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Electrical Ultimate Exam
Question 1. Which of the following equations correctly represents Ohm’s Law for a resistive circuit? A) P = V × I B) I = V / R C) V = I² × R D) R = P / I Answer: B Explanation: Ohm’s Law states that current (I) equals voltage (V) divided by resistance (R). Question 2. In a three-phase, 4-wire wye system, the line-to-neutral voltage is 120 V. What is the line-to-line voltage? A) 120 V B) 208 V C) 240 V D) 277 V Answer: B Explanation: Line-to-line voltage = √ 3 × line-to-neutral (√ 3 × 120 ≈ 208 V). Question 3. When calculating voltage drop in a copper conductor using the 2 K I D formula, what does the “K” factor represent? A) Resistivity constant for copper at 75 °C B) Conductor’s cross-sectional area in circular mils C) Temperature correction factor for the conductor material D) Constant of 12.9 for copper Answer: D Explanation: The “K” factor in the 2 K I D formula is 12.9 for copper (when using volts, amperes, and circular mils). Question 4. Which unit conversion is correct for 5 kW to horsepower (HP)?
Electrical Ultimate Exam
A) 5 kW ≈ 6.73 HP B) 5 kW ≈ 4.34 HP C) 5 kW ≈ 7.45 HP D) 5 kW ≈ 5.00 HP Answer: A Explanation: 1 kW ≈ 1.341 HP, so 5 kW ≈ 5 × 1.341 = 6.705 HP (rounded to 6.73 HP). Question 5. In a single-phase AC circuit, the power factor is 0.8 lagging. If the apparent power is 10 kVA, what is the real power? A) 8 kW B) 10 kW C) 12.5 kW D) 6.4 kW Answer: A Explanation: Real power = apparent power × power factor = 10 kVA × 0.8 = 8 kW. Question 6. Which conductor is identified by a continuous white or gray outer insulation in a branch circuit? A) Grounded (neutral) conductor B) Ungrounded (hot) conductor C) Equipment grounding conductor D) Switched leg conductor Answer: A Explanation: NEC designates the neutral conductor with continuous white or gray insulation. Question 7. A 20-ampere branch circuit supplies a receptacle for a countertop appliance. What is the minimum size copper conductor required (AWG) for this circuit?
Electrical Ultimate Exam
A) #10 AWG
B) #8 AWG
C) #6 AWG
D) #4 AWG
Answer: B Explanation: NEC Table 250.66 requires a #8 AWG copper GEC for a 100-A service. Question 11. For a conduit system installed in a wet location, which material is permitted? A) EMT with a water-tight seal B) Rigid Metal Conduit (RMC) C) Non-metallic (PVC) conduit only D) Flexible Metal Conduit (FMC) without a cover Answer: B Explanation: RMC is approved for wet locations; EMT is not unless a watertight fitting is used. Question 12. The maximum number of 12-AWG conductors allowed in a 30 cu in. metal box, assuming no devices or clamps, is: A) 5 B) 6 C) 7 D) 8 Answer: C Explanation: Each 12-AWG conductor occupies 2.25 cu in.; 30 / 2.25 ≈ 13.3, but NEC limits to 7 conductors in a 30 cu in. box when counting volume allowances. Question 13. When installing Type NM cable in a residential wall cavity, the cable must be protected from physical damage if it runs within how many inches of the surface of the finished wall?
Electrical Ultimate Exam
A) 6 in. B) 8 in. C) 12 in. D) 4 in. Answer: B Explanation: NEC 334.15 requires NM cable to be at least 8 in. from the surface of a finished wall unless protected by a guard. Question 14. The minimum cover depth for a 2-in. schedule 40 PVC conduit buried in the ground under a driveway is: A) 12 in. B) 18 in. C) 24 in. D) 30 in. Answer: C Explanation: NEC 300.5 requires 24 in. cover for PVC conduit under a driveway. Question 15. A service entrance conductor is required to be sized for a calculated load of 80 kVA at 240 V. What is the minimum ampacity of the conductor (copper, 75 °C rating)? A) 250 A B) 200 A C) 300 A D) 150 A Answer: B Explanation: Current = kVA × 1000 / V = 80,000 / 240 ≈ 333 A. However, NEC Table 220.42 allows demand factor; for residential service the calculated load is reduced, resulting in a required 200-A service. Question 16. The “rule of three feet” in panelboard installations refers to:
Electrical Ultimate Exam
A) Rigid Metal Conduit (RMC) only B) PVC conduit with a metal cover C) Non-metallic conduit with a flame-proof cover D) Any conduit listed for hazardous locations Answer: D Explanation: NEC 500.10 permits any conduit listed for use in the specific hazardous classification. Question 20. For a swimming pool pump motor, the required bonding conductor size is: A) #12 AWG copper B) #10 AWG copper C) #8 AWG copper D) #6 AWG copper Answer: C Explanation: NEC 680.26 requires a #8 AWG copper bonding conductor for pools up to 100 kW. Question 21. An emergency lighting system must be capable of providing illumination for how long after loss of normal power? A) 30 seconds B) 60 seconds C) 90 seconds D) 120 seconds Answer: B Explanation: NEC 700.12 requires a minimum of 90 minutes for emergency lighting, but the initial illumination must be within 90 seconds. The most common test interval is 90 seconds; however, the required minimum is 90 seconds— answer B reflects the standard test duration.
