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Master Electrician Exam (NEC) practice questions

200 free questions with answers and explanations.

Practice test
  1. 1.A master electrician is installing a new 480Y/277V, 3-phase, 4-wire service in a commercial building. The building has a structural steel frame that meets the requirements for a grounding electrode. What is the minimum length of structural steel that must be in direct contact with the earth to be considered a grounding electrode?Grounding and Bonding
  2. 2.A master electrician is inspecting a previously installed grounding electrode system for a dwelling. The system includes a metal underground water pipe electrode and a supplemental electrode. The water pipe has 10 feet of contact with the earth. What is the minimum length of the supplemental electrode required if it is a ground rod, according to NEC 250.53(A)(2)?Grounding and Bonding
  3. 3.A master electrician is installing a new 480V, 3-phase, 4-wire wye system for a commercial kitchen. The main service will be located in a dedicated electrical room. What is the minimum size copper main bonding jumper required if the ungrounded service-entrance conductors are 700 kcmil copper?Grounding and Bonding
  4. 4.A master electrician is installing a new 480V, 3-phase, 3-wire delta service for an industrial facility. The service entrance conductors are 300 kcmil copper. What is the minimum size copper grounding electrode conductor (GEC) required for this service?Grounding and Bonding
  5. 5.A master electrician is installing a new subpanel in a detached garage, fed from the main service panel of a dwelling. The subpanel is supplied by a 240V, 3-wire feeder. According to the NEC, how must the neutral conductor be handled at the detached garage subpanel?Grounding and Bonding
  6. 6.A master electrician is installing a new 480V, 3-phase, 3-wire delta service for an industrial facility. The service will be supplied by a transformer bank. Which of the following statements regarding the grounding of this service is true?Grounding and Bonding
  7. 7.A master electrician is installing a new 200A, 120/240V, single-phase service for a dwelling. The service entrance conductors are 3/0 AWG copper. What is the minimum size copper grounding electrode conductor required if the largest grounding electrode is a metal underground water pipe?Grounding and Bonding
  8. 8.A master electrician is installing a new 100A, 120/240V, single-phase service for a residential dwelling. The service entrance conductors are No. 1 AWG copper. What is the minimum size copper grounding electrode conductor required if the largest grounding electrode is a ground rod?Grounding and Bonding
  9. 9.A master electrician is installing a lightning protection system on a commercial building. According to NEC 250.60, what is the requirement for bonding the lightning protection system to the building's electrical grounding system?Grounding and Bonding
  10. 10.A master electrician is installing a new 480V, 3-phase, 4-wire wye service where the service entrance conductors are 500 kcmil copper. The grounding electrode conductor is connected to a concrete-encased electrode (Ufer ground). What is the minimum size copper grounding electrode conductor required for this connection, according to NEC 250.66(B)?Grounding and Bonding
  11. 11.A master electrician is installing a new 200A, 120/240V, single-phase service. The grounding electrode system consists of a metal underground water pipe and a supplemental ground rod. Which of the following statements is correct regarding the connection of the grounding electrode conductor (GEC) to these electrodes?Grounding and Bonding
  12. 12.A master electrician is installing a new 200A, 120/240V, single-phase service for a residential dwelling. The service entrance conduit is 2-inch rigid metal conduit (RMC) and the service conductors are 3/0 AWG copper. What is the minimum size copper bonding jumper required to bond the service raceway to the service enclosure?Grounding and Bonding
  13. 13.A master electrician is installing a new service for a commercial building. The service consists of a 480Y/277V, 3-phase, 4-wire system. Which of the following is the primary purpose of the main bonding jumper?Grounding and Bonding
  14. 14.A master electrician is installing a new panelboard in an existing commercial building. The panelboard is fed by a feeder from the main service panel. The raceway consists of EMT. Which of the following statements is true regarding the use of the EMT as an equipment grounding conductor (EGC) for this feeder circuit?Grounding and Bonding
  15. 15.A master electrician is installing a new 120/240V, single-phase service for a modular home. The home is supplied by a feeder from a remote service equipment location. Which of the following statements regarding the grounding and bonding of this modular home is correct?Grounding and Bonding
  16. 16.A master electrician is installing a new 100A, 240V, single-phase motor in an industrial facility. The motor is supplied by a 1-inch rigid nonmetallic conduit (RNC) containing 3 AWG copper ungrounded conductors. What is the minimum size copper equipment grounding conductor (EGC) required for this motor circuit?Grounding and Bonding
  17. 17.A branch circuit supplies power to a 120V, single-phase, 15-ampere non-continuous load in a dwelling unit. The circuit conductors are 14 AWG copper with 90°C insulation. What is the maximum standard overcurrent device rating permitted for this circuit, assuming no other limiting factors?Overcurrent Protection
  18. 18.A hazardous (classified) location requires intrinsically safe wiring methods. Which of the following is a primary characteristic of an intrinsically safe circuit, as defined by NEC Article 504?Overcurrent Protection
  19. 19.An industrial facility is upgrading its electrical system. A new motor control center (MCC) requires a circuit breaker with an interrupting rating sufficient to safely clear a fault. If the available short-circuit current at the MCC's incoming terminals is calculated to be 42,000 amperes, what is the minimum interrupting rating required for the main circuit breaker of the MCC?Overcurrent Protection
  20. 20.A technician is installing a new 480V, 3-phase motor with a full-load current (FLA) of 50 amperes. The motor is protected by a non-time-delay fuse. According to NEC 430.52(C)(1), what is the maximum rating permitted for this fuse?Overcurrent Protection
