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50 Cards in this Set
- Front
- Back
- 3rd side (hint)
1. The cross-sectional area of a conductor is commonly expressed in ______. |
Circular mils |
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2. According to Chapter 9, Table 8, what's the cross-sectional area in circular mils for a 4 AWG conductor? |
41,740 cmil |
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3. According to Chapter 9, Table 8, what's the cross-sectional area in circular mils for a 2 AWG conductor? |
66,360 cmil |
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4. According to Chapter 9, Table 8, what's the cross-sectional area in circular mils for a 1 AWG conductor? |
83,690 cmil |
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5. According to Chapter 9, Table 8, what's the cross-sectional area in circular mils for a 1/0 AWG conductor? |
105,600 cmil |
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6. According to Chapter 9 Table 8 what's the cross-sectional area in circular mils for a 3/0 AWG aluminum conductor? |
167,800 cmil |
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7. The resistance of a conductor is directly proportional to its length. True or false? |
True |
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8. The resistance of a conductor changes with temperature. Temperature coefficient describes the effect temperature has on the resistance of a conductor. Conductors with a _________ temperature coefficient have an increase in resistance with an increase in temperature. |
Positive |
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9. The larger the cross-sectional area of a conductor, the _______ the number of paths for elections, which lowers the resistance of the conductor. |
Greater |
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10. Conductor resistance is determined by the _______. Material type Cross-sectional area Conductor length All of these |
All of these |
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11. The NEC lists the resistance and area in circular mils for both direct current and alternating current conductors. Direct current conductor resistances are listed in Chapter 9, Table_____ and alternating current conductor resistances and reactance are listed in Chapter 9, Table____. |
8,9 |
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12. What's the direct current resistance of a 6 AWG copper conductor that's 400 ft long? |
.20 ohms |
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13. What's the direct current resistance of a 1 AWG copper conductor that's 200 ft long? |
.0308 ohms |
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14. What's the direct current resistance of a 3 AWG aluminum conductor that's 1000 ft long? |
.403 ohms |
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15. What's the direct current resistance of a 1/0 AWG aluminum conductor that's 800 ft long? |
.16 ohms |
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16. What's the direct current resistance of a 1 AWG copper conductor that's 100 ft long? |
.0154 ohms |
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17. What's the direct current resistance of a 3 AWG aluminum conductor that's 500 ft long? |
.2015 ohms |
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18. What's the direct current resistance in ohms for three 300 kcmil copper conductors in a parallel run that are 1000 ft long? |
.014 ohms |
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19. The intensity of a magnetic field depends on the intensity of alternating current. The greater the current flow, the greater the overall magnetic field. True or false? |
True |
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20. In alternating current circuits, the expanding and collapsing magnetic field within the conductor induced an electromotive force that opposes the flow of alternating current. This opposition to the flow of alternating current is called "inductive reactance." True or false? |
True |
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21. _______ currents are small independent currents that are produced as a result of the expanding and collapsing magnetic field. They flow erratically within the conductor opposing current flow and consuming power. |
Eddy |
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22. The expanding and collapsing magnetic field induces a counter voltage within the conductors, which repels the flowing electrons towards the conductor surface. This is known as "_______ effect." |
Skin |
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23. The opposition to current flow is greater for alternating current circuits than for direct current circuits because of ______. Eddy currents Skin effects Inductive reactance All of these |
All of these |
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24. The alternating current conductor resistances listed in Chapter 9 Table 9 of the NEC are different for copper and aluminum, and for nonmagnetic and magnetic raceways. True or false? |
True |
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25. What's the alternating current ohms-to-neutral resistance for a 2/0 AWG copper conductor that's 300 ft long? |
.03 ohms |
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26. What's the alternating current ohms-to-neutral resistance for a 500 kcmil copper conductor installed in an aluminum raceway that's 1000 ft long? |
.032 ohms |
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27. What's the alternating current ohms-to-neutral resistance for a 3 AWG copper conductor that's 100 ft long? |
