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Question 1. Which law states that the current through a conductor between two points is directly proportional to the voltage across the two points? A) Kirchhoff’s Voltage Law B) Ohm’s Law C) Faraday’s Law D) Joule’s Law Answer: B Explanation: Ohm’s Law defines the relationship I = V/R, indicating current is proportional to voltage for a constant resistance. Question 2. In a series circuit, the total resistance is: A) The sum of all individual resistances B) The reciprocal of the sum of reciprocals of each resistance C) Equal to the largest resistance only D) Independent of the number of resistors Answer: A Explanation: Series resistances add directly because the same current flows through each component. Question 3. For a parallel circuit with three resistors of 4 Ω, 6 Ω, and 12 Ω, the total resistance is closest to: A) 2 Ω B) 3 Ω C) 7 Ω D) 22 Ω Answer: B
Explanation: 1/R_total = 1/4 + 1/6 + 1/12 = 0.25 + 0.1667 + 0.0833 = 0.5 → R_total = 2 Ω. (Rounded to 2 Ω; answer closest is 3 Ω, but the correct calculation yields 2 Ω. The nearest provided answer is B.) Question 4. The power factor of an AC circuit is defined as: A) The ratio of real power to apparent power B) The ratio of apparent power to reactive power C) The cosine of the angle between voltage and current phasors D) Both A and C Answer: D Explanation: Power factor = Real Power / Apparent Power = cos θ, where θ is the phase angle between voltage and current. Question 5. In a three‑phase wye‑connected system, the line voltage is √3 times the phase voltage. If the phase voltage is 120 V, the line voltage is: A) 120 V B) 208 V C) 240 V D) 415 V Answer: B Explanation: V_line = √3 × V_phase = 1.732 × 120 ≈ 208 V. Question 6. A transformer’s primary winding has 500 turns and the secondary has 125 turns. If 240 V is applied to the primary, the secondary voltage will be: A) 60 V B) 120 V C) 480 V
D) (Synchronous speed − Rotor speed) / Rotor speed Answer: A Explanation: Slip quantifies the difference between synchronous and actual rotor speed as a fraction of synchronous speed. Question 10. According to NEC Article 90, the purpose of the National Electrical Code is to: A) Promote the use of renewable energy B) Protect public safety from electrical hazards C) Standardize electrical pricing D) Regulate utility rates Answer: B Explanation: NEC’s primary purpose is to safeguard life and property by establishing safety standards. Question 11. NEC Article 100 defines “accessible” as: A) Capable of being reached without the use of tools or removing obstacles B) Reachable only after a lockout/tagout procedure C) Available only to qualified personnel D) Able to be reached only by qualified electricians Answer: A Explanation: “Accessible” means a component can be reached without tools, ladders, or removing any part of the building structure. Question 12. Which NEC article governs the requirements for grounding and bonding of electrical systems? A) Article 110 B) Article 210
C) Article 250 D) Article 300 Answer: C Explanation: Article 250 contains the rules for grounding and bonding to ensure safety and proper operation. Question 13. The term “listed” in the NEC refers to equipment that has been: A) Approved by the AHJ (Authority Having Jurisdiction) only B) Tested and evaluated by a recognized testing laboratory for compliance with standards C) Installed in a listed location D) Marked with a serial number Answer: B Explanation: “Listed” indicates that a product has been examined and found to meet applicable standards by a recognized testing organization (e.g., UL). Question 14. When using a multimeter to measure voltage, it is essential to: A) Set the meter to the highest range to avoid overload B) Ensure the meter’s leads are shorted together before testing C) Connect the meter in series with the circuit D) Select the appropriate voltage range and connect the leads in parallel across the source Answer: D Explanation: Voltage is measured across (parallel to) the component; selecting the correct range prevents damage and ensures accurate reading. Question 15. The OSHA lockout/tagout (LOTO) procedure is intended to: A) Prevent unauthorized access to a worksite B) Ensure that electrical equipment is de‑energized and cannot be re‑energized while servicing
B) 1 VA per square foot of floor area C) 120 VA per square foot of floor area D) 30 VA per square foot of floor area Answer: A Explanation: The NEC requires 3 VA per square foot for general lighting and receptacle loads in dwellings. Question 19. When calculating demand load for a commercial building, the NEC permits the use of demand factors for: A) All continuous loads only B) Motor loads only C) Lighting loads, receptacles, and fixed appliances D) None; demand factors are not allowed in commercial calculations Answer: C Explanation: NEC Table 220.42 provides demand factors for lighting, receptacles, and fixed appliances in commercial occupancies. Question 20. A continuous load is defined as a load that: A) Operates for more than 3 hours continuously B) Operates for less than 1 hour continuously C) Operates intermittently throughout the day D) Is a motor load only Answer: A Explanation: NEC defines a continuous load as one that runs for 3 hours or more. Question 21. The neutral conductor of a residential service must be sized to carry: A) The maximum unbalanced load of the system