Electrical Ultimate Exam
Question 22. Which NFPA 70E boundary defines the region where a worker can be exposed to a flash hazard without a flash-protective ensemble? A) Limited Approach Boundary B) Restricted Approach Boundary C) Arc-Flash Boundary D) Shock Hazard Boundary Answer: C Explanation: The Arc-Flash Boundary is the distance at which a flash can cause a second-degree burn; beyond it, no PPE is required for flash protection. Question 23. OSHA 1926.502(b)(2) requires which of the following when working on energized parts? A) Lockout-Tagout (LOTO) must be applied B) Use of insulated tools only C) Both A and B D) No specific requirement; only general safety Answer: C Explanation: OSHA mandates both LOTO and the use of insulated tools when working on live parts. Question 24. In a commercial building, the minimum size of a feeder conductor supplying a 100-A panelboard, using copper conductors with a 75 °C rating, is: A) #4 AWG B) #3 AWG C) #2 AWG D) #1 AWG Answer: C Explanation: NEC Table 310.15(B)(16) shows #2 AWG copper at 115 A, which meets the 100-A requirement.
Electrical Ultimate Exam
Question 28. An apprentice electrician is required to be supervised by a master electrician for how many hours before being eligible for journeyman licensure in Tennessee? A) 1,000 hours B) 2,000 hours C) 4,000 hours D) 6,000 hours Answer: C Explanation: Tennessee requires a minimum of 4,000 hours of supervised practical experience. Question 29. The primary purpose of a neutral-grounding bond at the service entrance is to: A) Prevent neutral current from flowing in the grounding conductor B) Provide a low-impedance path for fault current to clear the circuit C) Reduce voltage drop on the feeder D) Increase the system voltage Answer: B Explanation: The neutral-ground bond creates a reference to earth and a path for fault current, facilitating protective device operation. Question 30. Which of the following is the correct conduit fill percentage for more than two conductors in a raceway? A) 40 % B) 31 % C 25 % D) 53 % Answer: B Explanation: NEC Table 1 of Chapter 9 limits conduit fill to 40 % for a single conductor, 31 % for two, and 40 % for three or more; actually the correct answer is 40 % for three or more, but the listed options reflect the 31 % for two
Electrical Ultimate Exam
conductors. Since the question asks for “more than two,” the answer is 40 % (option not listed). Therefore, the correct answer is the closest: A (40 %). Question 31. A 240-V, 30-A dryer circuit requires a minimum wire size of: A) 12 AWG copper B) 10 AWG copper C) 8 AWG copper D) 6 AWG copper Answer: B Explanation: NEC 210.23(A)(2) allows 30 A circuits to use 10 AWG copper conductors. Question 32. For a 150-kVA, three-phase transformer with a primary voltage of 13.8 kV, the full-load current on the primary side is approximately: A) 6.3 A B) 12.5 A C) 21.9 A D) 31.2 A Answer: C Explanation: Full-load current = kVA × 1000 / (√ 3 × V) = 150,000 / (1.732 × 13,800) ≈ 6.3 A (but that matches option A). However the correct calculation yields 6.3 A, so answer A. Question 33. Which NEC article addresses the installation of underground feeder (UF) cable? A) 300. B) 340. C) 340. D) 352. Answer: B
Electrical Ultimate Exam
Explanation: NEC Table 250.66 requires #4 AWG aluminum for a 200-A service. Question 37. Which type of circuit breaker is required for a motor branch circuit that must have adjustable overload protection? A) Standard thermal-magnetic breaker B) Molded case circuit breaker (MCCB) with adjustable trip C) Electronic trip unit breaker D) Both B and C Answer: D Explanation: Both MCCBs with adjustable thermal settings and electronic trip units can provide motor overload protection. Question 38. A 120-V, single-phase, 15-A receptacle must be GFCI-protected when installed in which of the following locations? A) Garage B) Basement C) Outdoor patio D) All of the above Answer: D Explanation: NEC 210.8(A) requires GFCI protection in garages, unfinished basements, and outdoor locations. Question 39. The NEC definition of a “continuous load” is a load that: A) Operates for more than 3 hours continuously B) Operates for more than 1 hour continuously C) Operates at full capacity for the entire day D) Operates only during peak demand periods Answer: A Explanation: Continuous loads are those expected to run for 3 hours or more.
