Spring Test 7 due 05/03/2013

Transcription

1 Spring Test 7 due 05/03/2013 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. A raceway contains two 3-phase, 3-wire circuits that supply 38 ampere continuous loads. The circuit conductors are copper with THHN insulation, and all circuit conductor terminations are 75 C rated. In route to supply the load, the circuits run through a room for a distance of 30 ft (9.14 m) that typically has an ambient temperature of 120 F (48.9 C). The minimum size conductors permitted for these circuits is: a. 8AWG. b. 6 AWG. c. 4 AWG. d. 3 AWG. e. 2 AWG. 2. Lighting outlets are not required in which dwelling unit? a. kitchens b. attics c. crawl spaces d. clothes closets 3. The conductor fill requirements for nonmetallic boxes is determined by: a. Table (A). b. Table (B). c. both of the above.. 4. The voltage drop at the controller line terminals shall not drop more than below normal (controller-rated voltage) under motor starting conditions. a. 10% b. 5% c. 15% 5. If a fuse is used for primary protection of a transformer not in a supervised location with a primary rated over 600 volts. it must be sized at a maximum of of the transformer full-load amperes. a. 300% b. 125% c. 250% 6. A crane is operating over an magneseum electrolytic cell line. The crane may be operated while the line is functioning. The controller installation is required to be. a. isolated and ungrounded c. isolated and ungrounded b. radio operated d. any of these 7. Receptacle outlets in floors shall not be counted as part of the required outlets unless located within of the wall. a. 18 in. (450 mm) b. 6 in. (150 mm) c. 12 in. (300 mm)

2 8. For motors with a service factor of 1.15, the overload relay may be set at of the motor full-load current. a. 125% b. 115 % c. 140% 9. Nine type THHN size 4 AWG copper conductors are to be run in Rigid Metal Conduit. The minimum trade size permitted is: a. 3/4 (21). b. 1 (27). c. 11/2 (41). d. 2 (53). e. 21/2 (63). 10. The supply voltage for electric vehicle charging equipment shall not be greater than: a. 120 volts. b. 240 volts. c. 480 volts A device box with cable clamps contains a 3-way switch and there is one Nonmetallic Sheathed Cable entering the box, Type NM-B 12/3 w.g. with three conductors and an equipment ground. The equivalent conductor count for the device box is: a. 3. b. 4. c. 5. d. 6. e A 50-kVA, 3-phase, 480/240-volt transformer has a full-load current of amperes on the secondary. a. 240 b. 360 c Taps to control transformers shall be considered as protected where the secondary circuit is protected by an overcurrent device rated or set at not more than of the rated secondary current of the transformer and not more than 200% of the ampacity of the control circuit conductors. a. 500% b. 300% c. 200% 14. An overhead feeder conductor supplies single-phase 120/240 volt power to a storage building from an office building at commercial property. If the feeder passes over a driveway used for truck traffic, the minimum clearance of the conductors over the drive is: a. 10 ft (3 m). b. 12 ft (3.7 m). c. 15 ft (4.5 m). d. 18 ft (5.5 m). e. 22 ft (6.7 m).

3 15. The continuous ampere rating of the runway conductor disconnecting means shall not be less than of the combined short-time ampere rating of the motors. a. 50% b. 75% c. 100% 16. A 480V/208Y/120V, 50-kVA transformer has a primary rated current of: a amperes. b amperes. c amperes Neon tubing and conductor must be supported not more than from the electrode connection. a. 12 in. (300 mm) b. 6 in. (150 mm) c. 24 in. (600 mm) 18. The conductor that is intentionally grounded is: a. service-entrance phase. b. transformer tap. c. neutral Individual partitions or groups of interconnected individual partitions shall not contain more than 15-ampere, 125-volt receptacle outlets. a. thirteen b. ten c. eight 20. The disconnecting means for a fire pump shall be a supervised connection. The disconnecting means shall be supervised in the closed position by: a. central station, proprietary, or remote signal device. b. local signaling device that causes sounding of an audible alarm signal at a constantly attended point. c. locking the disconnecting means in the closed position. d. any of the above. 21. The combined length of FMC, FMT, and LFMC in the same ground path must not exceed: a. 6 ft (1.8 m). b. 10 ft (3.0 m). c. 3 ft (900 mm). d. all of the above. 22. A 3-phase, alternating-current motor requires overload trip units in the motor controller. a. one b. two c. three

