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Master Electrician Exam (NEC) practice questions

200 free questions with answers and explanations.

Practice test
  1. 51.A master electrician is planning the electrical installation for a new indoor swimming pool at a residential property. The pool is 20 feet long and 10 feet wide. Which of the following statements regarding the grounding and bonding requirements for the pool is correct according to the NEC?Special Occupancies, Equipment, and Conditions
  2. 52.A master electrician is inspecting a marina for compliance with NEC requirements. The marina has several docks with multiple receptacles for shore power. Which of the following is a mandatory requirement for these shore power receptacles?Special Occupancies, Equipment, and Conditions
  3. 53.A master electrician is installing a new sign for a commercial business. The sign is an outline lighting system with individual letters. According to NEC Article 600, what is the minimum required rating for the branch circuit supplying this sign?Special Occupancies, Equipment, and Conditions
  4. 54.A master electrician is installing a new manufactured building that will be used as an office. The building is designed to be relocated at a later date. According to NEC, where must the feeder assembly for this manufactured building terminate?Special Occupancies, Equipment, and Conditions
  5. 55.A master electrician is installing a communication system in a commercial building. The system includes a power-limited fire alarm circuit that extends beyond the building. According to NEC, what is the minimum required separation distance between the exposed communication cables and exposed electric light or power conductors that are not in a raceway or cable, if the power conductors operate at 300 volts or less?Special Occupancies, Equipment, and Conditions
  6. 56.A master electrician is installing a new fuel cell system as a supplemental power source for a commercial building. The fuel cell system is rated at 20 kW. According to NEC, what is the maximum continuous current that a single fuel cell inverter output circuit is permitted to exceed?Special Occupancies, Equipment, and Conditions
  7. 57.A master electrician is installing temporary power for a construction site. The temporary service will be supplied by a 200A panelboard. Which of the following statements is true regarding the overcurrent protection and grounding requirements for this temporary installation according to the NEC?Special Occupancies, Equipment, and Conditions
  8. 58.A master electrician is installing lighting fixtures in an agricultural building that houses livestock and has a corrosive atmosphere due to animal waste. According to NEC Article 547, which of the following statements regarding the wiring methods is correct?Special Occupancies, Equipment, and Conditions
  9. 59.A master electrician is installing a fuel cell system as a standalone power source for a remote cabin. The fuel cell system generates DC power, which is then converted to AC by an inverter. Which of the following statements regarding the grounding of the fuel cell system is correct according to NEC Article 692?Special Occupancies, Equipment, and Conditions
  10. 60.A master electrician is planning the electrical installation for a new solar photovoltaic (PV) system on a commercial rooftop. The system includes PV modules, an inverter, and a DC combiner box. Which of the following statements regarding the PV system's disconnecting means is correct according to NEC Article 690?Special Occupancies, Equipment, and Conditions
  11. 61.A master electrician is installing a new electric vehicle (EV) charging station at a commercial parking garage. The charging station is rated for 48A continuous operation. Which of the following overcurrent protective device (OCPD) ratings is compliant with NEC requirements for this installation?Special Occupancies, Equipment, and Conditions
  12. 62.A master electrician is installing a new escalator in a shopping mall. According to NEC Article 620, what is the maximum permissible overcurrent protective device (OCPD) rating for the power and control circuits of the escalator, relative to the motor nameplate current rating?Special Occupancies, Equipment, and Conditions
  13. 63.A master electrician is installing an electric vehicle (EV) charging station at a multi-family dwelling. The EV charging equipment has a continuous rating of 40 amperes. What is the minimum continuous current rating required for the overcurrent protective device (OCPD) supplying this EV charging equipment?Special Occupancies, Equipment, and Conditions
  14. 64.A master electrician is installing a new fire alarm system in a multi-story commercial building. The fire alarm control unit (FACU) requires a dedicated branch circuit. What is the maximum overcurrent protective device (OCPD) rating permitted for this dedicated branch circuit supplying the FACU?Special Occupancies, Equipment, and Conditions
  15. 65.A master electrician is installing a new emergency system in a large assembly hall. The emergency system is intended to provide illumination and power for exit signs, emergency lighting, and essential communication systems upon failure of the normal power supply. What is the maximum permitted time delay for the emergency system to automatically come into full operation after the normal power failure?Special Occupancies, Equipment, and Conditions
  16. 66.A master electrician is installing a new service for a recreational vehicle (RV) site in a campground. The RV site is intended for a large RV requiring a 50-amp, 120/240-volt supply. According to NEC Article 551, what is the minimum overcurrent protective device (OCPD) rating required for the individual RV site supply equipment?Special Occupancies, Equipment, and Conditions
