| 1. |
For general calculation of voltage drop using the equation VD = ((2 x K x L x I) / CMA) x multiplier we can use K for copper equal to ______ and K for aluminum equal to _____ at 75 degrees Centigrade. Where K equals the resistance on a conductor 0.001 inches in diameter and one foot long referred to as the circular mil ohm resistance per foot of conductor. Where L is one way circuit length, I is current in amperes, CMA is circular mil area as given in Table 8, Chapter 9 of the NEC, and multiplier is 1.0 for single phase and direct current circuits, 0.866 for three phase three wire circuits, or 0.5 for three phase four wire circuits where the load is balanced when the neutral carries no current.
|
|
|
|
|
|
|
|
|
a)
|
10.37, 17.002
|
|
b)
|
12.5, 20.5
|
|
c)
|
12.9, 21.2
|
|
|
|
|
|
|
| 2. |
In this graph K for copper is equal to ____ at 60 degrees C.
|
|
|
|
|
|
|
|
|
a)
|
11.9 circular mil ohms per ft.
|
|
b)
|
12.9 ohms per 1000 feet
|
|
c)
|
9.5 ohms
|
|
|
|
|
|
|
| 3. |
The circuit one way length is the distance in feet from the ________ to the load along the circuit conductors.
|
|
|
|
|
|
|
|
|
a)
|
supply
|
|
b)
|
service
|
|
c)
|
branch circuit circuit breaker
|
|
d)
|
either a, b, or c
|
|
|
|
|
|
|
| 4. |
The one way circuit length in Problem No. 1 is ______ .
|
|
|
|
|
|
|
|
|
a)
|
88 feet
|
|
b)
|
60 feet
|
|
c)
|
20 feet
|
|
|
|
|
|
|
| 5. |
In a resistive circuit when the load is balanced in a three phase four wire wye system the current in the neutral is ______ .
|
|
|
|
|
|
|
|
|
a)
|
the same as the line currents
|
|
b)
|
0 amperes
|
|
c)
|
the same as A phase
|
|
|
|
|
|
|
| 6. |
13.8 volts is what percent of 240 volts?
|
|
|
|
|
|
|
|
|
a)
|
11.5 / 2 percent
|
|
b)
|
11.5 x 2 percent
|
|
c)
|
11.5 percent
|
|
|
|
|
|
|
| 7. |
3 percent of 480 volts is _______ .
|
|
|
|
|
|
|
|
|
a)
|
0.03 x 480 volts
|
|
b)
|
0.3 x 480 volts
|
|
c)
|
3 x 480 volts
|
|
|
|
|
|
|
| 8. |
If the circuit in Problem No. 1 were only 75 feet long for a one way distance the voltage drop would be approximately _______ .
|
|
|
|
|
|
|
|
|
a)
|
2.35 volts at 10 percent
|
|
b)
|
1/2 of 4.76 volts at 1/2 of 19.8 percent
|
|
c)
|
a or b
|
|
|
|
|
|
|
| 9. |
Class 2 circuits that operate damper motors using 2 or 3 amperes have a very ______ circuit length because of the voltage drop.
|
|
|
|
|
|
|
|
|
a)
|
limited
|
|
b)
|
long
|
|
c)
|
short
|
|
d)
|
a or c
|
|
|
|
|
|
|
| 10. |
By increasing supply voltage the percent voltage drop _____ for a given load and length.
|
|
|
|
|
|
|
|
|
a)
|
drops
|
|
b)
|
increases
|
|
|
|
|
|
|