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Master Examination Practice Drill #5 2011

Master Examination Practice Drill #5 2011. Ted “ Smitty ” Smith. Given: a 150 kVA service transformer has a 480Y/277 volt, 3-phase secondary. What is the approximate full-load ampere rating of the primary of the transformer? 180 amperes 312 amperes 542 amperes 416 amperes . 1. A 180.32 A.

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Master Examination Practice Drill #5 2011

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  1. Master Examination Practice Drill #5 2011 Ted “Smitty” Smith

  2. Given: a 150 kVA service transformer has a 480Y/277 volt, 3-phase secondary. What is the approximate full-load ampere rating of the primary of the transformer? • 180 amperes • 312 amperes • 542 amperes • 416 amperes

  3. 1. A • 180.32 A

  4. Where a conductor is marked RHW-2 on the insulation what does the -2 represent? • The cable has 2 conductors • The conductor is double insulated • The conductor has a nylon outer jacket • The conductor has a maximum operating temperature of 90°C.

  5. 2. D Table 310.104(A)

  6. For a grounded electrical system, the equipment grounding conductor shall be sized in accordance with ___________? • The undergrounded circuit conductors • The overcurrent protective device • The service entrance conductors • The grounding electrode

  7. 3. B • 250.32(B)(1) • Table 250.122

  8. Determine the allowable ampacity of a size kcmil THW aluminum conductor installed in a raceway with four (4) other current-carrying conductors when the expected ambient temperature is 44 deg. C. • 151 amperes • 164 amperes • 210 amperes • 146 amperes

  9. 4. B • Tbl. 310.15(B)(16) • Tbl. 310.15(B)(2)(a) • Tbl. 310.15(B)(3)(a)

  10. Determine the MAXIMUM number of 120-volt, general-purpose duplex receptacles the NEC® permits to be protected by a 20-ampere, 120-volt single-pole circuit breaker in a commercial building. • 18 • 15 • 13 • 10

  11. 5. C • 120 volts x 20 amperes= 2400 VA • 2400 VA / 180 VA= 13 receptacles

  12. For4 lighting systems operating at 30 volts or less, the output circuits of the power supply are to be rated for NOT more than ___________? • 15 amperes • 20 amperes • 25 amperes • 30 amperes

  13. 6. C • 411.2

  14. Where there are tenant spaces in a retail shopping mall, each occupant shall have access to the main disconnecting means, EXCEPT: • Where the service and maintenance are provided by the building management. • Where there are more than six disconnecting means provided. • Where the primary feeder transformer does not exceed 600 volts. • Where the secondary of the service transformer does not exceed 240 volts to ground.

  15. 7. A • 240.24(B)(1)(1)

  16. Determine the conductor allowable ampacity given the following related information: • Ambient temperature of 44°C • 250 kcmil THWN copper conductors • Four (4) current-carrying conductors in the raceway • Length of raceway is 50 feet. • 160 amperes • 167 amperes • 200 amperes • 209 amperes

  17. 8. B • Tble. 310.15(B)(16) • Tbl. 310.15(B)(2)(a) • Tbl. 310.15(B)(3)(a) • 250 kcmil THWN copper ampacity 255 A • 255 A x .82 temp correction x .8 adj factor

  18. In general, the grounded conductor and the grounding conductor must be bonded together in _____________? • I. Panelboards used as service equipment • All sub-panels • I only • II only • Both I and II • Neither I not II

  19. 9. A • 250.24(A) • 250.24(A)(5) • 408.3(C)

  20. Using the standard method of calculation, what is the demand, in kW, on the undergrounded service-entrance conductors of an apartment complex that has thirty-five (35) electric ranges rated at 11.5 kW each? • 403 kW • 15 kW • 280 kW • 50 kW

  21. 10. D • Tbl 220.55, Col. C

  22. A grounding ring consisting of a size 2 AWG bare copper wire encircling a building, buried 36 in. deep, in direct contact with the earth, is required to have a MINIMUM length of ____________? • 15 feet • 20 feet • 25 feet • 50 feet

  23. 11. B • 250.52(A)(4)

  24. Where applying the optional method of calculation for one-family dwelling, what is the demand load for the heating and cooling, in kW, on the ungrounded service-entrance conductors for a residence that has the following? • One blower motor rated 1.2 kW, interlocked with both space heating and AC equipment. • One central electric space-heating unit rated 25 kW • One air-conditioning unit rated 6.5 kW • 32.75 kW • 25.00 kW • 17.03 kW • 26.20 kW