  17. 67.A master electrician is installing a new manufactured building that will serve as a permanent office space. The manufactured building is equipped with a 100-ampere, 120/240-volt service. Where is the main disconnecting means for this manufactured building required to be located?Special Occupancies, Equipment, and Conditions
  18. 68.A master electrician is installing a new wind electric system for a commercial property. The system includes an inverter that is connected to the normal power supply. The inverter has a continuous output current of 50 amperes. What is the minimum continuous current rating required for the conductors connecting the inverter output to the building's electrical system?Special Occupancies, Equipment, and Conditions
  19. 69.A master electrician is installing a new solar photovoltaic (PV) system on a residential property. The system includes PV modules, an inverter, and a battery energy storage system. Which of the following statements is true regarding the marking requirements for the system's disconnecting means?Special Occupancies, Equipment, and Conditions
  20. 70.A master electrician is installing a new elevator in a commercial building. The elevator machine room requires specific lighting. According to NEC Article 620, what is the minimum illumination level required at the floor level in the elevator machine room?Special Occupancies, Equipment, and Conditions
  21. 71.A master electrician is designing the electrical system for a new health care facility. The facility includes patient care areas where critical patient care is administered. Which specific type of receptacle is required for patient bed locations in these critical care areas?Special Occupancies, Equipment, and Conditions
  22. 72.A master electrician is installing a new critical operations power system (COPS) for a data center. The COPS is designed to supply power to loads that, if interrupted, would jeopardize the safety and health of personnel or result in losses affecting national security or the economy. Which of the following is a specific requirement for the wiring of COPS circuits?Special Occupancies, Equipment, and Conditions
  23. 73.A master electrician is installing a new fire alarm control unit (FACU) in a commercial building. The FACU requires a dedicated branch circuit. According to NEC Article 760, what is the maximum overcurrent protective device (OCPD) rating permitted for this dedicated branch circuit when the FACU's full-load current is 2.5 amperes?Special Occupancies, Equipment, and Conditions
  24. 74.A master electrician is installing a new industrial control panel in a Class I, Division 2 hazardous location where flammable gases are present. The panel contains switches, relays, and other control devices. Which wiring method is generally permitted for connecting components within this control panel?Special Occupancies, Equipment, and Conditions
  25. 75.A master electrician is installing a new general-purpose receptacle for maintenance equipment within 20 feet of a permanently installed swimming pool. The receptacle is located 7 feet horizontally from the inside wall of the pool. Which of the following statements is true regarding its installation?Special Occupancies, Equipment, and Conditions
  26. 76.A master electrician is performing a short-circuit current calculation for a commercial service. The utility transformer is rated 1000 kVA, 480Y/277V, with an impedance of 5%. The service conductors have a total impedance (including busway) of 0.0005 ohms. What is the approximate available symmetrical short-circuit current at the service entrance?General Electrical Knowledge
  27. 77.A master electrician is inspecting a newly installed 4-inch rigid metal conduit (RMC) that will contain 10 AWG THHN conductors. What is the maximum number of 10 AWG THHN conductors permitted in this 4-inch RMC, assuming all conductors are the same size and insulation type?General Electrical Knowledge
  28. 78.A master electrician is performing an insulation resistance test on a newly installed 480V motor feeder circuit. What is the minimum acceptable insulation resistance value for this circuit, according to industry standards and common practice?General Electrical Knowledge
  29. 79.A master electrician is performing maintenance on a 480V, 3-phase, Delta-connected transformer. The secondary side is 208Y/120V. If one of the primary fuses blows, what will be the resulting voltage configuration on the secondary side?General Electrical Knowledge
  30. 80.A technician is performing insulation resistance testing on a new 600V motor feeder. According to generally accepted industry practices and standards like the NETA MTS, what is the minimum acceptable insulation resistance value for this feeder?General Electrical Knowledge
  31. 81.A master electrician is troubleshooting a transformer in a 480V primary, 208Y/120V secondary system. The transformer has a turns ratio of 2:1. If the primary voltage is correctly measured at 480V, what would be the expected line-to-line voltage on the secondary side of an ideal transformer with this ratio?General Electrical Knowledge
  32. 82.A master electrician is performing a continuity test on a newly installed 3-phase motor winding. The multimeter reads a very low resistance (e.g., 0.5 ohms) between each winding and between the windings and the motor frame. What does this reading indicate?General Electrical Knowledge
