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Question 1. What is the formula for Ohm’s Law? A) P = IV B) V = IR C) R = P/I D) I = PV Answer: B Explanation: Ohm’s Law states that voltage (V) equals current (I) times resistance (R). Question 2. In a series circuit, how is the total resistance calculated? A) Product of resistances B) Reciprocal of sum of reciprocals C) Sum of all resistances D) Difference between highest and lowest resistance Answer: C Explanation: In a series circuit, total resistance is the sum of all resistances. Question 3. What type of current reverses direction periodically? A) Direct Current (DC) B) Alternating Current (AC) C) Static Current D) Polarized Current Answer: B Explanation: Alternating Current (AC) changes direction periodically, while DC remains constant.
Question 4. Three-phase power systems are typically used in what type of installations? A) Small residential homes B) Large commercial and industrial buildings C) Battery-powered devices D) Low-voltage lighting Answer: B Explanation: Three-phase systems are standard for large commercial/industrial settings due to efficiency. Question 5. What is the unit of electrical resistance? A) Ampere B) Volt C) Ohm D) Watt Answer: C Explanation: Resistance is measured in ohms (Ω). Question 6. Which device measures electrical current? A) Voltmeter B) Ammeter C) Ohmmeter D) Thermometer Answer: B Explanation: An ammeter measures current in a circuit.
Question 10. What is the purpose of a ground fault circuit interrupter (GFCI)? A) Protect against lightning B) Prevent overloads C) Protect against electric shock from ground faults D) Increase current flow Answer: C Explanation: GFCIs detect ground faults and quickly shut off power to prevent shock. Question 11. What is the main difference between grounding and bonding? A) Grounding is only for neutral wires B) Bonding connects electrical components together, grounding connects to earth C) Bonding is for water pipes D) Grounding is for insulation Answer: B Explanation: Grounding connects to earth; bonding connects conductive components together. Question 12. In what NEC article are definitions such as "Accessible" and "Labeled" found? A) Article 90 B) Article 100 C) Article 200 D) Article 300 Answer: B Explanation: NEC Article 100 contains definitions of critical terms.
Question 13. What is the minimum working space required in front of electrical equipment (up to 600V)? A) 1 foot B) 2 feet C) 3 feet D) 4 feet Answer: C Explanation: NEC generally requires 3 feet of clearance in front of equipment. Question 14. What is the NEC requirement for marking electrical equipment? A) Only on the back B) Only on packaging C) Must be marked with manufacturer’s name and ratings D) Not required if UL listed Answer: C Explanation: NEC requires equipment to be marked with manufacturer and ratings for safety. Question 15. Which conductor is typically color-coded green or bare? A) Neutral B) Hot C) Equipment grounding conductor D) Control wire Answer: C
Explanation: Feeders run from the service equipment to distribution points for branch circuits. Question 19. What is the purpose of overcurrent protection? A) Increase current B) Prevent excessive current that could cause damage/fire C) Provide backup power D) Measure voltage Answer: B Explanation: Overcurrent devices protect circuits from dangerous currents. Question 20. Which protection device is typically used for motor circuits? A) GFCI B) Circuit breaker C) Overload relay D) Photocell Answer: C Explanation: Overload relays are designed to protect motors from overheating due to overload. Question 21. When must GFCI protection be provided in residential garages? A) Never B) Only for dedicated circuits C) For all 125V, single-phase, 15- and 20-amp receptacles D) Only for ceiling outlets Answer: C
Explanation: NEC requires GFCI protection for all 125V, single-phase, 15- and 20-amp receptacles in garages. Question 22. What is the minimum burial depth for a direct-buried 120V circuit using UF cable? A) 6 inches B) 12 inches C) 18 inches D) 24 inches Answer: C Explanation: UF cable must be buried at least 18 inches deep per NEC. Question 23. What is the maximum allowed voltage drop for feeders and branch circuits? A) 1% B) 3% C) 5% D) 10% Answer: B Explanation: NEC recommends not exceeding a 3% voltage drop. Question 24. What is the required ampacity adjustment factor for three current-carrying conductors in a raceway? A) 80% B) 70% C) 100% D) 60%
D) Plastic water pipe Answer: B Explanation: Steel rebar is acceptable; aluminum and plastic pipes are not. Question 28. What is the purpose of a bonding jumper? A) Increase current flow B) Electrically connect metal parts to ensure continuity C) Insulate wires D) Reduce voltage Answer: B Explanation: Bonding jumpers ensure electrical continuity and safe fault current paths. Question 29. Where are GFCIs NOT required in a dwelling unit? A) Bathrooms B) Kitchens C) Hallways D) Laundry areas Answer: C Explanation: Hallways do not require GFCIs per NEC. Question 30. What is the minimum required clearance from the edge of framing for NM cable? A) 1/4 inch B) 1/2 inch C) 1 inch
