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Journeyman Electrician Exam (NEC) practice questions

215 free questions with answers and explanations.

Practice test
  1. 51.A Class I, Division 2 hazardous location contains a permanently installed luminaire. The luminaire is not intrinsically safe. According to NEC Article 500, which of the following is an acceptable method of protection for this luminaire?Special Occupancies, Equipment, and Conditions
  2. 52.A temporary carnival ride is being installed in a public park. The main overcurrent protective devices for the temporary installation are located in an enclosure accessible to the public. According to NEC Article 590, what is the minimum height, from the ground or operating surface, at which the operating handles of these devices must be located?Special Occupancies, Equipment, and Conditions
  3. 53.A swimming pool deck area requires a 125-volt, 15- or 20-ampere receptacle for maintenance equipment. This receptacle is not more than 2.0 m (6.5 ft) from the inside wall of the pool. According to NEC Article 680, what type of ground-fault circuit interrupter (GFCI) protection is required for this receptacle?Special Occupancies, Equipment, and Conditions
  4. 54.A residential client reports that some lights in their home flicker intermittently, and certain appliances seem to operate at reduced power. Upon inspection, the electrician measures the voltage at the service entrance and finds it to be 115V AC under load, but when checking a specific branch circuit, the voltage drops to 108V AC when a hair dryer is turned on. What is the approximate voltage drop percentage for this branch circuit?General Electrical Knowledge and Plan Reading
  5. 55.A client is installing a new solar photovoltaic (PV) system with a maximum system voltage of 600V. The PV output circuit conductors are rated for 75°C. What is the minimum temperature rating required for the terminals of the overcurrent protective devices (OCPDs) and disconnects used in this PV system, according to NEC?Special Occupancies, Equipment, and Conditions
  6. 56.A commercial building has a 120/208-volt, 3-phase, 4-wire service. The main bonding jumper is made of copper. If the ungrounded service-entrance conductors are 350 kcmil copper, what is the minimum size copper main bonding jumper required, according to NEC® Table 250.102(C)(1)?Grounding and Bonding
  7. 57.A journeyman is installing a new 200-ampere, 120/240-volt single-phase service. The service-entrance conductors are 3/0 AWG copper. The grounding electrode conductor is connected to a metal underground water pipe electrode and a supplemental ground rod. What is the minimum size of the grounding electrode conductor where it connects to the metal underground water pipe?Grounding and Bonding
  8. 58.A technician is installing a new 120-volt, 60-watt incandescent luminaire in a dwelling unit hallway. The fixture is rated for a maximum of 75 watts. According to NEC 410.16(A)(1), what is the minimum required free conductor length that must be left in the outlet box for making connections?Equipment and Devices
  9. 59.A technician is installing a new 200-ampere feeder to a subpanel in a commercial office. The feeder conductors are 3/0 AWG copper. The equipment grounding conductor (EGC) is run with the feeder. What is the minimum size copper EGC required for this feeder?Grounding and Bonding
  10. 60.A technician is installing a new 60-ampere, 208-volt, 3-phase circuit for a rooftop HVAC unit. The circuit is protected by a 60-ampere circuit breaker. The circuit conductors are 6 AWG copper. What is the minimum size copper equipment grounding conductor required for this circuit?Grounding and Bonding
  11. 61.A journeyman is installing a new 400-ampere, 120/208-volt service for a commercial tenant. The service-entrance conductors are 500 kcmil copper. The main bonding jumper is made of copper. What is the minimum size copper main bonding jumper required for this service, according to NEC® 250.102(C)(1)?Grounding and Bonding
  12. 62.A journeyman is installing a new 200-ampere service in a residence. The service-entrance conductors are 3/0 AWG copper. If the grounding electrode conductor (GEC) is connected to a metal underground water pipe and supplemented by a driven ground rod, what is the minimum size copper GEC required for the connection to the water pipe, according to NEC® Table 250.66?Grounding and Bonding
  13. 63.A commercial building utilizes a 277/480-volt, 3-phase, 4-wire service. The main service disconnect enclosure is made of metal. What is the primary purpose of bonding this metal enclosure to the neutral conductor at the service point?Grounding and Bonding
  14. 64.A technician is installing a new service disconnect for a commercial building. The disconnect handle is required to be readily accessible. According to NEC 230.72(C), what is the maximum height above the working platform or grade level for the center of the grip of the operating handle of the disconnect switch?Equipment and Devices
  15. 65.A journeyman electrician is calculating the minimum required feeder size for a commercial kitchen. The kitchen has 10 general-purpose 120V, 20A receptacle outlets. According to NEC 220.14(I), what is the minimum demand load per receptacle for this calculation?Equipment and Devices
  16. 66.A residential garage requires a new 120-volt, 20-ampere branch circuit for general-purpose receptacles. According to NEC 210.11(C)(4), how many such branch circuits are required at a minimum for garages of dwelling units?Equipment and Devices
