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Mike Holt’s Illustrated Guide to Understanding the National Electrical Code®, Volume 1, Based on the 2017 NEC®2017

Click on the TEXTBOOK corrections listed below to go to view the corrected page. Then click anywhere on that page to return to this page.

Page # Reference Correction

26 Author Comment DeletionThe Author's Comment relating to Cable Routing Assembly that was under Figure 100-19 needs to be relocated to under Figure 100-21 on page 27.

27Author Comment Relocated

The Author's Comment relating to Cable Routing Assembly that was under Figure 100-19 from page 26 needs to be relocated to under Figure 100-21.

49 "Service" definitionThe definition of “Service” was revised to read, “The conductors and equipment for delivering electric energy from the serving utility to the wiring system of the premises served.

82 110.27(A)(4)(b) Section 110.27(A)(4)(b) should be: 8 ft 6 in. for 301V through 600V between ungrounded conductors.

210 Section 240.21(B)(1)(1) Section 240.21(B)(1)(1) was revised to read, “The tap conductors must have an ampacity not less than:”

315 Question 28Answer choice (a) was revised to read, “ground detectors installed for ac systems operating at not less than 120V and at 1,000V or less”

428 338.10(B)(4)(a) The reference to Table 310.15(B)(16) was removed.

466 356.22 Example The reference for the answer to the example was changed to [Annex C, Table C.6].

602 Section 445.13(A In the last paragraph, the phrase “that aren’t a separately derived system” was removed.

613 Question 13The question was revised to read, “In dwelling units, all Nonlocking-type 125V and 250V, 15A and 20A receptacles installed _____ shall be listed as tamper resistant.”

623 Question 55 The phrase “the conductor’s” was changed to “60°C (140°F) conductor.”

625 Question 90The question was revised to read, “A building or structure shall have the interior metal water piping system bonded with a bonding jumper sized in accordance with _____.”

632 Question 64

The question was revised to read, “Where raceways or cables are exposed to direct sunlight on or above rooftops and where the distance above the roof to the bottom of the raceway is less than _____ in., a temperature adder of 60°F must be added to the outdoor temperature to determine the applicable ambient temperature for application of the correction factors in Table 310.15(B)(2)(a) or Table 310.15(B)(2)(b).

633 Question 79Answer choice (a) was revised to read, “fished between access points through concealed spaces in finished buildings or structures and supporting is impracticable”

634 Question 95 Answer choice (a) was changed to (a) 15V, 25V.

TextbookPrinted: February 20, 2017Reprinted: January 2020Last Correction Update: January 11, 2020

Mike Holt’s Illustrated Guide to Understanding the National Electrical Code®, Volume 1, Based on the 2017 NEC®2017

Page # Reference Correction

7 Final Exam B, Answer 49 The Code reference was changed to 250.104(A)(3)(1), (2), and (3).

Answer KeyPrinted: February 20, 2017Reprinted: August 31, 2018Last Correction Update: October 21, 2018

*Note: If you have an Answer Key dated before April 16, 2019, then call our office for an updated Answer Key. Page #s below reflect this version.

100 | Definitions

Mike Holt’s Illustrated Guide to Understanding the 2017 National Electrical Code, Volume 126

Cabinet [Article 312]. An enclosure for either surface mounting or flush mounting provided with a frame in which a door can be hung. }Figure 100–20

Author’s Comment:

Cabinets are used to enclose panelboards. See the definition of “Panelboard” in this article.

Cable Routing Assembly. A channel or channels, with their fittings, that support and route communications wires and cables, optical fiber cables, data cables, Class 2 and Class 3, and Type PLTC cables, and power‑limited fire alarm cables in plenum, riser, and general‑purpose applications. }Figure 100–21

Author’s Comment:

Multiwire branch circuits offer the advantage of fewer conduc-tors within a raceway, smaller raceway sizing, and a reduction of material and labor costs. In addition, multiwire branch circuits can reduce circuit voltage drop by as much as 50 percent. However, because of the dangers associated with multiwire branch circuits, the NEC contains additional requirements to ensure a safe installation. See 210.4, 300.13(B), and 408.41 in this textbook for details.

Building. A structure that stands alone or is separated from adjoining structures by fire walls. }Figure 100–19

}Figure 100–19

}Figure 100–18

}Figure 100–17

Service

Panelboard

Generator - ( )SDSTransfer Switch

Copyright 2017, www.MikeHolt.com

GEC GEC

SBJ

EGC EGC

EG

C

N

N

NN

EGC: Equipment Grounding Conductor: Grounding Electrode ConductorGEC

: System Bonding JumperSBJ: Main Bonding JumperMBJ

N: Neutral

Legend

MBJ

Bonding Jumper, SystemSeparately Derived System, Generator

Article 100 Definition

The connection between the neutral conductor and SSBJor , or both, at a separately derived system generator.EGC

}Figure 100–16

Mike Holt Enterprises • www.MikeHolt.com • 888.NEC.CODE (632.2633)

Definitions | 100

27

Circuit Breaker. A device designed to be opened and closed manually, and which opens automatically on a predetermined overcurrent without damage to itself. Circuit breakers are available in different configura-tions, such as inverse time, adjustable trip (electronically controlled), and instantaneous trip/motor-circuit protectors. }Figure 100–23

Circuit Breaker, Inverse Time. Inverse time breakers operate on the principle that as the current increases, the time it takes for the devices to open decreases. This type of breaker provides overcurrent protec-tion (overload, short circuit, and ground fault). This is the most common type of circuit breaker that you’ll buy over-the-counter.

