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Illustrated Guide tuthe

National Electrical Code'

6TH E D I T I O N

Charles R. Miller

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Notice to the Reader P u b lis h e r d o e s n o t w a r r a n t o r g u a r a n te e a n y o f t h e p r o d u c t s d e s c r ib e d h e r e in o r p e r fo r m a n y in d e p e n d e n t a n a ly s is in c o n n e c t io n w it h a n y o f t h e p r o d u c t in f o r m a t io n c o n t a in e d h e r e in . P u b lis h e r d o e s n o t a s s u m e , a n d e x p r e s s ly d is c la im s , a n y o b lig a tio n to o b ta in a n d i n c lu d e in f o r m a tio n o t h e r th a n t h a t p ro v id e d to it by t h e m a n u f a c t u r e r . T h e r e a d e r is e x p r e s s ly w a r n e d to c o n s id e r a n d a d o p t all s a f e t y p r e c a u t io n s t h a t m ig h t be in d ic a t e d b y t h e a c t iv it ie s d e s c r ib e d h e r e in a n d to a v o id all p o t e n t ia l h a z a rd s . B y f o llo w in g t h e i n s t r u c t io n s c o n t a in e d h e r e in , t h e r e a d e r w illin g ly a s s u m e s all r is k s in c o n n e c t io n w ith s u c h i n s t r u c t io n s . T h e p u b lis h e r m a k e s n o r e p r e s e n t a t io n s o r w a r r a n t ie s o f a n y k in d , in c lu d in g b u t n o t lim it e d to , t h e w a r r a n t ie s o f f it n e s s fo r p a r t ic u la r p u r p o s e o r m e r c h a n t a b ilit y , n o r a r e a n y s u c h r e p r e s e n t a t io n s im p lie d w ith r e s p e c t to t h e m a te r ia l s e t f o r t h h e r e in , a n d t h e p u b lis h e r ta k e s n o r e s p o n s ib ilit y w it h r e s p e c t t o s u c h m a t e r ia l. T h e p u b lis h e r s h a ll n o t be lia b le f o r a n y s p e c ia l, c o n s e q u e n t ia l, o r e x e m p la r y d a m a g e s r e s u lt in g , in w h o le o r p a rt , f r o m th e r e a d e r s ' u s e of, o r r e lia n c e u p o n , t h is m a te r ia l.

Printed in the U nited States o f A m erica

1 2 3 4 5 6 7 18 17 16 15 14

Contents P reface.................................................................................................................................

ix

Acknowledgments.............................................................................................................

xii

S E C T I O N 1 FOUNDATIONAL PROVISIONS U N IT 1 Introduction to th e National Electrical Code® .............

1

Objectives.....................................................................................................

1

The National Electrical C o d e ...................................................................

2

Wiring System Product Standards............................................................

5

This B ook.....................................................................................................

7

Additional Electrical Requirements..........................................................

8

C onclusion...................................................................................................

9

U N IT 2 D efinitions...............................................................................

10

Objectives.....................................................................................................

10

Introduction................................................................................................

10

D efinitions..................................................................................................

11

Summary.......................................................................................................

27

Unit 2 Competency Test.............................................................................

28

U N IT 3 Boxes and E n c lo s u re s ........................................................

30

Objectives.....................................................................................................

30

Introduction................................................................................................

30

Box Fill Calculations.................................................................................

31

Additional M arkings.................................................................................

32

General Installation...................................................................................

35

Box and Luminaire Support .....................................................................

39

Junction and Pull Box Sizing ..................................................................

45

Width and Depth of the B o x .....................................................................

45

Summary.......................................................................................................

52

Unit 3 Competency Test.............................................................................

53

U N IT 4 C a b le s ......................................................................................

55

Objectives.....................................................................................................

55

Introduction................................................................................................

55

General Installation...................................................................................

56

Conductor Identification...........................................................................

62

Grounded Conductors Provided at Switch Locations............................

64

Grounded Conductor Provided for the Future.........................................

65

Underground Installations.........................................................................

65

iv

CONTENTS

Special Application C a b le s .......................................................................

68

Summary .....................................................................................................

70

Unit 4 Competency T est.............................................................................

71

U N IT 5 Racew ays and C o n d u c to r s ...............................................

73

Objectives.....................................................................................................

73

Introduction................................................................................................

73

General Provisions......................................................................................

74

Nonflexible Conduit (and Tubing)............................................................

76

Flexible Conduit..........................................................................................

83

Other Raceways..........................................................................................

86

Raceway Fill................................................................................................

95

Conductors..................................................................................................

96

Summary.......................................................................................................

104

Unit 5 Competency Test.............................................................................

104

S E C T I O N 2 ONE-FAMILY DWELLINGS U N IT 6 General Provisions................................................................

107

Objectives.....................................................................................................

107

Introduction................................................................................................

107

Electrical Floor Plan (Blueprint)..............................................................

108

Branch Circuits............................................................................................

109

Receptacles..................................................................................................

113

Receptacle Replacements...........................................................................

119

Receptacles Requiring AFCI P rotection.................................................

121

Other Considerations When Replacing Receptacles..............................

121

Lighting and Sw itching.............................................................................

122

Outdoor Receptacles and Lighting............................................................

125

Summary.......................................................................................................

129

Unit 6 Competency Test.............................................................................

130

U N IT 7 Specific P ro v isio n s..............................................................

132

Objectives.....................................................................................................

132

Introduction................................................................................................

132

Kitchens, Dining Rooms, and Breakfast R oom s....................................

133

Hallways and Stairways.............................................................................

140

Clothes Closets............................................................................................

141

B athroom s..................................................................................................

143

CONTENTS

Basements and G arages.............................................................................

146

Laundry A re a s ............................................................................................

149

Attic and Crawl S paces.............................................................................

150

Summary.......................................................................................................

151

Unit 7 Competency Test.............................................................................

152

U N IT 8 Load C a lc u la tio n s ................................................................

154

Objectives.....................................................................................................

154

Introduction.................................................................................................

154

Compiling Information Essential to Load Calculations..........................

155

Standard Method: One-Family Dwellings...............................................

156

Optional Method: One-Family Dwellings...............................................

164

Summary.......................................................................................................

169

Unit 8 Competency Test.............................................................................

169

U N IT 9 S ervices and Electrical E q u ip m e n t................................

171

Objectives.....................................................................................................

171

Introduction.................................................................................................

171

Service-Entrance Wiring M ethods............................................................

172

Service and Outside Wiring Clearances...................................................

176

Working Space around Equipment............................................................

180

Service Equipment and Panelboards........................................................

184

Grounding.....................................................................................................

195

Summary.......................................................................................................

208

Unit 9 Competency T est.............................................................................

208

S E C T I O N 3 MULTI FAMILY DWELLINGS U N IT 1 0 Com prehensive P ro v isio n s.............................................

211

Objectives.....................................................................................................

211

Introduction.................................................................................................

211

Plans (Blueprints)........................................................................................

212

S erv ices.......................................................................................................

213

Service Wiring Clearances.........................................................................

217

Panelboards and Equipment.......................................................................

218

Branch Circuits............................................................................................

220

Voltage Drop................................................................................................

224

Summary.......................................................................................................

229

Unit 10 Competency Test...........................................................................

229

v

Vi

CONTtNTS

UNIT 1 1 Load C alcu latio n s..............................................................

232

Objectives.....................................................................................................

232

Introduction................................................................................................

232

Compiling Load Calculation Inform ation...............................................

233

Standard Method: Multifamily Dwellings...............................................

233

Six-Unit Multifamily Dwelling Calculation...........................................

242

Standard Load Calculation for Each Unit of a Multifamily Dwelling.. .

246

Optional Method: Multifamily Dwellings...............................................

250

Six-Unit Multifamily Dwelling Calculation—Optional Method...........

257

Optional Load Calculation for Each Unit of a Multifamily Dwelling . . .

260

Summary.......................................................................................................

264

Unit 11 Competency Test...........................................................................

264

S E C T I O N 4 COMMERCIAL LOCATIONS UNIT 1 2 General P ro v isio n s............................................................

267

Objectives.....................................................................................................

267

Introduction................................................................................................

267

Branch Circuits ..........................................................................................

268

Receptacles...................................................................................................

273

L ighting.......................................................................................................

276

Summary.......................................................................................................

287

Unit 12 Competency Test...........................................................................

288

UNIT 1 3 Nondwelling Load C a lc u la tio n s ....................................

291

Objectives.....................................................................................................

291

Introduction................................................................................................

291

Nondwelling Load Calculations ..............................................................

292

Sample Load Calculation— Store ............................................................

301

Sample Load Calculation—B a n k ............................................................

306

Summary .....................................................................................................

311

Unit 13 Competency T est...........................................................................

311

UNIT 1 4 S ervices, F eeders, and E q u ip m en t..............................

314

Objectives.....................................................................................................

314

Introduction................................................................................................

314

Clearances and Working S p a c e ................................................................

315

Switchboards, Switchgear, and Panelboards...........................................

319

Separately Derived Systems.......................................................................

328

B usways.......................................................................................................

335

Summary.......................................................................................................

337

Unit 14 Competency T est...........................................................................

337

CONTENTS

S E C T I O N 5 SPECIAL OCCUPANCIES, AREAS, AND EQUIPMENT UNIT 1 5 Hazardous(Classified) Locations ..................................

341

Objectives.....................................................................................................

341

Introduction................................................................................................

341

O verview .....................................................................................................

342

Class I L ocations........................................................................................

348

Class II Locations........................................................................................

359

Class III Locations......................................................................................

362

Summary.......................................................................................................

364

Unit 15 Competency T est...........................................................................

365

UNIT 1 6 Health C are .........................................................................

367

Objectives.....................................................................................................

367

Introduction................................................................................................

367

G eneral.........................................................................................................

368

Patient Care A re a s......................................................................................

374

Hospitals.......................................................................................................

378

Nursing Homes and Limited-Care Facilities...........................................

382

Inhalation AnesthetizingLocations...........................................................

385

X-Ray Installations......................................................................................

386

Summary.......................................................................................................

388

Unit 16 Competency Test...........................................................................

388

UNIT 1 7 Industrial Locations ..........................................................

391

Objectives.....................................................................................................

391

Introduction................................................................................................

391

G eneral.........................................................................................................

392

M o to rs.........................................................................................................

401

Specific Equipm ent....................................................................................

409

Summary.......................................................................................................

414

Unit 17 Competency Test...........................................................................

414

UNIT 1 8 Special Occupancies ........................................................

417

Objectives.....................................................................................................

417

Introduction................................................................................................

417

Motion Picture (and Television Studio) Audience Areas, Performance Areas, Theaters,and Similar Locations.........................

418

Carnivals, Circuses, Fairs,and Similar E v e n ts........................................

423

Places of A ssem bly....................................................................................

425

Motion Picture (and Television) Studios and Similar Locations...........

426

Motion Picture Projection R oom s............................................................

428

Manufactured Buildings.............................................................................

429

viii

CONTENTS

Agricultural B uildings...............................................................................

430

Mobile Homes, Manufactured Homes, and Mobile Home P ark s.........

431

Recreational Vehicles and Recreational Vehicle P a rk s ..........................

436

Floating B uildings......................................................................................

438

Marinas and Boatyards...............................................................................

439

Summary.......................................................................................................

440

Unit 18 Competency Test...........................................................................

440

U N IT 1 9 Specific E q u ip m e n t..........................................................

443

Objectives.....................................................................................................

443

Introduction................................................................................................

443

E quipm ent..................................................................................................

444

Sensitive Electronic Equipment................................................................

452

Elevators, Dumbwaiters, Escalators, Moving Walks, Platform Lifts, and Stairway ChairLifts.........................................................................

455

Swimming Pools, Fountains, and Similar Installations..........................

460

Summary.......................................................................................................

474

Unit 19 Competency Test...........................................................................

474

I N D E X .....................................................................................................

All

Preface Illustrated Guide to the National Electrical Code offers an exciting new approach to understanding and applying the provisions of the National Electrical Code" Unlike the Code, this text gathers and presents detailed information in a format, such as one-family or multifamily dwellings, based on “type of occupancy.” Code specifications applicable to a given type of occupancy are logically organized in easy-to-read units and graphically enhanced by numerous technical illustrations. Going an extra step, the occupancy-specific material is subdivided into specific rooms and areas. Information relevant to more than one type of occupancy is organized into independent units for easier reference. For instance, items such as raceways and conductors are covered in Unit 5 but are related to every type of occupancy. Students who wish to acquire a comprehensive grasp of all electrical codes will want to study this text section by section and unit by unit. Practicing electricians who have specialized in one type of occupancy and who wish to understand an unfamiliar segment may want to focus on those new areas. For example, an electrician who has been wiring commercial facilities for a number of years wants to wire a new house. Being unfamiliar with the codes concerning resi­ dential wiring, this individual can turn to Section 2, “One-Family Dwellings.” Here, everything from receptacle placement to the placement of the service point is explained. Section 2 is made up of four units: Units 6 through 9. Unit 6, “General Provisions,” contains general requirements for one-family dwellings, both interior and exterior. Unit 7, “Specific Provisions,” addresses more complex issues, requiring additional provisions for specific areas such as kitchens, hallways, clothes closets, bathrooms, garages, basements, etc. Unit 8, “Load Calculations,” simplifies the standard as well as optional load calculation methods for one-family dwellings. Unit 9, “Services and Electrical Equipment,” is divided into five subheadings: Service-Entrance Wiring Methods; Service and Outside Wiring Clearances; Working Space around Equipment; Service Equipment and Panelboards; and Grounding. The “what,” “when,” “where” adoption of the provisions of the NEC is under the discretion­ ary control of state and local jurisdictions. State and local jurisdictions also have the liberty of appending additional codes, which in many cases may be more stringent than those outlined by the N E C . The Code may be adopted in whole or in part. For example, while some local codes do not allow the use of nonmetallic-sheathed cable for residential or commercial wiring, others allow its use in residential but not in commercial wiring applications. To ensure compliance, obtain a copy of any additional rules and regulations for your area. This guide’s objective is to provide the information needed to complete your project— without the necessity of learning the NEC from cover to cover. Illustrated Guide to the National Electrical Code will bring your project to life as quickly and as accurately as any text on the market today. In the electrical field, as in any career, the learning experience never ends. Whether you are an electrician’s apprentice, a master electrician, or an electrical inspector, Illustrated Guide to the National Electrical Code has something for you. We believe you will find it to be a valuable addition to your reference library. In fact, you may want to include it in your toolbox or briefcase! Take note that this guidebook was completed after all the normal steps in the National Fire Protection Association (NFPA) 70 review cycle— Proposals to Code-Making Panels, review by

*Nationcil E lectrical Code a n d NEC® a re re g is te re d tra d e m a rk s o f th e N a tio n a l F ire P ro te c tio n A sso c ia tio n , In c ., Q u in cy , M A 02169.

ix

PREFACE

Technical Correlating Committee, Report on Proposals, Comments to Code-Making Panels, review by Technical Correlating Committee, Report on Comments, NFPA Annual Meeting, and ANSI Standards Council— and before the actual publication of the 2014 edition of the NEC. Every effort has been made to be technically correct, but there is always the possibility of typo­ graphical errors or appeals made to the NFPA Board of Directors after the normal review cycle that could change the appearance or substance of the Code. If changes do occur after the printing of this book, they will be included in the Instructor’s Guide and will be incorporated into the guidebook in its next printing. Note also that the Code has a standard method to introduce changes between review cycles, called “Tentative Interim Amendment,” or TIA. These TIAs and correction of typographical errors can be downloaded from the NFPA Web site, www.nfpa.org, to make your copy of the Code current.

SU PPLEM EN TS: An Instructor Resource CD is available for this text. It contains an Instructor’s Guide, unit pre­ sentations in PowerPoint, and a computerized test bank. ISBN 978-1-133-95911-3

COURSEM ATE CourseMate complements the text and course content with study and practice materials. Cengage Learning’s CourseMate brings course concepts to life with interactive learning, study, and exam preparation tools that support the printed textbook. Watch student comprehension soar as your class works with the printed textbook and the textbook-specific website. CourseMate includes an integrated MindTap reader; interactive teaching and learning tools, including quizzes, flashcards, and Engagement Tracker, a first-of-its-kind tool that monitors student engagement in the course; and more. CourseMate goes beyond the book to deliver what you need! To access additional course materials, including CourseMate, please visit www.cengagebrain .com. At the CengageBrain home page, search for the ISBN (from the back cover of the book), using the search box at the top of the page. This will take you to the product page where these resources can be found.

IN STR UCTOR SITE An Instructor Companion website containing supplementary material is available. This site contains an Instructor Guide, an image gallery of text figures, unit presentations done in PowerPoint, and testing powered by Cognero. Cengage Learning Testing Powered by Cognero is a flexible, online system that allows you to • Author, edit, and manage test bank content from multiple Cengage Learning solutions. • Create multiple test versions in an instant. • Deliver tests from your LMS, your classroom or wherever you want. Contact Cengage Learning or your local sales representative to obtain an instructor account.