4 23. The electrical connection between freestanding-type partitions may be a extra-hard usage flexible cord with or larger conductors with an insulated grounding conductor. a. 14 AWG b. 12 AWG c. 16 AWG 24. An electrical system not required to be grounded is a: a. single-phase, 3-wire, 120/240 volt system. b. three-phase, 4-wire, 208/120 volt wye system. c. 240/120 volt, 4-wire, three-phase delta system. d. 480/277 volt, 4-wire, three-phase wye system serving 277 volt loads. e. 240 volt, three-phase, 3-wire delta system. 25. The motor full-load current of a 1/2-hP, single-phase, 230-volt alternating-current motor is: a. 4.9 amperes. b. 9.8 amperes. c. 5.4 amperes A 6 in. by 6 in. (150 mm by 150 mm) metal wireway has a 3 (78) trade size Electrical Metallic Tubing (EMT) entering from the bottom and a 2 (53) trade size EMT entering from the top and the two EMT entries are offset so the conductors make a 90 bend immediately upon entering the wireway. A set of size 2 AWG conductors pass directly from one EMT to the other. The two EMT entries are required to be separated from each other a distance of not less than: a. 6 in. (150 mm). b. 12 in. (300 mm). c. 14 in. (350 mm). d. 18 in. (450 mm). e. 2 ft. (600 mm). 27. A single-family dwelling has three bathrooms, each with a lighting fixture, a fan, and one receptacle outlet. Only in one bathroom, the lighting fixture, fan, and receptacle outlet are installed on a dedicated 20 ampere circuit. For this dwelling, the minimum number of 20 ampere circuits required to serve bathrooms is: a. two. b. three. c. four. d. five. e. not specified in the Code. 28. A 10-Hp motor with a marked service factor of 1.15 can develop horsepower without deterioration of the motor winding insulation. a. 11 b. 12 c A voltage meter with a voltage transformer having a 16 to 1 ratio, connected to a 480-volt line would read. a. 30 volts b. 50 volts c. 60 volts

5 30. What are minimum size service conductors for a computed load of kva on a 3-phase, 4-wire, 208Y/120-volt system? a. 1/0 AWG THW CU b. 350 kcmil THW CU c. 400 kcmil THW CU 31. Power sources for a Class 2 or a Class 3 circuit shall be a listed. a. auto transformer b. control transformer c. Class 2 or Class 3 transformer 32. Electrical equipment and wiring methods on rides or concessions must be provided with where such equipment or wiring is subject to physical damage. a. overcurrent protection b. mechanical protection c. double insulation d. all of the above 33. Where a transformer supplies an electric motor-driven fire pump, it must be rated at 125% of the fire pump motor and pressure maintenance pump motor load and of the associated fire pump accessory equipment supplied by the transformer. a. 100% b. 125% c. 115% 34. For transformers not in a supervised location over 600 volts with secondary voltage of 600 volts or below, the rating of a fuse or circuit breaker must not be more than of the transformer secondary rated current? a. 300% b. 2540% c. 125% 35. Where structural members do not readily permit fastening RMC within 3 ft (900 mm) of an outlet or junction box, fastening can be increased to a distance of. a. 5 ft (1.5 m) b. 10 ft (3.0 m) c. 8 ft (2.5 m) 36. If cord- and plug-connected equipment is used, the interrupting device of a listed personnel protection system shall be provided and shall be an integral part of the attachment plug or shall be located in the power supply cable not more than from the attachment plug. a. 12 in. (300 mm) b. 18 in. (450 mm c. 6 in. (150 mm) 37. The power source of a Class 1 remote-control or signaling circuit shall not be more than volts. a. 24 b. 600