Author’s Comment:

A cable routing assembly is typically a “U” shaped trough, with or without covers, designed to hold cables, and it isn’t a raceway.

Charge Controller. Equipment that controls dc voltage or dc current, or both, and is used to charge a battery or other energy storage device. }Figure 100–22

}Figure 100–20

}Figure 100–23


Combiner

PV Source Circuit Inverter Input Circuit

Inverter Output Circuit

PV Output Circuit

CombinerDisconnect

Feeder

acDisconnect

Inverterdc Disconnect

Array

EnergyStorage

Charge ControllerArticle 100 Definition

ChargeController

String 1

String 2

Equipment that controls dc voltage or dc current, or both, andis used to charge a battery or other energy storage device.

}Figure 100–22

}Figure 100–21

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Definitions | 100

49

Service [Article 230]. The conductors and equipment for delivering electric energy from the serving utility to the wiring system of the prem-ises served. }Figure 100–100

Author’s Comment:

Conductors from a UPS system, solar PV system, generator, or transformer aren’t service conductors. See the definitions of “Feeder” and “Service Conductors” in this article.

Service Conductors. The conductors from the service point to the service disconnect. }Figure 100–101

Author’s Comment:

An alternate alternating-current power source such as an on-site generator isn’t a separately derived system if the neutral conductor is solidly interconnected to a service- supplied system neutral conductor. An example is a gener-ator provided with a transfer switch that includes a neutral conductor that’s not switched. }Figure 100–99

Separately derived systems are actually much more complicated than the above definition suggests, and understanding them requires additional study. For more information, see 250.30.

}Figure 100–98

}Figure 100–101

}Figure 100–100

}Figure 100–99


110.28 | Requirements for Electrical Installations

110.28 Enclosure Types

Enclosures must be marked with an enclosure-type number and be suitable for the location in accordance with Table 110.28. The enclo-sures aren’t intended to protect against condensation, icing, corrosion, or contamination that might occur within the enclosure or that enters via the raceway or unsealed openings. }Figure 110–80

Note: Raintight enclosures include Types 3, 3S, 3SX, 3X, 4, 4X, 6, and 6P; rain-

proof enclosures are Types 3R, and 3RX; watertight enclosures are Types 4, 4X, 6,

and 6P; driptight enclosures are Types 2, 5, 12, 12K, and 13; and dusttight enclo-

sures are Types 3, 3S, 3SX, 3X, 5, 12, 12K, and 13.

(3) Locating them on a balcony or platform to exclude unqualified persons.

(4) Elevating them above the floor or working surface, in accordance with the following:

(a) 8 ft for 50V through 300V between ungrounded conductors.

(b) 8 ft 6 in. for 301V through 600V between ungrounded conductors.

(c) 8 ft 7 in. for 601V through 1,000V between ungrounded conductors.

(B) Prevent Physical Damage. Electrical equipment must not be installed where subject to physical damage, unless enclosures or guards are arranged and they’re of sufficient strength to prevent damage. }Figure 110–79

(C) Warning Signs. Entrances to rooms and other guarded locations containing exposed live parts must be marked with conspicuous signs forbidding unqualified persons from entering.

}Figure 110–80

}Figure 110–79


240.21 | Overcurrent Protection

(2) The tap conductors must not extend beyond the equipment they supply.

(3) The tap conductors are installed within a raceway when they leave the enclosure.

(4) The tap conductors must have an ampacity not less than 10 percent of the rating of the overcurrent protection device that protects the feeder. }Figure 240–23

Note: See 408.36 for the overcurrent protection requirements for panelboards.

(1) 10-Foot Feeder Tap. Feeder tap conductors up to 10 ft long are permitted without overcurrent protection at the tap location if the tap conductors comply with the following:

(1) The tap conductors must have an ampacity not less than: }Figure 240–22

a. The calculated load in accordance with Article 220, and

b. The rating of the overcurrent protection device termination or equipment containing overcurrent protection devices supplied by the tap conductors.

Ex: Listed equipment, such as a surge protection device, can have their conductors sized in accordance with the manufacturer’s instructions.

Taps

Taps

Feeders

Tap of Tap

Feeders

Location of Protection240.21

ServiceConductors

Tap and secondaryconductors aren’tpermitted to supplyanother conductor.

VIOLATION60A

100A

100A

400A

Except as permitted by (A) through(H), overcurrent devices must beplaced at the point where theconductors receive their power.

ServiceFeederFeeder Tap

Legend


}Figure 240–20

ON

OFF

INTERRUPTING RATING

MAX AMPS. R.M.S.

