Deck 8: Feeders

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.

A)phase
B)neutral
C)parallel
D)circuit

Answer 1

C

Question 2

What are the requirements for installing parallel conductors?

Answer 2

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.

A)Overcurrents
B)Linear loads
C)Standing waves
D)Harmonics

Answer 3

D

Question 4

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

A)the next higher standard rating may
B)the next lower standard rating may
C)a custom rating may
D)a custom rating must

Question 5

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

A)neutral
B)clamp-on
C)average-reading
D)true rms

Question 6

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

A)30
B)50
C)60
D)90

Question 7

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

Question 8

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

Question 9

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

A)fuses and circuit breakers
B)series and parallel
C)linear and nonlinear
D)motors and hermetic units

Question 10

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

Question 11

The ampacity is the allowable ampacity multiplied by the factor.

A)grounding
B)EMT
C)overcurrent
D)derating

Question 12

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

A)100
B)400
C)900
D)1600

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 ____.

A)triplens
B)doublens
C)triple harmonies
D)all harmonics

Question 14

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

A)D
B)K
C)T
D)Y

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).

A)85
B)90
C)100
D)110

Question 16

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

A)Platinum
B)Aluminum
C)Copper
D)Tungsten

Question 17

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

A)motors
B)busbars
C)raceways
D)panelboards

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.

A)all of the
B)the average of the
C)only the larger of any
D)only the smaller of any

Question 19

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

Question 20

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

A)no
B)10 percent
C)50 percent
D)75 percent