B) The sum of all branch‑circuit currents C) The same ampacity as the hot conductors D) Only the grounding current Answer: A Explanation: The neutral only carries the unbalanced portion of the load; it is sized accordingly. Question 22. NEC Article 230 requires a service disconnecting means to be located: A) Inside the building only B) At the point of service entry, either inside or outside the building C) At the farthest point from the service entrance D) Only on the exterior of the building Answer: B Explanation: The disconnect must be at the point where the service conductors enter the building, which may be inside or outside. Question 23. The minimum clearance in front of a service equipment rated 600 A or less is: A) 30 in. B) 36 in. C) 42 in. D) 48 in. Answer: B Explanation: NEC 230.71 requires a minimum of 36 in. of clear working space in front of service equipment ≤ 600 A. Question 24. Overcurrent protection for a service entrance conductor shall not exceed: A) 125 % of the conductor’s ampacity B) 100 % of the conductor’s ampacity
B) Disconnected simultaneously by a common‑trip breaker or handle‑tied breakers C) Routed through separate panels D) Protected by a single‑pole breaker only Answer: B Explanation: NEC 210.4(B) requires simultaneous disconnect of the ungrounded conductors of an MWBC. Question 28. AFCI protection is required for which of the following locations in a new residential construction? A) All 125‑V, 15‑ and 20‑A branch circuits supplying outlets in living areas B) Only for circuits feeding kitchen appliances C) Only for circuits feeding outdoor receptacles D) Only for dedicated lighting circuits Answer: A Explanation: NEC 210.12(A) requires AFCI protection for all 125‑V, 15‑ and 20‑A branch circuits in dwelling unit living areas. Question 29. GFCI protection is NOT required for which of the following? A) Bathrooms B) Garages C) Outdoor receptacles D) Receptacles serving a dedicated hard‑wired fire alarm system Answer: D Explanation: NEC 210.8(A)(10) exempts fire alarm circuits from GFCI requirements. Question 30. When installing a feeder, the conductor ampacity must be determined using which NEC table as the primary reference?
A) Table 310. B) Table 210. C) Table 220. D) Table 240. Answer: A Explanation: Table 310.16 provides ampacities for conductors based on size, insulation, and temperature rating. Question 31. A feeder tap must not exceed which of the following lengths, unless otherwise permitted by the NEC? A) 10 ft B) 25 ft C) 50 ft D) 100 ft Answer: B Explanation: NEC 215.2(A)(1) limits feeder taps to 25 ft unless other conditions are met. Question 32. Which type of overcurrent protective device is required to protect a flexible cord set used for a portable tool? A) A fuse in the cord set B) A circuit breaker at the panel only C) A GFCI receptacle only D) No overcurrent protection is required for flexible cords Answer: A Explanation: NEC 240.5(G) requires overcurrent protection for flexible cords, typically a fuse or breaker sized for the cord’s ampacity.
Explanation: A grounding electrode must be buried or encased; a wire simply lying on the surface is not acceptable. Question 36. The minimum size of a grounding electrode conductor (GEC) for a 100‑A service is: A) 6 AWG copper B) 8 AWG copper C) 10 AWG copper D) 12 AWG copper Answer: B Explanation: NEC Table 250.66 specifies 8 AWG copper for a 100‑A service. Question 37. Equipment grounding conductors (EGCs) must be sized based on: A) The rating of the overcurrent protective device protecting the circuit B) The length of the circuit only C) The type of load served D) The number of receptacles on the circuit Answer: A Explanation: NEC Table 250.122 provides EGC sizes based on the OCPD rating. Question 38. Bonding of metal water piping is required when the piping is: A) Made of copper only B) Exposed and within 5 ft of the service equipment C) Continuous and not isolated from the grounding electrode system D) Used for decorative purposes only Answer: C
Explanation: NEC 250.104(A)(1) requires bonding of metal water piping that is part of the grounding electrode system. Question 39. The term “system grounding” refers to: A) Connecting the neutral to earth at the service entrance B) Connecting all exposed metal parts to the neutral conductor C) Providing a path for normal load current back to the source D) Connecting the grounding electrode conductor to the equipment grounding conductor only Answer: A Explanation: System grounding ties the neutral (grounded conductor) to the earth at the service entrance. Question 40. Which conductor material is prohibited for use in a wet location unless specifically listed for the purpose? A) Copper with THHN insulation B) Aluminum with XHHW‑2 insulation C) Copper with UF‑B cable D) Copper with NM‑B cable Answer: D Explanation: NM‑B (Romex) is not rated for wet locations; it may only be used in dry, interior spaces. Question 41. When applying temperature correction factors to conductor ampacity, the factor for a 40 °C ambient temperature (assuming 30 °C base) is: A) 0. B) 0. C) 1.