PREFACE

A c c e s s in g an Instru ctor Companion Website from SSO Front Door 1. Go to http://login.cengage.com and log in, using the instructor e-mail address and password. 2. Enter author, title, or ISBN in the Add a title to your bookshelf search. 3. Click Add to my bookshelf to add instructor resources. 4. At the Product page, click the Instructor Companion site link. ABO UT THE AUTHOR For eighteen years, Charles R. Miller owned and operated a successful commercial electrical contracting company (Lighthouse Electric Co., Inc.) in Nashville, Tennessee. Throughout those years, he prided himself on solving problems abandoned by less-skilled or less-dedicated tech­ nicians. In 1988, he began operating a second company, dedicated to electrical-related training and known as Lighthouse Educational Services. Mr. Miller teaches custom-tailored classes and seminars covering various aspects of the National Electrical Code and NFPA 70E. Countless numbers of students have taken advantage of his extensive experience in electrical contracting; regulatory exams (current electrical codes); electrical-related business and law; and electrical safety-related work practices. Class and seminar attendees have included individuals employed by companies such as Ford, Textron, the Aerostructures Corporation, Aladdin Industries, Lorillard Tobacco Company, Smith & Wesson, and McKee Foods; by academic institutions such as Tennessee State University, Vanderbilt University, and Purdue University; and governmental agencies including the National Aeronautics and Space Administration (NASA). In 1999, Charles started writing and illustrating the “Code In Focus” column in Electrical Contractor magazine. His attention-to-detail illustrations and writing style make this one of the top, if not the top, read columns in the monthly magazine. Charles Miller started writing for NFPA in 2003. Titles include Pocket Guide to Residential Electrical Installations, Pocket Guide to Commercial and Industrial Electrical Installations, NFPA’s Electrical References, NFPA’s Pocket Electrical References, Electrician’s Exam Prep Manual, and Ugly’s Electrical Safety and NFPA 70E. Besides teaching, writing, and illustrating, Charles cohosted a home improvement radio talk show in Nashville, Tennessee, for more than three years. Charles Miller has dedicated over 5000 hours to making Illustrated Guide to the National Electrical Code a reality. His unsurpassed attention to detail is evident on every page. Since this book’s inception, every day’s waking hours have been consumed with careful planning and execution of content and design. His unwavering commitment to quality, from the first page in Unit 1 to the last page in Unit 19, has produced a technically superior, quintessential^ userfriendly guide.

xi

Acknowledgments I would like to say “thank you” to my children, Christin and Adam, for being patient and understanding during the extremely long hours and endless days working on this text. My mother, Evelyn Miller, gets a special “thank you” and “I love you” for a lifetime of support and encour­ agement. She called every day to check on me and quite often sent encouraging greeting cards that always came at just the right time. “Thank you” to my wife, Linda, for all your love and support as I spend long hours writing and illustrating. Thank you to the Senior Content Developer at Cengage Learning, John Fisher, for the privilege of writing for such a professional publishing company. I also would like to thank the entire Cengage Learning project team, comprising all those listed on the copyright page at the front of this book. Last, but not least, the author and Cengage Learning would like to thank the following reviewers for their contributions: Gary Daggett Master Electrician Kevin Weigman Northeastern Wisconsin Technical College Marvin Moak Hinds Community College Jackson, Missourri Tom Collins Gateway Community and Technical College Florence, KY Fred Copy Northeast State Community College Blountville, TN Leland Floren Ridgewater College Wilmar, MN Jim Richardson Lee College Baytown, TX Applicable tables and section references are reprinted with permission from NFPA 70-2014, National Electrical Code, copyright © 2013, National Fire Protection Association, Quincy, MA 02169. This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety.

FOUND)\TIONAL PROVISIONS

section 1

UNI T

Introduction to the 1

National Electrical Code®

Objectives A fter stu d y in g this un it, th e student should: ► be able to give a b rie f acco u n t o f electricity in its infancy. ► be able to identify th e catalyst that b ro u g h t ab o u t the National Electric Code (N E C ). ► un d erstan d h o w th e N E C began and its purpose. ► u n d erstan d h o w changes to the Code evolve. ► be fam iliar w ith th e term inology, p resentation, and fo rm at o f the N E C . ► k n o w w h a t type o f in fo rm atio n is fo u n d in the N E C (its layout).

► be able to recognize various tradem ark logos that denote listed and labeled products. ► co m p re h en d the role o f nationally recognized test­ ing laboratories (N R T L ) and the N atio n al Electrical M anufacturers A ssociation (N EM A ) as w ell as the expanded role o f the N ational Fire P ro te ctio n A ssociation (N FPA ). ► be fam iliar w ith this b o o k ’s layout, text c o n v e n ­ tions, and illustration m ethods. ► be advised on h o w to study the Illustrated Guide to the N E C . ► be aw are th at electrical requirem ents in addition to the N E C m ay exist, and if so, that com pliance is required.

► un d erstan d the N E C ’s co n cern w ith eq u ip m en t and m aterial standards.

1

2

SECTION 1: FOUNDATIONAL PROVISIONS

THE NATIONAL ELECTRICAL CODE Ju st as an extensive education is req u ired for doctors to perform the duties o f their chosen field, a w o rk in g know ledge o f th e N E C is a necessity for anyone practicing a profession in the electrical industry. T h e N E C provides the standards by w h ic h all electrical installations are ju d g ed . A lthough o th er requirem ents, such as local ordinances and m anufac­ tu re r instructions, m ust be applied, the N E C is the foundation o n w h ich successful installations are built. It is the m ost w id ely recognized and used com pilation o f technical rules for the installation and operation o f electrical systems in the w o rld today. Because o f its w idespread effect o n the industry, it is im p o rtan t to understand the history o f the N E C .

The Beginning In 1882, N e w Y o rk C ity was h o m e to the first central-station electric generating plant developed by T hom as A. E diso n . T h e Pearl Street Station b egan o p eratio n at 3:00 . . on M o n d ay , S eptem ber 4. F ifty-nine custom ers had relu ctan tly consen ted to have th eir houses w ired on the prom ise o f three free m onths o f electric light. T h e y w ere given the o p tio n o f discarding th e service if it p roved to be unsatisfactory. B u t this n ew w ay o f lighting was m ore th a n satisfactory . . . it was a sensation. T h e n u m b er o f custom ers tripled in only four m onths. A nd, as th ey say, the rest is history. T h e n ew industry sw ept th e nation: N e w co n stru ctio n included the installation o f electricity, and p ro p e rty ow ners dem an d ed that existing structures be updated as w ell. N e w m aterials and eq u ip m en t w ere developed and m anufactured, and m ethods for installing and con n ectin g these item s to the electrical source w ere devised. For m o re th an a decade, m anufacturers, architects, engineers, inventors, electricians, and others w o rk e d ind ep en d en tly to dev elo p th eir co n trib u tio n s to the n e w technology. By 1895, there w ere as m any as five different electric installation codes in use, and no single set o f codes was accepted by all. T o fu rth er com plicate m atters, there was an u n ex p ected hazard darken in g the prospects o f this n e w industry. p

m

Purpose and History of the NEC E lectrically caused fires w ere b eco m in g com m onplace and, by 1897, the pro b lem was reaching epidem ic p ro p o r­ tions. A diverse group o f know ledgeable, co ncern ed individuals assem bled to address this critical issue. T h e need for standardization was apparent. T h e consensus o f m ore than 1200 individuals pro d u ced the first set o f nationally ad o p te d rules to govern electrical installations and operations— the National Electrical Code. T h e N E C states its purpose as . . . the practical safeguarding o f persons and property from hazards arising from the use o f electricity. T his objective has rem ain ed constant th ro u g h o u t the N E C ’s existence, and the principles it contains c o n tin u e to g ro w and change w ith th e dynam ic electrical industry.

Code Changes T h e N E C is regularly revised to reflect th e ev o lu tio n o f products, m aterials, and installation techniques. Since 1911, th e N atio n al Fire P ro tectio n A ssociation (N FPA ) o f Q u in cy , M assachusetts, has b een responsible for the m aintenance and p u b licatio n o f the N E C . T h e 2014 edition, w h ich contains hundreds o f rew orded, as well as new , regulations, represents th e diligent w o rk o f n in eteen co d e-m ak in g panels and th e technical correlating co m m ittee, com posed strictly o f volunteers from all professions w ith in the electrical industry. T h e se panels are co m p lem en ted by a host o f private individuals w h o subm it proposals or c o m m e n t o n proposals already subm itted for changes to th e N E C . A n yone w h o wishes to participate can contact the N atio n al Fire P ro tec ­ tio n A ssociation, 1 B atterym arch Park, Q u in cy , M A 02169-7471, and request a free booklet, “ T h e N F P A StandardsM a k in g System .” T h e cu rren t ed itio n o f the N E C provides info rm atio n in the back o f the b o o k for subm itting public inp u ts and public com m ents for changes to the nex t edition, a copy o f w h ich is rep roduced o n the n ex t page for y o u r reference. N o w let us exam ine w h at is inside th e N E C and h o w w e can go a b o u t understanding it.

Unit 1: Introduction to the National Electrical Code®

3

T h e P u b lic In p u t C lo sin g D a te fo r N F P A 70, N a tio n a l E lectrical C o d e is: O c to b e r 3, 2014 for Paper Submittals N o v e m b e r 7, 2014 for O n lin e Subm ittal (ePI) For the m ost u p -to -d ate schedule go to the N F P A w ebsite at w w w .nfpa.o rg /70next N FPA has launched a com prehensive set o f revisions to its current R egulations G overning C o m m ittee Projects, the R egulations G overning N FPA ’s Standards D evelopm ent Process. These new regulations, w hich include changes to som e familiar term s and add som e new term s, will be in effect for standards reporting in the Fall 2013 R evision Cycle and all subsequent revision cycles. N F P A ’s in ten t is to take advantage o f w eb-based technology and to make its standards developm ent process m ore convenient, efficient, and easy for participants to use. T h e developm ent o f new or revised N FPA Codes, Standards, Guides, or R eco m m en d ed Practices (NFPA Standards) will continue to take place in tw o principal stages. U n d er the current regulations, those stages are know n as the “ Proposal Stage” and the “ C o m m en t Stage” . U n d er the new regulations, the “Proposal Stage” has been renam ed the “ In p u t Stage” : the “ C o m m en t Stage” will operate m uch like the “ C o m m en t Stage” in the current regulations. A revision cycle begins w ith a call for the public to submit proposed revisions (“Public Input” , formerly called “Public Proposals”). P u b lic In p u t S tage N FPA accepts Public Input on docum ents via our online electronic subm ission system. To use the electronic submission system: • • • •

T o subm it a Public Input to N F P A 70 go the N F P A w ebsite at w w w .n fp a.o rg /7 0 n ex t. C hoose the link “T h e next edition o f this standard is n o w o pen for Public In p u t” . Y ou will be asked to sign-in o r create a free online account w ith N F P A before using this system. Follow the online instructions to subm it your Public Input. O n c e a Public Inp u t is saved or subm itted in the system, it can be located on the “M y P rofile” page by selecting “M y Public In p u t/C o m m e n ts” in the left navigation bar.

C o m m e n t Stage N F P A accepts Public C om m ents on N F P A docum ents via o u r online electronic submission system. T o use the electronic subm ission system: • • • • •

T o subm it a Public C o m m en t to N F P A 70 go to the N F P A w ebsite at w w w .n fp a.o rg /7 0 n ex t. Access the First D raft R e p o rt for use as background in the subm ission o f com m ents. C hoose the link “T h e n ext edition o f this standard is n o w open for Public C o m m e n t” . Y ou will be asked to sign-in or create a free online account w ith N F P A before using this system. F ollow the online instructions to subm it your Public C o m m en t. O n c e a Public C o m m en t is saved or subm itted in the system, it can be located on the “M y P rofile” page by selecting “M y Public In p u t/C o m m e n ts” in the left navigation bar.

For further instructions please go to w w w .nfpa.org/subm itpipc R ep rin te d w ith p e rm iss io n fro m N F P A 70®, National Electrical Codd®, C o p y rig h t© 201 4 , N a tio n a l Fire P ro te c tio n A s s o c ia tio n , Q uincy, M A 022 6 9. T h is rep rin ted m a te ria l is not the o ffic ia l po sition o f th e N a tio n a l Fire P ro tectio n A s s o c ia tio n , w h ic h is rep resen ted by th e sta n d a rd in its entirety.

NEC Terminology, Presentation, and Format Tables present a requirement's multiple application possibilities.

Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits

Diagrams, or figures, are used to further clarify NEC applications. Receptacles

Caps 1 2 5 V, 2 0 A , 2 - p o le , 3 - w ir e , g r o u n d in g ty p e

Circuit Rating (Amperes)

Receptacle Rating (Amperes)

i 20 A

15

Not over 15

20

15 or 20

30

30

40

40 or 50

50

50

R e p rin te d w ith p e rm issio n fro m N F P A 70® -2014, N ational Electrical Codd®, Cop y rig h t© 201 3 , N a tio n a l Fire P ro te c tio n A s s o c ia tio n , Q uincy, M A . T h is re p rin te d m a te ria l is not the c o m p le te and o ffic ia l p o sitio n

|

i

1 2 5 V, 1 5 A , 2 - p o le , 3 - w ir e ,

\J groundingtypeP

1 2 5 V.

2 - p o le , 3 - w ir e

v

'

g r o u n d in g ty p e

3 0 A , 1 2 5 V, 2 - p o le , 3 - w ir e , g r o u n d in g ty p e

DG (vQ

Dx)

DWy

o f the N F P A on th e refe re n c e d su b ject, w h ic h is rep resen ted o n ly by the sta n da rd in its entirety. 5 0 A , 1 2 5 / 2 5 0 V, 3 - p o le , 4 - w i r e , g r o u n d in g ty p e

Figure 551.46(C)(1) Configurations for grounding-type recep­ tacles and attachment plug caps used for recreational vehicle supply cords and recreational vehicle lots. © Cengage Learning 2012

4

SECTION 1: FOUNDATIONAL PROVISIONS

Dictionary-style header— The left header shows the first section referenced, and the right header shows the last section referenced.

C A U T IO N 110.24

ARTICLE 110— R E Q U IR E M E N T S F O R ELEC T R IC A L INSTALLATIO NS

110.24 Available Fault Current.

Informational Notes contain explanatory material such as references to other standards, references to related sections of the Code, or information related to a Code rule. These are informational only and do not require compliance

90.5(C)

(A) Field M arking. Service equipm ent in other than dwelling units shall be legibly m arked in the field with the maxim um available fault current. The field marking(s) shall include the date the fault-current calculation was perform ed and be o f sufficient durability to withstand the environm ent involved. Informational Note: The available fault-current mark­ ing^) addressed in 110.24 is related to required shortcircuit current ratings of equipment. NFPA 70E-2012, Standard fo r Electrical Safety in the Workplace, provides assistance in determining the severity of potential exposure, planning safe work practices, and selecting personal protec­ tive equipment.

.

Exceptions appear in italics and explain when and where a specific rule does not apply.

Sections are numerical listings where the Code requirements are located.

(B) M odifications. W hen m odifications to the electrical installation occur that affect the m axim um available fault current at the service, the m axim um available fault current shall be verified or recalculated as necessary to ensure the service equipment ratings are sufficient for the maximum available fault current at the line terminals o f the equipment. The required field marking(s) in 110.24(A) shall be adjusted to reflect the new level o f maximum available fault current. Exception: The field m arking requirements in and 110.24(B)[shall not be required)i7rTn3ustricil installa­ tions where conditions o f m aintenance and supervision en­ sure that only qualified persons service the equipment. 110.25 Lockable D isconnecting M eans. Where a discon­ necting means is required to be lockable open elsewhere in this Code, it shall be capable o f being locked in the open position. The provisions for locking shall rem ain in place with or w ithout the lock installed.

Be advised that the local authority having jurisdiction has the ability to am end the Code requirem ents. C onsult the pro p er authority to obtain applicable guidelines.

Highlighted text within sections indicates changes, other than editorial, since the last NEC edition. Vertical lines are placed in outside margins to identify large blocks of changed or new text and for new tables and changed or new figures. Normal black letters are used for basic Code definitions and explanations. Permissive rules contain the phrases "shall be permitted" or "shall not be required." These phrases normally describe options or alternative methods. Compliance is discretionary 90.5(B) .

Exception: Cord-and-plug connection locking provisions shall not be required to remain in p lace w ithout the lock installed.

Parts (subheadings) are used to break down articles into simpler topics. (Not all articles have subheadings.)

Not Shown Bullets (solid black circles) indicate areas where one or more complete para­ graphs have been deleted since the last edition.

II. 600 Volts, Nom inal, or Less 110.26 Spaces A bout Electrical Equipm ent. A ccess and working space shall be provided and m aintained about all electrical equipm ent to perm it ready and safe operation and m aintenance o f such equipment. (A) W orking Space. W orking space for equipm ent operat­ ing at 600 volts, nom inal, or less to ground and likely require exam ination, adjustm ent, s e m c ia e ro rm a m te n a n c e while energized f s h a lljrfim ply w ith the dim ensions o f 110.26(A)(1), (A)(2), and (A)(3) or as required or perm itted elsewhere in this Code. (1) Depth o f W orking Space. The depth o f the working space in the direction o f live parts shall not be less than that

NFPA document number fol­ lowed by a page number.

70-40 R eprin te d w ith p e rm iss io n fro m N F P A 70® -2014, N ational Electrical Codd®, C o p y rig h t© 2013, N a tio n a l Fire P rotectio n A s s o c ia tio n , Q uincy, M A . T h is rep rin ted m a te ria l is not the c o m p le te and o ffic ia l p o sitio n o f th e N F P A on th e re fe re n c e d su b je c t, w h ic h is re p re se n te d o n ly by th e sta n d a rd in its en tirety.

Mandatory rules use the terms "shall" or "shall not" and require compliance

90.5(A)

.