  17. 67.A client requests a motor control system that allows for precise speed adjustments of a three-phase AC motor for a conveyor belt application. The system needs to maintain constant torque across a wide speed range. Which type of motor control device is best suited for this application?Control Devices and Motors
  18. 68.A technician is installing a new 50 hp, 460V, three-phase motor. The motor has a full-load current (FLA) of 65A. The motor branch-circuit short-circuit and ground-fault protective device is a non-time-delay fuse. According to NEC Table 430.52, what is the maximum rating permitted for this protective device?Control Devices and Motors
  19. 69.A motor control circuit utilizes a Class 2 power-limited transformer for its control power. The primary side of the transformer is connected to a 480V circuit, and the secondary side provides 24V AC. According to NEC 430.72(A), which statement accurately describes the overcurrent protection requirements for the primary side of this control transformer?Control Devices and Motors
  20. 70.A journeyman is installing a new 400-ampere, 480Y/277-volt, 3-phase, 4-wire service. The service-entrance conductors are 500 kcmil copper. What is the minimum size for the main bonding jumper?Grounding and Bonding
  21. 71.A client has a critical industrial process that relies on a 100 hp, 460V, three-phase motor. Interruption of power to this motor, even for a brief moment, would cause significant financial loss and safety hazards. Which type of motor starter is specifically designed to resume operation automatically after a power outage, once power has been restored?Control Devices and Motors
  22. 72.A 75 hp, 460V, three-phase motor is controlled by a motor starter. The motor nameplate indicates a full-load current (FLA) of 96A. According to NEC 430.90, what is the required location for the motor controller disconnecting means relative to the controller?Control Devices and Motors
  23. 73.An industrial facility requires bonding of multiple metal piping systems. Which of the following conditions mandates the bonding of metal water piping systems to the service equipment enclosure, according to NEC® 250.104(A)(1)?Grounding and Bonding
  24. 74.A 15 hp, 460V, three-phase motor is part of a group of motors supplied by a common feeder. The largest motor has an FLA of 21A, and the other two motors have FLAs of 12A and 8A, respectively. All motors are continuous duty. According to NEC 430.24, what is the minimum ampacity required for the motor feeder conductors?Control Devices and Motors
  25. 75.A technician is installing a single-phase, 120-volt, 15-ampere hermetic refrigerant motor-compressor. The motor nameplate indicates a rated-load current (RLC) of 12 amperes and a locked-rotor current (LRC) of 60 amperes. According to NEC 440.22(A), what is the maximum rating of the branch-circuit short-circuit and ground-fault protective device (fuse) permitted for this motor-compressor?Equipment and Devices
  26. 76.A newly installed 20-ampere branch circuit for general-purpose receptacles in a dwelling unit must be protected by an overcurrent device. What is the maximum standard ampere rating for the overcurrent device permitted for this circuit?Equipment and Devices
  27. 77.A client requests a new 120-volt, 15-ampere duplex receptacle to be installed in a basement laundry area. According to NEC 210.8(A)(10), this receptacle must be GFCI protected. What is the primary purpose of Ground-Fault Circuit-Interrupter (GFCI) protection?Equipment and Devices
  28. 78.A residential electrician is installing a new 200-ampere service. What is the minimum size copper grounding electrode conductor required for a driven ground rod, according to NEC® 250.66(A)?Grounding and Bonding
  29. 79.A facility has a 480-volt, 3-phase, ungrounded delta system. An electrician is installing new equipment. Which of the following statements regarding the equipment grounding conductor for this ungrounded system is correct according to NEC® 250.4(B)(2)?Grounding and Bonding
  30. 80.A three-phase Squirrel Cage Induction Motor (SCIM) is operating at 480V, drawing 25A, and has a service factor of 1.15. The motor nameplate indicates a full-load current (FLA) of 23A. According to NEC 430.32(A)(1), what is the maximum continuous current rating for the overload protection device, assuming a continuous duty motor without code letter markings?Control Devices and Motors
  31. 81.A motor control circuit operates at 120V and is protected by a 10A fuse. The control circuit conductors are routed in a raceway with power circuit conductors supplying a 30A motor branch circuit. According to NEC 430.72(B), what is the minimum allowable size for the control circuit conductors?Control Devices and Motors
  32. 82.A journeyman is installing a new 480-volt, 3-phase, ungrounded delta system for a motor control center. Which of the following statements regarding the grounding of this system's associated equipment is true?Grounding and Bonding
  33. 83.A technician is installing a 120-volt, 15-ampere general-purpose receptacle in a dry location within a commercial office building. Which of the following receptacle configurations is most commonly used and appropriate for this application in the United States?Equipment and Devices
  34. 84.A journeyman is inspecting the grounding system of a new commercial service. The building has a metal frame, and the service-entrance conductors are 750 kcmil copper. The grounding electrode conductor is connected to the building's metal frame. What is the minimum size of the GEC to the metal frame?Grounding and Bonding
