Question 1

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

Accepted Answer

The table is divided into seven main columns. The first column lists the trade name of the insulation; the second lists its identification code letter; the third column lists its maximum operating temperature; and the fourth shows its applications and where it is permitted to be used. The fifth column lists the material from which the insulation is made; the sixth states its thickness; and the last column lists the type of outer covering over the insulation.

Question 2

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

Accepted Answer

Higher ambient temperatures can cause conductors to overheat, so their ampacity must be reduced to prevent overheating and ensure safe operation.

Question 3

What is the maximum operating temperature (in degrees Celsius) for Type SIS insulation?
A) 60
B) 90
C) 200
D) 250

Accepted Answer

Type SIS insulation is rated for a maximum operating temperature of 90 degrees Celsius.

Question 4

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

The answer of An aluminum wire 2250 feet long cannot...

Question 5

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

Accepted Answer

The answer of According to the NEC, what five conditions...

Question 6

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

Accepted Answer

An ohmmeter is used to measure resistance and can test for grounds and shorts by checking for continuity or unexpected resistance in the circuit.

Question 7

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

Accepted Answer

The answer of Twelve 14 AWG copper conductors with type...

Question 8

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

Accepted Answer

According to the National Electrical Code (NEC), when there are more than 30 current-carrying conductors in a raceway, the ampacity must be multiplied by an adjustment factor of 0.4.

Question 9

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

Accepted Answer

The resistance of a 6 AWG copper wire is approximately 0.3951 ohms per 1000 feet at 20 degrees Celsius. For 550 feet, the resistance is (0.3951 ohms/1000 feet) * 550 feet = 0.217305 ohms, which rounds to 0.218 ohms.

Question 10

_________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

Accepted Answer

Hysteresis loss occurs in magnetic materials due to the lag between the change in magnetization and the magnetic field, causing energy loss as heat.

Question 11

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

Accepted Answer

Eddy currents are induced in metallic conduits when single-phase conductors are run through them, leading to energy losses and heating.

Question 12

Currents of a three-phase system are_________ degrees out of phase with each other.
A) 60
B) 90
C) 120
D) 180

Accepted Answer

In a three-phase system, the currents are 120 degrees out of phase with each other to ensure balanced power delivery.

Question 13

How do wire material and diameter affect resistance?

Accepted Answer

The answer of How do wire material and diameter affect...

Question 14

How are wire installations tested for shorts and grounds?

Accepted Answer

The answer of How are wire installations tested for shorts...

Question 15

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)

Accepted Answer

The resistance (R) of a wire is calculated using the formula R = (K × L)/cmil, where K is the resistivity constant, L is the length, and cmil is the circular mil area of the wire.

Question 16

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

Accepted Answer

The standard reference temperature for conductor ampacity is typically 30 degrees Celsius. If the ambient temperature exceeds this, a correction factor is needed to ensure safe operation.

Question 17

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

Accepted Answer

The ampacity tables assume that the conductor's length will not significantly increase the resistance of the circuit, as increased resistance can lead to voltage drop and overheating.

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

Accepted Answer

The type of insulation used affects the current-carrying capacity of a conductor because different insulation materials have different thermal properties and temperature ratings.

Question 19

Materials that increase their resistance with an increase of temperature have a_________ coefficient of temperature.
A) decimal
B) constant
C) positive
D) negative

Accepted Answer

Materials that increase their resistance with an increase in temperature have a positive temperature coefficient.

Question 20

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

Accepted Answer

Copper has the highest electrical conductivity among the given materials, allowing it to carry the most current.

Quiz 6: Using Wire Tables and Determining Conductor Sizes

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

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

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

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?

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

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) _________ .

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?

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.

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

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

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

How do wire material and diameter affect resistance?

How are wire installations tested for shorts and grounds?

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

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

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.

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

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