Job Information Level 2: Lesson 1 Building Wire Construction and Insulation Properties

Question 1

The conductors that carry the current to electrical devices and ? equipment are the heart of all electrical systems. There are associated ? whenever current flows through a conductor.
Select one:

a.
relay / responses

b.
service / effects

c.
utilization / effects

d.
utilization / responses

Answer 1

utilization / effects

Question 2

? associated with the flow of current in a conductor is one of the most significant factors to be considered in designing electrical systems. The conductor’s rating is dependent upon its type of ? .
Select one:

a.
Heat / electrical insulation

b.
Heat / voltage

c.
Voltage / electrical insulation

d.
Voltage / heating

Answer 2

Heat / electrical insulation

Question 3

Conductors are assigned a ? ampacity that reflects the insulation’s ability to handle and dissipate heat under ? conditions.
Select one:

a.
high / ideal

b.
specific / ideal

c.
specific / varying

d.
variable / specific

Answer 3

specific / varying

Question 4

Conductors used in electrical systems are often defined by the material, if any, that is used to encase the actual electrical conductor. Three classifications exist for electrical conductors; they are ? , ? , and ? .

I. armored
II. bare
III. coated
IV. covered
V. insulated
VI. flat conductor
VII. Machine tool wire
VIII. thermoplastic

Select one:

a.
I., II., and IV.

b.
II., III., and IV.

c.
II., IV., and V.

d.
III., IV., and VI.

e.
III., IV., and VIII.

f.
IV., V., and VII.

Answer 4

II., IV., and V.

Question 5

Insulated conductors are the most common conductors installed in electrical systems. These conductors are constructed with a material that has been ? by the NEC as a ? electrical insulation.

Select one:

a.
approved / certified

b.
approved / listed

c.
identified / certified

d.
identified / recognized

Answer 5

identified / recognized

Question 6

There are numerous types of electrical insulations. The type of insulation selected depends upon the condition ? of the conductor. For example, a conductor for direct burial requires an insulation that is suitable for the conditions it is likely to be exposed to over the ? of the conductor.
Select one:

a.
of use / length

b.
of use / life

c.
or type / length

d.
or type / life

Answer 6

of use / life

Question 7

When conductors are installed in wet locations, the insulated conductors and cables shall be either moisture-impervious metal-sheathed, be of a type listed for use in wet locations, or be of one of the types contained in ? .
Select one:

a.
300.7(A)

b.
300.9

c.
310.1 Informational Note

d.
310.10(C)(2)

Answer 7

310.10(C)(2)

Question 8

The specific insulation types listed for use in wet locations contain the letter ? in the type designator.

Select one:

a.
“M”

b.
“N”

c.
“T”

d.
“W”

Answer 8

“W”

Question 9

An important consideration in selecting conductor insulation type is the temperature limitations of the insulation. The three basic insulation temperature ratings listed for the conductors used for general wiring are ? . The ? temperature that the conductor is exposed to along its entire length shall be used when determining the temperature rating of a conductor.
Select one:

a.
40°C, 75°C, and 90°C / maximum

b.
60°C, 75°C, and 90°C / maximum

c.
40°C, 75°C, and 90°C / minimum

d.
60°C, 75°C, and 90°C / minimum

Answer 9

60°C, 75°C, and 90°C / maximum

Question 10

The common factors that can contribute to conductor insulation degradation because of excessive operating temperature are the ? temperature in which the conductor insulation shall operate, the ? heat created in the conductor as a result of current flow, the dissipation rate of the heat into the surrounding environment, and the heat generated by adjacent current-carrying conductors.
Select one:

a.
adjacent / external

b.
ambient / external

c.
ambient / internal

d.
highest / internal

Answer 10

ambient / internal

Question 11

The two most common materials used for construction of electrical conductors are copper and aluminum. Copper has excellent ? and therefore has a higher allowable ? than a comparable aluminum conductor.
Select one:

a.
ampacity / resistance

b.
conductivity / ampacity

c.
conductivity / voltage

d.
resistive characteristics / voltage

Answer 11

conductivity / ampacity

Question 12

A factor to consider when installing electrical conductors is the weight of the conductors. Copper conductors installed in ? require support at ? intervals than are required for aluminum conductors.
Select one:

a.
horizontal raceways / longer

b.
horizontal raceways /shorter

c.
vertical raceways / longer

d.
vertical raceways / shorter

Answer 12

vertical raceways / shorter

Question 13

Copper conductors are available as hard-drawn, medium-hard-drawn, and soft-drawn. Hard-drawn copper has the greatest strength, but is difficult to work with. Because of the difficulty in shaping hard-drawn copper, its uses are limited.
Select one:
True
False

