| 1. |
An applied voltage of 10 percent below rating can result in a decrease in efficiency of substantially more than 10 percent — for example, fluorescent light output would be reduced by 15 percent, and incandescent light output would be reduced by __________ . Induction motors would run hotter and produce less torque.
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a)
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10 percent
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b)
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30 percent
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c)
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40 percent
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| 2. |
Energy costs can be _________ by decreasing voltage drop.
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a)
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lowered
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b)
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eliminated
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c)
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increased
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| 3. |
Article 647 states that for Sensitive Electronic Equipment the voltage drop on branch circuits supplying equipment connected using wiring methods in Chapter 3 shall not exceed _________ and the combined voltage drop of feeder and branch-circuit conductors shall not exceed __________ .
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a)
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5 percent, 2.5 percent
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b)
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3 percent, 5 percent
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c)
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1.5 percent, 2.5 percent
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| 4. |
By NEC Article 645 for fire pumps the voltage at the controller line terminals shall not drop more than _________ below normal (controller-rated voltage) under motor starting conditions. The voltage at the motor terminals shall not drop more than _________ below the voltage rating of the motor when the motor is operating at 115 percent of the full-load current rating of the motor.
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a)
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5 percent, 3 percent
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b)
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15 percent, 3 percent
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c)
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15 percent, 5 percent
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| 5. |
The energy Code has strict requirements and limits the voltage drop on branch circuits for the run from the final circuit breaker to the outlet or load to _______ maximum voltage drop allowed at design load and limits the voltage drop for the run between the service entrance equipment and the branch circuit distribution equipment to _______ maximum voltage drop allowed at design load.
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a)
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3 percent, 2 percent
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b)
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2 percent, 5 percent
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c)
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5 percent, 4 percent
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| 6. |
The effect of a power factor equal to 0.85 for 3 each 3-phase 500 kcmil conductors in a steel raceway increases voltage drop by ____________than the direct current method of calculation.
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a)
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94 percent more
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b)
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94 percent less
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c)
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100 percent more
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| 7. |
There are several ways to decrease voltage drop. They include:
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a)
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using larger size conductors
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b)
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shortening the circuit length
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c)
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decreasing the circuit load
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d)
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for decreasing voltage drop to neutral by balancing the load for 3-phase, 4 wire systems
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e)
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All of the above
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| 8. |
If power factor is not close to 1.0 voltage drop for 3 phase 3 wire circuits in raceway can be found using information from _______ of the NEC.
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a)
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Table 8
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b)
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Table 9
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c)
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Table 10
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| 9. |
When we use the direct current method of finding voltage drop we can use the resistances from Table 8 of the NEC or use the following equation: (where L is one way circuit length)
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a)
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VD = (2KLI/CMA) x multiplier
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b)
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VD = (KLI/CMA) x multiplier
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c)
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VD = (KLI/CMA)
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| 10. |
By Table 8 of the NEC the resistance of 1000 feet of No. 10 copper stranded conductor is _______ .
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a)
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1.24 ohms
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b)
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1.21 ohms
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c)
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2.04 ohms
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