10,000 .SYM

VOLTS

120/240

V.A.C.

Feeder Taps

FeederOvercurrent Protection Location

Feeder Tap Conductors240.21(B)

ON

OFF

INTERRUPTING RATING

MAX AMPS. R.M.S.

10,000 .SYM

VOLTS

120/240

V.A.C.

1 FeederAWGRated 130A at 75 Co

Next Size Up Okay[240.4(B)]

150AProtection,

but theload can’texceed130A.

WARNING

Arc Flash and Shock Hazard

Appropriate RequiredPPE

Available Fault Current:

Installation Date:

01/01/2011

9,500 Amps

The “next size up rule” [240.4(B)]for overcurrent devices doesn’tapply to tap conductors.

1/0 Feeder Taps RatedAWG150A at 75oC [310.15(B)(16)]


}Figure 240–21

ON

OFF


2nd Fl.Equipment

Room

2nd Fl.Machine

Room 207

2nd Fl.Air HandlerRoom 207

Panel 201Fed From Disconnect 200

Equipment Room 201

Feeder

The feeder tap conductor ampacity must not be less than:a. The calculated load in accordance with Article 220.b. The rating of the overcurrent device supplied by the

tap conductors.

Inside Feeder Taps Not Over 10 FtTap Ampacity

240.21(B)(1)(1)

WARNINGArc Flash Hazard

}Figure 240–22

ON

OFF


2nd Fl.Equipment

Room

2nd Fl.Machine

Room 207

2nd Fl.Air HandlerRoom 207

Panel 201Fed From Disconnect 200

Equipment Room 201

400A FeederProtection

Device( / = 40A)1 10

Inside Feeder Taps Not Over 10 FtTap Ampacity, 10% Rule

240.21(B)(1)(4)

The ampacity of tap conductors can’t be less than/ the rating of the device protecting the feeder.1 10


}Figure 240–23

Mike Holt Enterprises • www.MikeHolt.com • 888.NEC.CODE (632.2633) 315

Practice Questions | Chapter 2

33. A bare 4 AWG copper conductor installed horizontally near the bottom or vertically, and within that portion of a concrete foun‑dation or footing that is in direct contact with the earth, can be used as a grounding electrode when the conductor is at least _____ ft in length.

(a) 10(b) 15(c) 20(d) 25

34. Where more than one concrete‑encased electrode is present at a building or structure, it shall be permitted to bond only one into the grounding electrode system.

(a) True(b) False

35. Grounding electrodes of the rod type less than _____ in. in diameter shall be listed.

(a) ½(b) 5⁄8(c) ¾(d) 1

36. _____ shall not be used as grounding electrodes.

(a) Metal underground gas piping systems(b) Aluminum(c) Metal well casings(d) a and b

37. Where rock bottom is encountered when driving a ground rod at an angle up to 45º, the electrode can be buried in a trench that is at least _____ deep.

(a) 18 in.(b) 30 in.(c) 4 ft(d) 8 ft

38. Grounding electrode conductors of the wire type shall be _____.

(a) solid(b) stranded(c) insulated or bare(d) any of these

28. Ungrounded alternating‑current systems from 50V to 1,000V or less that are not required to be grounded in accordance with 250.20(b) shall have _____.

(a) ground detectors installed for ac systems operating at not less than 120V and at 1,000V or less

(b) the ground detection sensing equipment connected as close as practicable to where the system receives its supply

(c) a and b(d) ground‑fault protection for equipment

29. Ungrounded alternating‑current systems from 50V to less than 1,000V shall be legibly marked “Caution: Ungrounded System—Operating _____ Volts Between Conductors” at _____ of the system, with sufficient durability to withstand the environment involved.

(a) the source(b) the first disconnecting means(c) every junction box(d) a or b

30. The grounded conductor of an alternating‑current system oper‑ating at 1,000V or less shall be routed with the ungrounded conductors and connected to each disconnecting means grounded conductor terminal or bus, which is then connected to the service disconnecting means enclosure via a(n) _____ that is installed between the service neutral conductor and the service discon‑necting means enclosure.

(a) equipment bonding conductor(b) main bonding jumper(c) grounding electrode(d) intersystem bonding terminal

31. When supplying a grounded system at a separate building or structure, an equipment grounding conductor shall be run with the supply conductors and connected to the building or structure disconnecting means and to the grounding electrode(s).

(a) True(b) False

32. High‑impedance grounded neutral systems shall be permitted for three‑phase ac systems of 480V to 1,000V where _____.

(a) the conditions of maintenance and supervision ensure that only qualified persons service the installation

(b) ground detectors are installed on the system(c) line‑to‑neutral loads are not served(d) all of these


338.6 | Service‑Entrance Cable (Types SE and USE)

Ex: In existing installations, uninsulated conductors may be used for the neutral conductor if the uninsulated neutral conductor of the cable origi nates in service equipment.

(3) Temperature Limitations. SE cable isn’t permitted to be subjected to conductor temperatures exceeding its insulation rating.