Answer 13

True

Question 14

Soft-drawn copper is easy to work with and can be installed in many different types of raceways and cable ? . Most general building wires used in electrical distribution systems are made of soft-drawn copper.
Select one:

a.
assemblies

b.
distribution systems

c.
jackets

d.
management systems

Answer 14

assemblies

Question 15

Aluminum conductors have been used extensively for a number of years in the utility distribution and transmission field. More recently, aluminum conductors have found increasing applications in building electrical distribution systems.
Select one:
True
False

Answer 15

True

Question 16

Despite the fact that aluminum is not as good a conductor as copper, its reduced ? is compensated by the considerable cost savings in using aluminum conductors.
Select one:

a.
conductivity

b.
resistance

c.
size

d.
weight

Answer 16

conductivity

Question 17

Because the surface of aluminum conductors oxidizes readily, terminations are generally made with the aid of ? designed to prevent the oxide from re-forming in the installation process.
Select one:

a.
copper coating

b.
dissimilar metals

c.
joint compounds

d.
stainless steel coating

Answer 17

joint compounds

Question 18

Conductors of different materials, like copper and aluminum, should not be terminated in a manner that causes the dissimilar metals to come in direct contact with each other unless the termination or splicing device is ? for such use.
Select one:

a.
accepted

b.
coated

c.
identified

d.
terminated

Answer 18

identified

Question 19

Manufacturers provide ? specifications for terminations. The termination should be tightened to those specifications to ensure that the connection is electrically sound.
Select one:

a.
bolting

b.
clading

c.
material

d.
torquing

Answer 19

torquing

Question 20

Copper-clad conductors are constructed using a minimum of ? copper, which is bonded metallurgically to the aluminum.
Select one:

a.
8%

b.
10%

c.
18%

d.
20%

Answer 20

10%

Question 21

Solid conductors are constructed of a single piece of wire (strand). Stranded conductors are constructed of multiple wire (strands).
Select one:
True
False

Answer 21

True

Question 22

Chapter 9, Table ? of the NEC lists conductor properties.
Select one:

a.
1

b.
4

c.
8

d.
9

Answer 22

8

Question 23

Match the maximum temperature ratings for each of the following cable/conductor insulation types. Note: Some of the following cable types might have more than one insulation type listed.

I. 40°C
II. 60°C
III. 60°C and 90°C
IV. 75°C
V. 90°C
VI. 250°C
VII. 60°C and 75°C

RHW =  
XHHW (wet) =  
MTW =  
TFE =  
UF =    
XHHW (dry) =  
THWN-2 =

Answer 23

iv, iv, iii, vi, vii, v, v

Question 24

In Table 8, Chapter 9 of the NEC, conductors are listed from size # ? , the smallest, to # ? , the largest.
Select one:

a.
14 AWG / 1,000 kcmil

b.
14 AWG / 2,000 kcmil

c.
18 AWG / 1,000 kcmil

d.
18 AWG / 2,000 kcmil

Answer 24

18 AWG / 2,000 kcmil

Question 25

A circular mil (CM) is the area of a circle with a diameter of ? .
Select one:

a.
one centimeter

b.
one mil

c.
one micron

d.
πr2

Answer 25

one mil

Question 26

As the diameter of the wire increases, the AWG number ? , and the resistance of the conductor ? .
Select one:

a.
decreases / decreases

b.
decreases / increases

c.
increases / decreases

d.
increases / increases

Answer 26

decreases / decreases

Question 27

calculations to determine circuit resistance, you must know the ? (abbreviated K) of a material.
Select one:

a.
conductance

b.
reactance

c.
resistance

d.
specific resistance

Answer 27

specific resistance

Question 28

The K of a material is defined as the resistance of the wire made from that material which is ? long, and ? in diameter.
Select one:

a.
1 foot / 1 mil

b.
1 meter / 10 mils

c.
100 feet / 1 mil

d.
1,000 feet / 10 mils

Answer 28

1 foot / 1 mil

Question 29

What happens to the resistance of most conductors as the temperature increases?
Select one:

a.
It decreases.

b.
It increases.

c.
It stays the same (no change).

Answer 29

It increases.

Question 30

The K factor of a copper conductor at 68°F is ? .
Select one:

a.
1.04

b.
1.76

c.
10.4

d.
17.6

Answer 30

10.4

Question 31

Match the following cable types to their identifying letters.

I. Armored
II. Flat conductor
III. Mineral insulated
IV. Machine tool wire
V. Nonmetallic-sheathed
VI. Underground feeder
VII. Service entrance cable
VIII. Thermoplastic

MTW
FCC
AC
MI
NM
THW
UF
SE

Answer 31

iv, ii, i, iii, v, viii, vi, vii

Question 32

What is the difference between insulation types THW and THWN?
Select one:

a.
THW has a nylon jacket.

b.
THWN has a nylon jacket.

c.
THWN does not have a nylon jacket.

d.
There is no difference in insulation type, only temperature rating.

