Deck 6: Using Wire Tables and Determining Conductor Sizes

Question 1

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

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

Answer 1

B

Question 2

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

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

Answer 2

C

Question 3

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

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

Answer 3

B

Question 4

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

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

Question 5

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?

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

Question 6

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

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

Question 7

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

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

Question 8

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

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

Question 9

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) ____.

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

Question 10

How are wire installations tested for shorts and grounds?

Question 11

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.

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

Question 12

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

Question 13

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

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

Question 14

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

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

Question 15

How do wire material and diameter affect resistance?

Question 16

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

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

Question 17

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

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

Question 18

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?

Question 19

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

Question 20

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

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