(4) Installation Methods for Branch Circuits and Feeders. SE cable used for branch circuits or feeders must comply with (a) and (b).

(a) Interior Installations. SE cable used for interior branch‑circuit or feeder wiring must be installed in accordance with the same require‑ments as Type NM Cable—Article 334, excluding 334.80.

Where installed in thermal insulation, the ampacity of conductors 10 AWG and smaller, must be sized in accordance with the 60°C (140°F) conductor temperature rating in accordance with Table 310.15(B)(16). For conductor ampacity correction and/or adjustment, the conductor temperature rating ampacity is to be used.

CAUTION: Underground service‑entrance cable (USE) isn’t permitted for interior wiring because it doesn’t

have a flame‑retardant insulation. It’s only permitted in interior wiring when listed as both a cable (USE) and a conductor, such as RHH, in accordance with Table 310.104.

(b) Exterior Installations. The cable must be supported in accordance with 334.30 and where run underground, the cable must comply with Part II of Article 340.

Type USE. USE cable is identified as a wiring method permitted for under‑ground use; its covering is moisture resistant, but not flame retardant.

Author’s Comment:

n USE cable isn’t permitted to be installed indoors [338.10(B)], except single-conductor USE dual rated as RHH/RHW.

338.6 Listing Requirements

Type SE and USE cables and associated fittings must be listed. }Figure 338–3

Part II. Installation

338.10 Uses Permitted

(A) Service‑Entrance Conductors. Service‑entrance cable used as service‑entrance conductors must be installed in accordance with Article 230.

(B) Branch Circuits or Feeders.

(1) Insulated Conductor. Type SE service‑entrance cable is permitted for branch circuits and feeders where the circuit conductors are insulated.

(2) Uninsulated Conductor. SE cable is permitted for branch circuits and feeders if the insulated conductors are used for circuit wiring, and the uninsulated conductor is only used for equipment grounding purposes. }Figure 338–4

SE Cable, Use of Uninsulated Conductor338.10(B)(2)

SE SERand cable can be used for branch circuitsand feeders, but the uninsulated conductor can onlybe used for equipment grounding.

SE

R

SE

Proper Installation

N N

G GL1 L1L2 L2

N

L1 L2


VIOLATION

}Figure 338–4 Type SE and USE Cable, Listing

338.6


Type SE and USE cable andassociated fittings must be listed.

}Figure 338–3


356.10 | Liquidtight Flexible Nonmetallic Conduit (Type LFNC)

(3) Longer than 6 ft, except if approved by the authority having juris-diction as essential for a required degree of flexibility.

(4) In any hazardous location, except as permitted by 501.10(B), 502.10(A) and (B), and 504.20.

356.20 Trade Size

(A) Minimum. Liquidtight flexible nonmetallic conduit smaller than trade size ½ isn’t permitted, except as in the following:

(1) Enclosing the leads of motors, 430.245(B).

(2) For tap connections to lighting fixtures as permitted by 410.117(C).

(B) Maximum. Liquidtight flexible nonmetallic conduit larger than trade size 4 isn’t permitted.

356.22 Number of Conductors

Raceways must be large enough to permit the installation and removal of conductors without damaging the insulation. When all conductors within a raceway are the same size and insulation, the number of conductors permitted can be found in Annex C for the raceway type.

Example: How many 8 THHN conductors can be installed in trade size ¾ LFNC-B? }Figure 356–4

Answer: Six conductors [Annex C, Table C.6]

Part II. Installation

356.10 Uses Permitted

Listed liquidtight flexible nonmetallic conduit is permitted, either exposed or concealed, at any of the following locations:

Note: Extreme cold can cause nonmetallic conduits to become brittle and more

susceptible to damage from physical contact.

(1) If flexibility is required.

(2) If protection from liquids, vapors, or solids is required.

(3) Outdoors, if listed and marked for this purpose.

(4) Directly buried in the earth, if listed and marked for this purpose. }Figure 356–3

(5) LFNC (gray color) is permitted in lengths over 6 ft if secured in accor-dance with 356.30.

(6) LFNC, Type B (black color) as a listed manufactured prewired assembly.

(7) Encasement in concrete if listed for direct burial.

356.12 Uses Not Permitted

(1) If subject to physical damage.

(2) If the ambient temperature and/or conductor temperature is in excess of its listing.

LFNC, Number of Conductors356.22 Example

When all conductors in a raceway are the samesize and insulation, the number of conductorspermitted can be found in Annex C.

A maximum of six 8 THHNconductors can be installed in

-B [Table C.7].3 4/ LFNC


}Figure 356–4

LFNC, Used Permitted356.10(4)


Listed liquidtight flexible nonmetallicconduit is permitted directly buried in theearth if listed and marked for this purpose.

}Figure 356–3


445.13 | Generators

(B) Overcurrent Protection Provided. Conductors can be tapped from the load side of the generator overcurrent protected device in accor‑dance with 240.21(B).