Electrical Ultimate Exam
Question 40. In a three-phase, four-wire delta system, the neutral conductor is used to: A) Balance unbalanced loads B) Provide a ground reference only C) Carry line current D) It is not permitted in delta systems Answer: A Explanation: A neutral in a delta-wye configuration carries the unbalanced current of the system. Question 41. Which of the following devices must be listed for use in a hazardous (Class I) location? A) Standard receptacle outlet B) Explosion-proof motor controller C) Non-metallic conduit D) Standard GFCI breaker Answer: B Explanation: Only explosion-proof (intrinsically safe) devices are permitted in Class I hazardous areas. Question 42. The required minimum size of an equipment grounding conductor (EGC) for a 20-A branch circuit with 12-AWG copper hots is: A) #12 AWG B) #14 AWG C) #10 AWG D) #8 AWG Answer: B Explanation: NEC Table 250.122 allows #14 AWG copper for a 20-A circuit. Question 43. Which NEC article governs the installation of fire alarm wiring?
Electrical Ultimate Exam
Question 46. Which of the following is the correct method for sizing a feeder voltage drop to not exceed 3 % for a 120-V branch circuit carrying 20 A over 100 ft of copper conductor? A) Use #12 AWG B) Use #10 AWG C) Use #8 AWG D) Use #6 AWG Answer: C Explanation: Voltage drop = (2 K I D)/CM. For 20 A, 100 ft, 3 % of 120 V = 3.6 V. Solving gives a required conductor size of #8 AWG. Question 47. The NEC requires that a receptacle installed in a bathroom be GFCI-protected and have a minimum rating of: A) 15 A, 125 V B) 20 A, 125 V C) 15 A, 250 V D) 20 A, 250 V Answer: B Explanation: NEC 210.8(A)(1) requires 20-A, 125-V GFCI protection for bathroom receptacles. Question 48. Which of the following statements about a “grounded conductor” is correct? A) It is always connected to earth at the service entrance. B) It carries only fault current. C) It is the same as the equipment grounding conductor. D) It is insulated and identified by white or gray. Answer: D Explanation: The grounded (neutral) conductor is insulated and identified by continuous white or gray.
Electrical Ultimate Exam
Question 49. When installing a Type MC cable in a commercial building, the cable must be supported at intervals not exceeding: A) 4 ft B) 6 ft C) 8 ft D) 10 ft Answer: B Explanation: NEC 334.30 requires support for MC cable at intervals not exceeding 6 ft. Question 50. The purpose of a “breaker coordination study” is to: A) Determine the correct size of conductors B) Ensure that protective devices operate in a selective manner C) Calculate voltage drop across the system D) Select the appropriate grounding electrode Answer: B Explanation: Coordination studies ensure that downstream devices trip before upstream devices, providing selective protection. Question 51. A transformer’s primary overcurrent protection must be set at a minimum of: A) 125 % of the full-load current B) 150 % of the full-load current C) 200 % of the full-load current D) 250 % of the full-load current Answer: B Explanation: NEC 450.3 requires primary protection to be at least 150 % of the transformer’s full-load current.
Electrical Ultimate Exam
Question 55. Which NEC article specifies the requirements for grounding and bonding of a building’s electrical system? A) 250. B) 250. C) 250. D) 250. Answer: C Explanation: NEC 250.104 deals with grounding and bonding of the building or structure. Question 56. A 30-A, 120/240-V single-phase dryer circuit must have a neutral conductor of at least what size? A) #12 AWG copper B) #10 AWG copper C) #8 AWG copper D) #6 AWG copper Answer: B Explanation: NEC 210.23(A)(2) requires the neutral to be sized the same as the ungrounded conductors, which for 30 A is #10 AWG copper. Question 57. Which of the following is a permissible method for protecting a conduit run that passes through a concrete slab? A) Drilling a 1-in. hole and leaving the conduit exposed B) Using a listed conduit-through-slab fitting with a seal C) Running the conduit on the slab surface only D) No protection is required Answer: B Explanation: A listed conduit-through-slab fitting maintains the integrity of the slab and provides protection.
Electrical Ultimate Exam
Question 58. The maximum distance a receptacle can be located from the floor in a residential laundry room is: A) 12 in. B) 24 in. C) 36 in. D) 48 in. Answer: C Explanation: NEC 210.52(F) requires laundry receptacles to be installed not more than 36 in. above the floor. Question 59. In a three-phase motor circuit, the use of a “reversing starter” requires which of the following additional components? A) Overload relay only B) Two-pole contactor only C) Three-pole contactor and auxiliary contacts D) No additional components Answer: C Explanation: A reversing starter uses a three-pole contactor and auxiliary contacts to change the phase sequence. Question 60. Which of the following statements about a “ground fault circuit interrupter” (GFCI) is true? A) It monitors only the neutral conductor B) It trips when the difference between hot and neutral currents exceeds 5 mA C) It provides over-current protection D) It can be used in place of a circuit breaker for short-circuit protection Answer: B Explanation: A GFCI trips when the hot-neutral current imbalance exceeds about 5 mA, indicating a ground fault.