  35. 85.A large commercial facility has a 480Y/277-volt service with ungrounded service-entrance conductors consisting of three 600 kcmil copper conductors per phase, run in parallel. What is the minimum size copper grounding electrode conductor (GEC) required for this service, connected to a metal underground water pipe, according to NEC® 250.66 and Table 250.66?Grounding and Bonding
  36. 86.A 20 hp, 230V, three-phase Squirrel Cage Induction Motor with a service factor of 1.0 is being installed. The motor branch-circuit conductors are sized for 125% of the motor's full-load current (FLA). According to NEC Table 430.250, the motor's FLA is 54A. What is the minimum ampacity required for the branch-circuit conductors?Control Devices and Motors
  37. 87.A residential electrician is installing a new 100-ampere service. The grounding electrode conductor (GEC) is connected to a single ground rod. What is the minimum size for this GEC, assuming the service entrance conductors are 3 AWG copper?Grounding and Bonding
  38. 88.A three-phase, 480V motor branch circuit is being installed. The disconnecting means for the motor must be capable of opening the circuit to the motor and its controller. According to NEC 430.109(A)(1), what is the minimum horsepower rating required for the disconnecting means that is a general-use switch?Control Devices and Motors
  39. 89.A journeyman is inspecting a lightning protection system on a commercial building. Which of the following is an acceptable component for a lightning protection grounding electrode system, according to generally accepted lightning protection standards like NFPA 780, often referenced by NEC® 250.106?Grounding and Bonding
  40. 90.A three-phase, 480-volt, 75 kVA transformer is being installed to supply a 208Y/120-volt panelboard. The primary overcurrent protection for this transformer is provided by a circuit breaker. Assuming the primary current is 90.2 amperes, what is the maximum standard rating for the primary circuit breaker, assuming continuous duty and no secondary overcurrent protection is provided for the transformer?Equipment and Devices
  41. 91.A variable frequency drive (VFD) is controlling a 20 hp, 460V, three-phase motor. The VFD's input power is supplied by a branch circuit. According to NEC 430.122(A), what is the minimum required ampacity for the conductors supplying the VFD, assuming the VFD is rated for the motor's full-load current (FLA) of 25A?Control Devices and Motors
  42. 92.A three-phase, 480V, 50 hp motor is protected by an inverse time circuit breaker for short-circuit and ground-fault protection. The motor nameplate indicates a locked-rotor current (LRC) code of 'J'. According to NEC 430.52(C)(1) Exception No. 2, if the standard maximum rating of 250% of FLA is not sufficient to allow the motor to start, what is the absolute maximum percentage of the motor's full-load current (FLA) that the circuit breaker rating is permitted to be increased to?Control Devices and Motors
  43. 93.A journeyman is installing a new 277/480-volt, 3-phase, 4-wire feeder to a subpanel in a commercial building. The feeder conductors are 3/0 AWG copper. What is the minimum size copper equipment grounding conductor required for this feeder, assuming the overcurrent device protecting the feeder is rated at 200 amperes, according to NEC® Table 250.122?Grounding and Bonding
  44. 94.An electrician is designing the grounding system for a new service where a metal underground water pipe is available as a grounding electrode. What is the minimum length of contact with the earth required for this water pipe to qualify as a grounding electrode, according to NEC® 250.52(A)(1)?Grounding and Bonding
  45. 95.A 480-volt, 3-phase, 50-horsepower motor is served by a feeder. The motor has a nameplate full-load current (FLA) of 65 amperes. The overcurrent protective device for the motor branch-circuit short-circuit and ground-fault protection is a non-time-delay fuse. According to NEC Table 430.250 and 430.52(C)(1) Exception No. 2, what is the maximum rating of this fuse, assuming the next higher standard rating is not permitted to exceed 175%?Equipment and Devices
  46. 96.A technician is installing a 3-phase, 480-volt, 30-horsepower squirrel-cage induction motor. The motor nameplate indicates a full-load current (FLA) of 40 amperes. According to NEC Table 430.250, what is the full-load current for a 30-horsepower, 480-volt, 3-phase motor, which should be used for sizing conductors and overcurrent protection?Equipment and Devices
  47. 97.A journeyman electrician is installing control wiring for a motor control center. The control circuit operates at 120 volts and uses No. 14 AWG copper conductors, which are protected by a 15-ampere overcurrent device. According to NEC 430.72(B), what is the maximum rating of the overcurrent protective device permitted for the control circuit, assuming the control circuit power is derived from a separate control power transformer?Equipment and Devices
  48. 98.A journeyman electrician is installing a 277-volt LED luminaire in a commercial warehouse. The luminaire is rated for 150 watts. The branch circuit supplying the luminaire is protected by a 20-ampere circuit breaker. According to NEC 210.23(A)(1), what is the maximum continuous load permitted on this 20-ampere branch circuit for luminaires?Equipment and Devices
  49. 99.A technician is installing a new service disconnect for a 400-ampere commercial service. The service conductors are 500 kcmil copper. What is the minimum size copper equipment grounding conductor required for this service, according to NEC® Table 250.122?Grounding and Bonding
  50. 100.A client requests a new separately derived system for a critical power supply in their facility. Which of the following is NOT an acceptable grounding electrode for this system?Grounding and Bonding