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Master Electrician Exam (NEC) practice questions

200 free questions with answers and explanations.

Practice test
  1. 151.A commercial building has a total connected load of 150 kVA, consisting of general lighting, receptacles, and fixed equipment. The building operates for 10 hours a day, 5 days a week. The calculated maximum demand over a 15-minute interval is 105 kVA. What is the demand factor for this building's service calculation?Load Calculations
  2. 152.A single-family dwelling unit has a 240V, 40A electric vehicle supply equipment (EVSE) installed. According to NEC 220.57, what is the minimum demand load that must be included for this EVSE in the service calculation?Load Calculations
  3. 153.A master electrician is installing a new 120V, 15A branch circuit to supply a continuous load. According to NEC Article 210.20(A), what is the maximum continuous load permitted on this circuit?General Electrical Knowledge
  4. 154.A master electrician is troubleshooting a 120V AC circuit that includes a capacitive load. Which of the following statements accurately describes the relationship between current and voltage in this circuit?General Electrical Knowledge
  5. 155.A commercial building has a total calculated general lighting load of 30,000 VA and a total calculated receptacle load of 10,000 VA. Assuming all loads are noncontinuous, what is the minimum required service size in amperes for a 208Y/120V, three-phase system?Load Calculations
  6. 156.A master electrician is calculating the service load for a large commercial office building. The building has 15 kW of fixed electric space heating and 12 kW of air-conditioning load. What is the demand load for these loads to be included in the service calculation, according to NEC 220.60?Load Calculations
  7. 157.A single-family dwelling unit has a 240V, 50A electric vehicle supply equipment (EVSE) installed. What is the minimum demand load that must be included for this EVSE in the service load calculation, according to NEC 220.57?Load Calculations
  8. 158.A master electrician is calculating the service feeder demand load for a single-family dwelling. The dwelling has a 3-ton (36,000 BTU/hr) central air conditioning unit, a 10 kW electric furnace, and a 4.5 kW electric water heater. What is the demand load for the largest motor-operated appliance or combination of motor loads, as per NEC 220.60?Load Calculations
  9. 159.A master electrician is installing a 30A, 120/240V, single-phase branch circuit for an electric clothes dryer in a dwelling unit. The circuit conductors are 10 AWG copper with 75°C insulation. What is the minimum size required for the equipment grounding conductor (EGC) for this circuit?Services, Feeders, and Branch Circuits
  10. 160.A master electrician is installing a new 200A, 120/240V, single-phase service for a residential dwelling. The service uses two 3/0 AWG copper ungrounded conductors and a 1/0 AWG copper grounded conductor. The grounding electrode system consists of a metal underground water pipe electrode and a supplemental ground rod. What is the minimum size copper grounding electrode conductor (GEC) required to connect to the metal underground water pipe electrode?Grounding and Bonding
  11. 161.A master electrician is performing a load calculation for a multi-family dwelling with 30 identical dwelling units. Each unit has an 8 kW electric range. Using NEC Table 220.55, Column C, what is the demand load for the electric ranges?Load Calculations
  12. 162.A master electrician is performing a service load calculation for a commercial office building. The building has a total connected general lighting load of 50,000 VA and a noncontinuous receptacle load of 15,000 VA. What is the total calculated demand load, assuming no other loads and a 120/208V, three-phase system?Load Calculations
  13. 163.A master electrician is calculating the service feeder load for a commercial office building. The building has a general lighting load of 25,000 VA and 50 general-purpose 15A, 120V duplex receptacles. What is the minimum calculated demand load for the general-purpose receptacles, according to NEC 220.44?Load Calculations
  14. 164.A single-family dwelling has a connected load of 12 kW for general lighting and receptacles, 3 kW for a permanently installed electric clothes dryer, and a 10 kW electric range. What is the calculated neutral current for the service feeder, assuming a 240/120V single-phase supply, according to NEC Article 220?Load Calculations
  15. 165.A master electrician is calculating the feeder demand load for a multi-family dwelling with 20 similar dwelling units. Each unit has an 8 kW electric range. According to NEC Article 220.55, what is the minimum demand load for the electric ranges?Load Calculations
  16. 166.A master electrician is performing an optional method load calculation for a single-family dwelling (NEC 220.82). The dwelling has a total general lighting and receptacle load of 10,000 VA, an electric range of 12 kW, a 5 kW electric water heater, and a 2 kW dishwasher. There is also a 10 kW central electric space heating system. What is the demand load for the electric space heating system using this method?Load Calculations
