: A) The windings are connected in series B) The windings are connected in parallel C) There is no neutral point D) The transformer is grounded Answer: C Explanation: A delta system lacks a neutral, making line and phase voltages identical. Question 20. According to NEC, the maximum allowable ampacity for a 60 °C rated conductor used as a feeder is: A) 55 % of its 90 °C rating B) 75 % of its 90 °C rating C) 100 % of its 90 °C rating
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D) Determined by the temperature rating of the termination point Answer: D Explanation: Conductors must be rated for the temperature of the equipment they terminate in; a 60 °C rating limits ampacity to the 60 °C column. Question 21. Which NEC article governs the installation of raceways and cable trays? A) Article 300 B) Article 320 C) Article 380 D) Article 410 Answer: A Explanation: Article 300 covers general requirements for wiring methods, including raceways and cable trays. Question 22. The minimum clearance between a grounded metal conduit and a combustible wall surface is: A) 1 in. B) 1½ in. C) 2 in. D) No clearance required if conduit is metal Answer: A Explanation: NEC 300.21 requires a minimum of 1 in. clearance between metal raceways and combustible surfaces unless the raceway is listed for direct contact. Question 23. A 120/240 V single-phase residential service typically uses which type of grounding electrode system?
Ultimate Exam
Question 26. The correct minimum size of a copper grounding electrode conductor (GEC) for a 400 kVA, 3-phase, 4.16 kV service is: A) 4 AWG B) 2 AWG C) 1/0 AWG D) 2/0 AWG Answer: C Explanation: Table 250.66 indicates a 1/0 AWG copper GEC for services up to 600 kVA. Question 27. When installing a branch circuit that supplies a 20 A receptacle in a dwelling unit, the smallest permissible copper conductor size is: A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: B Explanation: NEC 210.19(A)(1) requires a minimum of 12 AWG copper for a 20 A branch circuit. Question 28. The NEC permits the use of a single-pole breaker to protect a 240 V, 2-pole motor circuit if: A) The motor is listed for single-pole protection B) The breaker is a “dual function” type C) The motor has a permanently attached overload D) The breaker is rated at least 125 % of motor FLC
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Answer: C Explanation: A motor with a listed permanent overload can be protected by a single-pole breaker only if the overload provides the required short-circuit protection. Question 29. Which of the following is the correct method for determining the number of conductors allowed in a 1-in. EMT conduit? A) Use Table 1 in Chapter 9 of the NEC B) Use Table 310.15(B)(16) C) Use Table 1 in Chapter 9 for conduit fill percentages D) Use Table 5 in Chapter 9 for conduit dimensions Answer: C Explanation: Conduit fill calculations use Table 1 in Chapter 9 (percentage of conduit cross-sectional area) combined with Table 5 for conduit dimensions. Question 30. A 30 kW, 208 V, three-phase motor has a full-load current of approximately: A) 75 A B) 83 A C) 90 A D) 100 A Answer: B Explanation: FLC = (kW × 1000) / (√3 × V × PF). Assuming PF = 0.9, FLC ≈ 30,000 / (1.732 × 208 × 0.9) ≈ 83 A. Question 31. For a lighting circuit serving 10 receptacles, each rated 180 W, the calculated load is: A) 1,800 W
Ultimate Exam
Explanation: Article 702 covers emergency lighting and power systems. Question 34. The allowable ampacity for a 3-wire 6 AWG aluminum feeder in a raceway with three current-carrying conductors, using the 75 °C column, is: A) 40 A B) 45 A C) 50 A D) 55 A Answer: B Explanation: 6 AWG Al has 55 A at 75 °C; with three conductors, the adjustment factor is 1.0 (no derating). Therefore 55 A is the ampacity; however the nearest standard breaker is 45 A for a 6 AWG Al feeder per NEC Table 310.12, so the answer is B (45 A). Explanation: NEC requires the next lower standard rating. Question 35. For a 120 V, 20 A circuit supplying a kitchen countertop receptacle, the required GFCI protection must be provided by: A) A GFCI receptacle only B) A GFCI breaker only C) Either a GFCI receptacle or a GFCI breaker D) No GFCI required because it is a 20 A circuit Answer: C Explanation: NEC allows GFCI protection to be provided at the receptacle or at the breaker. Question 36. The correct minimum burial depth for a PVC raceway containing a single 12 AWG copper circuit in residential outdoor applications is:
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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. cover for PVC raceways under residential driveways and sidewalks. Question 37. Which of the following statements about AFCI (Arc-Fault Circuit Interrupter) protection is true? A) AFCI devices protect only against ground faults B) AFCI protection is required for all 120 V, 15-A and 20-A branch circuits in dwelling units C) AFCI devices must be installed in commercial kitchens only D) AFCI protection is optional for bedroom circuits Answer: B Explanation: NEC 210.12(A) requires AFCI protection for all 120 V, 15-A and 20 - A circuits in dwelling unit bedrooms, living rooms, etc. Question 38. When sizing an equipment grounding conductor for a 60 A circuit using 6 AWG copper conductors, the required EGC size is: A) 12 AWG copper B) 10 AWG copper C) 8 AWG copper D) 6 AWG copper Answer: B Explanation: Table 250.122 lists a 10 AWG copper EGC for a 60 A circuit.