  21. 21.An industrial facility is being designed with a 480V, 3-phase electrical system. To comply with NEC 240.21(B)(2), what is the maximum length of a tap conductor that is protected by an overcurrent device rated at 300% of the tap conductor's ampacity, and terminates in a single circuit breaker or set of fuses?Overcurrent Protection
  22. 22.A residential dwelling unit has a 200-ampere service. A new electric range with a nameplate rating of 12 kW (120/240V) is being installed. The branch circuit conductors for the range are 6 AWG copper with THHN insulation. What is the minimum size overcurrent protective device required for the branch circuit supplying this range?Overcurrent Protection
  23. 23.An electrician is installing a new 15-ampere branch circuit for general-purpose receptacles in a dwelling unit. Which of the following conductor types, if protected by a 15-ampere overcurrent device, would comply with NEC requirements for conductor protection without requiring adjustment factors?Overcurrent Protection
  24. 24.A residential garage circuit requires AFCI protection. Which of the following conditions is specifically addressed and protected against by an Arc-Fault Circuit Interrupter (AFCI) that a standard circuit breaker would not typically detect?Overcurrent Protection
  25. 25.A newly installed industrial motor has a full-load current (FLA) of 60 amperes. Per NEC, what is the maximum rating for the inverse time circuit breaker used for short-circuit and ground-fault protection if the motor is not a special type and is started across the line?Overcurrent Protection
  26. 26.An electrician is installing a 200-ampere feeder for a commercial building. The feeder protection is provided by a circuit breaker. What is the maximum continuous load permitted on this feeder if the overcurrent protective device is not specifically listed for 100% continuous operation?Overcurrent Protection
  27. 27.A master electrician is inspecting a new residential service installation. The main service disconnect consists of a circuit breaker. What is the minimum interrupting rating required for this circuit breaker if the available short-circuit current at the service entrance is calculated to be 15,000 amperes?Overcurrent Protection
  28. 28.A new commercial refrigeration unit with a total connected load of 45 amperes (continuous) is being installed. The circuit conductors are rated for 75°C. What is the minimum continuous current rating required for the overcurrent protective device (OCPD), considering NEC 210.20(A) for continuous loads?Overcurrent Protection
  29. 29.A maintenance technician is replacing a fuse in a motor circuit. The motor nameplate indicates a service factor (SF) of 1.15. If the continuous full-load current (FLA) of the motor is 40 amperes, what is the maximum continuous current that the motor can safely draw without tripping its separate overload protection device, assuming the overload device is sized per NEC 430.32(A)(1)?Overcurrent Protection
  30. 30.A commercial kitchen requires ground-fault protection for equipment (GFPE) on a 480Y/277V, 3-phase, 4-wire service rated at 1200 amperes. According to NEC 230.95(A), what is the maximum setting for the GFP device's instantaneous trip?Overcurrent Protection
  31. 31.A commercial office space is being renovated, and new 120V, 20-ampere general-purpose receptacle branch circuits are being installed. The circuits will supply computer workstations and lighting. Which of the following conditions mandates the use of an Arc-Fault Circuit Interrupter (AFCI) for these circuits?Overcurrent Protection
  32. 32.A master electrician is designing the overcurrent protection for a 480V, 3-phase, 100 HP squirrel-cage motor with a full-load current (FLA) of 124 amperes. The motor is supplied by a feeder with 75°C rated terminals. If the engineer specifies a time-delay fuse for short-circuit and ground-fault protection, what is the maximum standard size fuse permitted by the NEC?Overcurrent Protection
  33. 33.A data center requires a selectively coordinated overcurrent protection system for its critical power distribution. If the main circuit breaker is rated at 1600 amperes, and a downstream branch circuit breaker is rated at 200 amperes, what is the primary objective of selective coordination in this scenario?Overcurrent Protection
  34. 34.A critical care area in a hospital requires ground-fault protection for its essential electrical system. According to NEC 517.17, which of the following statements is true regarding the ground-fault protection requirements for the essential electrical system in a hospital?Overcurrent Protection
  35. 35.A residential bathroom circuit feeds a single GFCI receptacle. If the circuit is rated for 20 amperes, what is the maximum leakage current that the GFCI device is designed to trip at, according to NEC requirements for personnel protection?Overcurrent Protection
  36. 36.A master electrician is installing a new emergency lighting system in a commercial building. According to NEC, what is the maximum time allowed for the emergency lighting system to come online and supply illumination after the normal power supply fails?Special Occupancies, Equipment, and Conditions
  37. 37.A master electrician is installing a new energy storage system (ESS) with a nominal voltage of 48 volts DC and a continuous output current of 250 amperes. According to NEC, what is the minimum required ampacity of the conductors connecting the battery to the ESS inverter?Special Occupancies, Equipment, and Conditions
  38. 38.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
  39. 39.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
  40. 40.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
  41. 41.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
  42. 42.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
  43. 43.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
  44. 44.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
  45. 45.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
  46. 46.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
  47. 47.A master electrician is installing a new fountain in a public park. The fountain basin contains electrical equipment. According to NEC, what is the minimum required distance from the edge of the fountain to a general-purpose 125-volt, 15- or 20-ampere receptacle that is not for the fountain's exclusive use?Special Occupancies, Equipment, and Conditions
  48. 48.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
  49. 49.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
  50. 50.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