445.18 Disconnecting Means and Shutdown of Prime Mover

(A) Disconnecting Means. Each fixed generator disconnect must simul‑taneously disconnect all its associated ungrounded conductors and must be lockable in the open position in accordance with 110.25. }Figure 445–4

445.13 Ampacity of Conductors

(A) General. The ampacity of the conductors from the generator winding output terminals to the first overcurrent protection device, typically on the generator, must have an ampacity of not less than 115 percent of the nameplate current rating of the generator.

Author’s Comment:

n Since the overcurrent protection device is typically part of the generator, this rule applies to the generator manufacturer, not the field installer.

n Conductors from the load side of the generator overcurrent protection device to the transfer switch are sized in accor-dance with 240.4.

Example: What size conductor is required from a 100A overcurrent protection device on a 20 kW, 120/240V single‑phase generator to a 200A service rated transfer switch if the terminals are rated for 75ºC conductor sizing? }Figure 445–2

Answer: A 3 AWG conductor is required; Table 310.15(B)(16), rated 100A at 75°C [110.14(C)(1)(b)].

Generators that aren’t a separately derived system must have the neutral conductor sized to carry the maximum unbalanced current as determined by 220.61, serve as part of the effective ground‑fault current path, and not be smaller than required by 250.30. }Figure 445–3

NormalSupply

OtherLoads

EmergencyLoads

TransferSwitches

Generator Disconnect(s)445.18(A)

G


Each fixed generator disconnectmust be lockable in the openposition and simultaneouslydisconnect its associatedungrounded conductors.

}Figure 445–4

Service

Panelboard

Generator - (Not )SDSRunningTransfer Switch


GEC

EGC EGC

EG

C

N

N

NN

EGC: Equipment Grounding Conductor: Grounding Electrode ConductorGEC: Main Bonding JumperMBJ

N: NeutralSDS: Separately Derived System

Legend

MBJ

The neutral conductor must be sized to carry theneutral and fault current [250.30(A)(1) and 220.61].

Fault CurrentReturns to Source

Generator, Neutral Conductor Size445.13(A)

}Figure 445–3

3 RatedAWG100A at 75 Co

[Table 310.15(B)(16)]100A

GeneratorOvercurrent

Device

Conductors from the generatorovercurrent device to the transferswitch are sized in accordancewith 240.4.


Ampacity of Generator ConductorsLoad Side of Generator Overcurrent Device

445.13(A) Example



}Figure 445–2


Practice Questions | Chapter 4

11. Receptacles mounted to and supported by a cover shall be secured by more than one screw unless listed and identified for securing by a single screw.

(a) True(b) False

12. A receptacle is considered to be in a location protected from the weather when located under roofed open porches, canopies, marquees, and the like, where it will not be subjected to _____.

(a) spray from a hose(b) a direct lightning hit(c) beating rain or water runoff(d) falling or wind‑blown debris

13. In dwelling units, all Nonlocking type 125V and 250V, 15A and 20A receptacles installed _____ shall be listed as tamper resistant.

(a) in bedrooms(b) outdoors, at grade level(c) above counter tops(d) in all areas specified in 210.52 and 550.13

14. In dwelling units, all nonlocking‑type 125V and 250V, 15A and 20A receptacles installed _____ shall be listed as tamper resistant.

(a) in business offices, corridors, waiting rooms and the like in clinics, medical and dental offices and outpatient facilities

(b) as a subset of assembly occupancies described in 518.2 to include places of waiting transportation, gymnasiums, skat‑ing rinks, and auditoriums

(c) in dormitories(d) all of these

15. Nongrounding, nonlocking‑type, 15A and 20A, 125V and 250V receptacles used for replacements in a dwelling unit shall not be required to be listed as tamper resistant.

(a) True(b) False

7. Nonmetallic boxes for switches shall be installed with a wiring method that provides or includes a(n) _____.

(a) grounded conductor(b) equipment grounding conductor(c) inductive balance(d) none of these

8. Alternating‑current general‑use snap switches are permitted to control _____.

(a) resistive and inductive loads that do not exceed the ampere and voltage rating of the switch

(b) tungsten‑filament lamp loads that do not exceed the ampere rating of the switch at 120V

(c) motor loads that do not exceed 80 percent of the ampere and voltage rating of the switch

(d) all of these

9. General‑use _____ switches shall be used only to control perma‑nently installed incandescent luminaires unless listed for control of other loads and installed accordingly.

(a) dimmer(b) fan speed control(c) timer(d) all of these

Article 406. Receptacles, Cord Connectors, and Attachment Plugs (Caps)

10. Where attachment to an equipment grounding conductor does not exist in the receptacle enclosure, a non‑grounding‑type receptacle shall be permitted to be replaced with a GFCI‑type receptacle; however, some equipment or appliance manufacturers require that the _____ to the equipment or appliance includes an equip‑ment grounding conductor.

(a) feeder(b) branch circuit(c) small‑appliance circuit(d) none of these


Final Exam A

59. Exposed structural metal interconnected to form a metal building frame that is not intentionally grounded or bonded and is likely to become energized, shall be bonded to the _____.