6 c The distance of secondary circuit conductors, when installed in metal conduit, from the high voltage terminal of a transformer to the first neon tube electrode shall not exceed. a. 10 ft ( 7.5 m) b. 50 ft (15 m) c. 20 ft (6.0 m) 39. What is the demand factor percentage permitted to be used to size service-entrance conductors for 20 recreational vehicle sites? a. 60% b. 50% c. 45% 40. The sheath of nonmetallic cable must extend into a box not less than through a nonmetallic cable knockout opening. a. 1/8 in. (3.18 mm) b. 1/2 in. (12.7 mm) c. 1/4 in. (6 mm) d. 1/16 in. (1.6 mm) 41. A run of Intermediate Metal Conduit, IMC, contains three size 500 kcmil, THWN conductors and one size 3/0 AWG, THWN conductor. The minimum size IMC permitted for this installation is: a. 1 1/4 (35). b. 1 1/2 (41). c. 2 (53). d. 2 1/2 (63). e. 3 (78). 42. Amusement rides and amusement attractions must not be located under or within horizontally and extending vertically to grade of conductors operating in excess of 600 volts. a. 15 ft (4.5 m) b. 10 ft (3.0 m) c. 5 ft (1.5 m) 43. A commercial service entrance is rated at 200 amperes and the service entrance conductors are size 3/0 AWG copper with 75 C insulation and terminations. There is no metal underground water pipe entering the building, and the building does not have a metal frame. Two 8 ft (2.5 m) ground rods are driven into moist soil and bonded together to act as the grounding electrode for the building. The minimum size copper grounding electrode conductor permitted for this service is: a. 8 AWG. b. 6 AWG. c. 4 AWG. d. 3 AWG. e. 3/0 AWG. 44. Hallways measuring more than or more in length must have at least one receptacle outlet. a. 12 ft (3.7 m) b. 10 ft (3.0 m)

7 c. 8 ft (2.5 m) d. None of the above 45. The largest trade size flexible metal conduit permitted to be installed is: a. 1(27). b. 1 1/2 (41). c. 2 (53). d. 2 1/2 (63). e. 4 (103). 46. All circuit breakers having an interrupting rating other than amperes must be marked to show their interrupting rating. a. 100 b. 250 c. 10,000 d An unbroken length of kitchen counter along a wall in a dwelling is 10 ft (3.05 m) long. The counter extends from the edge of the sink for 4 ft (1.22 m), then makes a corner and continues for 6 ft (1.83 m) to the end of the counter at the refrigerator. The minimum number of receptacle outlets required on this length of wall space is: a. not specified and the number is up to the owner of the dwelling. b. one. c. two. d. three. e. four. 48. A receptacle outlet must be installed at each wall counter that is or wider. a. 36 in. (900 mm) b. 24 in. (600 mm) c. 12 in. (300 mm) d. 18 in. (450 mm) 49. A stand alone fuel cell system is connected to a premises wiring system. The output of the inverter is 120 volt and is connected to 120/240 volt, 3 wire distribution equipment. This output is allowed to supply_. a. multiwire branch circuits only c. 120 volt circuits only b. 240 volt circuits only d. all of these 50. For portable or mobile signs the ground-fault circuit-interrupter shall be an integral part of the attachment plug or be located in the power-supply cord within of the attachment plug. a. 12 in. (300 mm) b. 6 in. (150 mm) c. 24 in. (600 mm) 51. The conductor total cross-sectional area when the wires are run through a nipple is not permitted to exceed: a. 30% of the nipple cross-sectional area. b. 40% of the nipple cross-sectional area. c. 60% of the nipple cross-sectional area. d. 80% of the nipple cross-sectional area. e. 100% of the nipple cross-sectional area.

