Question 1

The formula for calculating resistance of a certain length, size, and type of wire is: R =_________ .

Accepted Answer

A)  (K × L)/cmil 
B)  K/(L × cmil) 
C)  L/(K × cmil) 
D)  L × (cmil/K) 
A)  (K × L)/cmil 
B)  K/(L × cmil) 
C)  L/(K × cmil) 
D)  L × (cmil/K) A

Question 2

How do wire material and diameter affect resistance?

Accepted Answer

Different types of material have different wire resistances. A copper conductor will have less resistance than an aluminum conductor of the same size and length. An aluminum conductor will have less resistance than a piece of iron wire the same size and length. The larger the diameter, the less resistance it will have. The diameter of a wire is measured in mils. One mil equals 0.001 inch. The circular mil area of a wire is the diameter of the wire in mils squared.

Question 3

_________loss is caused by the continuous aligning and realigning of molecules, which produces heat due to friction.

Accepted Answer

A)  Insulation 
B)  Hysteresis 
C)  Short 
D)  Ground 
A)  Insulation 
B)  Hysteresis 
C)  Short 
D)  Ground B

Question 4

A conductor made out of what material is allowed to carry the most current, assuming that size and insulation type are held constant?

Accepted Answer

A)  copper-clad aluminum 
B)  silicone 
C)  aluminum 
D)  copper 
A)  copper-clad aluminum 
B)  silicone 
C)  aluminum 
D)  copper

Question 5

An aluminum wire 2250 feet long cannot have a resistance greater than 0.2 ohm. What is the minimum size wire (in circular mils) that may be used?

Accepted Answer

To find the size of wire, use:
cmil = K

Question 6

Currents of a three-phase system are_________ degrees out of phase with each other.

Accepted Answer

A)  60 
B)  90 
C)  120 
D)  180 
A)  60 
B)  90 
C)  120 
D)  180

Question 7

If conductors are to be used in a location with a higher ambient temperature, the ampacity of the conductor must be ____.

Accepted Answer

A)  kept constant 
B)  doubled 
C)  reduced 
D)  increased by 20 amperes 
A)  kept constant 
B)  doubled 
C)  reduced 
D)  increased by 20 amperes

Question 8

Twelve 14 AWG copper conductors with type RHW insulation are to be installed in conduit in an area with an ambient temperature of 110 degrees F (43 degrees C). What will be the ampacity of these conductors?

Accepted Answer

A)  4.1 amperes 
B)  8.2 amperes 
C)  16.4 amperes 
D)  32.8 amperes 
A)  4.1 amperes 
B)  8.2 amperes 
C)  16.4 amperes 
D)  32.8 amperes

Question 9

According to the NEC, what five conditions must be met when conductors are in parallel?

Accepted Answer

Five conditions must be met when conduct

Question 10

Materials that increase their resistance with an increase of temperature have a_________ coefficient of temperature.

Accepted Answer

A)  decimal 
B)  constant 
C)  positive 
D)  negative 
A)  decimal 
B)  constant 
C)  positive 
D)  negative

Question 11

How are wire installations tested for shorts and grounds?

Accepted Answer

Wire installations are generally tested

Question 12

Describe the information in NEC Table 310.104(A), which specifies types of insulation.

Accepted Answer

The table is divided into seven main col

Question 13

What is the maximum operating temperature (in degrees Celsius) for Type SIS insulation?

Accepted Answer

A)  60 
B)  90 
C)  200 
D)  250 
A)  60 
B)  90 
C)  200 
D)  250

Question 14

If the ambient temperature is above_________ degrees Celsius, a correction factor must be applied to allowable ampacities for conductors.

Accepted Answer

A)  15 
B)  20 
C)  25 
D)  30 
A)  15 
B)  20 
C)  25 
D)  30

Question 15

If you have a raceway with 35 current-carrying conductors, by what adjustment factor must you multiply the ampacity?

Accepted Answer

A)  0.2 
B)  0.3 
C)  0.4 
D)  0.5 
A)  0.2 
B)  0.3 
C)  0.4 
D)  0.5

Question 16

Find the resistance of 6 AWG copper wire 550 feet long. Assume a temperature of 20 degrees Celsius.

Accepted Answer

A)  0.00201 ohm 
B)  0.159 ohm 
C)  0.218 ohm 
D)  4.59 ohm 
A)  0.00201 ohm 
B)  0.159 ohm 
C)  0.218 ohm 
D)  4.59 ohm

Question 17

The listed ampacities in the Code tables assume that the length of the conductor will not significantly increase the_________ of the circuit.

Accepted Answer

A)  ampacity 
B)  resistance 
C)  capacitance 
D)  inductance 
A)  ampacity 
B)  resistance 
C)  capacitance 
D)  inductance

Question 18

A factor that determines the amount of current a conductor is permitted to carry is the type of_________used, which is the nonconductive covering around the wire.

Accepted Answer

A)  insulation 
B)  raceway 
C)  busway 
D)  voltage 
A)  insulation 
B)  raceway 
C)  busway 
D)  voltage

Question 19

The conductors of a single phase are not permitted to be run in metallic conduit because_________ currents will be induced.

Accepted Answer

A)  eddy 
B)  series 
C)  parallel 
D)  superconducting 
A)  eddy 
B)  series 
C)  parallel 
D)  superconducting

Question 20

After the conductors have been installed in conduits or raceways, it is accepted practice to test the installation for grounds and shorts. This test requires a(n)_________ .

Accepted Answer

A)  faradmeter 
B)  ammeter 
C)  voltmeter 
D)  ohmmeter 
A)  faradmeter 
B)  ammeter 
C)  voltmeter 
D)  ohmmeter

Exam 6: Using Wire Tables and Determining Conductor Sizes

The formula for calculating resistance of a certain length, size, and type of wire is: R =_________ .

How do wire material and diameter affect resistance?

_________loss is caused by the continuous aligning and realigning of molecules, which produces heat due to friction.

A conductor made out of what material is allowed to carry the most current, assuming that size and insulation type are held constant?

An aluminum wire 2250 feet long cannot have a resistance greater than 0.2 ohm. What is the minimum size wire (in circular mils) that may be used?

Currents of a three-phase system are_________ degrees out of phase with each other.

If conductors are to be used in a location with a higher ambient temperature, the ampacity of the conductor must be ____.

Twelve 14 AWG copper conductors with type RHW insulation are to be installed in conduit in an area with an ambient temperature of 110 degrees F (43 degrees C). What will be the ampacity of these conductors?

According to the NEC, what five conditions must be met when conductors are in parallel?

Materials that increase their resistance with an increase of temperature have a_________ coefficient of temperature.

How are wire installations tested for shorts and grounds?

Describe the information in NEC Table 310.104(A), which specifies types of insulation.

What is the maximum operating temperature (in degrees Celsius) for Type SIS insulation?

If the ambient temperature is above_________ degrees Celsius, a correction factor must be applied to allowable ampacities for conductors.

If you have a raceway with 35 current-carrying conductors, by what adjustment factor must you multiply the ampacity?

Find the resistance of 6 AWG copper wire 550 feet long. Assume a temperature of 20 degrees Celsius.

The listed ampacities in the Code tables assume that the length of the conductor will not significantly increase the_________ of the circuit.

A factor that determines the amount of current a conductor is permitted to carry is the type of_________used, which is the nonconductive covering around the wire.

The conductors of a single phase are not permitted to be run in metallic conduit because_________ currents will be induced.

After the conductors have been installed in conduits or raceways, it is accepted practice to test the installation for grounds and shorts. This test requires a(n)_________ .

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