  17. 167.A commercial building has a total connected general lighting load of 45,000 VA. This load is considered continuous. What is the minimum feeder capacity required for this lighting load?Load Calculations
  18. 168.A commercial building has a 200A, 480Y/277V, 3-phase, 4-wire service. The service entrance conductors are 250 kcmil copper. What is the minimum size required for the service grounded conductor (neutral) if it is copper?Services, Feeders, and Branch Circuits
  19. 169.A commercial office building has a total calculated general lighting load of 25,000 VA. This load is considered continuous. What is the minimum feeder capacity required for this lighting load?Load Calculations
  20. 170.A commercial building has a total of 15 kW of fixed electric space heating and 10 kW of air-conditioning load. According to NEC 220.60, what is the demand load to be used for the feeder and service calculation for these loads?Load Calculations
  21. 171.A master electrician is performing a service load calculation for a 12-unit apartment building. Each unit has an electric range rated at 10 kW, a 4.5 kW electric dryer, and a 1.5 kW water heater. What is the minimum demand load for the electric ranges for the entire building, according to NEC Table 220.55?Load Calculations
  22. 172.A commercial office space is being renovated, and a new 40A, 208V, 3-phase, 3-wire feeder is being installed to supply a small subpanel. The feeder conductors are 8 AWG copper with 75°C insulation. What is the minimum size copper equipment grounding conductor (EGC) required for this feeder?Services, Feeders, and Branch Circuits
  23. 173.A commercial building has a total connected general lighting load of 45,000 VA. This load is considered continuous. What is the minimum calculated load for general lighting that must be used for feeder and service calculations?Load Calculations
  24. 174.A multi-family dwelling unit has a 12 kW electric range, a 4.5 kW electric dryer, and two 1.5 kW 120V electric water heaters. All other general loads for the unit are 6000 VA. Using the optional method for dwelling units (NEC Article 220.84), what is the calculated demand load for this unit?Load Calculations
  25. 175.A master electrician is performing a service load calculation for a 200A, 120/240V, single-family dwelling. The dwelling has a 12 kW electric range, a 5.5 kW electric dryer, a 4.5 kW water heater, and 3000 VA of general lighting and receptacle load. Using the standard method (NEC 220.40 and 220.50 series), what is the calculated demand load for the fixed appliances (excluding range and dryer)?Load Calculations
  26. 176.A master electrician is performing a standard method load calculation for a multi-family dwelling. There are 20 dwelling units, each equipped with a 10 kW electric range. What is the demand load for the electric ranges to be included in the service calculation?Load Calculations
  27. 177.An electrician is installing a new 120V, single-phase circuit in a residential garage. The circuit supplies power to a single-gang receptacle for general-purpose use. What is the maximum overcurrent protective device (OCPD) rating permitted for a 14 AWG copper conductor feeding this receptacle, assuming the conductor is rated for 75°C?Overcurrent Protection
  28. 178.A master electrician is installing a new 480Y/277V, 3-phase, 4-wire service to a commercial building. The service conductors are 600 kcmil copper. What is the minimum size copper main bonding jumper required for this installation?Grounding and Bonding
  29. 179.A master electrician is calculating the feeder demand load for a farm dwelling and two associated farm buildings. The dwelling load is 20,000 VA, Farm Building 1 (dairy barn) is 15,000 VA, and Farm Building 2 (poultry house) is 10,000 VA. What is the total demand load for the farm buildings (excluding the dwelling) to be applied to the service, according to NEC 220.102?Load Calculations
  30. 180.A master electrician is performing a standard method load calculation for a single-family dwelling. The dwelling has a 3-wire, 120/240V service. The general lighting and receptacle load is calculated at 8,000 VA. There are four small-appliance branch circuits, each rated at 1500 VA. What is the minimum demand load for the small-appliance branch circuits to be included in the service calculation?Load Calculations
  31. 181.A master electrician is calculating the feeder demand load for a commercial building with a continuous lighting load of 30,000 VA and a continuous motor load of 15,000 VA. What is the total continuous demand load that must be accounted for in the feeder calculation?Load Calculations
  32. 182.A master electrician is performing an optional method load calculation (NEC 220.82) for a single-family dwelling unit. The dwelling has a 16 kW electric furnace and a 5 kW central air-conditioning unit. What is the demand load for these heating/cooling loads?Load Calculations
  33. 183.A master electrician is performing an optional method load calculation (NEC 220.82) for a 200A, 120/240V single-family dwelling. The dwelling has a 4.5 kW electric clothes dryer. What is the calculated load for the dryer using this optional method?Load Calculations