Answer 32

THWN has a nylon jacket.

Question 33

Conductors, type SIS, for switchboard wiring, have a maximum operating temperature of ? .

Select one:

a.
90°F

b.
175°F

c.
194°F

d.
212°F

Answer 33

194°F

Question 34

THW wire is available in sizes from ? to ? .
Select one:

a.
14 AWG / 1,000 kcmil

b.
14 AWG / 2,000 kcmil

c.
18 AWG / 1,000 kcmil

d.
18 AWG / 2,000 kcmil

Answer 34

14 AWG / 2,000 kcmil

Question 35

Indicate which two of the following cable types are allowed for use in wet locations.

I. RHH 
II. RHW 
III. RHW-2 
IV. XHH
Select one:

a.
I. and II.

b.
I. and III.

c.
I. and IV.

d.
II. and III.

Answer 35

II. and III.

Question 36

Type XHHW conductors are listed for use in ? location(s).
Select one:

a.
damp

b.
dry

c.
wet

d.
all of the above

Answer 36

all of the above

Question 37

Listed wire types designated with the suffix ? shall be permitted to be used at a continuous 90°C operating temperature in both wet and dry locations.
Select one:

a.
−2

b.
−9

c.
−90°C

d.
“WD”

Answer 37

−2

Question 38

The ? of a conductor is defined as the diameter of the conductor in mils, squared.
Select one:

a.
circular-mil area

b.
circumference

c.
mil area

d.
square-mil area

Answer 38

circular-mil area

Question 39

Match the following inches to their correct conversion in mils.

I. 125 mil 
II. 250 mils 
III. 750 mils 
IV. 1,333 mils 
V. 4,000 mils 
VI. 80,000 mils

0.25 inches = mils
0.125 inches = mils
1/4 inch = mils
3/4 inch = mils

Answer 39

ii, i, ii, iii,

a. 0.25inches x 1000 = 250mils
b. 0.125inches × 1,000 = 125 mils
c. convert 1/4 to 0.25inches 0.25 × 1,000 = 250 mils
d. convert 3/4 to 0.75 0.75inches × 1,000 = 750 mils

Question 40

Match the following mils to their correct conversion in inches.

I. 1/8" 
II. 3/16" 
III. 1/4" 
IV. 5/16" 
V. 3/8" 
VI. 1/2"
VII. 3/4"
500 mils   =      inches
375 mils   =      inches	
750 mils   =      inches	
187.5 mils   =      inches

Answer 40

vi, v, vii, ii

a. 500 mils/1,000 = 0.5” or 1/2”
b. 375 mils/1,000 = 0.375” or 3/8”
c. 750 mils/1,000 = 0.75” or 3/4”
d. 187.5 mils/1,000 = 0.1875” or 3/16”

Question 41

To find the area of a wire in circular mils, square the diameter expressed in ? .
Select one:

a.
centimeters

b.
feet

c.
inches

d.
mils

Answer 41

mils

Question 42

Which formula is used to find circular mil area?
Select one:

a.
Acmils = df2

b.
Acmils = dmils2

c.
Acmils = dcmils2

d.
d = Amils2

Answer 42

Acmils = dmils2

Question 43

Which formula determines the resistance of a conductor?
Select one:

a.
Rohms = K × 2Lfeet / ACM

b.
Rohms = K × Lfeet / Am

c.
Rohms = K × Lfeet / ACM

d.
Rohms = K × Lmeters / ACM

Answer 43

Rohms = K × Lfeet / ACM

Question 44

What is the resistance of 1,000 feet of No. 14 copper wire? Use given properties.

Given: copper = 10.4 ohms per circular mil foot No. 14 wire circular mil area = 4,110 cmil
Select one:

a.
0.253 Ω

b.
2.53 Ω

c.
25.3 Ω

d.
42.74 Ω

Answer 44

2.53 Ω

R in ohms = K × Length in feet / Area in CM
= 10.4 × 1,000/4,110
= 2.53 Ω

Question 45

In reference to wire size, AWG stands for American Wire Gauge.
Select one:
True
False

Answer 45

True

Question 46

Write out in words what 250 kcmil means.
Select one:

a.
two hundred and fifty circular mils

b.
two hundred and fifty thousand circular mils

c.
two hundred and fifty kilo mils

d.
two hundred and fifty million circular mils

Answer 46

two hundred and fifty thousand circular mils

Question 47

What is the circular mil area of wires having the following diameters?