Question 44. Rigid Metal Conduit (RMC) must be supported within how many inches of each outlet box? A) 6 in. B) 12 in. C) 24 in. D) 36 in. Answer: B Explanation: NEC 358.30 requires RMC to be secured within 12 in. of each outlet box. Question 45. The fill capacity for EMT (Electrical Metallic Tubing) when using 3/4‑in. conduit and 14‑AWG THHN conductors is: A) 40 % B) 53 % C) 60 % D) 75 % Answer: B Explanation: NEC Chapter 9 Table 1 lists a 53 % fill for EMT when three or more conductors are present. Question 46. PVC conduit (Schedule 40) may be used in wet locations because: A) Its metal jacket prevents moisture ingress B) The PVC material itself is non‑conductive and resistant to water C) It must be filled with a water‑tight sealant D) It is only allowed in dry locations Answer: B Explanation: PVC is inherently water‑resistant, making it suitable for wet locations.
Question 47. The minimum burial depth for a non‑metallic sheathed cable (NM‑B) protected by a 2‑in. concrete slab is: A) 6 in. B) 12 in. C) 18 in. D) 24 in. Answer: B Explanation: NEC 334.15(B) allows a reduced burial depth of 12 in. for NM‑B when protected by at least 2 in. of concrete. Question 48. A flexible metal conduit (FMC) must be supported at intervals not exceeding: A) 3 ft B) 4 ft C) 6 ft D) 8 ft Answer: C Explanation: NEC 376.30 requires FMC to be supported within 6 ft intervals. Question 49. Armored Cable (AC) is permitted to be used as a feeder in a commercial building provided that: A) The cable is listed for feeder use and the ampacity is not less than the load B) The cable is installed in a raceway only C) The cable is no longer than 50 ft in length D) The cable is used only for lighting circuits Answer: A Explanation: NEC 320.30 permits AC to be used as a feeder if it meets the ampacity and listing requirements.
Explanation: NEC 408.4 requires at least 30 in. of clear working space in front of panelboards. Question 53. When a receptacle is installed in a location that requires GFCI protection, the device must be: A) A GFCI receptacle or protected by a GFCI breaker upstream B) A standard receptacle with a separate GFCI module C) A duplex receptacle only D) An AFCI receptacle only Answer: A Explanation: NEC 210.8 requires GFCI protection either at the receptacle or upstream via a breaker. Question 54. The minimum ampacity for a feeder supplying a 30‑A range circuit using 10 ‑AWG copper conductors is: A) 30 A B) 35 A C) 40 A D) 45 A Answer: C Explanation: 10‑AWG copper is rated for 30 A in Table 310.16, but a 30‑A range circuit may require a 40 A feeder due to continuous load considerations; the next standard OCPD size is 40 A. Question 55. Which of the following devices is used to protect a circuit from overcurrent and also provides a visual indication of a fault? A) Fuse B) Circuit breaker with a trip indicator C) GFCI receptacle
D) AFCI breaker Answer: B Explanation: Circuit breakers often include a trip indicator light, providing both overcurrent protection and visual fault indication. Question 56. The NEC allows the use of a 3‑wire cable (hot‑hot‑ground) for a 240‑V circuit without a neutral because: A) The neutral is not required for purely 240‑V loads B) The ground can serve as the neutral C) The circuit must always include a neutral D) A 3‑wire cable is never permitted for 240‑V circuits Answer: A Explanation: Pure 240‑V loads do not need a neutral; a hot‑hot‑ground configuration is acceptable. Question 57. Which of the following is the correct method for sizing a grounding electrode conductor for a 200‑A service? A) 6 AWG copper B) 4 AWG copper C) 2 AWG copper D) 1/0 AWG copper Answer: B Explanation: NEC Table 250.66 indicates 4 AWG copper for a 200‑A service. Question 58. According to NEC 300.5, the minimum cover for a PVC conduit buried in residential soil not less than 24 in. deep is: A) 6 in.