  34. 184.A master electrician is performing an optional calculation for a 200A, 120/240V single-family dwelling unit according to NEC Article 220.82. The dwelling has a 5 kW electric clothes dryer, a 3 kW water heater, and a 12 kW electric furnace. What is the demand load for these fixed appliances before applying the general optional method demand factors?Load Calculations
  35. 185.A master electrician is installing a new 20A, 120V branch circuit for a bathroom receptacle in a dwelling unit. The circuit will serve only this receptacle. What is the minimum size copper equipment grounding conductor (EGC) required for this circuit?Services, Feeders, and Branch Circuits
  36. 186.A master electrician is calculating the feeder and service load for a multi-family dwelling with ten units. Each unit has a 12 kW electric range. The building also has a 20 kW central electric space heating system and a 15 kW central air-conditioning system. What is the demand load for the larger of the space heating or air-conditioning loads for the entire building, according to NEC 220.60?Load Calculations
  37. 187.A master electrician is performing a service load calculation for a single-family dwelling. The dwelling has a 240V, 50A electric vehicle supply equipment (EVSE) installed. What is the demand load for this EVSE to be included in the service calculation, according to NEC 220.57?Load Calculations
  38. 188.A three-phase, 480V motor has a full-load current (FLA) of 65A. The motor is served by a feeder. What is the minimum continuous current rating for the feeder conductors supplying this motor, according to NEC Article 430.22(A)?Load Calculations
  39. 189.A commercial building has a continuous lighting load of 15,000 VA and a noncontinuous receptacle load of 5,000 VA. What is the minimum calculated branch circuit load for the purposes of overcurrent device sizing, assuming a 120V system?Load Calculations
  40. 190.A master electrician is performing a standard method load calculation for a single-family dwelling. The dwelling has a 12 kW electric range, a 5.5 kW electric dryer, a 3 kW water heater, and a 1.5 kW dishwasher. What is the calculated demand load for these fixed appliances before applying the general lighting and receptacle demand factor?Load Calculations
  41. 191.A commercial building has 40 general-purpose 15A, 120V duplex receptacles. What is the minimum calculated receptacle load for this building, according to NEC Article 220.14(I)?Load Calculations
  42. 192.A master electrician is performing a standard method load calculation for a single-family dwelling. The dwelling has a 12 kW electric range, a 5.5 kW electric dryer, and a 4 kW electric water heater. What is the calculated demand load for these fixed appliances before applying general lighting and receptacle loads?Load Calculations
  43. 193.A new commercial retail space requires a 120/208V, 3-phase, 4-wire service. The calculated demand load for the service, including continuous and noncontinuous loads, is 150A. All conductors are copper with 75°C insulation. What is the minimum ampere rating required for the service entrance conductors?Services, Feeders, and Branch Circuits
  44. 194.A commercial office building has a total calculated general lighting load of 30,000 VA and a total receptacle load of 15,000 VA. The building operates at 208Y/120V, three-phase. What is the total calculated current for the service feeder (in amperes)?Load Calculations
  45. 195.A master electrician is calculating the feeder demand load for a commercial office building. The building has 10,000 VA of general-purpose receptacle load and 5,000 VA of fixed electric signs. What is the minimum demand load for the general-purpose receptacles, according to NEC 220.44?Load Calculations
  46. 196.A commercial kitchen has three 5 kW, 208V single-phase electric cooking appliances. What is the minimum demand load for these appliances, according to NEC Table 220.56?Load Calculations
  47. 197.A master electrician is performing a short-circuit fault current calculation for a new 480V, 3-phase commercial service. The utility provides a maximum available fault current of 25,000A at the service entrance. The service conductors are 500 kcmil copper, 100 feet long, and the transformer impedance is negligible. What is the approximate impedance of the service conductors per phase, considering a conductor resistance of 0.025 ohms per 1000 feet?General Electrical Knowledge
  48. 198.A commercial building has a total connected general lighting load of 60,000 VA. This load is supplied by a 208Y/120V, three-phase service. What is the minimum general lighting load demand used for service calculations, considering it is a continuous load?Load Calculations
  49. 199.A master electrician is performing a standard method load calculation for a single-family dwelling. The dwelling has a 4.5 kW electric water heater, a 3 kW dishwasher, and a 2 kW trash compactor. What is the demand load for these fixed appliances before applying any additional demand factors?Load Calculations
  50. 200.A master electrician is calculating the feeder demand load for a commercial building. The building has 10 general-purpose receptacle outlets, each rated for 15A, 120V. According to NEC 220.44, what is the minimum demand load for these receptacles?Load Calculations