(a) service equipment enclosure or building disconnecting means

(b) grounded conductor at the service(c) grounding electrode conductor where of sufficient size(d) any of these

60. Receptacle outlets in meeting room fixed walls shall be installed in accordance with _____.

(a) 210.52(A)(1) (b) 210.52(A)(1) and (A)(2)(c) 210.52(A)(1) through (A)(3) (d) 210.52(A)(1) through (A)(4)

61. Where two or more branch circuits supply devices or equipment on the same yoke or mounting strap, a means to disconnect simul-taneously the ungrounded supply conductors shall be provided at the _____.

(a) point where the branch circuits originate(b) location of the device or equipment(c) point where the feeder originates(d) none of these

62. The bonding jumper used to bond the metal water piping system shall be sized in accordance with _____ except as permitted in 250.104(A)(2) and 250.104(A)(3).

(a) Table 250.102(C)(1) (b) Table 250.122(c) Table 310.15(B)(16) (d) Table 310.15(B)(6)

63. Receptacle outlets that are a part of a _____ kW or smaller portable generator shall have listed ground-fault circuit- interrupter protection (GFCI) for personnel integral to the gener-ator or receptacle.

(a) 10 (b) 15 (c) 20 (d) 25

64. The bonding jumper used to bond the metal water piping system shall be installed in accordance with 250.64(A), 250.64(B), and 250.64(E) and the points of attachment of the bonding jumper(s) shall be _____.

(a) readily accessible (b) accessible(c) a or b (d) none of these

53. All nonlocking-type, 125V, 15A and 20A receptacles that are controlled by _____, or that incorporate control features that remove power from the receptacle for the purpose of energy management or building automation, shall be permanently marked with the word “controlled.”

(a) wall switches(b) remote control(c) wireless communication(d) an automatic control device

54. Unbonded 15 kW or smaller portable generators with both 125V and 125/250V receptacle outlets shall have _____ GFCI protec-tion for personnel integral to the generator or receptacle on all 125V, 15A and 20A receptacle outlets.

(a) identified (b) labeled (c) listed (d) approved

55. For interior installations of Type SE cable with ungrounded conductor sizes _____ AWG and smaller, where installed in thermal insu-lation, the ampacity shall be in accordance with 60°C (140°F) conductor temperature rating.

(a) 14 (b) 12 (c) 10 (d) 8

56. For conductor sizes and combinations not included in Chapter 9, Tables 1 or 2, the total cross-sectional area of the fill shall not exceed the cross-sectional area of the conductors specified in the _____, based on the type of conductor identified as part of the product listing.

(a) marking (b) listing (c) labeling (d) all of these

57. A “_____” is the total components and subsystem that, in combi-nation, converts solar energy into electric energy for connection to a utilization load.

(a) photovoltaic system (b) solar array(c) a and b (d) none of these

58. In installations within or behind noncombustible walls or ceil-ings, the front edge of a box, plaster ring, extension ring, or listed extender employing a flush-type cover, shall be set back not more than _____ in. from the finished surface.

(a) 1⁄8 (b) 1⁄4 (c) 3⁄8 (d) 1⁄2


Final Exam A

86. The label required for switchboards, switchgear, and panelboards [408.4(B)] shall be permanently affixed, of sufficient durability to withstand the environment involved, and handwritten.

(a) True (b) False

87. Luminaires that require adjusting or aiming after installation can be cord connected without an attachment plug provided the exposed cord is suitable for hard-usage or extra-hard-usage and is not longer than that required for maximum adjustment.

(a) True (b) False

88. Cabinets, cutout boxes, and meter socket enclosures can be used for conductors feeding through, spliced, or tapping off to other enclosures, switches, or overcurrent devices where _____.

(a) the total area of the conductors at any cross section does not exceed 40 percent of the cross-sectional area of that space

(b) the total area of conductors, splices, and taps installed at any cross section does not exceed 75 percent of the cross-sectional area of that space

(c) a warning label on the enclosure identifies the closest dis-connecting means for any feed-through conductors

(d) all of these

89. The number of multiconductor cables, rated _____ or less, permitted in a single cable tray shall not exceed the require-ments of 392.22 and, where dividers are used, fill calculations shall apply to each divided section of the cable tray.

(a) 1,000V (b) 1,500V (c) 2,000V (d) 2,500V

90. A building or structure shall have the interior metal water piping system bonded with a bonding jumper sized in accordance with _____.

(a) Table 250.102(C)(1) (b) Table 250.122(c) Table 310.15(B)(16) (d) none of these

91. When calculating box fill, each space within a box installed with a barrier shall be calculated separately.

(a) True (b) False

79. Where equipment operating at 1,000 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized is required by installation instruc-tions or function to be located in a space with limited access, all enclosure doors or hinged panels shall be capable of opening a minimum of _____ degrees.

(a) 60 (b) 90 (c) 120 (d) 180

80. Metal faceplates for snap switches, including dimmer and similar control switches, shall be _____.

(a) bonded to the grounded electrode (b) grounded(c) a and b (d) none of these

81. A receptacle outlet shall be installed at each dwelling unit kitchen wall countertop and work surface space that is 12 in. or wider and receptacle outlets shall be installed so that no point along the wall line is more than _____ in., measured horizontally from a receptacle outlet in that space.