Unit 1: Introduction to the National Electrical Code®

5

Formal Interpretations S ection 90.6 states: To promote uniformity o f interpretation and application o f the provisions o f this Code, formal interpreta­ tion procedures have been established and are found in the N F P A Regulations Governing Committee Projects. (T he N F P A R eg u latio n s G o v ern in g C o m m itte e Projects are in the N F P A D irectory. C o n ta c t N F P A for a copy o f this annual publication.)

The NEC Layout T h e table o f contents in the N E C provides a b reakdow n o f the in fo rm atio n fo u n d in the book. C hapters 1 th ro u g h 4 co n tain th e m o st-o ften used articles in th e Code, because they include general, or basic, provisions. C h a p te r 1, w hile relatively b rief, includes definitions essential to th e p ro p er application o f the N E C . It also includes an in tro d u c tio n and a variety o f general requirem ents for electrical installations. M o re general requirem ents are fo u n d in C hapters 2, 3, and 4, addressing W irin g and P ro tectio n , W irin g M ethods and M aterials, and E q u ip m e n t for G eneral U se. Special issues are covered in C hapters 5 th ro u g h 7. C h a p ter 5 contains in fo rm a tio n o n Special O ccupancies; C h a p ter 6, Spe­ cial E q u ip m e n t; and C h ap ter 7, Special C o n d itio n s. T h e contents o f these chapters are applied in addition to the g en­ eral rules given in earlier chapters. C h a p te r 8 covers C o m m u n icatio n s Systems and is basically in d e p en d en t o f oth er chapters, excep t w h ere cross-references are given. T h e final chapter, C h a p te r 9, contains Tables and Exam ples. Each ch ap ter contains one o r m ore articles, and each article contains sections. Sections may be fu rth er subdivided by the use o f lette re d o r n u m b ered paragraphs. T h e Code is co m pleted by A nnexes A th ro u g h J, an index, and a proposal form .

WIRING SYSTEM PRODUCT STANDARDS In ad d itio n to installation rules, the N E C is co n cern ed w ith the type and quality o f electrical w iring system materials. T w o term s are synonym ous w ith acceptability in this area: labeled and listed . T h e ir definitions, fo u n d in Article 100, are very similar. Similarities w ith in these definitions include: (1) an organization that is responsible for providing the listing o r labeling, (2) that these organizations m ust be acceptable to the au th o rity having ju risd ictio n , (3) that b o th are c o n cern ed w ith the evaluation o f products, and (4) that b o th m aintain periodic inspection o f the p ro d u c ­ tio n (or m anufacturing) o f the eq u ip m en t o r m aterials w h ich have b een listed o r labeled. A m anufacturer o f labeled eq u ip m e n t (or material) m ust co n tin u e to com ply w ith the appropriate standards (or perform ance) u n d e r w h ich the labeling was granted. “ L isted” also m eans that the eq uipm ent, m aterials, or services m eet appropriate designated standards o r have b een tested and fo u n d suitable for a specified purpose. T his in form ation is com piled and published by the organization. T h e Inform ational N o te u n d er “L isted” states that each organization m ay have different means for iden tify in g listed eq u ip m en t. In fact, som e do n o t recognize e q u ip m en t as listed unless it is also labeled. Listed or labeled e q u ip m e n t m ust be installed and used as instructed 1 10.3(B) ’ . T h e organizations described in th e follow ing directly affect the Code as it relates to eq u ip m en t and m aterial acceptability and play a role in developing and m aintaining the standards set forth in the N E C .

Nationally Recognized Testing Laboratories P rio r to 1989, there w ere only tw o organizations perceived as capable o f p ro v id in g safety certification o f products that w o u ld be used n ationw ide. Because there w ere only tw o, innovative tech n o lo g y was slow to be tested and approved. W h e n C ongress created the O ccu p atio nal Safety and H ealth A dm inistration (O SH A ) in the early 1970s, O S H A was d irected to establish safety regulations for the w orkplace and for the m o n ito rin g o f those regulations. O S H A ad o p ted an explanation from the N E C and included it in the Code o f Federal Regulations. In part, it reads: “ an installation o r eq u ip m en t is acceptable to the Assistant Secretary o f L abor . . . if it is acceptable or certified, or listed, o r labeled, o r otherw ise d eterm in ed to be safe by a nationally recognized testing laboratory. . . . ”

6

SECTION 1: FOUNDATIONAL PROVISIONS

T estin g by a nationally recognized testing laboratory (N R T L ) was specified in the C o d e o f Federal R egulations, b u t req u irem en ts for b eco m in g an N R T L had n o t yet b een identified. A lthough O S H A in tro d u c ed “A ccreditation o f T estin g L aboratories” in 1973, th e process th ro u g h w h ich a laboratory w o u ld receive accreditation was still miss­ ing. C o o p erativ e efforts p ro d u c e d th e O S H A regulation finalized in 1988, and called “ O S H A R e c o g n itio n Process for N ationally R ec o g n iz e d T estin g L aboratories.” O S H A ’s N R T L pro g ram greatly benefits m anufacturers by pro v id in g a system that certifies that a p ro d u c t m eets natio n al safety standards. Ju st as im p o rtan t, the d o o r was op en ed for a greater n u m b er o f laboratories to provide cer­ tification, and m anufacturers are n o w b e tte r able to m eet the dem ands o f to d ay ’s highly com petitive m arket. T h e aim o f N R T L s is to ensure that electrical products properly safeguard against reasonable, identifiable risks. A n extensive n e tw o rk o f field personnel co n d u ct u n a n n o u n ce d inspections at m anufacturing facilities that use the lab o ra to ry ’s “ seal o f approval.” Som e o f th e b e tte r-k n o w n tradem arks o f testing laboratories are sh o w n below :

Cl

S o u rc e Interek.

S o u rc e M E T La b o ra to rie s, Inc.

C£

®

S o u rc e U n d e rw rite rs La b o ra to rie s, Inc.

S o u rc e A n tie ta m C o m p lia n c e Com pany.

S o u rc e F M G lo b a l.

S o u rc e Interek.

S o m e o f the labels that appear o n evaluated and certified electrical products, such as the ones that follow , carry the tradem arks o f th e testing laboratory o r th e laboratory’s standards b eing used for com parison.

©

UNDERWRITERS LABORATORIES

usreo

CO M PLIES WITH

in c . ®

pi

m

ENCLOSED PANELBOARD ISSUE NO. B - 8 7 2 5

^ m e t ® Listing #12345

UL 1990

S o u rc e U n d e rw rite rs L a b o ra to rie s, LLC.

/ frt\ ( v im O st E^ ® 9700670

E T L L IS T E D High Intensity D isch a rg e Lig hting B a lla s ts

CONFORMS TO UL Std. 1029 & 935

S o u rc e U n d e rw rite rs L a b o ra to rie s, LLC.

N o.FE-0 00 0 FIELD EVALUATED PRODUCT

©

Evaluation of this product limited to those features and characteristics apparent at the installed site. S o u rc e U n d e rw rite rs L a b o ra to rie s, LLC.

MET Laboratories M E T Laboratories, Inc., w o rk in g w ith th e D ep a rtm e n t o f L abor as w ell as o th e r agencies, served as a w o rk in g exam ­ ple fo r th e accreditation process for in d e p e n d e n t testing laboratories. In fact, M E T becam e the first U .S. laboratory to successfully com plete th e process (1989), and thus becam e the first N R T L licensed by O S H A . M E T field inspectors interact w ith local electrical inspectors th ro u g h o u t the co u ntry to ensure p ro d u c t acceptance by all federal and state regulatory officials. T h e M E T label is accepted by all fifty states, the federal g o v ern m en t, and m ajo r retailers.

Unit 1: Introduction to the National Electrical Code®

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Underwriters Laboratories, Inc. P rio r to th e form alizatio n o f N R T L s in 1989, electrical p ro d u c t standards w ere p rim arily w ritte n by U n d erw rite rs L aboratories, Inc. (U L), w h o also p e rfo rm e d certification testing. Standards w ritte n by U L are still w idely used. T h e appearance o f th e U L logo o n a label indicates that the p ro d u ct com plies w ith th e U L standard. It does n o t m ean, necessarily, th at U L did th e p ro d u c t testing. A lth o u g h o ne o f m any N R T L s, U n d e rw rite rs L aboratories is perhaps the m ost w id ely recognized and respected testing lab oratory in o p eratio n today. F oun d ed in 1894, U L is a n o t-fo r-p ro fit c o rp o ra tio n w h o se m ission is to b rin g safer products to th e m arketplace and to serve th e public th ro u g h rigorous p ro d u c t safety testin g .T h is organ izatio n offers a w ide range o f services, w h ich include, b u t are n o t lim ited to, p ro d u ct listing, classification, c o m p o n e n t recognition, field certification, field eng in eerin g , facility registration, inspection, fact-fin d in g , and research. As one can see from this list, U L plays a m ajor role in g u iding the safety o f the electrical industry.

Intertek Testing Services Select laboratories o f In tertek T estin g Services (ITS) have passed O S H A ’s stringent N R T L accreditation p ro ce­ dures an d th ereb y have earned th e rig h t to issue p ro d u c t approvals and list products using the fam iliar E T L listed and C E marks. ITS has b een c o n d u ctin g perform ance and reliability tests to nearly 200 safety standards applicable to w o rk p lace-related p roducts since 1896. In te rte k ’s com prehensive program includes testing, listing, labeling, and quarterly fo llo w -u p inspections. W h ile recognized internationally by its m any listed m arks, the E T L listed m ark is accepted th ro u g h o u t th e U n ite d States, by all jurisdictions for electrical products, w h e n d en o tin g com pliance w ith nationally recog n ized standards such as W yle L aboratories (W L), International E lectrotechnical C om m ission (IEC), U L , C an ad ian Standards A ssociation (CSA), and FM A pprovals (FM).

National Electrical Manufacturers Association F o u n d e d in 1926, N atio n al Electrical M anufacturers A ssociation (N E M A ) com prises com panies that m anufacture eq u ip m e n t for all facets o f electrical application, from g en eratio n th ro u g h utilization. Its expansive objectives include p ro d u c t quality m ain ten an ce and im p ro v em en t, safety standards for p ro d u c t m anufacture and usage, and a variety o f p ro d u c t standards, such as ratings and perform ance. N E M A contributes to the dev elo p m en t o f the National Electrical Safety Code as w ell as the N E C .

National Fire Protection Association T h e N F P A , m o re than a cen tu ry old, dedicates itself to safety standards, gathering statistical data, con d u ctin g research, pro v id in g crucial in fo rm atio n on fire p ro tectio n , p rev en tio n , and suppression m ethods, and m u c h m ore. Boasting an intern atio n ally diverse m em bership o f m ore than 75,000, this leading n o n p ro fit organization publishes over 300 w idely recognized consensus codes and standards, including the N E C . In addition, the N F P A is involved in training and ed u catio n . Its prim ary pursuit is to p ro tect lives and p ro p erty from the often catastrophic hazards o f fire.

THIS BOOK T h e Illustrated Guide to the N E C is designed to teach th ro u g h visualization. If a p icture is truly w o rth a thousand w ords, this b o o k should pro v id e a m o re in -d ep th look at the National Electrical Code than can be found in any other single publicatio n . Its highly detailed illustrations are co m p lem e n ted w ith concise, easy-to-understand w ritten infor­ m ation . N o t in te n d e d as a h o w -to b o o k , the Illustrated Guide to the N E C instead strives to translate difficult material in to sim pler, straightforw ard principles. O n ce the reader understands h o w the Code translates in a specific area, the same tech n iq u es can be applied th ro u g h o u t.

8

SECTION 1: FOUNDATIONAL PROVISIONS

Its Layout N o t only is th e presentation o f m aterial in this tex t different from others on the m arket, b u t the organization o f info rm atio n also offers a n ew approach. A fter covering the fundam ental provisions in the balance o f U n it 1, this tex t proceeds to address code requirem ents by type o f occupancy. C o m prehensive inform ation is given for o n efam ily dw ellings, m ultifam ily dw ellings, com m ercial locations, and special occupancies. T o accom plish this task, info rm atio n has b een gathered logically from th ro u g h o u t the Code b o o k and co n cen trated in one section, u n d er the appropriate occupancy. Each occupancy type is b ro k e n d o w n into its finite co m ponents, and each c o m p o n en t is th o ro u g h ly discussed and illustrated (see table o f contents).

Text Conventions G eneral tex t is g ro u p ed in small areas su rro u n d in g an illustration. N o tes provide additional in form ation considered relevant to th e p o in t b ein g discussed. C autions indicate that particular care is need ed during application. W arnings indicate p o ten tial danger and are in ten d ed to p rev en t m isunderstanding o f a given rule.

Terms Luminaire and Lighting Fixture T h e w o rd luminaire is the intern atio n al term for lighting fixture. As defined in A rticle 100, a lum inaire is a com plete lig h tin g u n it consisting o f a light source such as a lam p o r lamps, to g eth er w ith the parts designed to position the light source and to co n n e c t it to the p o w e r supply. It m ay also include parts to p ro te ct the light source, ballast, or distribute the light. A lam p h o ld er itself is n o t a lum inaire. Starting w ith the 2002 edition, luminaire becam e the m ain term and fixture o r lighting fixture follow ed in parentheses. In the 2008 edition, fixture and lighting fixture w ere rem o v ed and do n o t follow th e te rm luminaire. T h ro u g h o u t this tex t, fixture and lighting fixture have also been om itted.

Studying This Text As th e title im plies, freq u en t references are m ade to the National Electrical Code. K eep a copy o f the latest edition o f the Code close at hand. A ny confusion about term in o lo g y n o t cleared up by the “D e fin itio n s” section o f this text m ay be explained by consulting the Code’s Article 100— Definitions section. W h en ev er direct references are m ade to the Code, benefits w ill be gained by taking the tim e to read the suggested article or section. T h e Illustrated Guide to the N E C is n o t in ten d ed , in any w ay, to replace the Code. Each u n it’s “ C o m p ete n cy T e st” requires a th o ro u g h understanding o f related N E C subject m atter. U se o f this text alone is insufficient to successfully com plete the test. It is, how ever, in te n d e d as an indispensable su pplem ent to th e N E C . N o te that w h e n com p arin g calculations m ade by b o th the English and m etric systems, slight differences will o c c u r due to th e conversion m e th o d used. T hese differences are n o t significant, and calculations for b o th systems are, th erefore, valid.

ADDITIONAL ELECTRICAL REQUIREMENTS Local Ordinances T h e im p o rtan ce o f local (state, city, etc.) electrical codes can n o t be overem phasized. Local agencies can adopt the N E C exactly as w ritte n o r can am end the Code by inco rp o ratin g m ore or less stringent regulations. W hile the N E C represents the m in im u m standards for safety, som e jurisdictions have additional restrictions. O b ta in a copy o f addi­ tional requirem en ts (if any) for y o u r area.

Unit 1: Introduction to the National Electrical Code®

9

E ngin eers o r architects w h o design electrical systems m ay also set req u irem en ts bey o n d the provisions o f the N E C . F o r exam ple, an eng in eer m ig h t require the installation o f 20 -am p ere circuits in areas w h ere the N E C allows 1 5-am pere circuits. R e q u ire m e n ts from engineers or architects are fo u n d in additional docum ents, such as the follow ing.

Plans and Specifications If plans and specifications are p ro v id ed for a p ro ject by know ledgeable engineers or architects, this info rm atio n m ust be co n sid ered and, if need be, com p ared to the requirem ents set forth by the N E C . It is unlikely that th e plans or specifications p ro v id ed by co m p eten t professionals w ill conflict w ith or co n trad ict the Code. N onetheless, it is best to be dilig en t in applying the go v ern in g principals o f the N E C .

Manufacturer Instructions E q u ip m e n t o r m aterial m ay include instructions from the m anufacturer. In accordance w ith 110.3(B), these instruc­ tions m u st be follow ed. F or exam ple, baseboard heaters generally include installation instructions. T h e N E C does n o t p ro h ib it the installation o f receptacle outlets above baseboard heaters, b u t the m an u factu rer’s instructions m ay p ro h ib it th e installation o f its heater b elo w receptacles.

CONCLUSION W h ile this u n it briefly discusses th e history o f th e National Electrical Code, it is n o t possible to do ju stice to the im p o r­ tance o f th e Code in a few short pages. W ith only a glimpse into its history and present-day supporting structure, this tex t m o v es o n to th e task o f u n d erstan d in g th e contents o f the Code. T h e Illustrated Guide to the N E C presents visually stim u latin g in fo rm atio n in an occupancy -o rg an ized, concise form at. T o b egin the jo u rn e y th ro u g h th e 2014 edition o f th e National Electrical Code, simply tu rn the page, read, look, and understand.

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S EC T IO N O N E : F O U N D A T IO N A L P R O V IS IO N S

2

ins

Objectives

Introduction

A fter studying this unit, the stu d en t should:

W h a t is the difference betw een accessible and readily accessible? W h ich is appropriate in a given application? W h e n sizing a branch circuit or feeder, is the electrical load considered continuous or noncontinuous? W h at is the difference b etw een a dam p location and a w et location? T hese and m any other questions can be accurately answ ered only through a tho ro u g h understanding o f National Electrical Code (N E C ) term inology. K now ing the correct definition o f w ords and phrases as found in Article 100 is crucial to installing a hazard-free electrical system. Article 100 does n o t include com m only defined general o r technical terms from related codes and stan­ dards. N orm ally, only terms used in tw o or m ore articles are defined in Article 100. O th e r term s are defined w ithin the article in w hich they appear b u t m ay be referenced in Article 100. Part 1 o f A rticle 100 contains definitions to be applied w herever the term s are used th ro u g h o u t the N E C . Part 2 contains definitions applicable only to the parts o f articles specifically covering installations and equipm ent operating at over 600 volts, nom inal.