.025 ohms |
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28. What's the alternating current ohms-to-neutral resistance of a 500 kcmil copper conductor installed in PVC conduit that's 400 ft long? |
.0108 ohms |
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29. A 2-wire circuit supplies a 36A load that's located 100 ft from the panelboard. The load is wired with 1 AWG aluminum conductors in PVC conduit. What's the total alternating current ohms-to-neutral resistance of the circuit conductors? |
.62 ohms |
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30. What size copper conductor in a steel raceway can be used to replace 1/0 AWG aluminum conductors that supply a 110A load? |
2 AWG |
Hint: find a copper conductor with the same resistance per foot as the existing aluminum conductors. |
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31. What's the alternating current ohms-to-neutral resistance for three 1/0 AWG aluminum conductors run in parallel for 1000 ft installed in a steel raceway? |
-- |
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32. The opposition to current flow results in voltage drop. All circuits have voltage drop, simply because all conductors have resistance. True or false? |
True |
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33. When sizing conductors for feeders and branch circuits, the NEC _______ that we take voltage drop into consideration. |
suggests |
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34. When a conductor resistance caused the voltage to be dropped below an acceptable point, the conductor size should be increased. True or false? |
True |
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35. How can conductor voltage drop be reduced? Increase the supply voltage Increase the conductor size Decrease the conductor length All of these |
All of these |
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36. If the branch circuit supply voltage is 208V, the maximum recommended voltage drop of the circuit shouldn't be more than_____. |
6.24V |
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37. If the feeder supply voltage is 240V, the maximum recommended voltage drop of the feeder shouldn't be more than______. |
3.60V |
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38. What's the voltage drop of two 12 AWG conductors supplying a 12A continuous load located 100 ft from the power supply? |
4.75V to 4.80V |
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39. What's the voltage drop of two 12 AWG conductors that supply a 10A, 120V, single phase load located 100 ft from the power supply? |
4V |
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40. A 240V, 20A, single phase load is located 100 ft from the panelboard and is wired with 10 AWG conductors. What's the voltage drop of the circuit conductors? |
4.80V |
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41. A single-phase, 5 HP motor is located 110 ft from a panelboard in a dry location. The nameplate indicates that the voltage is 115V and the FLA is 52A. What size conductor is required? Note: Apply the NEC recommended voltage drop limit for this branch circuit. |
3 AWG |
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42. A single-phase, 5 HP motor is located 110 ft from a panelboard. The nameplate indicates that the voltage is 230V and the FLA is 26A. What size conductor is required? Note: Apply the NEC recommended voltage drop limits. |
8 AWG |
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43. What size conductor should be used to limit voltage drop from exceeding three percent of the equipment nameplate indicates an 18A continuous load at 480V, three phase and it's located 300 ft from the power supply? |
10 AWG |
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45. A 240V, 24A l, single-phase load is located 160 ft from the panelboard. The load is wired with 10 AWG conductors. What's the approximate voltage drop of the branch circuit conductors? |
9.50V |
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46. A 100A, three phase load is located 100 ft from the panelboard and is wired with 1 AWG aluminum conductors. What's the approximate voltage drop of the circuit conductors? |
4.40V |
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47. What's the approximate distance that a 240V, 31A, single-phase load can be located form a panelboard so the voltage drop doesn't exceed three percent? The load is wired with 8 AWG copper. |
145 ft |
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48. What's the approximate distance a 480V, 45A, three phase transformer, wired with 6 AWG copper can be located form a panelboard so the voltage drop doesn't exceed three percent? |
375 ft |
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51. What's the maximum recommended continuous load that should be placed on 1/0 AWG aluminum conductors in a nonmetallic raceway to a panelboard located 200 ft from a 240V, single-phase power source so the NEC recommendation for volt drop isn't exceeded? |
90A |
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49. What's the maximum distance a 240V, single-phase, 10A continuous load can be located from a panelboard so the voltage drop doesn't exceed three percent? The load is wired with 12 AWG. |
182 ft. |
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50. What's the maximum distance a 100A, 208V, three phase non-continous load wired with 1 AWG conductors can be located from a panelboard so the voltage drop doesn't exceed three percent? |
234 ft |
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