(a) 10 (b) 12 (c) 16 (d) 24

82. Flexible cord sets and power-supply cords shall not be used where they are _____.

(a) run through holes in walls, ceilings, or floors(b) run through doorways, windows, or similar openings(c) attached to building surfaces, unless permitted by 368.56(B)(d) all of these

83. A buried iron or steel plate used as a grounding electrode shall expose not less than _____ sq ft of surface area to exterior soil.

(a) 2 (b) 4 (c) 9 (d) 10

84. Cable ties used to securely fasten ENT shall be _____ as suit-able for the application and for securing and supporting.

(a) identified (b) labeled (c) listed (d) a and c

85. Type TC-ER cable used for interior wiring in one- and two-family dwelling units that is suitable for pulling through structural members is marked “TC-ER-JP.”

(a) True (b) False


Final Exam B

69. _____ drainage openings not smaller than 1/8 in. and not larger than 1/4 in. in diameter shall be permitted to be installed in the field in boxes or conduit bodies listed for use in damp or wet locations.

(a) Listed (b) Approved (c) Labeled (d) Identified

70. Where a box is provided with _____ or more securely installed barriers, the volume shall be apportioned to each of the resulting spaces; each barrier, if not marked with its volume, shall be consid-ered to take up 1/2 cu in. if metal, and 1 cu in. if nonmetallic.

(a) one (b) two (c) three (d) four

71. According to the NEC, the volume of a 3 x 2 x 2 in. device box is _____ cu in.

(a) 8 (b) 10 (c) 12 (d) 14

72. Where nonmetallic-sheathed cable or multiconductor Type UF cable is used, the sheath shall extend not less than _____ in. inside the box and beyond any cable clamp.

(a) 1⁄4 (b) 3⁄8 (c) 1⁄2 (d) 3⁄4

73. In installations within walls or ceilings constructed of wood or other combustible surface material, boxes, plaster rings, exten-sion rings, or listed extenders shall _____.

(a) extend to the finished surface(b) project from the finished surface(c) a or b(d) be set back no more than 1⁄4 in.

74. _____ can be used to secure boxes to a structural member using brackets on the outside of the enclosure.

(a) Nails (b) Screws (c) Bolts (d) a and b

75. Boxes used at luminaire or lampholder outlets in a ceiling shall be designed so that a luminaire or lampholder can be attached and the boxes shall be required to support a luminaire weighing a minimum of _____ lb.

(a) 20 (b) 30 (c) 40 (d) 50

76. A luminaire that weighs more than _____ lb can be supported by an outlet box that is listed for the weight of the luminaire to be supported.

(a) 20 (b) 30 (c) 40 (d) 50

63. Sectioned equipment grounding conductors smaller than _____ AWG shall be permitted in multiconductor cables, if the combined circular mil area of the sectioned equipment grounding conduc-tors in each cable complies with 250.122.

(a) 3 (b) 2 (c) 1 (d) 1/0

64. Where raceways or cables are exposed to direct sunlight on or above rooftops, and where the distance above the roof to the bottom of the raceway is less than _____ in., a temperature adder of 60°F must be added to the outdoor temperature to determine the applicable ambient temperature for application of the correc-tion factors in Table 310.15(B)(2)(a) or Table 310.15(B)(2)(b).

(a) 1⁄4 (b) 1⁄3 (c) 1⁄2 (d) 7⁄8

65. The wiring space within enclosures for switches and overcurrent devices shall be permitted for other wiring and equipment subject to limitations for specific equipment as provided in _____.

(a) 312.8(A) (b) 312.8(B)(c) a and b (d) none of these

66. Enclosures for switches or overcurrent devices are allowed to have conductors feeding through where the wiring space at any cross section is not filled to more than _____ percent of the cross-sectional area of the space.

(a) 20 (b) 30 (c) 40 (d) 60

67. The wiring space of enclosures for switches or overcurrent devices shall be permitted to contain power monitoring equipment where the _____.

(a) power monitoring equipment is identified as a field install-able accessory as part of the listed equipment, or is a listed kit evaluated for field installation in switch or overcurrent device enclosures

(b) total area of all conductors, splices, taps, and equipment at any cross section of the wiring space does not exceed 75 percent of the cross-sectional area of that space

(c) a and b(d) none of these

68. Boxes, conduit bodies, and fittings installed in wet locations shall be listed for use in wet locations.

(a) True (b) False


Final Exam B

85. Aluminum fittings and enclosures shall be permitted to be used with galvanized steel RMC, and galvanized steel fittings and enclo-sures shall be permitted to be used with aluminum RMC where not subject to _____.

(a) physical damage(b) severe corrosive influences(c) excessive moisture(d) all of these

86. FMC to a luminaire or electrical equipment within an accessible ceiling is permitted to be unsupported for not more than 6 ft from the last point where the raceway is securely fastened, including securement and support by listed FMC fittings.

(a) True (b) False

87. Cable ties used to secure and support LFNC shall be _____ as suitable for the application and for securing and supporting.