► u n d erstan d th e m eaning o f th e term accessible (1) w h e n applied to w irin g m eth o d s and (2) w h en applied to equip m en t. V b e able to identify accessible eq u ip m e n t that is n o t readily accessible. ► b e able to accurately evaluate a lo catio n as acces­ sible, readily accessible, o r n o t readily accessible. ► b e able to identify eq u ip m en t classified as appliances. ► b e fam iliar w ith the fo u r categories o f b ranch cir­ cuits and be able to list th eir differences. ► b e able to distinguish the difference b e tw e e n the term s en clo sed and guarded. ► b e able to determ in e w h e th e r a load is co n tinuous o r n o n co n tin u o u s. ► k n o w th e difference b e tw e e n b ra n c h -c ircu it con­ ductors and feeder conductors. ► u n d erstan d the term in o lo g y associated w ith g ro u n d e d and grounding. ► k n o w th e m ax im u m distance p e rm itte d for w ith in sig h t situations. ► b e able to give exam ples o f dam p, dry, and w et locations. ► b e able to d eterm in e w h ic h co n d u cto rs are neutral conductors. ► c o m p re h e n d the electrical vocabulary associated w ith the w o rd service. ► b e fam iliar w ith w h at constitutes a separately d eriv ed system. ► u n d erstan d that the au th o rity having ju risd iction (AHJ) could p rovide special perm ission, w h ich is d efin ed as w ritten con sen t.

10

Unit 2 : Definitions

11

DEFINITIONS Accessible (As Applied to Wiring Methods) Wiring components are considered accessible when (1) access can be gained without damaging the structure or finish of the building or (2) they are not permanently closed in by the structure or finish of the building >>Article 100 © Conductors in junction boxes behind luminaires are considered accessible if, by removing the luminaire, access to the conductors is available. ( ? ) Conductors connected to switches and receptacles are accessible by removing the cover-plate and device. 0

Receptacles behind furniture are accessible because the furniture can be moved N O T E U nlike readily accessible, w iring m ethods m eet the definition o f being accessible if access to the w iring m eth o d can be gained by using tools to rem ove covers o r by clim bing on ladders.

Accessible (As Applied to Equipment) © Accessible equipment is equipment not guarded by locked doors, elevators, or other effective means Article 100 . Equipment installed in locations requiring the use of portable means, such as a ladder, is consid­ ered accessible, but not readily accessible. ( ? ) Overcurrent devices do not have to be readily accessible if located adjacent to the equipment where access is achieved by the use of portable means 240.24(A)(4) .

Accessible, Readily (Readily Accessible) H VA C Equipm ent

Readily accessible means capable of being reached quickly (for operation, renewal, or inspections) without having to take actions such as to use tools, to climb over or remove obstacles, or resort to portable ladders, etc.

Article 100

Q The service disconnecting means must be readily acces­ sible. It may be located either outside or inside, near the entry point of the service conductors 230.70(A)(1) .

© C en g ag e Learn in g 2012

Accessible © Ready accessibility to wiring in luminaires is not required. In most cases, access can be gained through the use of a ladder, scaffolding, etc. O Conductors within junction boxes of recessed luminaires can be accessed by removing part of the luminaire, such as trims, lamps, internal shells, etc.

© Cengage Learning 2012

© Cengage Learning 2012

12

SECTION 1: FOUNDATIONAL PROVISIONS

Appliance

/

s

J/

Appliance designates utilization equipment (generally not industrial) of commonly built-in standardized types and sizes, installed as a unit to perform specific function(s), such as launder­ ing, air conditioning, food preparation, etc. ©

Article 100«.

© C e n g a g e Learning 2012

Arc-Fault Circuit Interrupter (AFCI)

Not Readily Accessible © W hile a ceiling receptacle installed for a garage door opener is not readily accessible, it is accessible. Even though this receptacle is not readily accessible, it must have groundfault circuit-interrupter (GFCI) protection for personnel

210.8(A)(2) « .

A device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected » Article 100 « .

© C e n g a g e Learning 201 2

Attachment Plug (Plug Cap) (Plug) © An attachment plug (plug cap) (plug) is a device that, when inserted into a receptacle, establishes connection between the conductors of the attached flexible cord and the conductors permanently connected to the receptacle Article 100 . © C e n g a g e Learn in g 2012

© Cengage Learning 2012

Unit 2: Definitions

Bonding Conductor or Jumper; Supply-Side Bonding Jumper, and Main Bonding Jumper

13

Bonded (Bonding) Bonded is connected to establish electrical continuity and conductivity » Article 100« .

o

When metal parts are required to be electrically con­ nected, a reliable conductor (bonding jumper) is installed, thereby guaranteeing the required electrical conductivity Article 700 « .

fO

ro

© A supply-side bonding jumper is a conductor installed on the supply side of a service or within a service equipment enclosure(s) that ensures the required electrical conductivity between metal parts required to be electrically connected. A supply-side bonding jumper is also a conductor installed for a separately derived system that ensures the required elec­ trical conductivity between metal parts required to be electri­ cally connected.

-tj-

The main bonding jumper is the connection at the service between the grounded circuit conductor and the equipment grounding conductor » Article 1 0 0 « .

- m

-

© C e n g a g e Learn in g 201 2

Bonding Jumper, Equipment

N O T E M ain b onding jum pers m ust be made o f copper o r oth er corrosion-resistant material. A w ire, bus, screw, o r similar suitable conductor is acceptable as a m ain b o n d in g jum per » 2 5 0 .2 8 (A )« .

Q An equipment bonding jumper is the connection between two or more portions of the equipment grounding conductor » Article 100 .

Service Disconnecting Means

Main Bonding Jumper

Equipment Bonding Jumpers ^ Grounding Electrode Conductor (GEC) Bonding Bushing Supply-Side Bonding Jumper

Bonding Bushing Bonding Conductor or Jumper © C e n g a g e Learn in g 2015.

© C e n g a g e Learning 2015.

14

SECTION 1: FOUNDATIONAL PROVISIONS

Branch Circuit, Appliance © An appliance branch circuit supplies energy to one or more outlets for the purpose of connecting appliance(s). These circuits exclude the connection of luminaires unless they are part of the appliance being connected Article 1 0 0 « .

© C e n g a g e Learn in g 2012

Branch Circuit

Branch Circuit, Individual

© The circuit conductors found between a circuit's final overcurrent protective device (such as the last fuse or circuit breaker) and the circuit's outlet(s) is called a branch circuit Article 100 . Branch circuits are divided into four catego­ ries: appliance, general purpose, individual, and multiwire.

© An individual branch circuit supplies only one piece of utilization equipment Article 100 .

Panelboard

\

o 1 V

J © C e n g a g e Learn in g 201 2

Branch Circuit, General Purpose © A general purpose branch circuit supplies two or more receptacles or outlets for lighting and appliances

Article 1 0 0 « .

© ©

© ©

© ©

© ©

© ©

© ©

© Cengage Learning 2012

Unit 2: Definitions

15

Branch Circuit, Muftiwire © A voltmeter will not register a voltage (potential difference) when connected to the same ungrounded (hot) phase. Therefore, a multiwire circuit must O f - -----------> r consist of conductors connected to different phases. ( 3 A multiwire branch circuit consists of two or more ungrounded (hot) con­ ductors that have a voltage between them » Article 1 0 0 « .

[2401 Volts

^

J-

0

The one grounded (neutral) conductor of a multiwire circuit must be connected to the neutral or grounded conductor of the system

» Article 1 0 0 « .

120/240-volt, Single-Phase Panelboard

7

To M ultiw ire Branch

I \ X

C ircuit

( • ) All conductors of a multiwire branch circuit must originate from the same panelboard or similar distribution equipment » 2 7 0.4(A ) « . © There must be only one grounded (neutral) conductor, and there must be an equal voltage between it and each ungrounded conductor of the circuit

» Article 1 0 0 « .

N O T E See 210.4(A) through (D) for additional requirem ents for m ultiw ire branch circuits. © C e n g a g e Learning 2012

Concealed © Concealed means rendered inaccessible by the struc­ ture or finish of the building » Article 70 0 K . (T ) Conductors in concealed raceways, even though they may become accessible by withdrawing them, are still considered concealed » Article 1 0 0 « .

Raceway Containing Branch-Circuit Conductors in Concrete Slab © Cengage Learning 2012

16

SECTION 1: FOUNDATIONAL PROVISIONS

Receptacles on Multiwire Branch Circuits A multiwire receptacle circuit consists of one (or more) duplex receptacles, one (or more) multiple receptacles, two (or more) single receptacles, or combinations thereof. © A duplex receptacle can be supplied by two branch circuits by removing the tab. This receptacle is fed from a multiwire branch circuit. (T ) The tab has been removed to allow separate feed of each outlet.

® Each multiwire branch circuit must be provided with a means that simultaneously disconnects all ungrounded (hot) conductors at the point where the branch circuit originates » 27 0.4(B) « . This is accomplished through the use of either one double-pole breaker or two single-pole breakers with identified handle ties. Q ) Although the box contains a multiwire branch circuit, only one ungrounded (hot) conductor is feeding this duplex receptacle.

N O T E Sw itch-controlled split-w ire duplex receptacle(s) are som e­ times installed in lieu o f a lighting outlet Y>210.70(A)(1) Exception No. 1 « . O n e half o f the duplex receptacle is controlled by a wall switch , w hile the oth er h alf is a typical receptacle. A split-w ire receptacle receiving pow er from a single source (one breaker or one fuse) is not a m ultiw ire receptacle.

© Cengage Learning 2012

Unit 2 : Definitions

17

Conduit Body Q A conduit body is a separate portion of a conduit (or tubing) system providing access to the interior of the system through a removable cover(s) at a junction of multiple sections or at a terminal point of the system

Cover and Gasket

» Article 1 0 0 « . © FS, FD, and larger boxes (cast or sheet metal) are not classified as conduit bodies » Article 100 . @ A single conduit is not permitted as sole support for an FS-type or weatherproof junction box 314.23(E) LL Conduit Body

and 314.23(F) « .

LB Conduit Body

LR Conduit Body

JD Conduit Body Conduit Body

© C e n g a g e Learning 2012

FS Box

FSS Box © C e n g a g e Lea rning 2012

Continuous Load

Device

A load having the maximum level of current sustained for three hours or more is referred to as a continuous load

© A unit of an electrical system, other than a conductor, that carries or controls electrical energy as its principal function is known as a device » Article 1 0 0 « .

Article 1 0 0 « . Office lighting is an example of a continuous load.

© Cengage Learning 2012

18

SECTION 1: FOUNDATIONAL PROVISIONS

Effective Ground-Fault Current Path © An effective ground-fault current path is an intentionally con­ structed, low-impedance electrically conductive path designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system to the electrical supply source. The reason for this intentionally constructed, low-impedance electri­ cally conductive path is to facilitate the operation of the overcurrent protective device or ground-fault detector during a ground-fault condi­ tion Article 100 .

Feeder

Equipment Grounding Conductor (EGC)

© A ground-fault current path is defined as an electrically conductive path from the point of a ground fault on a wiring system through nor­ mally non-current-carrying conductors, equipment, or the earth to the electrical supply source. Examples of ground-fault current paths are any combination of equipment grounding conductors, metallic raceways, metallic cable sheaths, electrical equipment, and any other electrically conductive material such as metal, water, and gas piping; steel framing members; stucco mesh; metal ducting; reinforcing steel; shields of communications cables; and the earth itself Article 100

) Equipment Grounding Conductor (EGC)

N O T E Electrical equipm ent and w irin g and o th er electrically conductive m aterial likely to becom e energized shall be installed in a m ann er that creates a low -im pedance circuit facilitating the operation o f the overcurrent device o r g round-fault detector. It shall be capable o f safely carrying the m axim um ground-fault current likely to be im posed on it from any p o in t on the w irin g system w here a ground fault may occur to the electrical supply source. T h e earth shall n o t be considered as an effective g round-fault cu rren t path V>250.4(A)(5)«.

Equipment Bonding Jumper © C e n g a g e L e a r n in g 2015

.

Enclosed Equipment, conductors, etc., surrounded by a case, housing, fence, or walls that prevent persons from accidentally con­ tacting energized parts are referred to as enclosed Article 100 .

© Panelboards located within cabinets or cutout boxes are considered enclosed. (jj) Electrical equipment installed within the perimeter of a fence, or similar area, qualifies as enclosed. Conductors are also considered enclosed when installed in panels, wireways, raceways, etc.

© Cengage Learning 2012

Unit 2: Definitions

Enclosure

Equipment

© Any case, housing, apparatus, fence, or walls surrounding an installation, designed to prevent personnel from ac­ cidentally contacting energized parts or to protect the equipment from physical damage, serves as an enclosure

Article 100

19

Devices

©-3-®

.

Luminaires

© Equipment is a general term, including fittings, devices, appliances, luminaires, apparatus, machinery, etc. used either directly or indirectly in an electrical installation Article 1 00 «.

Appliances 314-.16(B)(5)«. W h en m ultiple isolated equipm ent g rounding co n ­ ductors o f different sizes en ter the box, only the largest is counted.

0

© C e n g a g e Learn in g 2012

Determining the Number of Conductors © Raceway fittings (connectors, hubs, etc.) are not counted. © Each conductor originating outside the box that is terminated or spliced inside the box counts as one conductor 314.16(B)(1) . These red conductors are counted as two conductors.

Metal box

@ This box, as pictured, contains five conductors. If all of the conductors are 12 A W G , the box could hold a maximum of nine Table 314.16(A) . conductors

4" x 4" x 11/2"

A conductor that does not leave the box, such as equipment bonding jumpers and pigtails, is not counted 314.16(B)(1) . © A conductor that passes through the box without splice or termina­ tion (unbroken) counts as one conductor. Each loop or coil of unbroken conductor not less than twice the minimum length required for free conductors in 300.14 must be counted twice 314.16(B)(1) .This black unbroken conductor is counted as one conductor. Each conductor originating outside the box that is terminated or spliced inside the box counts as one conductor 314.16(B)(1) . These white conductors count as two conductors. ( ? ) W ire connectors are not counted.

© C en g ag e Learn in g 2012

Cable Clamps and Connectors

Luminaire Studs and Hickeys

Q

© Luminaire stud(s) shall be counted as one conductor

External cable connectors are not counted.

© Cable connector(s) with the clamping mechanism outside the box are not counted 314.16(B)(2) . © Two internal cable clamps count as one conductor. © Internal cable clamp(s), whether factory or field supplied, shall be counted as one conductor 314.16(B)(2) . Where more than one size conductor is present in the box, the clamp shall be counted as the largest conductor.

314.16(B)(3)

.

© One or more hickeys shall be counted as one conductor

314.16(B)(3)

.

® If conductors of different sizes are present in the box, each one shall be counted as the largest conductor

314.16(B)(3)

.

---w — © Cengage Learning 2012

© C e n g a g e Learning 201 2

34

SECTION 1: FOUNDATIONAL PROVISIONS

Devices or Equipment

Volume per Conductor

o

Table 314.16(B) lists the cubic-inch volume for

This duplex receptacle counts as two 12 AW G conductors.

© This single-pole switch counts as two 14 AW G conductors.

conductors, sizes 18 AWG

© Each mounting yoke or strap counts as two conductors. A mounting yoke or strap can contain one or more devices, such as a single receptacle, a duplex receptacle, a single switch, a double switch, a triple switch, or any combination. The size of the two conductors (when calculating box fill) shall be equal in size to the largest conductor connected to the device 314.16(B)(4) 12 AWG

N O T E C o n d u c to r insulation is not a factor w h en d eterm ining box fill calculations.

through 6 AWG. Boxes, enclosures, and conduit bodies containing

18 AW G

conductors, size 4 AWG or larger, must also comply

= 1 .5 0 in 3

with 314.28 provisions » 3 1 4 .1 6 C.

14 AWG

1.75 in.3 = 2.00 in.3

N O T E A device or utiliza­ tion equipm ent w ider than a single 2-in. (50-m m ) device box as described in Table 314.16(A) shall have double-volum e allowances p ro ­ vided for each gang required for m o u n t­ ing » 3 1 4 .1 6 (B )(4 )« .

= 2.2 5 in.3

= 2.5 in.3

8 AW G = 3.0 in.3

6 AWG = 5.0 in.3 C e n g a g e Learn in g 2012

Box Fill Calculation Wire connectors, pigtails, locknuts, bushings, raceway connectors, grounding screws, and equipment bonding jumpers are not factors when calculating box fill O

These three conductors, although spliced, count as three conductors.

© Tw o conductors that terminate in the box count as two conductors.

All Co nductors

© O ne receptacle counts as two 12 AW G conductors. ( • ) An unbroken conductor counts as one conductor unless the conductor is not less than twice the minimum length required for free conductors in 300.14.

M etal Box 4" x 4" x V/2"

© These three equipment grounding conductors that enter the box from the three raceways count as one conductor. Q ) These two conductors terminating in the box are counted as two conductors. © A single unbroken conductor is counted as one conductor.

Total 12 AWG conductors: Twelve Volume per 12 AWG

2.25 in.3 (each) (36.9 cm3 [each])

Minimum volume for conductors

12 x 2.25 in.3 = 27 in.3 (12 x 36.9 cm3 = 442.8 cm3)

Volume for box (including raised cover)

21 in.3 + 6 in.3 = 27 in.3 (344 cm3 + 98.4 cm3 = 442.4 cm3)

This installation complies with 314.16 provisions.