Ultimate Exam
Explanation: Secondary current = kVA × 1000 / (√3 × V) = 50,000 / (1.732 × 250) ≈ 115 A. However with rounding, the closest answer is 144 A, which corresponds to a slightly higher kVA. The correct calculation yields ~115 A, but none of the options match; the nearest is B (100 A). Explanation: Approximate full-load current is 115 A; standard practice selects the next standard size, 120 A, but given options, 100 A is the closest. Question 42. Which NEC article governs the installation of photovoltaic (PV) systems? A) Article 690 B) Article 705 C) Article 710 D) Article 720 Answer: A Explanation: Article 690 contains the requirements for solar photovoltaic systems. Question 43. The minimum distance that a receptacle must be installed from a bathtub in a residential bathroom is: A) 12 in. B) 18 in. C) 24 in. D) 30 in. Answer: B Explanation: NEC 210.8(A)(1) requires at least one GFCI-protected receptacle within 3 ft (36 in.) of a bathtub; the minimum mounting height is 12 in. above the floor, but the distance from the tub edge must be at least 18 in.
Ultimate Exam
Question 44. When using THHN conductors in a conduit, the maximum temperature rating allowed for the conductors is: A) 60 °C B) 75 °C C) 90 °C D) 105 °C Answer: C Explanation: THHN insulation is rated for 90 °C in dry locations. Question 45. The required ampacity for a 30 A branch circuit feeding a 120 V, 12 A electric dryer is: A) 30 A B) 36 A C) 40 A D) 45 A Answer: A Explanation: The branch-circuit rating must be at least the load; a 30 A breaker is sufficient for a 12 A dryer. Question 46. Which of the following devices is used to protect a transformer secondary winding from overcurrent? A) Fused disconnect switch B) Ground-fault breaker C) Arc-fault circuit interrupter D) Surge protector Answer: A Explanation: NEC requires a fused or circuit-breaker type disconnect for transformer secondary protection.
Ultimate Exam
Explanation: 1/0 AWG copper is rated for 150 A at 75 °C, which exceeds the 100 A load, making it the smallest acceptable size. Question 50. Which of the following is considered a “continuous load” under NEC definitions? A) A lighting load that operates for 2 hours per day B) A motor that runs for 3 hours at a time C) A refrigerator that cycles on and off D) An HVAC system that runs for 8 hours or more each day Answer: D Explanation: Loads expected to run for 3 hours or more continuously are classified as continuous. Question 51. The NEC requires that a receptacle in a laundry room be GFCI protected if it is: A) Within 6 ft of the washing machine B) Within 6 ft of a sink C) Any receptacle in the laundry room D) Only the receptacle that powers the dryer Answer: C Explanation: NEC 210.8(A)(10) mandates GFCI protection for all receptacles in laundry areas. Question 52. The maximum number of conductors allowed in a ½-in. EMT conduit without exceeding 40 % fill is: A) 5 B) 6 C) 7
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D) 8
Answer: B Explanation: Using Table 1 (40 % fill) and conduit dimensions, a ½-in. EMT can accommodate up to 6 #12 AWG conductors. Question 53. Which of the following is the correct method for bonding a metal water pipe that is used as a grounding electrode? A) Connect a #6 copper grounding electrode conductor directly to the pipe B) Use a listed bonding jumper of any size C) No bonding is required if the pipe is already grounded D) Bond with a #10 aluminum conductor Answer: A Explanation: NEC 250.52(A)(1) allows a #6 copper GEC to bond a metal water pipe used as a grounding electrode. Question 54. The required ampacity for a 120 V, 20 A branch circuit that supplies a bathroom vanity light and a receptacle is: A) 15 A B) 20 A C) 25 A D) 30 A Answer: B Explanation: The branch circuit must be sized for the highest load; a 20 A circuit is appropriate. Question 55. Which NEC article deals with the installation of fire alarm systems? A) Article 700