D) 1-1/4 inch Answer: D Explanation: NM cable must be at least 1-1/4 inches from the edge to prevent nail damage. Question 31. Which cable type is known as “Romex”? A) MC B) AC C) NM D) SE Answer: C Explanation: NM (nonmetallic-sheathed) cable is commonly called “Romex.” Question 32. What is the maximum number of 12 AWG conductors allowed in a standard 4-inch square, 2 - 1/8 inch deep box? A) 6 B) 9 C) 12 D) 14 Answer: B Explanation: Box fill calculations show a 4-inch square box allows up to 9 12 AWG conductors. Question 33. Which raceway material is NOT approved for use in wet locations? A) EMT B) PVC
B) 75°C
C) 90°C
D) 105°C
Answer: B Explanation: Most NM cable is rated for 75°C. Question 37. Which conduit type is most resistant to physical damage? A) EMT B) PVC C) RMC D) FMC Answer: C Explanation: Rigid metal conduit (RMC) offers the highest resistance to physical damage. Question 38. What is the volume allowance in cubic inches for a standard device in a box fill calculation? A) 1. B) 2. C) 2. D) 4. Answer: C Explanation: Each device counts as 2.5 cubic inches in box fill calculations. Question 39. How many 10 AWG THHN conductors fit in a 3/4" EMT conduit? A) 6
B) 10
C) 16
D) 21
Answer: B Explanation: NEC Chapter 9, Table 1 allows 10 10 AWG THHN conductors in 3/4" EMT. Question 40. Which of the following is an acceptable use for flexible cord? A) Permanent wiring in walls B) Temporary portable equipment C) Lighting circuit in ceilings D) Service entrance conductors Answer: B Explanation: Flexible cords are for portable and temporary equipment only. Question 41. What is the NEC Article for temporary wiring installations? A) 210 B) 225 C) 305 D) 310 Answer: C Explanation: Article 305 covers temporary wiring installations. Question 42. Which color is commonly used for the neutral conductor in a 120/240V system? A) Black
A) No protection needed B) Secure NM cable within 6 feet of the attic access C) Protect cable within 6 feet of access D) Use MC cable only Answer: C Explanation: NM cable must be protected within 6 feet of attic access with permanent stairs. Question 46. What is the NEC requirement for supporting flexible metal conduit (FMC)? A) Every 6 feet B) Every 4.5 feet C) Every 3 feet D) Every 10 feet Answer: B Explanation: FMC must be supported at intervals not exceeding 4.5 feet. Question 47. Which NEC article covers raceway fill calculations? A) Article 310 B) Article 314 C) Article 300 D) Article 358 Answer: A Explanation: Article 310 contains conduit fill tables and requirements. Question 48. What is required for outdoor receptacles in a wet location?
A) No cover needed B) Ordinary indoor cover C) Weatherproof enclosure with in-use cover D) GFCI only Answer: C Explanation: Outdoor wet-location receptacles require weatherproof, in-use covers. Question 49. What is the minimum height for service drop conductors above a residential driveway? A) 8 feet B) 10 feet C) 12 feet D) 18 feet Answer: B Explanation: NEC requires at least 10 feet above residential driveways. Question 50. When must a disconnecting means be located on the outside of a dwelling? A) Never B) Always C) When required by local code or for new installations D) Only for mobile homes Answer: C Explanation: Some local codes and NEC revisions require outdoor disconnects for new services.
Question 54. What is the purpose of conduit bushings? A) Increase voltage B) Reduce friction on wire pulls and protect insulation C) Ground the conduit D) Support the conduit Answer: B Explanation: Bushings protect wire insulation from abrasion at conduit ends. Question 55. What is the minimum burial depth for rigid metal conduit (RMC) outdoors? A) 6 inches B) 12 inches C) 18 inches D) 24 inches Answer: B Explanation: RMC must be buried at least 6 inches, but most local codes recommend 12 inches or more. Question 56. Where are tamper-resistant receptacles required? A) Only in kitchens B) Only in garages C) In all areas of dwelling units accessible to children D) Only in unfinished basements Answer: C Explanation: NEC requires tamper-resistant receptacles in all accessible areas of dwellings.
Question 57. What is the maximum distance between supports for EMT conduit? A) 3 feet B) 6 feet C) 10 feet D) 16 feet Answer: C Explanation: EMT must be supported every 10 feet maximum. Question 58. What is the minimum size of an equipment grounding conductor for a 30A circuit? A) 14 AWG B) 12 AWG C) 10 AWG D) 8 AWG Answer: A Explanation: NEC Table 250.122 specifies 14 AWG minimum for 30A. Question 59. Which of the following is NOT a grounding electrode? A) Metal underground water pipe B) Ground rod C) Concrete-encased electrode D) Plastic underground pipe Answer: D Explanation: Plastic pipes cannot serve as grounding electrodes.