© Cengage Learning 2012

Unit 3: Boxes and Enclosures

35

Domed Covers and Canopies Q Four or fewer luminaire wires (smaller than 14 AW G ) and an equipment ground­ ing conductor can be omitted from box fill calculations where they enter a box from a domed luminaire (or similar canopy) and terminate within that box 314.16(B)(1) Exception '>314.17(C) E xception ii.

.

C A U T IO N All perm itted w iring m ethods must be secured to the box, unless the exception in 314.17(C) has been met.

© C e n g a g e Learning 201 2

© C e n g a g e Learn in g 201 2

Back-to-Back Boxes in Fire-ResistantRated Wall

Boxes in Combustible and Noncombustible Materials © Boxes employing a flush-type cover or faceplate in walls or ceilings constructed of noncombustible material (concrete, tile, etc.) shall be installed so that the front edge of the box is 314.20 within 1/4 in. (6 mm) of the finished surface © Boxes employing a flush-type cover or faceplate in walls or ceilings constructed of combustible material, such as wood, shall be flush with or extend beyond the finished surface

314.20

12 in. (300 mm)

© The cable sheath shall extend into the box at least 1/4 in. (6 mm) through the cable knockout or opening 314.17(C) .

© The cable sheath shall extend into the box at least 1/4 in. (6 mm) through the cable knockout or opening

314.17(C) Exception

© Cables entering a nonmetallic box must be secured to the box, unless it is a single-gang nonmetallic box » 314.17(C) « .

© Qualified testing laboratories publish electrical construction material directories listing installation restrictions that apply to maintaining fire-resistive ratings of assemblies involving penetrations, or openings. (An example is the minimum 24-in. [600-mm] horizontal separation usually required between boxes on opposite sides of the wall.) These fire-resistance directories, product listings, and building codes offer assistance in 300.21 compliance 300.21 (Informational Note) .

.

Fire-Resistant-Rated Walls

Noncombustible Material

t v. 0cr?c «

Fire-Resistant-Rated Walls

8 m m

.

A

o R M

—------------2 4 " -------------►

1/4 in. Maximum

Non-Fire-Resistant-Rated Walls © C en g a g e Learn in g 2012

O II 1

O

m M

Permitted © Cengage Learning 2012

Unit 3: Boxes and Enclosures

37

Gaps or Open Spaces © Damaged or incomplete plaster, dry wall, or plasterboard surfaces around boxes employing a flush-type cover or faceplate must be repaired so that no gap or open space greater than V8 in. (3 mm) surrounds the box or fitting » 3 1 4 .2 1 « .

©

r

-------- 11

/ /

oHL if i /(iV

----

© C e n g a g e Learning 2 01 2

Surface Extensions Equipment grounding, where required, must be in accordance with Part VI of Article 250. © Surface extensions must have an extension ring mounted and mechani­ cally secured to the box 314.22

Minimum Internal Depth © Except as permitted in 250.112(1), all metal boxes shall be grounded and bonded in accordance with Parts I, IV, V, VI, VII, and X of Article 250, as applicable 314.4 © Outlet boxes that do not enclose devices or utilization equipment must have an internal depth of at least 1/2 in. (12.7 mm) 314.24(A)« .

Surface Extensions Made from Covers © The cover of a flush-mounted box can provide a surface extension where the cover is designed so that it is unlikely to fall off or be removed if its securing means becomes loose. The wiring method shall be flexible for an approved length that permits removal of the cover and provides access to the box interior and shall be arranged so that any grounding continuity is independent of the connection between the box and the cover 314.22 Exception« .

© Cengage Learning 2012

38

SECTION 1: FOUNDATIONAL PROVISIONS

Metal Faceplates Covering Nonmetallic Boxes © Snap switches (including dimmer switches) must be con­ nected to an equipment grounding conductor and must also provide a means to connect metal faceplates to the equip­ ment grounding conductor, even if a metal faceplate is not installed » 404.9(B) « .

N O T E M etal receptacle faceplates (cover plates) shall be grounded »406.6(B ){40 4 .9(B) Exception N o. 2 to (B )« .

Receptacles Mounted on Covers

© To complete the installation, each box must have a cover, faceplate, lampholder, or luminaire canopy, except where the installation complies with 410.24(B) 314.25 © Screws used for the purpose of attaching covers, or other equipment, to the box shall be either machine screws match-

© Cengage Learning 2015.

© Where receptacles are mounted and supported by a cover, they must be secured by more than one screw, unless the box cover or device assembly is listed and identified as single-screw

Unit 3: Boxes and Enclosures

39

g -TTiyjf'. I M

Floor Boxes

O nly a limited num ­ ber o f boxes are listed specifically for w ood floor construction.

o Boxes containing receptacles, located in the floor, must be listed for the specific application » 314.27(B) . N O T E Boxes located in elevated floors (such as show w indow s) do n o t have to be listed specifically as floor boxes if the authority having jurisdiction (AHJ) judges them free from likely exposure to physical damage, m oisture, and dirt. R eceptacles and covers shall be listed as an assembly for this type o f location '>'>314.27(B) Exception«

© C en g ag e Learning 201 2

Access to Outlet Boxes Q Unless meeting one of the three exceptions, luminaires and equipment shall be mechanically connected to an equipment grounding conductor as specified in 2 5 0 .1 1 8 and sized in accor­ dance with 2 5 0 .1 2 2 » 4 7 0 .4 4 « . © A means for connecting an equipment grounding conduc­ tor must be provided for luminaires with exposed metal parts

» 4 1 0 .4 6 « . Electric-discharge luminaires, such as fluorescent luminaires, that are surface mounted over concealed boxes (outlet, pull, or junction) and are designed not to be supported solely by the outlet box shall have suitable openings in back of the luminaire providing access to the wiring in the box 410.24(B)« . This provision also applies to LED luminaires. N O T E S upplem entary overcurrent protective devices, w h en used w ithin lum inaires, do n o t have to be readily accessible » 2 4 0 .1 0 « .

BOX AND LUMINAIRE SUPPORT Box and Enclosure Supports

N O T E

© Nails, where used, can attach brackets on the outside of the enclosure or extend through the interior within 1/4 in. (6 mm) of the back or ends of the enclosure 314.23(B)(1 ) « . ( ] ) An enclosure supported from a structural member or from grade shall be rigidly supported either directly or by use of a brace (metal, polymeric, or wood) 314.23(B) Wood braces must have a cross section of at least 1 in. by 2 in. (25 mm by 50 mm) » 314.23(B)(2) « . © C e n g a g e L e a rn in g 201 2

C A U T IO N Screws passing through the box (with exposed threads in the box) are not perm itted, unless they are protected using approved means. Exposed threads could be abrasive to conductor insulation »314.23(B )(i)K i.

An enclosure m oun ted on a build­ ing o r oth er surface shall be rigidly and securely fastened in place. If the m o u n t­ in g surface does n o t provide rigid and secure support, additional support m ust be provided in accordance w ith 314.23 provisions » 3 1 4 .2 3 (A )«

40

SECTION 1: FOUNDATIONAL PROVISIONS

Mounting Enclosures in Finished Surfaces © No support is required where the cable is fished between access points, concealed in the finished surface, and where such supporting of the cable is impractical. Provisions are found in 320.30(D )(1) for armored cable support, in 330.30(D )(1) for metal-clad cable support, and in 334.30(B )(1) for nonmetallic-sheathed cable support. (» ) An enclosure mounted in a finished surface must be rigidly secured to the surface by clamps, anchors, or fittings identified for the application

314.23(C)

.

N O T E N o support is required for unbroken lengths (w ithout coupling) o f electri­ cal metallic tubing (EM T) that is fished betw een access points, concealed in the finished surface, and w here such securing o f the raceway is impractical Y>358.30(A) Exception N o. 2 «

Enclosures in Suspended Ceilings © Raceways shall not be supported by ceiling grid support wires. Raceways can be secured to independent (additional) support wires that are secured at both ends 300.11(A) . © An enclosure mounted in a suspended ceiling system shall be fastened to framing members by mechanical means (bolts, screws, rivets, clips, etc.) identified for use with the enclosure(s) and ceiling framing member(s) employed. The framing members shall be supported in an approved manner and securely fastened to each other as well as to the building structure 314.23(D)(1) .

C A U T IO N See 300.11(A)(1) and (A)(2) for w iring located w ithin the cavity o f a fire-rated and n o n -fire-rated floor—ceiling (or roof-ceiling) assembly.

N O T E Boxes can be secured to in dependent (additional) support wires that are attached at b o th ends y>300.11(A )«

© Cengage Learning 2012

Unit 3: Boxes and Enclosures

41

Enclosures (without Device, Luminaires, or Lampholders) Supported by Raceways © An enclosure that contains no devices or supports no luminaires can be supported by entering raceways when all of the following conditions are met: (1) the enclosure does not exceed 100 in.3 (1650 cm3) size; (2) the enclosure has threaded entries or identified hubs; (3) the enclosure is supported by two or more conduits threaded wrenchtight into the enclosure or hubs; and (4) each conduit is secured within 36 in. (900 mm) of the enclosure, unless all entries are on the same side

(T ) O nly rigid or intermediate metal conduit with threaded ends are permitted in 314.23(E).

» 314.23(E) « .

Enclosures (with Devices, Luminaires, or Lampholders) Supported by Raceways © An enclosure that contains devices (other than splicing devices) or supports luminaires, lampholders, or other equipment can be supported by entering raceways when all of the following conditions are met: (1) the enclosure does not exceed 100 in.3 (1650 cm3) in size; (2) the enclosure has threaded entries or identified hubs; (3) the enclosure is supported by two or more conduits threaded wrenchtight into the enclosure or hubs; and (4) each conduit is secured within 18 in. (450 mm) of the enclosure 314.23(F) . ( ] ) An outlet box can support a luminaire weighing 50 pounds (23 kg) or less, unless the outlet box is listed and marked on the interior of the box to indicate the maximum weight the box shall be permitted to support

© C e n g a g e Learning 2012

» 314.27(A)(2) « .

Enclosures with Conduit Entries on One Side o

An enclosure can be supported by conduits entering on the same side when

all of the following conditions are met: (1) the enclosure does not exceed 100 in.3 (1650 cm3) in size; (2) the enclosure has threaded entries or identified hubs; (3) the enclosure is supported by two or more conduits threaded wrenchtight into the enclosure or hubs; and (4) each conduit is secured within 18 in. (450 mm) of the enclosure 314.23(E) . © Unused cable or raceway openings, other than those intended for the opera­ tion of equipment, those intended for mounting purposes, or those permitted as part of the design for listed equipment, must be closed so that the protec­ tion provided is at least equal to that provided by the wall of the equipment

» 1 10.12(A) « . Q

Boxes must be supported within 18 in. (450 mm), whether or not they contain devices or support fixtures, if all the conduits enter on the same side, unless the requirements of 314.23(F) Exception No. 2 are met.

N O T E Boxes shall not be supported by one conduit unless the requirem ents o f 314.23(F) Exception N o. 2 are m et. © Cengage Learning 2012

42

SECTION 1: FOUNDATIONAL PROVISIONS

Support for Conduit Bodies © Any size conduit body not containing a device(s), luminaire(s), lampholder(s), or other equipment can be supported by rigid metal conduit, intermediate metal conduit, rigid poly­ vinyl chloride conduit, reinforced thermosetting resin conduit or electrical metallic tubing, provided the conduit body's trade size is no larger than the largest trade size of the sup­ porting raceway 314.23(E) Exception . © Conduit body support must be rigid and secure

314.16(C)(2)

The conduit body's trade size is not larger than largest trade size raceway.

N O T E A racew ay supported con­ d uit body that contains a device (s), luminaire(s), lam pholder(s), or other eq u ip m en t m ust be sup­ p o rted by either rigid metal o r interm ediate metal con­ duit only. T h e trade size o f the cond u it body m ust not be larger than the largest trade size o f the supporting raceway >'>314.23(F) E xception N o. 1 « . T h e only cond u it body n o t requiring tw o support raceways is a conduit body constructed w ith only one con d u it entry » 3 1 4 .2 3 (E ) E xception« .

\ Permitted raceways include ' Type RM C, Type IMC, Type PVC, Type RTRC, and Type EMT. © C en g ag e Learning 2015.

Supporting Luminaires Using Lengths of Conduit Longer than 18 in. © Section 314.23(F) Exception No. 2 permits unbroken length(s) of rigid or intermediate metal conduit to support a box used for luminaire or lampholder support or to support a wiring enclo­ sure within a luminaire where all of the following conditions are met: ( ? ) The length of conduit extending beyond the last point of securely fastened support does not exceed 3 ft (900 mm). A luminaire supported by a single conduit does not exceed 12 in. (300 mm), in any direc­ tion, from the point of conduit entry. ( | ) The weight supported by any single conduit shall not exceed 20 pounds (9 kg). © At the luminaire end, each conduit (if more than one) is threaded wrenchtight into the box or wiring enclosure or into identified hubs. © W here accessible to unqualified persons, the luminaire's lowest point is at least 8 ft (2.5 m) abovegrade (or standing area) and at least 3 ft (900 mm) [measured horizontally to the 8 ft (2.5 m) elevation] from windows, doors, porches, fire escapes, or similar locations. © The unbroken conduit before the last point of support is 12 in. (300 mm) or greater and that portion of the conduit is securely fastened not less than 12 in. (300 mm) from its last point of support. © Cengage Learning 2012

Unit 3: Boxes and Enclosures

Strain Relief for Flexible Cords

Luminaire Hanger

© Multiconductor cord or cable used to support a box must be protected in an approved manner so that the conductors are not subjected to strain. A strain relief connector threaded into a box with a hub would be acceptable

© Section 31 4.27(A )(2) requires an independent support, such as a luminaire hanger, for luminaires that weigh more than 50 pounds (23 kg) unless the outlet box is listed and marked on the interior of the box to indicate the maximum weight the box shall be permitted to support.

43

( 3 When raceway fit­ tings are used to support luminaire(s), they must be capable of supporting the combined weight of the luminaire assembly and lamp(s) » 410.36(E) « .

314.23(H)(1) « .

© C e n g a g e Learn in g 201 2 © C e n g a g e Learning 2012

Conduit Stems Supporting Luminaires © An outlet box used exclusively for lighting shall be designed or installed so that a luminaire or lampholder may be attached. Boxes must be able to support a luminaire weighing at least 50 pounds (23 kg). A luminaire that weighs more than 50 pounds (23 kg) shall be supported independently of the outlet box, unless the outlet box is listed and marked on the interior of the box to indicate the maximum weight the box shall be permitted to support » 3 1 4 .2 7 (A )(2 )« . ( 3 Stems longer than 18 in. (450 mm) shall be connected to the wiring system with flexible fit­ tings suitable for the location. At the luminaire end, the conduit(s) shall be threaded wrenchtight into the box or wiring enclosure or into identified hubs » 314.23(H)(2) « . A box supporting lampholders, luminaires, or wiring enclosures within luminaires used in lieu of boxes in compliance with 300.15(B) must be supported by rigid or intermediate metal conduit stems » 314.23(H)(2) « . ( • ) A luminaire supported by a single conduit shall not exceed 12 in. (300 mm) in any hori­ zontal direction from the point of conduit entry

C A U T IO N Any point o f a luminaire sup­ ported by a single conduit must be at least 8 ft (2.5 m) abovegrade (or standing area) and at least 3 ft (900 mm) (measured horizontally to the 8 ft [2.5 m] elevation) from windows, doors, porches, fire escapes, or similar locations, unless an effective means to prevent the threaded jo in t from loosening (such as a set screw) is used » 314 .2 3 (H )(2 )« .

» 314.23(H)(2) « .

Device Boxes Supporting Luminaires or Lampholders © A vertically mounted luminaire or lampholder weighing no more than 6 pounds (3 kg) can be supported by boxes (such as device boxes) not specifically designed to support luminaires or lampholders, provided the luminaire or its supporting yoke, or the lampholder, is secured to the box with at least two No. 6 or larger screws. Plaster rings, secured to other boxes, are also acceptable 314.27(A) Exception «.

The luminaire or lampholder must not weigh over 6 pounds (3 kg).

The box must contain holes for at least two No. 6 (6/32) screws.

© Cengage Learning 2012

44

SECTION 1: FOUNDATIONAL PROVISIONS

Mounting Nonmetallic Boxes © Supporting screws for nonmetallic boxes must be mounted outside of the box, unless the box is constructed in a manner that prevents contact between the conductors in the box and the supporting screws »3 1 4.4 3

N O T E A pproved drainage openings n o t larger than 1/4 in. (6 m m ) shall be perm itted to be installed in the field in boxes or conduit bodies listed for use in dam p o r w et locations. For installation o f listed drain fittings, larger openings are perm itted to be installed in the field in accordance w ith m anufacturer’s instructions Y>314.15«.