8 52. A transformer with an impedance of 2% would require a multiplier of to determine short-circuit current. a. 50 b. 35 c. 40

9 Spring Test 7 due 05/03/2013 Answer Section MULTIPLE CHOICE 1. ANS: B Adjustment factor of 0.8 for 6 wires in raceway - Table (B)(2)(b) Temperature correction factor of Table (B)(16) Ampacity of 6 AWG copper - 75 A - Table (B)(16) 75 A = 49.2 A 2. ANS: D (A) 3. ANS: B (A)(2) 4. ANS: C ANS: A Table 450.3(A) 6. ANS: D Article Special Requirements for Particular Locations,(C) Electrolytic Cell Lines, refers the to Cranes and Hoists. (B) Hazardous Electrical Conditions. Remote crane or hoist controls that could introduce hazardous electrical conditions into the cell line working zone shall employ one or more of the following systems: (1) Isolated and ungrounded control circuit in accordance with (A) (2) Nonconductive rope operator (3) Pendant pushbutton with nonconductive supporting means and having nonconductive surfaces or ungrounded exposed conductive surfaces (4) Radio 7. ANS: A (A)(3) 8. ANS: A 43032(A)(1)

10 9. ANS: C , Chapter 9 Note 1, Table C8 10. ANS: D ANS: E Wires 3 Grounds 1 Device 2 Clamps (A), Table (A) 12. ANS: C 50, ( ) = 120 amperes Ugly s/ferm s 13. ANS: C (A) 14. ANS: D ANS: A ANS: A 50,000 (50.0 kva) 830 ( ) = ANS: B (C) 18. ANS: D ANS: A 605.8(C)

11 20. ANS: D 695.4(B)(5) 21. ANS: A (6)(c) 22. ANS: C ANS: B ANS: E (B) 25. ANS: A Table ANS: D 6 3 in = 18 in 6 78 mm = 468 mm , (A)(2) 27. ANS: A One circuit for the bathroom where the light and fan are combined with the receptacle, and one circuit for the receptacle in the other two bathrooms (C)(3) 28. ANS: C Ugly s/ferm s 29. ANS: A Ugly s/ferm s 30. ANS: C 120,000 (120.0 kva) 360 ( ) = 333 amperes (Table (B)(16) 31. ANS: C

12 725.41(A)(1) 32. ANS: B ANS: A 695.5(A) 34. ANS: C Table 450.3(A) 35. ANS: A (A) 36. ANS: A ANS: B (B) 38. ANS: C (J)(1) 39. ANS: A Table ANS: C (C) 41. ANS: E 500 kcmil THWN in 2 = in 2 3/0 AWG THWN in 2 = in in kcmil THWN mm 2 = 1369 mm 2 3/0 AWG THWN mm 2 = _173 mm 2 Look up size in 40% fill column of Table 4 Chapter 9 Table 1, Table 5, Table mm 2

13 42. ANS: A 525.5(B)(2) 43. ANS: B (A) 44. ANS: B (H) 45. ANS: E (B) or Chapter 9, Table ANS: D (C) 47. ANS: D (C)(1) 48. ANS: C (C)(1) 49. ANS: C Stand-Alone Systems. (C) Single 120-Volt Nominal Supply. The inverter output of a stand-alone fuel cell system shall be permitted to supply 120 volts, nominal, to single-phase, 3-wire 120/240-volt service equipment or distribution panels where there are no 240-volt loads and where there are no multiwire branch circuits. In all installations, the rating of the overcurrent device connected to the output of the fuel cell system(s) shall be less than the rating of the service equipment. This equipment shall be marked as follows: 50. ANS: A (C)(2) REF: (C) 51. ANS: C Chapter 9, Note ANS: A Ugly s/ferm s