  33. 83.A master electrician is installing a 20A, 120V branch circuit in a dwelling unit to supply a refrigerator. The circuit conductors will be run in NM cable. What is the maximum distance the circuit can extend from the panel to the refrigerator receptacle to maintain voltage drop within the recommended 3% for the branch circuit, assuming a power factor of 1 and using 12 AWG copper conductors?General Electrical Knowledge
  34. 84.A journeyman electrician is installing a new battery backup system in a data center. The system uses lead-acid batteries. Which of the following is a critical safety concern unique to charging lead-acid batteries that requires proper ventilation?General Electrical Knowledge
  35. 85.A master electrician is supervising the installation of a new 400A, 480Y/277V service for a commercial building. The service entrance conductors are 500 kcmil copper, type THWN-2. According to NEC 250.66(A), what is the minimum size required for the grounded conductor (neutral) for grounding electrode conductor connection purposes, assuming it is not smaller than required for carrying neutral current?General Electrical Knowledge
  36. 86.A residential service entrance conductor is being installed between the utility's drip loop and the service disconnect. The service is 200A, 240V single-phase. The conductors are copper with a 75°C insulation rating. What is the minimum size copper conductor required for the ungrounded service entrance conductors, according to NEC 310.12?General Electrical Knowledge
  37. 87.A master electrician is designing a lighting circuit for a new commercial office space. The circuit will primarily supply LED luminaires. Which type of transformer is typically used to step down the utility voltage (e.g., 480V) to the building's main distribution voltage (e.g., 208Y/120V) for general-purpose loads like lighting and receptacles?General Electrical Knowledge
  38. 88.A master electrician is planning the installation of a new 480V, 3-phase motor with a full-load current (FLA) of 60A. According to NEC Article 430, what is the minimum continuous current rating required for the branch-circuit conductors supplying this motor if it is not a hermetic refrigerant motor?General Electrical Knowledge
  39. 89.A master electrician is evaluating a circuit with two 10-ohm resistors connected in parallel, which are then connected in series with a 5-ohm resistor. If the total voltage applied to this circuit is 20V, what is the total current flowing through the circuit?General Electrical Knowledge
  40. 90.A newly installed motor in a commercial facility draws 50A at 480V, 3-phase. The motor nameplate indicates a power factor of 0.85. What is the approximate apparent power (S) consumed by this motor?General Electrical Knowledge
  41. 91.A master electrician is installing a new 277V, 3-phase lighting circuit in a commercial office. The circuit uses 12 AWG copper conductors, each carrying 16A of continuous load. What is the minimum temperature rating of the terminal lugs and conductors required for this application, assuming no other adjustments are necessary?General Electrical Knowledge
  42. 92.A master electrician is designing a grounding electrode system for a new commercial building. Which of the following is NOT generally permitted as a grounding electrode by NEC Article 250?General Electrical Knowledge
  43. 93.A master electrician is installing a new 480V, 3-phase motor with a full-load current (FLA) of 60A. The motor will be started directly across the line. What is the minimum continuous current rating required for the motor feeder conductors, assuming 75°C terminals?General Electrical Knowledge
  44. 94.A master electrician is inspecting a newly installed 30A, 240V circuit for an electric vehicle charging station in a garage. The circuit consists of two ungrounded conductors, a grounded conductor, and an equipment grounding conductor. Which of the following statements regarding the grounded conductor is correct, per NEC requirements?General Electrical Knowledge
  45. 95.A master electrician is installing a new 200A service for a residential dwelling. The service entrance conductors are 2/0 AWG copper. What is the minimum size required for the main bonding jumper (MBJ) in this service, per NEC Article 250?General Electrical Knowledge
  46. 96.A maintenance electrician is replacing a faulty contactor coil in a motor control circuit. The circuit operates at 24V AC. The new coil must have the correct impedance to ensure proper operation and prevent damage. If the coil draws 0.5A at 24V AC, what is its approximate impedance?General Electrical Knowledge
  47. 97.A master electrician is troubleshooting a 120V AC circuit that has an inductive load. A voltmeter measures 120V and an ammeter measures 10A. A wattmeter, however, indicates only 960W. What is the power factor of this circuit?General Electrical Knowledge
  48. 98.A technician is installing a new 480V, 3-phase, 60 Hz motor with a nameplate RPM of 1750. What is the approximate synchronous speed of this motor?General Electrical Knowledge
  49. 99.A master electrician is supervising the rough-in wiring for a new commercial office space. A 20A, 120V general-purpose receptacle branch circuit has a total calculated load of 15A. The circuit will use 12 AWG THHN copper conductors. What is the maximum voltage drop permitted for this branch circuit, assuming a total circuit length (feeder + branch) of 100 feet, according to NEC recommendations?General Electrical Knowledge
  50. 100.A master electrician is troubleshooting a control circuit that occasionally experiences nuisance tripping due to inductive kickback when a large contactor de-energizes. Which of the following components would be most effective in mitigating this issue?General Electrical Knowledge