Luminaire Outlet Boxes Q Boxes used at luminaire or lampholder outlets in a ceiling must be designed for the purpose and shall be required to support a luminaire weighing a minimum of 50 pounds (23 kg). Every box used exclusively for lighting must be designed and installed so that a luminaire may be attached » 314.27(A)(2) « . © An outlet box can support a luminaire weighing no more than 50 pounds (23 kg), unless the outlet box is listed and marked on the interior of the box to indicate the maximum weight the box shall be permitted to support 314.27(A)(2) © Inspection of the connections between luminaire conduc­ tors and circuit conductors must be possible without having to disconnect any part of the wiring (unless the luminaires are connected by attachment plugs and receptacles) 410.8

Ceiling-Suspended (Paddle) Fan Boxes © An outlet box or outlet box system shall not be used as the sole means of support for a ceiling-suspended (paddle) fan unless the box is (1) listed, (2) marked by the manufac­ turer as suitable for the purpose, and (3) supporting a ceilingsuspended (paddle) fan weighing 70 pounds (32 kg) or less. For outlet boxes or outlet box systems designed to support ceiling-suspended (paddle) fans weighing more than 35 pounds (16 kg), the required marking must include the maximum weight that can be supported 314.27(C) . © Ceiling-suspended (paddle) fans must be supported inde­ pendently of an outlet box, unless the listed outlet box or outlet box system is identified for the use and installed in accordance with 314.27(C ) 422.18

N O T E Typically, tw o N o. 8 (8/32) screws are used to attach a lum inaire or its supporting yoke to an outlet box.

N O T E B oxes used at lum inaire or lam pholder outlets in or on a vertical surface shall be identified and m arked on the interior o f the box to indicate the m axim um w eight o f the lum inaire that is perm itted to be supported by the box if oth er than 50 lb (23 kg) » 3 1 4 .2 7 (A )(!)«■

N O T E W h ere spare, separately sw itched, ung ro u n d ed conduc­ tors are provided to a ceiling-m ounted o utlet box, in a location acceptable for a ceiling-suspended (paddle) fan in single-family, tw o-fam ily, o r m ulti-fam ily dwellings, the outlet box or o utlet box system shall be listed for sole sup­ p o rt o f a ceiling-suspended (paddle) fan » 3 1 4 .2 7 (C )« .

Unit 3: Boxes and Enclosures

45

JUNCTION AND PULL BOX SIZING Straight Pull—Two Raceways Section 314.16 is used to determine box size requirements for 6 AWG and smaller conductors. Calculations are based

N O T E

on the sizes and numbers of conductors. Section 314.28 is used to determine the box size requirements for 4 AWG and

Use the trade dim ension that is applicable to the installation . For example, i f m illim eters o r centim eters are needed to size the ju n c tio n o r pull box, use the m etric designator in millim eters instead o f the trade size in inches. A ju n c tio n box is needed for a straight pull w ith tw o m etric designator 53 raceways. (A 2-in. trade size racew ay has a m etric designator o f 53 m m .) Calculate the m inim um length by m ultiplying th e m etric designation by eight (53 m m X 8 = 424 m m = 42.4 cm). T h e m inim um size pull box required is 424 m m or 42.4 cm.

larger conductors (under 600 volts). Calculations here are based on the sizes and numbers of raceways. © Box calculations for 4 AW G and larger conductors (under 600 volts) are performed based on the size and numbers of raceways » 314.28 ( 3 Boxes or conduit bodies containing straight pulls are sized according to the largest raceway entering the box. The length must be at least eight times the trade size (metric designator) of the largest raceway 314.28(A)(1) .

2M

)!

I2M Straight Pull 2

x 8 = 16 in.

(trade size of largest racew ay) © C e n g a g e Learn in g 2012

WIDTH AND DEPTH OF THE BOX © The box width must be large enough to provide proper installation of the raceway or cable, including locknuts and bushings. ( 3 The box depth must be large enough to provide proper installation of the raceway or cable, including locknuts and bushings. No requirement specifies the depth of the box, unless a raceway enters the back of the box.

© Cengage Learning 2012

46

SECTION 1: FOUNDATIONAL PROVISIONS

Straight Pull—Multiple Raceways Conduit bodies and boxes (junction, pull, and outlet) must be installed so that the wiring they contain can be made accessible without removing any part of the building or structure » 3 1 4 .2 9 « .

© The length must be at least eight times the trade size (metric designator) of the largest single raceway. No extra space is required for additional raceways when calculating the minimum length of straight pulls. However, additional space is needed for the width of additional raceways, including locknuts and bushings » 314.28(A)(1)

C A U T IO N Except as p erm itted in 250.112(1), all metal boxes shall be grounded and bonded in accordance w ith Parts I, IV,V,VI,VII, and X o f A rticle 250 as applicable » 3 I 4 . 4 « .

2 11L ..... 2 " '[I

Straight Pull x 8 =

Largest raceway

32 in.

(trade size of largest raceway)

32 in.© C en g ag e Learning 2012

Angle or U Pulls (or Splices)—Multiple Raceways ( • ) To calculate the dimension of a box with angle pulls, start with one wall where the raceways enter the box, and find the distance to the opposite wall of the box. The path of the con­ ductors is irrelevant to this calculation.

© W here splices or where angle or U pulls are made, the distance between each raceway entry into the box and the opposite wall must be at least six times the trade size (metric designator) of the largest raceway in a row. This distance is increased for additional raceway entries (in the same row on the same wall of the box) by the sum of the diameters of all other raceway entries » 314.28(A)(2) « .

Pick one wall and multiply the largest raceway (trade diam­ eter) by 6. Add to that number the trade diameter of all other raceway(s) in the same row, on the same side of the box.

Angle Pull for "Y " Dimension 3 +2

x 6 + (trade size of largest racew ay)

= 29 in.

(all other raceways in the same row, on the same w all)

W here a box contains both straight and angle (or U) pulls, or straight pulls and splices, calcu­ late each type o f pull individually to find the dimension. Always select the largest dimensions.

Q- rD

3' < n3 £r+0 o'

Angle Pull for "X " Dimension

O EL

x 6 +

-
'>406.9(B)(1) E xception« .

Unit 6: General Provisions

127

Receptacles More than 6 ft 6 in. (2.0 m) Above Grade o For a one-family dwelling and each unit of a twofamily dwelling that is at grade level, at least one recep­ tacle outlet readily accessible from grade and not more than 6V2 ft (2.0 m) above grade level shall be installed at the front and back of the dwelling 210.52(E)(1) . © Balconies, decks, and porches that are attached to the dwelling unit and are accessible from inside the dwelling unit shall have at least one receptacle outlet accessible from the balcony, deck, or porch. The recep­ tacle outlet shall not be located more than 6V2 ft (2.0 m) above the balcony, deck, or porch walking surface » 210.52(E)(3)« . N O T E G F C I protection is n o t required for receptacles that are n o t readily accessible and are supplied by a branch circuit dedicated to electric snow m elting—, deicing-, or pipeline- and vesselheating equipm ent. T h e installation m ust com ply writh 426.28 or 427.22, as applicable » 2 1 0 .8 (A ) (3) E xception« . (See 426.28 and 427.22 for ground-fault protection o f equipm ent.) O u td o o r receptacles that are n o t readily accessible (such as u n d er an eave) require G F C I protection.

CAUTION O u td o o r receptacles require G FC I protection © C e n g a g e Learning 201 2

» 2 t0 .8 (A )(3 )« .

Equipment Outlet o A 125-volt, single-phase, 15- or 20-ampere-rated recep­ tacle outlet shall be installed at an accessible location for the servicing of heating, air-conditioning, and refrigeration equipment. The receptacle shall be located on the same level and within 25 ft (7.5 m) of the heating, air-conditioning, and refrigeration equipment 210.63 . © At least one receptacle outlet, readily accessible from grade and not more than 6V2 ft (2.0 m) above grade level, shall be installed at the front and back of the dwelling 210.52(E)(1) « . © If installed in accordance with both 210.52(E) and 210.63, only one receptacle outlet is required. N O T E A receptacle outlet shall n o t be required at o n e- and tw o family dwellings for the service o f evaporative coolers y>210.63 Exception« .

CAUTION © Cengage Learning 2012

T h e receptacle outlet shall n o t be connected to the load side o f the equipm ent disconnecting means »210.63Ki.

1 28

SECTION 2: ONE-FAMILY DWELLINGS

Support for Receptacle Enclosures © As a general rule, a single conduit shall not support an enclosure that contains a device 314.23(F) . ( ? ) Rigidly and securely fasten in place all boxes and raceways 300.11(A) and 314.23(A) . @ Supporting an enclosure from grade requires rigid support in the form of conduit or a brace (metal, polymeric, or wood) 314.23(B) . Wood brace cross sections must be at least 1 in. x 2 in. (25 mm X 50 mm). Wood braces must be treated to withstand the conditions when used in w et locations 314.23(B)(2) . ( • ) An enclosure containing devices can be supported by two conduits under the condi­ tions found in 314.23(F): (1) the box shall not exceed 100 in.3 (1650 cm3); (2) the box has either threaded entries or identified hubs; (3) the box shall be supported by two or more conduits threaded wrenchtight into the enclosure or hubs; and (4) each conduit shall be secured within 18 in. (450 mm) of the enclosure.

© C e n g a g e L e a r n in g 2012

N O T E D w elling-unit o u td o o r receptacles require G FC I p ro tec­ tion for personnel >'>210.8(A)(3)i210.52(B)(1)

Receptacles inside appliance garages are permitted, but

.

A minimum of two small-appliance branch circuits are required for receptacles serving kitchen countertops

do not count as required countertop receptacles 2 10 .52(0(5) « .

210.52(B)(3) « . Either or both of these small-appliance branch circuits may feed other receptacles in the kitchen, pantry, breakfast room, or dining area.

© The maximum distance to any receptacle along the wall line measured horizontally is 24 in. (600 mm) 210.52(C)(1) . ( I ) A receptacle installed for refrigeration equipment may be fed from one of the 20-ampere small-appliance branch circuits, or from an individual branch circuit rated 15 amperes or greater 210.52(B)(1)

Exception No. 2 © Receptacles not serving kitchen countertops do not require GFCI protection. ( ? ) A receptacle installed behind a refrigera­ tor does not count as a required countertop receptacle 210.52(C)(5) 0 Each wall counter space 12 in. (300 mm) or wider requires a receptacle

»2 1 0.5 2 (C )(1 ) « .

Kitchen Countertop Receptacles © As a general rule, receptacle outlets shall be located on or above the countertop » 2 7 0.52(C )(5)« . Installation of receptacles below the countertop is allowed by some exceptions (see 210.52(C )(5) Exception). Q GFCI protection is not needed for receptacles installed along the wall to meet 210.52(A ) requirements. © GFCI protection is required for receptacles installed to serve kitchen countertops 210.8(A)(6) . Q ) Receptacles located inside cabinets or cupboards, which do not serve kitchen countertop surfaces, do not require GFCI protection unless the receptacle is supplying power to a dishwasher 210.8(A)(6) and 210.8(D) « . © Receptacles located inside cabinets or cupboards do not count as required kitchen countertop receptacles 210.52

N O T E R ecep tacle outlets are perm itted to be installed in countertops, b u t only if the outlet assem­ blies are listed for installation in countertops »210.52(C)(5)K< .

WA RN IN G Receptacles installed for countertop surfaces as speci­ fied in 210.52(C) shall not be considered as the recep­ tacles required by 210.52(A)

» 210.52(A)(4) « .

© Cengage Learning 2012

Unit 7: Specific Provisions

135

Island Receptacle Placement

Peninsular Receptacle Placement

At least o ne receptacle o utlet shall be installed at each island

Co u nter spaces separated by range tops, refrigerators, or sinks

co un ter sp a ce w ith a long d im en sion of 24 in. (60 0 mm)

require a receptacle for each 12- x 2 4 -in . (30 0- x 600-m m )

or m ore and a short d im en sion of 12 in. (3 0 0 mm) or more

area

2 1 0 .5 2 (C )(2 ) « .

2 1 0 .5 2 (C )(4 ) « .

A recep tacle is required for each p e n in su lar counter space

A recep tacle is required for each island counter space w ith at

w ith at least a 12- x 2 4 -in . (3 0 0 - x 6 0 0 -m m ) area that is

least a 1 2- x 2 4 -in . (3 0 0 - x 6 00 -m m ) area that is separated

sep arated from other counter space b ecau se of range tops,

from o ther counter space b ecau se of range tops, refrigera­

refrigerators, or sin ks

tors, or sin k s » 2 1 0 .5 2 (C )(4 )

2 1 0 .5 2 (C )(3 )

.

.

GFCI CT\ O NJ O -t* 3 5' 3 '

in ryUJ

&

58 in. (1.5 m) 12 in. (300 mm)

n

I lie e e e il

cn O KJ O■ £> o 3 5‘ Tl

u LL u

@(S

12 in. (300 mm)

r©

12 in. (300 mm)

. E .E E

st o

CN O

12 in. (300 mm) © C e n g a g e Lea rning 201 2

N O T E W here a range, counter-m ounted cooking unit, or sink is in­ stalled in an island or peninsular countertop and the countertop’s depth behind the range, counter-m ounted cooking unit, or sink is less than 12 in. (300 mm ), the range, counter-m ounted cooking unit, or sink is considered to divide the island into tw o separate countertop spaces. Each separate countertop space shall comply w ith the applicable requirements in 210.52(C) »210.52(C)(4)« . 58 in. (1.5 m) © C e n g a g e Learning 2012

Receptacles Mounted below Countertops W h e re an island or p en in su lar countertop is flat acro ss its entire surface, recep tacle installation b elo w the countertop is perm itted under certain co n d itio n s. If a w all, b acksp lash, overhead cabinet, or sim ilar area is av a ilab le above the counter, the receptacle m ust be m ounted above the countertop. R ecep tacles installed m ore than 20 in. (50 0 m m ) above the countertop, such as in an overhead cabinet, are perm itted but are not inclu d ed as required countertop recep tacles

2 1 0 .5 2 (C )(5 ) Ex cep tio n

O

Receptacles installed faceup in the work surface or countertop are not allowed unless the receptacle outlet assembly is listed for countertop applications » 210.52(C)(5) and 406.5(E)

(T ) GFCI protection is required for all receptacles installed to serve kitchen countertop surfaces 210.8(A)(6) . © C e n g a g e Learning 2012

@ Although receptacles located more than 12 in. (300 mm) below coun­ tertops are permitted, they are not to be included as required countertop receptacles > 210.52(C)(5) Exception (» ) Receptacles mounted in the cabinet are permitted under an overhang­ ing countertop but are not counted as required countertop receptacles where the countertop extends more than 6 in. (150 mm) beyond its support base 210.52(C)(5) Exception .

CAUTION A peninsular co u n ter side w ith o u t doors or drawers m ight be considered wall space by the authority having jurisd ictio n (AHJ). If so, and if longer than 6 ft ( 1 . 8 m), a receptacle is required.

1 36

SECTION 2: ONE-FAMILY DWELLINGS

Permanently Connected Appliances © For permanently connected appliances rated over 300 volt-amperes, a disconnecting means is not required if the branch-circuit switch or circuit breaker is within sight from the appliance or is lockable in accordance with 110.25 422.31(B) . ( • ) A disconnecting means is not required if the branch-circuit switch or circuit breaker can be locked in the open (off) position. The provision for locking or adding a lock to the disconnecting means must be installed on or at the switch or circuit breaker used as the disconnecting means and shall remain in place with or without the lock installed 422.31(B) and 110.25 . © W ater heaters shall not be connected with flexible cords

422.16(A)

( i ) Grounding must meet 250.134 requirements for equipment fastened in place or connected by permanent wiring methods. 0

Adequately protect conductors where subject to physical damage

300.4

N O T E A m eans m ust be provided to disconnect all ungrounded (hot) conductors from the appliance »422.J0«. A fastened-in-place appliance (dishwasher, in-sink waste disposer, etc.) shall not be connected to a small-appliance branch circuit

210.52(B)(2)

R

© A permanently connected appliance rated over 300 volt-amperes or V8 horsepower must have a means to disconnect all ungrounded (hot) conductors from the appliance 422.30 (T ) The disconnecting means shall comply with 430.109 and 430.110. For permanently connected motor-operated appliances with motors rated over 1/8 horsepower, the disconnecting means shall meet 422.31 (C)(1) or (2). (1)

The branch-circuit switch or circuit breaker shall be permitted to serve as the disconnecting means where the switch or circuit breaker is within sight from the appliance.

(2)

The disconnecting means shall be installed within sight of the appliance.

422.31(C)

0 Grounding must meet 250.134 requirements for equipment fastened in place or connected by permanent wiring methods.

. © C e n g a g e Learning 201 2

Kitchen In-Sink Waste Disposers

© The switch controlling an in-sink waste disposer serves as a disconnecting means. Also see 430.109(C ).

Some appliances (dishwashers, trash compactors, and

© Appliance receptacles installed inside cabinets for in-sink waste disposers and built-in trash compactors, as permitted by 422.16, do not require GFCI protection.

in-sink waste disposers) can be cord and plug connected. This arrangement provides a means of disconnect where accessible

422.33(A)

.

® Grounding must meet 250.138 requirements for cordand plug-connected equipment.

Electrically operated in-sink waste disposers can be cord and plug connected under certain conditions 422.16(B)(1) . The flexible cord must be identified as suitable in the manu­ facturer's installation instructions and must meet all of the following conditions: • The flexible cord shall be terminated with a grounding-type attachment plug. A listed in-sink waste disposer distinctly marked as protected by a system of double insulation or its equivalent does not require termination with a groundingtype attachment plug. • The cord must be between 18 and 36 in. (450 and 900 mm) in length. • The receptacle must be located so the flexible cord does not become damaged. • The receptacle shall be accessible.

© Cengage Learning 2012

Unit 7: Specific Provisions

137

Built-In Dishwashers and Trash Compactors Built-in dishwashers and trash compactors can be cord and plug connected under certain conditions »422.16(B)(2) . The flexible cord must be identified as suitable for the purpose by the appliance manufacturer's installation instructions and must meet all of the following conditions: • The flexible cord shall be terminated with a grounding-type attachment plug. A listed dishwasher or trash compactor distinctly marked as protected by a system of double insula­ tion, or its equivalent, does not require termination with a grounding-type attachment plug.