  25. 12. C • 220.82(C) and (C)(4) • Note: Use the large of the A/C or heating load

  26. Apply the general method of calculation for dwelling units and determine the Minimum demand load, in VA, where a one-family residence has the following fastened in place appliances. • Microwave oven – 1,250 VA • Trash compacter – 960VA • Dishwasher – 1,400 VA • Garage door opener – 960 VA • 3,428 VA • 3,656 VA • C. 4,570 • 4,883 VA

  27. 13. A 220.53 • Microwave Oven: 1250 VA • Trash Compactor: 960 VA • Dish Washer: 1400 VA • Garage Door Opener: 900 Va • Total: 4570 VA x .75= 3428 VA

  28. Where a service riser is installed in a wet location and contains THWN insulated conductors, the wiring method used ________________. • Is permitted to be Type AC cable • Shall be rigid metal conduit (RMC) • Is permitted to be electrical metallic tubing (EMT) • Shall be liquidtight flexible metal conduit (LFMC)

  29. 14. C 230.43(5)

  30. What is the MAXIMUM distance between supports for straight horizontal runs of trade size 1 ½ in. threaded rigid metal conduit (RMC)? • 10 feet • 12 feet • 14 feet • 16 feet

  31. 15. C • Tbl 344.30(B)(2)

  32. At least one receptacle outlet shall be installed directly above a show window of a department store for each __________ linear feet of show window area. • Six • Eight • Ten • Twelve

  33. 16. D • 210.62

  34. A thermal barrier shall be required if the space between the resistors and reactors, of 600 volts or less, and combustible material is Less than __________________? • 12 inches • 18 inches • 10 inches • 6 inches

  35. 17. A • 470.3

  36. In movie theaters, all switches for controlling the emergency lighting systems shall be located __________. • On the stage • In the lobby • In the manger’s office • In the project booth

  37. 18. B • 700.21

  38. Where a 90 ampere, 240-volt, single-phase load is located 225 feet from a panelboard and is supplied with size 3 AWG copper conductors, determine the approximate voltage drop on the conductors. (K=12.9) • 6 volts • 4 volts • 8 volts • 10 volts

  39. 19. D • VD= 2KDI/CM • 2x12.9x225x90/52620= 9.92

  40. A one-family residence is served with insulated 120/240 colt service-drop conductors, supported with a grounded messenger wire from the utility company. This service-drop crosses the swimming pool; the pool has a diving board that is 5 feet above the water level. The NEC® requires the conductors to be a Minimum height of ______ above the pool water level. • 25 feet • 14 ¼ feet • 22 ½ feet • 19 ½ feet

  41. 20. C • Fig. 580.8 • Tbl. 680.8

  42. Given: A trade size 2 in. electrical metallic tubing (EMT) containing four (4) size 2/0 AWG THWN copper conductors is to be installed in a pull box for a straight pull of the conductors. What is the MINIMUM required length of the pull box? • 4 inches • 12 inches • 16 inches • 24 inches

  43. 21. C • 314.28 • 2x8= 16

  44. In a commercial garage work area, which of the following receptacles, if any, are required to have GFCI protection? • I. 15 ampere general-purpose receptacles for hand tools and portable lights. • II. 20 ampere receptacles serving electrical diagnostic equipment only. • I only • II only • Both I and II • Neither I and II

  45. 22. C • 210.8(B)(8) • 511.12

  46. Conductors tapped from a feeder and supplying the primary of a transformer need not have overcurrent protection, if the length of the tap conductors are not over 25 feet and have an ampacity of at LEAST ______ of the rating of the overcurrent device protecting the feeder conductors. • One-third • One-half • 80 percent • 75 percent

  47. 23. A • 240.21(B)(3)(1)

  48. Where conductors carrying alternating current are installed in ferrous metal raceways, ________. • All phase conductors, the grounded conductor and equipment grounding conductors shall be grouped together • The phase conductors shall not be grouped with the grounded conductor • The equipment grounding conductor is not permitted to be in the same raceway with the grounded and ungrounded conductors • The equipment grounding conductors are not permitted to be installed in a common raceway with the grounded conductors.

  49. 24. A • 300.20(A)

  50. When connecting utilization equipment to a 20-ampere rated branch-circuit that also serves luminaires (lighting fixtures), the utilization equipment shall have an ampere rating of NOT more than _______. • 10 amperes • 15 amperes • 16 amperes • 12 amperes

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