(a) identified (b) labeled (c) listed (d) a and c

88. The use of EMT shall be permitted for both exposed and concealed work in _____.

(a) concrete, in direct contact with the earth or in areas sub-ject to severe corrosive influences where installed in accor-dance with 358.10(B)

(b) dry, damp, and wet locations(c) any hazardous (classified) location as permitted by other

articles in this Code(d) all of these

89. Where a metal wireway houses and protects conductors, and where single conductor cables comprising each phase, neutral, or grounded conductor of an alternating-current circuit are connected in parallel as permitted in 310.10(H), the conductors shall be installed in groups consisting of not more than _____ conductor(s) per phase, neutral, or grounded conductor to prevent current imbalance in the paralleled conductors due to inductive reactance.

(a) one (b) two (c) three (d) four

77. Power distribution blocks installed on the line side of the service equipment shall be _____ “suitable for use on the line side of service equipment” or equivalent.

(a) marked (b) listed(c) a and b (d) none of these

78. Armored cable used to connect recessed luminaires or equipment within an accessible ceiling can be unsupported and unsecured for lengths up to _____ ft.

(a) 2 (b) 3 (c) 41⁄2 (d) 6

79. Type MC cable can be unsupported and unsecured where the cable is _____.

(a) fished between access points through concealed spaces in finished buildings or structures and support is impracticable

(b) not more than 2 ft in length at terminals where flexibility is necessary

(c) not more than 6 ft from the last point of support within an accessible ceiling for the connection of luminaires or other electrical equipment

(d) a or c

80. Type NM cable and associated fittings shall be _____.

(a) marked (b) approved (c) identified (d) listed

81. Type NM cable can be supported and secured by _____.

(a) staples(b) cable ties listed and identified for securement and support(c) straps(d) any of these

82. Type TC cable and associated fittings shall be _____.

(a) identified (b) approved (c) listed (d) labeled

83. Where Type TC cable is installed in one- and two-family dwelling units, 725.136 provides rules for limitations on Class 2 or 3 circuits contained within the same cable with conductors of electric light, power, or Class 1 circuits.

(a) True (b) False

84. Types SE and USE cables and associated fittings shall be _____.

(a) identified (b) approved(c) listed (d) labeled


Final Exam B

95. Article 411 covers lighting systems and their associated compo-nents operating at no more than _____ ac or _____ dc.

(a) 15V, 25V (b) 30V, 60V (c) 60V, 125V (d) 125V, 250V

96. The GFCI required for appliances shall be readily accessible, listed, and located _____.

(a) within the branch circuit overcurrent device(b) in a device or outlet within the supply circuit(c) in an integral part of the attachment plug(d) any of these

97. The GFCI required for appliances shall be readily accessible, listed, and _____.

(a) located within the supply cord not more than 12 in. from the attachment plug

(b) factory installed within the appliance(c) a and b(d) none of these

98. An in-sink waste disposer can be cord-and-plug-connected, but receptacles shall be _____ to protect against physical damage to the flexible cord.

(a) located (b) shielded (c) guarded (d) any of these

99. The length of the cord for a built-in dishwasher shall not be longer than _____ ft, measured from the face of the attachment plug to the plane of the rear of the appliance.

(a) 6.50 (b) 7 (c) 7.50 (d) 8

100. Range hoods shall be permitted to be cord-and-plug-connected with a flexible cord identified as suitable for use on range hoods in the installation instructions of the appliance manufacturer provided _____.

(a) the length of the cord is not less than 18 in. and not over 4 ft(b) receptacles are located to protect against physical damage

to the flexible cord(c) a and b(d) none of these

90. Switches controlling line-to-neutral lighting loads shall have a grounded conductor provided at the switch location unless the _____.

(a) conductors enter the device box through a raceway that has sufficient area to accommodate a grounded conductor

(b) box enclosing the switch is accessible for the installation of an additional or replacement cable without removing finish materials

(c) lighting consists of all fluorescent fixtures with integral dis-connects for the ballasts

(d) a or b

91. Snap switches, including dimmer and similar control switches, shall be connected to an equipment grounding conductor and shall provide a means to connect metal faceplates to the equip-ment grounding conductor, whether or not a metal faceplate is installed.

(a) True (b) False

92. Effective January 1, 2020, electronic lighting control switches shall not introduce current on the equipment grounding conductor during _____ operation.

(a) normal (b) emergency(c) a and b (d) none of these

93. Receptacles in or on countertop surfaces or work surfaces shall not be installed _____, unless listed for countertop or work surface applications.

(a) in the sides of cabinets(b) in a face-up position(c) on GFCI circuits(d) on the kitchen small-appliance circuit

94. All switchboards, switchgear, and panelboards supplied by a feeder(s) in _____ shall be permanently marked to indicate each device or equipment where the power supply originates.

(a) other than one- or two-family dwellings(b) all dwelling units(c) all nondwelling units(d) b and c

2017 mike holt’s illustrated guide to c… · mike holt’s illustrated guide to understanding...

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