• The receptacle must be located so the flexible cord does not become damaged. • The receptacle must be located in the space occupied by the appliance or adjacent thereto. • The receptacle shall be accessible. © Where accessible, cord and plug arrangements may serve as a disconnecting means 422.33(A) . A receptacle installed under the sink (inside the cabinet) may serve as a means of disconnect.

• The cord must be between 3 and 4 ft (0.9 and 1.2 m) in length when measured from the face of the attachment plug to the plane of the rear of the appliance.

© C e n g a g e Learn in g 201 2

Appliance Branch-Circuit Rating Branch circuits, rated 15 or 20 amperes, may feed lighting units, utilization equipment, or a combination of both. The

(T ) This receptacle could be split-wired to accommodate two individual branch circuits.

rating of any one cord- and plug-connected utilization equip­

® The total load shall not exceed the branch-circuit rating 220.18 . For motor-operated, fastened-in-place appli­ ances with a motor larger than V8 horsepower, multiply the largest motor by 125% and add 100% of the other loads

ment shall not exceed 80% of the branch-circuit ampere rating 210.23(A) . Cord- and plug-connected equipment may be portable or may be fastened-in-place equipment. Fastened-in-place utilization equipment shall not exceed 50% of the branch-circuit ampere rating where the circuit also feeds lighting units or non-fastened-in-place utilization equipment 210.23(A)(2)

Q The full-load current for a single-phase motor is found in Table 430.248.

220.18(A)

.

N O T E Local codes may require a separate branch circuit for the dishwasher and the in-sink waste disposer, that is, one branch circuit for each.

© Cengage Learning 2015.

138

SECTION 2: ONE-FAMILY DWELLINGS

Calculation for One Counter-Mounted Cooking Unit (Cooktop)

Calculation for One Wall-Mounted Oven

Branch-circuit calculation for one cooktop with a nameplate

Branch-circuit calculation for one oven with a nameplate

rating of 6.5 kW at 240 volts:

rating of 4 kW at 240 volts:

• Use the nameplate rating to determine the branch-circuit conductor size and the overcurrent protection for one counter-mounted cooking unit Table 220.55, Note 4

• Use the nameplate rating to determine the branch-circuit conductor size and the overcurrent protection for one wall-mounted oven Table 220.55, Note 4

• 6.5 kW = 6500 watts

• 4 kW = 4000 watts 4000 watts -r- 240 = 16.7 amperes

6500 watts -r- 240 = 27.1 amperes • Overcurrent protective device = 30 amperes

240.4(B)

• Conductor size = 10 AW G »T able 3 10 .15(B)(16)«

• Overcurrent protective device = 20 amperes

240.4(B)

• Conductor size = 12 AW G » Table 310.15(B)(16)

Counter-Mounted Cooking Units (Cooktops) and Wall-Mounted Ovens Q The nameplate rating of a counter­ mounted cooking unit or a wall oven shall be the minimum branch-circuit load » Table 220.55, N o t e 4 « . ( i ) Wall-mounted ovens and counter­ mounted cooking units may be con­ nected permanently or by cord and plug

» 4 22 .16(B)(3)

.

A disconnecting means is required

422.30 « .

© C en g a g e Learn in g 201 2

Cooktop and Wall-Mounted Oven(s) on Same Branch Circuit © Tap conductors from a 50-ampere branch circuit must have an ampacity of at least 20 and not less than the ampacity of the individual unit served. These tap conductors include any conductors that are part of the pigtail supplied with the appliance that are smaller than the branch-circuit conductors. The taps shall not be longer than necessary for servicing the appliance

210.19(A)(3) Exception No. 1

Miller

too:

.

W here a single branch circuit feeds one cooktop and one or two ovens (in the same room), add the nameplate ratings of the appliances, treating the total kW as one range to be found in Table 220.55

Table 220.55, N o te 4 « . No disconnecting means is required if the branchcircuit switch or circuit breaker can be locked in the open (off) position » 422.31(B) U ) It is permissible to feed one cooktop and one or two wall-mounted ovens with one branch circuit where all of the units are in the same room Table 220.55,

Note 4 « . © Cengage Learning 2012

Unit 7: Specific Provisions

139

Electric Ranges © Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be connected to the equipment grounding conductor in the manner specified by 250.134 or 250.138 2 5 0 .1 4 0 « . © It is permissible to compute the branch-circuit load for one range in accordance with Table 220.55 » Table 220.55, Note 4 « .

N O T E R anges connected to existing branch circuits can be connected to the g rounded circuit co n d u cto r in accordance w ith the exception to 250.140.

0

A disconnecting means is required » 4 2 2 .3 0 « . An accessible separable connector or an accessible plug and receptacle can serve as the disconnecting means >422.33(A) « . © C e n g a g e Learning 201 2

o M ost household electric ranges are cord and plug connected. The attachment plug and receptacle can serve as the disconnect­ ing means if they are accessible by remov­ ing a drawer on the front of the range » 422.33(B) « .

N O T E T h e neutral c o n d u ctor fo r a household electric range, a w all-m o u n ted oven, or a c o u n ter-m o u n ted cook in g u n it shall n o t be smaller than 10 A W G copper » 2 1 0 .1 9 (A )(3 ) Exception N o. 2 « .

© New branch-circuit conductors installed for a range must have an insulated grounded (neutral) conductor and a grounding means. Grounding must meet 250.138 requirements for cord- and plug-connected equipment.

© C e n g a g e Learning 2012

Calculation for Ranges Rated 83/4 kW through 12 kW

Calculation for Ranges Rated More than 12 kW

Branch-circuit calculation for one range with a nameplate rating of 12 kW at 240 volts:

Branch-circuit calculation for one range with a nameplate rating of 15 kW at 240 volts:

• Compute the branch-circuit load for one range in accor­ dance with Table 220.55.

• Compute the branch-circuit load for one range in accor­ dance with Table 220.55.

• 12 kW = 8 kW (Column C) 8 kW = 8000 watts

• Column C is for 12-kW and under ranges; Note 1 applies to ranges over 12 kW

8000 watts -T- 240 = 33.3 amperes

• First, subtract 12 kW from the 15-kW range:

• Overcurrent protective device = 40 amperes

240.4(B)

• Conductor size = 8 AW G »T a b le 3 10.15(B)(16)«

15 kW - 12 kW = 3 kW • Next, multiply 3 kW by 5% = 15% • Then, multiply 8 kW (Column A) by 15 % : 8 k W x 15% = 1.2 kW

N O T E T h e m inim um branch-circuit rating for a range rated 8 ) 4 kW or m ore is 40 amperes Y>210.19(A)(3)« .

• Finally, add 1.2 kW to 8 kW: 1.2 kW + 8 kW = 9.2 kW = 9200 watts • 9200 watts h- 240 volts = 38.3 amperes • Overcurrent protective device = 40 amperes

• Conductor size = 8 AW G

240.4(B)

Table 310.15(B)(16)

140

SECTION 2: ONE-FAMILY DWELLINGS

Kitchen, Dining Room, and Breakfast Room © At least one wall switch-controlled lighting outlet shall be installed in dining rooms, kitchens, and breakfast rooms » 210.70(A)(1) « . One or more receptacles controlled by a wall switch are permitted in lieu of a lighting outlet in dining rooms and breakfast rooms, but not in kitchens »210.70(A ) (1) Exception No. 1 « .

© A minimum of two small-appliance branch circuits are required for receptacles serving kitchen countertops » 2 7 0.52(B)(3 ) « . Either or both of these small-appliance branch circuits may feed other receptacles in the kitchen, pantry, breakfast room, or dining room. (T ) Noncountertop receptacle placement is determined by wall space 210.52(A) . © The receptacle outlet installed for refrigeration equipment can be supplied from an individual branch circuit rated 15 amperes or greater » 2 1 0.52(B)(1) Exception No. 2 . ( • ) Range hoods and lights are not permitted on small-appliance branch circuits 210.52(B)(2) . Q All wall and floor receptacle outlets covered by 210.52(A) and all countertop outlets covered by 210.52(C ) in the kitchen, pantry, breakfast room, dining room, or similar area shall be supplied from 20-ampere branch circuits (except for refrigeration equipment) 210.52(B)(1)

N O T E All 120-volt, single-phase, 15- and 20-am pere branch circuits supplying outlets o r devices installed in dw elling u n it kitchens, family room s, dining room s, living room s, parlors, libraries, dens, bedroom s, sunroom s, recreation room s, closets, hallways, laundry areas, o r similar room s or areas shall be arc-fault circu it-in terru p ter (AFCI) protected by any o f the means described in 210.12(A)(1) through (6 ) » 2 1 0 .1 2 (A )« .

Q A minimum of two circuits is required for receptacles located in the kitchen, pantry, breakfast room, dining 210.52(B)(1) . room, or similar areas =€> il

/ I

Breakfast Room

o-N

GFCI

-ES

1

\

/s* ’ b y / it GFCI 1

t © C e n g a g e Learning 2012

HALLWAYS AND STAIRWAYS Hallway and Stairway Lighting A minimum of one lighting outlet is required in each hall­ way and stairway » 210.70(A)(2)(a) « . The light must be wall switch-controlled, except where controlled by remote, central, or automatic means » 210.70(A)(2) Exception . A receptacle controlled by a wall switch is not permitted. o Interior stairways of six or more risers (steps) shall have a wall switch located at each floor level and landing level that includes an entryway » 210.70(A)(2)(c) .

© Cengage Learning 2012

Unit 7: Specific Provisions

141

Hallway Receptacle Placement Receptacles in hallways are not subject to the general provisions for placement determined by wall space. © If length is less than 10 ft (3.0 m), no receptacle is required.

© Hallways measuring 10 ft (3.0 m) or more in length must have at least one receptacle outlet 210.52(H) . Hallway length is determined by measuring along the hallway centerline, without passing through a doorway. If length is 10 ft (3.0 m) or more, a recep­ tacle is required.

C A U T IO N Foyers that are not part o f a hallway in accor­ dance w ith 210.52(H) and that have an area that is greater than 60 ft2 (5.6 m 2) shall have a receptacle (s) located in each wall space 3 ft (900 mm) or m ore in width. Doorways, door-side w indow s that extend to the floor, and similar openings shall not be considered wall space

» 2 t0 .5 2 (I)«.

CLOTHES CLOSETS Luminaire Types Not Permitted in Clothes Closets »410.16(B)« ©

Pendant luminaires or lampholders

(T ) Incandescent luminaires with open or partially enclosed lamps N O T E T h e volum e is bou n d by the sides and back closet walls and planes extending from the closet floor vertically to a height o f 6 ft (1 . 8 m) or to the highest clotheshanging rod and parallel to the walls at a horizontal distance o f 24 in. (600 mm) from the sides and back o f the closet walls, respectively, and continuing vertically to the closet ceiling parallel to the walls at a horizontal distance o f 12 in. (300 mm) or the w idth o f the shelf, w hichever is greater; for a closet that permits access to both sides o f a hanging rod, this space includes the volum e below the highest rod extending 12 in. (300 mm ) on either side o f the rod on a plane horizontal to the floor extending the entire length o f the rod >}410.2410.16(A)(3)240.24(E)240. lO ii.

Receptacle within 36 in. (900 mm) of Sink © A t least one receptacle shall be located within 3 ft (900 mm) of the outside edge of each basin (lavatory or sink)

210.52(D)

N O T E

.

In no case shall th e receptacle be located m ore than 1 2 in. (300 mm) below th e top o f the basin » 2 1 0 .5 2 (D )«

Bathroom Branch-Circuit Rating © Bathroom receptacle outlets shall be supplied by at least one 120-volt, 20-ampere branch circuit >, 210.11 (C)(3 ) « . GFCI Protected

15-ampere Overcurrent Device

20-ampere Overcurrent Device

© Cengage Learning 2012

144

SECTION 2: ONE-FAMILY DWELLINGS

Bathroom Receptacles Receptacles, unless listed as receptacle assem­ blies for countertop applications, shall not be installed in a face-up position in countertops or similar work surfaces » 406.5(E)

GFCI Protected

.

© At least one receptacle shall be located within 36 in. (900 mm) of the outside edge of each basin (lavatory or sink) 210.52(D) . © Receptacles may have an individual rating of either 15 or 20 amperes, but must be sup­ plied from a 20-ampere branch circuit 210.11(C)(3) . GFCI protection for personnel is required for all bathroom receptacles. The ground-fault circuit interrupter must be installed in a readily accessible location 210.8(A)(1) . N O T E Receptacle outlet assemblies listed for the application shall be perm itted to be installed in the countertop »2i0.52(D)«.

© C e n g a g e Learning 201 2

C A U T IO N T h e receptacle outlet shall be located on a wall o r partition that is adjacent to the basin or basin countertop, located on the countertop, o r installed on the side or face o f the basin cabinet. In no case shall the receptacle be located m ore than 12 in. (300 mm) below the top o f the basin V>210.52(D)i.{.

Bathroom © A branch circuit providing power to a bathroom receptacle may also provide power to other bathroom receptacles, whether in the same bathroom or in differ­ ent bathrooms 210.11(C)(3) . © A branch circuit providing power to a bathroom receptacle may also provide power to other equipment, such as lighting and exhaust fans, but only within the same bathroom 210.11(C)(3) Exception . If the branch circuit provides power to a bathroom recep­ tacle and other equipment, the circuit shall not provide power to any other bathroom. © A branch circuit providing power to bathroom receptacles shall not provide power to any receptacle or lighting outside of bathrooms 210.11(C)(3) .

2 0 - A m p e re O vercu rren t D e v ic e

B a th

© Cengage Learning 2012

Unit 7: Specific Provisions

145

Bathtub and Shower Zone © Luminaire permitted (not in zone) ( 3 Luminaire not permitted © No parts of cord-connected luminaires, chain-, cable-, or cord-suspended luminaires, lighting track, pendants, and ceiling-suspended (paddle) fans are permitted within a certain zone of a bathtub 410.10(D) . The bathtub zone mea­ sures 3 ft (900 mm) horizontally and 8 ft (2.5 m) vertically from the top of the bathtub rim or shower stall threshold and includes the space directly over the tub.

Designated Zone

G FC I P ro te c te d

I

WARNING Luminaires located within the actual outside dimension of the bathtub or shower to a height of 8 ft (2.5 m) vertically from the top of the bathtub rim or shower threshold shall be marked for damp locations, or marked for wet locations where subject to shower spray 410.10(D)

O Recessed lights, surface-mounted lights, and exhaust fans are permitted within the bathtub zone. Exposed, nor­ mally non-current-carrying metal parts must be connected to an equipment grounding conductor in accordance with 25 0.1 10. © Chain-, cable-, or cord-suspended luminaires, cord-connected luminaires, lighting track, pendants, and ceiling-suspended (paddle) fans are permitted only outside the zone. The bathtub zone measures 3 ft (900 mm) horizontally and 8 ft (2.5 m) vertically from the top of the bathtub rim or shower stall threshold. The zone is all-encompassing and includes the space directly over the tub or shower stall

» 410.10(D) « .

3 ft (900 mm)

3 ft (900 mm) Sunken Bathtub

© C en g ag e Learning 201 2

CAUTION A receptacle shall n o t be installed w ith in o r directly over a bathtub o r show er stall V>406.9(C)210.52(G)(3)i,i.

148

SECTION 2: ONE-FAMILY DWELLINGS

Disconnecting Means © A disconnecting means is not required if the branch-circuit switch or circuit breaker is within 50 ft (15 m) and can be seen while working on the appliance 422.31(B) © A disconnecting means is required unless the branch-circuit switch or cir­ cuit breaker can be locked in the open (off) position. The provision for locking or adding a lock to the disconnecting means shall be installed on or at the switch or circuit breaker used as the disconnecting means and must remain in place whether the lock is installed or not »4 2 2 .3 1 (B ) and 1 1 0 .2 5 « . © In this illustration, the branchcircuit switch or circuit breaker cannot be seen while working on the appliance. ( » ) A permanently connected appli­ ance rated over 300 volt-amperes requires a means to simultaneously disconnect all ungrounded (hot) con­ ductors from the appliance » 4 2 2 .3 0 « .

Detached Garages © At least one receptacle is required in each detached garage with electric power

»2 1 0.5 2 (G )(1) « . © All receptacles installed in detached garages must have GFCI protection, unless installed under one of the exceptions found in 210.8(A)(2).

0

At least one wall switch-controlled lighting outlet is required for detached garages with electric power

» 210.70(A)(2)(a) « . (» ) A detached garage with electric power requires at least one wall switch-controlled lighting outlet to provide illumination on the exterior side of an outside entrance or exit with grade-level access »210.70(A )(2)(b)

N O T E L ighting and receptacles are n o t required in detached garages. T here are no provisions to provide electric p o w e r to detached garages. H ow ever, w h e n electric p o w er is provided, the provisions for attached garages must be m et » 2 1 0 .5 2 (G )(2 )« .

CAUTION In all areas specified in 210.52, all nonlocking-type 125-volt, 15- and 20-am pere receptacles shall be listed tam per-resistant receptacles )>406.12(A)H.

Unit 7: Specific Provisions

149

Accessory Buildings © All receptacles installed in accessory buildings having a floor located at or below grade level not intended as habitable rooms and limited to storage areas, work areas, and areas of similar use must have GFCI protection 210.8(A)(2) . © Lighting and receptacles are not required in accessory buildings. There are no provisions to provide electric power to detached garages or accessory buildings.

