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Illustrated Guide to the National Electrical Code

Charles R. Miller

Chapter 14

Services, Feeders, and Equipment - all with Video Answers

Educators

Chapter Questions

04:58

Problem 1

A separately derived system's grounding electrode conductor connection can be made at any point from the source to the system disconnecting means or overcurrent device.

Aparna Shakti
Aparna Shakti
Numerade Educator
03:36

Problem 2

For the purposes of Article 408, a 3-pole circuit breaker shall be considered overcurrent device(s).

Arpit Gupta
Arpit Gupta
Numerade Educator

Problem 3

Internal parts of electrical equipment, including busbars, wiring terminals, insulators, and other surfaces, shall not be by foreign materials such as paint, plaster, cleaners, abrasives, or corrosive residues.

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02:17

Problem 4

An alternate ac power source such as an on-site generator is not a separately derived system if the is solidly interconnected to a service-supplied system

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 5

For equipment rated 1200 amperes or more and over $6 \mathrm{ft}$ wide that contains overcurrent devices, switching devices, or control devices, there shall be entrance(s).

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02:09

Problem 6

A 480-volt transformer, equipped with coordinated thermal overload protection by the manufacturer and arranged to interrupt the primary current, shall be permitted to have primary overcurrent protection rated or set at a current value that is not more than the rated current of the transformer for a transformer having $8 \%$ impedance.

Manish Kumar
Manish Kumar
Numerade Educator

Problem 7

The width of the working space in front of the electric equipment shall be the width of the equipment or in., whichever is greater.

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Problem 8

Where field-installed wiring passes through an opening in an enclosure, conduit box, or barrier, a shall be used to protect the conductors from the edges of an opening having sharp edges within generators.

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01:01

Problem 9

On a switchboard, switchgear, or panelboard supplied from a 4-wire, delta-connected system where the midpoint of one phase winding is grounded, that phase busbar or conductor having the higher voltage to ground shall be durably and permanently marked by an outer finish that is in color or by other effective means.

Raj Bala
Raj Bala
Numerade Educator

Problem 10

Ground-fault protection of equipment shall be provided for solidly grounded wye electrical systems of more than 150 volts to ground, but not exceeding 1000 volts phaseto-phase for each individual device used as a building or structure main disconnecting means rated or more.

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01:42

Problem 11

The conductor of each separately derived system shall be bonded to the nearest available point of the interior metal water piping system(s) in the area served by each separately derived system.

Manik Pulyani
Manik Pulyani
Numerade Educator
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Problem 12

Busways shall be securely supported at intervals not exceeding $\mathrm{ft}$ unless otherwise designed and marked.

Rashmi Sinha
Rashmi Sinha
Numerade Educator
01:04

Problem 13

What is the minimum vertical clearance (in $\mathrm{ft}$ ) for $208 \mathrm{Y} / 120$-volt, 3-phase overhead service conductors in a commercial area subject to minimal truck traffic?

Narayan Hari
Narayan Hari
Numerade Educator

Problem 14

Covered, shielded, fenced, enclosed, or otherwise protected by means of suitable covers, casings, barriers, rails, screens, mats, or platforms to remove the likelihood of approach or contact by persons or objects to a point of danger is the definition of

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Problem 15

Where the overcurrent device is rated over amperes, the ampacity of the conductors it protects shall be equal to or greater than the rating of the overcurrent device as defined in 240.6 .

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Problem 16

The enclosure for a panelboard shall have the top and bottom wire-bending space sized in accordance with for the largest conductor entering or leaving the enclosure.

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Problem 17

$\mathrm{A}(\mathrm{n})$ is an electrical source, other than a service, having no direct connection(s) to circuit conductors of any other electrical source other than those established by grounding and bonding connections.

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Problem 18

Dry-type transformers 1000 volts, nominal, or less and not exceeding shall be permitted in hollow spaces of buildings not permanently closed in by structure.

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01:07

Problem 19

Where rear access is required to work on nonelectrical parts on the back of enclosed equipment, a minimum horizontal working space of in. shall be provided.

Sachin Rao
Sachin Rao
Numerade Educator

Problem 20

The ampacity of the conductors from the generator terminals to the first distribution device(s) containing overcurrent protection shall not be less than $\%$ of the nameplate current rating of the generator.

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Problem 21

Where exposed to the weather, raceways enclosing service-entrance conductors shall be suitable for use in wet locations and

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Problem 22

For industrial establishments only, omission of overcurrent protection shall be permitted at points where busways are reduced in ampacity, provided that the length of the busway having the smaller ampacity does not exceed $\mathrm{ft}$ and has an ampacity at least equal to one-third the rating or setting of the overcurrent device next back on the line, and provided that such busway is free from contact with combustible material.

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Problem 23

Circuit breakers shall be marked with their ampere rating in a manner that will be after installation.

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Problem 24

The minimum height for work space about service equipment, switchboards, switchgear, panelboards, or motor control centers shall be $\mathrm{ft}$.

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03:21

Problem 25

A 480Y/277-volt switchboard, having exposed live parts on one side and a concrete wall on the other side, requires a minimum working space depth of in.

Kudakwashe Mapiki
Kudakwashe Mapiki
Numerade Educator
02:13

Problem 26

Transformers, other than , shall have a disconnecting means located either in sight of the transformer or in a remote location. Where located in a remote location, the disconnecting means shall be lockable in accordance with 110.25 , and its location shall be field-marked on the transformer.

Ashly Sunny
Ashly Sunny
Numerade Educator

Problem 27

In other than industrial establishments, where a vertical riser penetrates two or more dry floors, a minimum in.-high curb shall be installed around all floor openings for riser busways to prevent liquids from entering the opening.

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Problem 28

are generally accessible from the rear as well as from the front and are not intended to be installed in cabinets.

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06:17

Problem 29

Generators shall be equipped with , lockable in the open position, by means of which the generator and all protective devices and control apparatus are able to be disconnected entirely from the circuits supplied by the generator.

Keshav Singh
Keshav Singh
Numerade Educator
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Problem 30

The space equal to the width and depth of switchboards, switchgear, panelboards, and motor control centers and extending from the floor to a height of ft above the equipment or to the structural ceiling, whichever is lower, shall be dedicated to the electrical installation.

Rashmi Sinha
Rashmi Sinha
Numerade Educator

Problem 31

For other than a totally enclosed switchboard or switchgear, a space not less than $\mathrm{ft}$ shall be provided between the top of the switchboard or switchgear and any combustible ceiling, unless a noncombustible shield is provided between the switchboard or switchgear and the ceiling.

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03:07

Problem 32

Where the service-entrance phase conductors are larger than 1100 -kcmil copper or 1750-kcmil aluminum, the main bonding jumper shall have an area that is not less than of the area of the largest phase conductor.

Jennifer Stoner
Jennifer Stoner
Numerade Educator

Problem 33

is defined as being surrounded by a case, housing, fence, or walls that prevent persons from accidentally contacting energized parts.

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Problem 34

Busways shall be permitted to be extended vertically through dry floors if totally enclosed (unventilated) where passing through and for a minimum distance of $\mathrm{ft}$ above the floor to provide adequate protection from physical damage.

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Problem 35

Where a terminal bar is installed in a dry-type transformer, the terminal bar shall be bonded to the enclosure in accordance with 250.12 and shall not be installed on or over any of the enclosure.

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