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Voltage Drop Test 8

Course Name:  Voltage Drop
Quiz Number:  No. 8
Teacher:  Gerald Newton
Teacher's Email:  electrician@electrician2.com

No. of Questions= 10


1.  By Table 551.73 the demand factor the feeder and service demand factor for 4 each 50 ampere recreational vehicle sites is _______ percent.
a) 75
b) 60
c) 55
2.  The total voltage drop for this 10 site feeder is ______ volts.
a) 4.6
b) 0.9
c) 9.8
3.  When using Annex B for underground installations we can use an ambient of ______ instead of 30 degrees C.
a) 20 degrees C.
b) 10 degrees C.
c) 25 degrees C.
4.  When the actual ambient of 20 degrees C is used for direct buried conductors or when the actual current is below the table ampacity values for 75 degrees C we can use a _____ value for K and find a lower voltage drop.
a) lower
b) higher
5.  We can find the (1+Yc)RCA value used in the Neher McGrath paper by using the amperes given in NEC Tables and doing a ___________ to find the conductor temperature and then use this to find a calculated value for K or the circular mil ohm resistance per foot.
a) heat transfer calculation
b) NM calculation
c) reverse calculation
6.  In the Neher McGrath equation Current is given in kiloamperes, but resistance, Rdc has to be in _________ .
a) microhms per foot
b) ohms per foot
c) kilo ohms per foot
7.  To get microhms per foot values for rdc used in the NM equation we can use Table 8 in Chapter 9 and move the decimal place ________ in the ohms/1000 ft column to get microhms per foot.
a) three places to the left
b) three places to the right
c) one place to the left
8.  pc = circular mil ohms per foot of conductor at 20 degrees C. (10.371 ohms for 100% IACS copper, or _________ ohms for 61% IACS aluminum)
a) 10.371
b) 17.002
9.  Once we find the operating temperature of a conductor we can calculate the ________ and get a reduced voltage drop in most cases.
a) voltage drop
b) resistance
c) k value
10.  By finding the actual voltage drop using a calculated K we can _______ the costs of an installation.
a) reduce
b) decrease
c) save on
d) a, b and c



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