I. 10.404 
II. 100 
III. 250 
IV. 1,000 
V. 10,404 
VI. 25,000 
VII. 250,000 
500 mils =      circular mil area
10 mils =     circular mil area
0.1020 inch =     circular mil area

Answer 47

vii, ii, v

a. 500 × 500 = 250,000 cm or 250 kcmil
b. 10 × 10 = 100 cm
c. 102 × 102 = 10,404 cm or 10.404 kcmil

Question 48

To find the approximate resistance of a given copper conductor, drop the ? digit from the circular mil area. The result is the number of ? per ohm.
Select one:

a.
first / feet

b.
first / meters

c.
last / feet

d.
last / meters

Answer 48

last / feet

Question 49

Using the approximate resistance method, what is the resistance of 3,302 feet of 8 AWG copper wire that has a circular mil area of 16,510?
Select one:

a.
0.5 Ω

b.
2 Ω

c.
5 Ω

d.
5,451,602 or 5.5 MΩ

Answer 49

2 Ω

1,651 feet per ohm
3,302/1,651= 2 Ω

Question 50

What length of 12 AWG copper wire would be required to produce a resistance of five ohms? (Use the approximation method.)
Select one:

a.
0.008 feet

b.
130.6 feet

c.
3,265 feet

d.
32,650 feet

Answer 50

3,265 feet

cm area is 6,530 cm
653 feet per ohm
5 × 653 = 3,265 feet

Question 51

Match the circular mil area of the following wire sizes.

I. 4,110 cm 
II. 6,530 cm 
III. 10,380 cm 
IV. 16,510 cm 
V. 26,240 cm 
VI. 41,740 cm

10 AWG     circular mil area 
8 AWG     circular mil area 
6 AWG     circular mil area 
14 AWG     circular mil area 
4 AWG     circular mil area 
12 AWG     circular mil area

Answer 51

iii, iv, v, i, vi, ii

Question 52

In general, all conductors ? AWG and larger, installed in a raceway, shall be stranded.

a. 4
b. 6
c. 8
d. 10

Answer 52

c. 8

310. 3(c)

Question 53

A person has a piece of wire that has 12 strands, each strand with a diameter of 118.3 mils. To determine the size of wire will require three steps. The first step is to calculate the circular mil area for each strand. What is the circular mil area of each strand? (Round the FINAL answer for this question to the nearest whole number.)

_______ circular mil

Answer 53

13995 CM

CMA = d2
CMA = 118.32
CMA = 13994.89 circular mils
CMA = 13995 circular mils

Question 54

A person has a piece of wire that is 12 strands of 118.3 mils diameter. What is the approximate size of wire? This is the second step in a three step process. You will need this answer for the next question. Second Step: Multiply circular mil area by number of strands.

____ circular mil

Answer 54

167940

13,995 × 12 = 167,940 cmil

Question 55

A person has a piece of wire that is 12 strands of 118.3 mils diameter. What is the approximate size of wire? This is the third and final step in a three step process. Third Step:

Use Chapter 9, Table 8 of the Code to locate size closest wire size.

The AWG for a wire made up of 12 strands that is 118.3 mils diameter is ? .
Select one:

a.
AWG 18

b.
AWG 8

c.
AWG 1/0

d.
AWG 3/0

e.
250 kcmil

Answer 55

AWG 3/0

Question 56

How many strands of 10 AWG wire would it take to make a 500-kcmil cable?
Select one:

a.
19

b.
37

c.
49

d.
95

Answer 56

49

Question 57

The largest size wire listed in wire gauge number is ? .
Select one:

a.
#1

b.
4/0

c.
250

d.
2000

Answer 57

4/0

Question 58

In general, the smallest size conductor permitted for 2,000 V is ? AWG copper or ? AWG aluminum or copper-clad aluminum.

a. 18 / 14
b. 18 / 12
c. 14 / 14
d. 14 / 12

Answer 58

14/12

code: 310.3(A)

Question 59

Match the conductors to the ampacity that indicates the allowable current-carrying capacity.

Amperes for 3 1/0 AWG, THW, copper in conduit

Amperes for a single 1/0 AWG, THW, copper conductor in free air

Amperes for 3 1/0 AWG, THW, aluminum in conduit

Amperes for a single 1/0 AWG, THW, aluminum conductor in free air

1. 150
2. 230
3. 120
4. 180
5. 100

Answer 59

150, 230, 120, 180

Question 60

There are no color coding requirements for grounded conductors found in the NEC.

true or false

Answer 60

false

200.6

Question 61

What might happen to thermoplastic insulation at temperatures colder than -10°C (+14°F)?
Select one:

a.
This will cause the resistance of the conductor to increase.

b.
The insulation might stiffen.

c.
The insulation will crack.

d.
Nothing. Thermoplastic insulation is designed to stay flexible down to -25°C.

Answer 61

The insulation might stiffen.

Question 62

The allowable ampacities in Table 310.16 and Table 310.17 are based on an ambient temperature of ? .
Select one:

a.
75°F

b.
86°F

c.
90°F

d.
100°F

Answer 62

86°F