Question 1

NEC 310.10(H) sets forth the requirements for installing conductors.These requirements are intended to ensure the conductors will share the current equally to prevent overloading individual conductors.

Accepted Answer

NEC 310.10(H) specifically sets forth the requirements for parallel conductors, which are installed to share the current and prevent overloading individual conductors. Therefore, the best choice is parallel.

Question 2

What are the requirements for installing parallel conductors?

Accepted Answer

NEC 310.10(H) sets forth the requirements for installing parallel conductors.These requirements are intended to ensure the conductors will share the current equally to prevent overloading individual conductors.The parallel conductors are required to
∙be 1/0 AWG or larger.
∙be the same length.
∙be of the same material (copper-copper or aluminum-aluminum).
∙have the same insulation type.
∙be the same size in circular mil area.
∙be terminated in the same manner.
The raceway or cables shall have the same electrical characteristics.For example, for the
∙ raceways in a 3­parallel run installation, don't use schedule 80 PVC for one raceway,
aluminum for another, and steel for another.

Question 3

are multiples of a fundamental frequency.

Accepted Answer

Harmonics are multiples of a fundamental frequency.

Question 4

If the ampacity of a feeder does not match a standard OCPD rating, then be used.

Accepted Answer

If the ampacity of a feeder does not match a standard OCPD rating, the next higher standard rating may be used. This is because OCPDs must be sized to protect the conductor at its rated ampacity, and using a lower OCPD would create a safety hazard by allowing the conductor to overheat. However, using a larger OCPD than necessary may not provide adequate protection against overcurrent. Therefore, the next higher standard rating should only be used if it falls within an acceptable range of overcurrent protection and if it is listed and labeled for use with the conductor.

Question 5

To get accurate current readings where harmonics are involved, ammeters referred to as " " must be used.

Accepted Answer

True RMS ammeters are the most accurate in measuring currents that contain harmonics. They measure the effective or RMS value of an AC current regardless of the waveform shape. Other types of ammeters may provide inaccurate readings due to waveform distortion caused by harmonics.

Question 6

In the United States, Hz is standard or the fundamental frequency.

Accepted Answer

In the United States, the standard or fundamental frequency is 60 Hz. This refers to the frequency at which the electrical power is supplied to homes and buildings.

Question 7

What wire and cable options do you have for combating excessive neutral current?

Accepted Answer

The answer of What wire and cable options do you...

Question 8

What three circuit parameters must be known before feeder component selection can begin?

Accepted Answer

The answer of What three circuit parameters must be known...

Question 9

To determine a reasonable minimum size for a neutral conductor, two types of loads must be considered- .

Accepted Answer

The two types of loads that must be considered when determining a reasonable minimum size for a neutral conductor are linear and nonlinear. Linear loads have a consistent current flow that is directly proportional to voltage, while nonlinear loads cause harmonic distortion that can result in an increased neutral current. Therefore, to ensure safe and reliable operation of the electrical system, the neutral conductor must be sized appropriately for both linear and nonlinear loads.

Question 10

What can you do to determine the root cause of voltage drop problems?

Accepted Answer

The answer of What can you do to determine the...

Question 11

The ampacity is the allowable ampacity multiplied by the factor.

Accepted Answer

The term "derating" refers to the reduction of the ampacity of a conductor or cable due to environmental factors such as temperature, altitude, or proximity to other heat sources. The ampacity rating of a conductor or cable is multiplied by a "derating factor" to determine the maximum safe carrying capacity under these conditions.

Question 12

Often the load is such that parallel conductors should be considered.This usually occurs with loads over amperes.

Accepted Answer

According to the statement, parallel conductors should be considered for loads over amperes. The only option given that exceeds 100 amperes is B, which is 400 amperes. Therefore, B is the best choice.

Question 13

Currents of the 3rd harmonic and odd multiples of the 3rd harmonic (9th, 15th, 21st, etc.) add together in the common neutral conductor of a 3-phase system, instead of canceling each other.These odd multiples are referred to as ____.

Accepted Answer

Odd multiples of the 3rd harmonic are referred to as triplens, and they do not cancel each other out in the neutral conductor of a 3-phase system.

Question 14

For installations where the nonlinear load is huge, most consulting engineers will specify -rated transformers.

Accepted Answer

K-rated transformers are specified for installations with a significant nonlinear load because they are designed to handle the harmonic currents generated by such loads without overheating or suffering from premature failure.

Question 15

If the selected OCPD has a rating greater than 100-amperes, the conductors to be installed shall be selected from either the 75 degrees Celsius or degrees Celsius column of NEC Table 310.15(B)(16).

Accepted Answer

According to the statement, if the OCPD rating is greater than 100 amperes, conductors can be selected either from the 75 degrees Celsius or degrees Celsius column of NEC Table 310.15(B)(16). The options given in the question are all lower than 100, so this condition doesn't apply. Therefore, the correct choice is simply the highest option, which is 90.

Question 16

wire is seldom used in branch circuits, but because of weight and cost factors, it is frequently selected for feeders and services.

Accepted Answer

Aluminum is frequently selected for feeders and services because it is lighter and less expensive than copper.

Question 17

Feeders are the part of the electrical system that connects the branch-circuit to the electrical service equipment.

Accepted Answer

Feeders are the components in an electrical system that connect the branch-circuit panelboards to the electrical service equipment, ensuring the distribution of power throughout the system.

Question 18

When sizing feeder conductors, noncoincident loads (loads unlikely to be operated simultaneously such as the air-conditioning and the heating) need be included.

Accepted Answer

Noncoincident loads are those that are unlikely to be operated simultaneously. Therefore, only the larger of any noncoincident loads needs to be included when sizing feeder conductors. This ensures that the conductor is able to handle the maximum expected load without being overloaded. Including the smaller noncoincident loads would result in an oversized conductor, which is unnecessary and costly.

Question 19

What are the three conditions of failure that may occur with a 3-phase, 4-wire wye system?

Accepted Answer

The answer of What are the three conditions of failure...

Question 20

On a 3-phase, 4-wire, wye system, reduction is allowed for nonlinear loads.

Accepted Answer

In a 3-phase, 4-wire, wye system, no reduction is allowed for nonlinear loads because these loads can cause significant harmonic distortion, which can affect the system's performance and reliability.

Quiz 8: Feeders