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Question 1. What is the primary purpose of the National Electrical Code (NEC)? A) To set standards for construction materials B) To ensure safe installation of electrical wiring and equipment C) To regulate energy usage in buildings D) To provide guidelines for electrical utility billing Answer: B Explanation: The NEC is designed to safeguard persons and property from hazards arising from the use of electricity through safe installation requirements. Question 2. Which NEC article defines commonly used terms within the Code? A) Article 100 B) Article 110 C) Article 310 D) Article 250 Answer: A Explanation: Article 100 contains definitions for terms used throughout the NEC. Question 3. According to the NEC, what are considered “qualified persons”? A) Anyone with basic electrical knowledge B) Only licensed electrical engineers C) Individuals with skills and knowledge related to electrical equipment and installations D) Building inspectors Answer: C Explanation: A qualified person is someone who has the technical skills and knowledge to work safely with electrical systems. Question 4. What must be included in the working space for electrical equipment rated 600 volts, nominal, or less? A) Minimum clear workspace B) A fire extinguisher
C) A step ladder D) Non-conductive flooring Answer: A Explanation: NEC requires a minimum clear workspace to allow safe access to electrical equipment. Question 5. The NEC is updated on what schedule? A) Every 2 years B) Every 3 years C) Every 5 years D) Annually Answer: B Explanation: The NEC is revised and published every three years. Question 6. What is the symbol for a duplex receptacle on a blueprint? A) Circle with two parallel lines B) Square with an X C) Circle with two slashes D) Triangle Answer: C Explanation: A circle with two slashes is the standard symbol for a duplex receptacle. Question 7. In blueprint reading, what does a dashed line often represent? A) Wall B) Hidden feature or future work C) Electrical circuit D) Plumbing Answer: B Explanation: Dashed lines typically indicate hidden elements or future installation work.
Answer: B Explanation: OSHA requires a minimum approach distance of 3 feet for systems 600V and below. Question 12. What is the first step in basic first aid for electrical shock? A) Call for help B) Remove the victim from the source with a non-conductive object C) Start CPR immediately D) Cover the victim with a blanket Answer: B Explanation: Safety first—remove the victim from the source without endangering yourself. Question 13. Ohm’s Law is best represented by which formula? A) V = I x R B) P = V x R C) I = V x P D) R = P x I Answer: A Explanation: Ohm’s Law relates voltage (V), current (I), and resistance (R) as V = I x R. Question 14. In a parallel circuit, what happens to the total resistance as more branches are added? A) It increases B) It stays the same C) It decreases D) It becomes infinite Answer: C Explanation: Adding branches in parallel reduces the total resistance. Question 15. Which of the following is true for DC circuits? A) Voltage alternates direction
B) Current alternates direction C) Current flows in one direction only D) Resistance is not present Answer: C Explanation: In DC circuits, current flows in a single direction. Question 16. What is the primary difference between AC and DC? A) AC is used only in batteries B) AC reverses direction periodically; DC flows one way C) DC is always at high voltage D) AC cannot be transformed Answer: B Explanation: AC changes direction, while DC has a constant direction. Question 17. Which formula calculates electrical power in watts? A) P = V / I B) P = V x I C) P = I / R D) P = R x V Answer: B Explanation: Electrical power (P) is the product of voltage (V) and current (I). Question 18. If a circuit has a voltage of 120V and a resistance of 12 ohms, what is the current? A) 5A B) 10A C) 12A D) 20A Answer: B Explanation: I = V/R = 120V/12Ω = 10A.
D) Voltage of the circuit Answer: B Explanation: Ampacity is derated for higher temperatures and more conductors in a raceway. Question 23. Overcurrent protection devices (OCPDs) are required to protect against: A) Ground faults only B) Overload, short circuit, and ground faults C) Lightning strikes D) Voltage surges Answer: B Explanation: OCPDs protect against overloads, short circuits, and ground faults. Question 24. How is the size of an OCPD selected? A) By the color of insulation B) By load calculation and conductor size C) Randomly D) By length of run Answer: B Explanation: OCPD size is based on calculated load and ampacity of conductors. Question 25. Voltage drop in a feeder should not exceed: A) 1% B) 3% C) 5% D) 10% Answer: B Explanation: NEC recommends voltage drop not exceed 3% for feeders. Question 26. When calculating residential load, what is the general lighting load per square foot?
A) 1 VA
B) 3 VA
C) 5 VA
D) 10 VA
Answer: B Explanation: NEC specifies 3 VA per square foot for general lighting load. Question 27. Which factor is used to reduce calculated loads for diversified demand? A) Demand factor B) Power factor C) Correction factor D) Service factor Answer: A Explanation: Demand factors account for the likelihood not all loads operate simultaneously. Question 28. For a 20A branch circuit supplying receptacles, what is the maximum number of general- purpose receptacles recommended? A) 6 B) 10 C) 13 D) 15 Answer: C Explanation: While not a strict NEC rule, 180 VA per receptacle allows up to 13 on a 20A circuit. Question 29. Which of the following is a rigid metal conduit? A) EMT B) FMC C) RMC D) NM
A) Increase voltage B) Stabilize voltage and provide a path for fault current C) Reduce current D) Eliminate need for fuses Answer: B Explanation: System grounding stabilizes voltage and provides a safe path for faults. Question 34. Bonding is required to: A) Increase resistance B) Ensure electrical continuity and safe fault current path C) Reduce voltage D) Prevent overcurrent Answer: B Explanation: Bonding connects metal parts to ensure safe fault current return. Question 35. Fuses protect circuits by: A) Tripping on ground faults B) Melting when current exceeds rating C) Reducing voltage spikes D) Increasing circuit resistance Answer: B Explanation: Fuses melt and open the circuit if current exceeds their rating. Question 36. Which device is designed to protect against arc faults? A) GFCI B) AFCI C) SPD D) OCPD Answer: B
Explanation: AFCIs (Arc-Fault Circuit Interrupters) detect and trip on arc faults. Question 37. Ground-fault circuit-interrupters (GFCIs) are required in which location? A) Bedroom B) Living room C) Bathroom D) Dining room Answer: C Explanation: GFCIs are required to protect bathroom outlets. Question 38. The minimum size service entrance conductor for a 100A residential service using copper wire is: A) 8 AWG B) 6 AWG C) 4 AWG D) 2 AWG Answer: D Explanation: NEC Table 310.15(B)(16) requires 2 AWG copper for 100A services. Question 39. The main service disconnect must be: A) Accessible only to utility personnel B) Located outside only C) Readily accessible to the building occupants D) Locked at all times Answer: C Explanation: Service disconnects must be readily accessible. Question 40. Which of the following is NOT a type of overcurrent protection device? A) Circuit breaker
Question 44. Which of the following is considered a branch circuit? A) Main service entrance B) Feeder C) Circuit from panel to outlet D) Utility drop Answer: C Explanation: Branch circuits run from the panel to the final outlet or load. Question 45. What is the definition of a feeder? A) Wire from utility pole to building B) Wire from main panel to subpanel C) Circuit from panel to device D) Underground service entrance Answer: B Explanation: Feeders supply subpanels or distribution points from the main panel. Question 46. According to the NEC, which color is typically used for the grounded conductor? A) Red B) Green C) White D) Black Answer: C Explanation: White or gray insulation is used for grounded (neutral) conductors. Question 47. What is the maximum distance between supports for EMT conduit? A) 3 feet B) 6 feet C) 10 feet
D) 12 feet Answer: D Explanation: EMT must be supported at intervals not exceeding 10 feet (NEC 358.30). Question 48. Where must an equipment grounding conductor be run? A) In all branch circuits B) Only in circuits over 120V C) Only in commercial buildings D) Only when using metal boxes Answer: A Explanation: Equipment grounding conductors are required in all branch circuits. Question 49. The minimum burial depth for a direct burial UF cable is: A) 6 inches B) 12 inches C) 18 inches D) 24 inches Answer: C Explanation: NEC Table 300.5 requires 18 inches for direct burial UF cable. Question 50. What is the standard voltage for most residential branch circuits in the US? A) 120V B) 208V C) 240V D) 480V Answer: A Explanation: 120V is standard for most residential branch circuits. Question 51. Which is the correct wire type for wet locations?
Explanation: NEC 110.26 requires 36 inches of working space. Question 55. Which of these is a common cause of electrical fires in residences? A) Overfusing B) Ground faults C) Undersized grounding D) Loose connections Answer: D Explanation: Loose connections can overheat and cause fires. Question 56. In a 277/480V system, what is the phase-to-neutral voltage? A) 120V B) 208V C) 240V D) 277V Answer: D Explanation: 277V is the phase-to-neutral voltage in a 277/480V system. Question 57. What is the minimum size copper conductor for a grounding electrode conductor for a 200A service? A) 8 AWG B) 6 AWG C) 4 AWG D) 2 AWG Answer: B Explanation: NEC Table 250.66 requires minimum 6 AWG copper for 200A. Question 58. Which of the following is NOT a function of an electrical junction box? A) Splice conductors
B) Provide a mounting point for devices C) Protect wire splices D) Increase circuit ampacity Answer: D Explanation: Junction boxes do not increase ampacity. Question 59. Which device is used to test for the presence of voltage? A) Ohmmeter B) Voltmeter C) Clamp meter D) Ammeter Answer: B Explanation: Voltmeters test for voltage presence. Question 60. What is the minimum size of a grounding rod required by the NEC? A) 4 feet B) 6 feet C) 8 feet D) 10 feet Answer: C Explanation: NEC requires grounding electrodes (rods) to be at least 8 feet long. Question 61. When installing NM cable, what is the minimum staple spacing from a box? A) 2 inches B) 6 inches C) 8 inches D) 12 inches Answer: B Explanation: NEC 334.30 requires NM cable stapled within 8 inches of a box.
B) 3%
C) 5%
D) 10%
Answer: B Explanation: NEC recommends keeping branch circuit voltage drop under 3%. Question 66. Which of the following is considered a “continuous load” by the NEC? A) Load operating less than 1 hour B) Load operating for 2 hours C) Load operating for 3 hours or more D) Load operating for 10 minutes Answer: C Explanation: Continuous loads run for 3 hours or more. Question 67. For a continuous load, the branch circuit must be sized at what percent of the load? A) 80% B) 100% C) 125% D) 150% Answer: C Explanation: Circuits for continuous loads must be sized at 125% of the load. Question 68. What is the minimum size for a service disconnect in a one-family dwelling? A) 60A B) 100A C) 125A D) 150A Answer: B Explanation: NEC 230.79(C) requires at least 100A for a single-family dwelling.
Question 69. Which of the following is NOT a type of service disconnect? A) Fusible switch B) Circuit breaker C) Knife switch D) Snap switch Answer: D Explanation: Snap switches are not approved for service disconnects. Question 70. When are neutral-to-ground bonds permitted? A) At every subpanel B) At the main service disconnect only C) At every outlet D) Never Answer: B Explanation: Neutral-to-ground bonding is allowed only at the main service point. Question 71. What is the minimum clearance required above the roof for overhead service conductors? A) 8 feet B) 10 feet C) 12 feet D) 18 feet Answer: B Explanation: Overhead service conductors require 10 feet clearance above roofs. Question 72. Service entrance cables must be supported at intervals not exceeding: A) 18 inches B) 30 inches C) 36 inches