© C en g ag e Learning 201 2

LAUNDRY AREAS Receptacles and Lighting © The clothes dryer outlet must have an insulated grounded (neutral) conductor and an equipment grounding conductor » 2 5 0 .1 3 8 « . ( ] ) A lighting outlet is required for spaces containing equipment that requires servicing 210.70(A)(3) . A lighted area immediately adjacent to a laundry area (such as a hallway) may provide sufficient light for both areas. @ Laundry receptacle outlet(s) must be fed from a 20-ampere branch circuit » 2 1 0.11 (C)(2) « . (» ) At least one receptacle outlet shall be installed in areas designated for the installation of laundry equipment 210.52(F) . N O T E Electric clothes dryers connected to existing branch cir­ cuits are perm itted to follow 250.140. © C e n g a g e Learning 201 2

Receptacles and Lighting © Laundry receptacle outlet(s) must be fed from a 20-ampere branch circuit 210.11(C)(2) . ( 3 In dwelling units, at least one receptacle outlet shall be installed in areas designated for the installation of laundry equipment *>210.52(F)«. © Multiple receptacles are permitted on the laundry circuit as long as all of the outlet(s) are designated for laundry equipment » 27 0.11 (C)(2 ) « . (» ) All 125-volt, single-phase, 15- and 20-ampere receptacles installed in laundry areas shall have ground-fault circuit-interrupter protection for per­ sonnel 210.8(A)(10) « . © Outlet(s) not designated for laundry equipment are not permitted on a laundry branch circuit » 210.11 (C )(2)« . N O T E A laundry ro o m /are a is n o t subject to the general pro v i­ sions for receptacle placem ent found un d er 210.52(A). A lthough additional laundry area receptacles are perm itted, only o n e receptacle outlet is required for the installation o f laundry equ ip m en t » 2 i0 .5 2 ( F ) « .

1 50

SECTION 2: ONE-FAMILY DWELLINGS

Receptacles and Lighting (continued) A receptacle outlet installed for a specific appliance, such as laundry equipment, shall be installed within 6 ft (1.8 m) of the intended location of the appliance » 2 1 0 .5 0 (C )« . © The clothes dryer outlet must have an insulated grounded (neutral) conductor and an equipment grounding conductor

250.138 « .

( 3 Laundry receptacle outlet(s) must be fed from a 20-ampere branch circuit »210.11 (C)(2)« . A duplex receptacle installed on an individual 20-ampere branch circuit may have either a 1 5 - or 20-ampere rating 210.21(B)(2) . © Height requirements for laundry receptacle outlet(s) are not specified, except that they shall not be located more than 51/2 ft (1.7 m) above the floor 210.52 .

© C e n g a g e Learn in g 2012

ATTIC AND CRAWL SPACES Attic Spaces A receptacle is not required for attic spaces that do not contain equipment that may require servicing. Attic spaces not used for storage or attics that do not contain equipment that may require ser­ vicing do not require lighting outlets. © Attic spaces used for storage or containing equipment that may require servicing must have at least one lighting outlet 210.70(A)(3) . At least one switch shall be located at the usual entry and exit to the attic space » 2 7 0.70(A)(3) « . If the luminaire contains a switch and is located at the usual point of entry, a separate switch may not be required. Cables not installed within framing members may need protection up to a height of at least 7 ft (2.1 m) »32 0.2 3 (A ), 330.23, and 3 3 4 .2 3 « .

© Cengage Learning 2012

Unit 7: Specific Provisions

151

Crawl and Underfloor Spaces Q Crawl spaces with lighting outlet(s) require at least one switch located at the usual entry and exit to the crawl space 210.70(A)(3) . I f the lumi­ naire contains a switch and is located at the usual point of entry, a separate switch may not be required.

--------

( 3 A 125-volt, single-phase, 15- or 20-ampere rated receptacle outlet shall be installed at an accessible loca­ tion for the servicing of equipment. The receptacle shall be located on the same level and within 25 ft (7.5 m) of the equipment. The receptacle shall not be connected to the load side of the equipment disconnecting means

—---—

» 2 1 0 .63 « . © Receptacle outlet(s) require GFCI protection where installed in a crawl space that is not above grade level

» 210.8(A)(4) « . ( • ) Underfloor spaces used for storage containing equipment that may require servicing must have at least one light­ ing outlet. A lighting outlet shall be located at or near equipment that may require servicing » 27 0.70(A)(3 ) « . © A disconnecting means must be provided for HVAC equipment » 440.3(B), 422.30, and 424.19 « . No lighting outlets are required for underfloor spaces that are not used for

© C e n g a g e Learning 201 2

CAUTION W h ere cable is run at angles w ith joists in crawl spaces, it shall be permissible to secure cables n o t smaller than tw o 6 A W G or three 8 A W G conductors directly to the low er edges o f the joists. Smaller cables m ust be run either through bored holes in joists or on ru nning boards » 3 3 4 . 15(C)H.

storage or contain no equipment that may require servicing.

Summary ■ R e c e p ta c le b ran ch circuits rated 20 am peres are re q u ire d fo r sm all-appliance b ra n c h circuits in k itch en s, pantries, d in in g room s, breakfast room s, an d sim ilar areas. ■ T h e m a x im u m distance to any c o u n te rto p receptacle,

■ S o m e appliances can be c o rd an d p lu g co n n e cte d . ■ P erm an e n tly c o n n e c te d as w ell as c o rd - an d p lu g -c o n n e c te d appliances re q u ire a d isco n n ectin g m eans. ■ B ra n c h -c irc u it c o n d u cto rs installed for ranges an d clothes

a lo n g th e w all line m easu red horizontally, is 24 in.

dryers m u st have an insulated g ro u n d e d (neutral) c o n d u c ­

(600 m m ).

to r an d a g ro u n d in g m eans.

■ G en eral provisions for c o u n te rto p receptacle p la c e m e n t do n o t apply to islands and peninsulars. ■ A m in im u m o f tw o circuits is req u ired fo r receptacles serv­ in g k itc h e n co u n terto p s. ■ R ece p ta c le s lo cated in k itchens, pantries, d in in g ro o m s, breakfast ro om s, and sim ilar areas also req u ire a m in im u m o f tw o circuits. ■ All receptacles installed to serve k itch en co u n te rto p s shall have G F C I p ro tectio n .

■ H allw ays m ea su rin g 10 ft (3.0 m ) o r m o re in len g th req u ire o n ly o n e receptacle. ■ C lo th e s closets hav e ded ica ted space w h e re lum inaires are n o t p e rm itte d . ■ O n ly certain types o f lu m in aires are p e rm itte d in th e d ed i­ cated space w ith in b ath ro o m s. ■ R ecep ta c les in b a th ro o m s m u st be G F C I p ro te c te d and be supplied by

2 0

-a m p e re b ran ch circuit(s).

■ All garage receptacles req u ire G F C I p ro te ctio n .

1 52

SECTION 2: ONE-FAMILY DWELLINGS

■ A recep tacle is re q u ired on th e sam e level and w ith in

■ L ig h tin g is re q u ire d at o r n ear e q u ip m e n t th at m ay re q u ire

25 ft (7.5 m) o f H V A C e q u ip m e n t th at m ay require

servicing.

servicing.

■ All 1 2 5 -v o lt, single-phase, 15- an d 2 0 -a m p e re receptacles

■ G F C I p ro te c tio n shall be p ro v id e d for outlets th a t supply

installed in lau n d ry areas shall have G F C I p ro te c tio n .

dishw ashers installed in dw ellin g u n it locations.

■ U n d e r certain con d itio n s, attics an d craw l spaces m ay re q u ire a lig h tin g o u tle t and receptacle.

Unit 7 Competency Test NEC Reference

Answer

_____________

_____________

1. T h e m a x im u m distance b e tw e e n k itc h e n c o u n te rto p receptacles i s ______ ft.

_____________

_____________

2. H a n g in g lum in aires lo cated directly ab o v e any p art o l th e b a th tu b shall be installed so th at th e lu m in aire is n o t less t h a n ______ ft above th e to p o f th e b a th tu b rim .

_____________

_____________

3. A 1 5 -am p ere rated d u p lex recep tacle m ay b e installed on a ______ b ra n c h circuit. a) 1 5 -am p ere

b)

2 0 -a m p e re

c) 15- o r 2 0 -a m p e re d) _____________

_____________

15-, 2 0 -, o r 2 5 -a m p ere

4. T h e m in im u m size T H H N c o p p e r n e u tra l c o n d u c to r p e rm itte d fo r an

8

V4 k W ,

2 4 0 -v o lt, 3 -w ire h o u se h o ld electric ran g e i s ______ . a) 12 A W G _____________

_____________

b) 10 A W G

c)

8

AWG

d)

6

AW G

5. L u m in aires shall b e co n stru c te d o r installed so th at adjacent co m b u stib le m aterial w ill n o t be su b jected to tem p eratu res in excess o f ______ °F ah ren h eit.

_____________

_____________

6

. A o n e-fam ily d w ellin g has a fro n t en tra n ce o n th e east side o f th e h ouse, an attach ed garage w ith tw o

1 0

-ft w id e doors o n th e so u th side, and a back en tran ce d o o r o n th e

w est side o f th e ho u se. T h is o n e-fam ily d w ellin g re q u ire s ______lig h tin g outlet(s) for these o u td o o r entrances. _____________

_____________

7. O v e rc u rre n t devices shall n o t be lo cated in th e vicin ity o f easily ignitib le m aterial such as i n ______ .

_____________

_____________

8

. A single receptacle installed o n an in d iv id u al b ra n c h circu it shall have an am p ere ratin g n o t less t h a n ______ % o f th e ratin g o f th e b ra n ch circuit. a) 125

_____________

_____________

b) 100

c) 80

d) 50

9. A p p lian ce recep tacle outlets installed fo r specific appliances, such as lau n d ry eq u ip m e n t, shall b e placed w i t h i n ______ft o f th e in te n d e d lo catio n o f th e appliance.

_____________

_____________

10. T ap c o n d u c to rs fo r h o u se h o ld c o o k in g e q u ip m e n t supplied fro m a 5 0 -a m p e re b ran ch circu it shall have an am pacity o f n o t less t h a n ______ am peres.

_____________

_____________

11. O n e c o o k to p and tw o ovens are c o n n e c te d to o n e b ra n c h circu it in a k itc h e n o f a o n e fam ily dw elling. T h e c o o k to p has a n am ep late ratin g o f 4 k W at 240 volts, w h ile each o v e n has a n am ep late ratin g o f 5.5 k W at 240 volts. T h e m in im u m load calcu lation for this b ra n c h circu it i s ______w atts.

______________

_____________

12. T h e ratin g o f a single c o rd - and p lu g -c o n n e c te d u tilizatio n e q u ip m e n t shall n o t ex ceed ______ % o f th e b ra n c h -c irc u it am p ere rating.

_____________

_____________

13. A recessed in can d e scen t lu m in aire w ith a co m p letely enclosed lig h t source installed in th e ceiling o f a clothes closet m ust have a m in im u m clearance o f ______ in. b e tw e e n th e lu m in aire and th e nearest p o in t o f th e closet storage space.

______________

_____________

14. W h e re th e N E C specifies th at o n e e q u ip m e n t shall be “ w ith in sight o f ” a n o th e r e q u ip ­ m en t, th e specified e q u ip m e n t shall be visible and n o t m o re t h a n ______ ft distant fro m th e o th er.

Unit 7: Specific Provisions

NEC Reference

Answer

______________

_____________

153

15. In a d w ellin g u n it, a h allw ay m easu rin g 2 lY 2 ft in le n g th req u ires a m in im u m o f ______ recep tacle outlet(s).

_____________

_____________

16. A p e rm a n e n tly c o n n e c te d d ishw ash er has a n am ep late ratin g o f 780 v o lt-am p eres. T h e c ircu it b rea k e r is p e rm itte d to serve as th e d isco n n ectin g m eans w h e re it is: I. w ith in sight fro m th e dishw asher. II. lockable in acco rd an ce w ith 110.25. III. capable o f b e in g lo c k e d in th e closed position. a) I o nly

b) I o r III o n ly

c) I o r II o nly

d) I, II, o r III

17. In te rio r stairw ay lig h tin g o u tlets shall b e c o n tro lle d by a w all sw itch at each flo o r level, w h e re th e difference b e tw e e n levels i s ______ steps o r m o re. 18. S u p p lem en tary o v e rc u rre n t devices shall n o t be re q u ire d to b e ______ . 19, T h e m a x im u m le n g th c o rd p e rm itte d o n an electrically o p e ra te d trash c o m p a c to r is ______ in.

20 . F o r a on e-fam ily dw ellin g , at least o n e recep tacle o u tle t shall b e installed in each: I. basem ent. II. attach ed garage. III. d etac h ed garage. a) I o nly

21

b) I and II o n ly

c) II an d III o nly

d) I, II, an d III

A refrig erato r recep tacle can b e fed fro m a: I. 1 5 -am p ere in d iv id u al b ra n c h circuit. II. 2 0 -am p ere in d iv id u al b ra n c h circuit. III. 2 0 -am p ere small appliance b ra n c h circuit. a) II o nly

b) III o n ly

c) II o r III

d) I, II, o r III

22 , A recep tacle installed in an area desig n ated fo r th e installation o f lau n d ry e q u ip m e n t and w h e re th ere are n o o th e r receptacles can b e a: I. 15 -am p ere single recep tacle. II. 15 -am p ere d u p lex recep tacle. III.

2 0 -a m p e re d u p lex recep tacle. a) III o nly

b) I o r III

c) II o r III

d) I, II, o r III

23, A t least o n e G F C I-p ro te c te d recep tacle shall be lo cated w i t h i n ______ ft fro m th e outside edge o f each b a th ro o m sink. 24

R e cep tacles are p e rm itte d u n d e r an o v e rh an g in g c o u n te rto p , b u t are n o t c o u n te d as re q u ire d c o u n te rto p receptacles, w h e re th e c o u n te rto p ex ten d s m o re t h a n ______ in. b e y o n d its su p p o rt base.

25,

A b ra n c h circu it p ro v id in g p o w e r to a b a th ro o m recep tacle m ay also p ro v id e p o w e r to: I. tw o o th e r receptacles, tw o lum inaires, and an exh au st fan in th e sam e b a th ro o m . II. tw o o th e r receptacles in th e sam e b a th ro o m and receptacles in tw o additio nal bath ro o m s. III.

o n e lu m in aire in th e sam e b a th ro o m and o n e lu m in aire in a n o th e r b a th ro o m , a) I o nly

b) I o r II o n ly

c) II o r III o nly

d) I, II, o r III

U

N

I

T

8

Load Calculations

Objectives

Introduction

A fter studying this un it, th e stu d en t should:

Load calculations m ust be perfo rm ed in o rd er to deter­ m ine the size o f services and feeders. Service co n d u c­ tors are the conductors b e tw ee n the p o w er provider and the disconnecting m eans, w h e th e r a m ain breaker o r m ain lug panel. A feeder is defined as all circuit co n ­ ductors betw een the service disconnecting m eans and the panelboard containing fuses or breakers that feed b ranch circuits. A dditional load calculations are needed for dwellings w ith panelboards that are n o t part o f the service. F or exam ple, a separate panelboard m ight be installed near the m iddle o f the house to help elim inate voltage drop in b ran c h -circu it conductors. Since the rem o te panelboard (subpanel) does n o t carry the total load, an additional calculation is need ed to size the feeder and panelboard. This u n it simplifies the standard and optional load calculation m ethods for one-fam ily dwellings. A blank form is pro v id ed at the b e g in n in g o f each m ethod. T h e floor plan o f the one-fam ily dw elling b eing calculated is fo u n d o n page 108 w hile the specifications are on page 157. B o th calculation m ethods use the same speci­ fications. Each line o n each form is explained in detail using that inform ation. T h e com pleted form follows the explanations.

► be able to calculate th e general lighting load in a o ne-fam ily dw elling. ^ k n o w the m in im u m v o lt-am p ere (VA) req u irem en ts for sm all-appliance and laundry b ran ch circuits. ► k n o w h o w to apply d em an d factors to the general lig h tin g load. ► be able to apply d em an d factors to fastened-in-place appliances. ► be able to calculate feed er-d em an d loads for h o u se­ h o ld clothes dryers. ► k n o w h o w to calculate feed er-d em an d loads for h o u seh o ld co o k in g eq u ip m en t. f be able to calculate h eating and air-co n d itio n in g feed er-d em an d loads. ► b e able to calculate a one-fam ily dw elling service o r feeder using th e standard m eth o d . ► b e able to calculate a one-fam ily dw elling service o r feeder using th e optio n al m eth o d . ► k n o w h o w to size service and feeder conductors. ► be able to calculate and choose th e appropriate size n eu tral co n d u cto r. ► u n d erstan d h o w the g ro u n d in g electrode co n d u cto r is selected.

154

Unit 8: Load Calculations

155

COMPILING INFORMATION ESSENTIAL TO LOAD CALCULATIONS Front Door

Total Floor Area Square Footage © Open porches are not included in the calculated floor area of dwelling units » 220.12 « . Although this porch has a roof, it is considered open and, therefore, is not included in the calculation.

Front Porch

© Scale rulers are also useful in determining the location of outlets (receptacles, lights, switches, etc.).

=□

Before a scale ruler can be used to determine dimensions, the scale used to produce the blueprint (floor plan) must be known. (Then the area of an exterior porch, for example, is simple to calculate.)

n=

© Scale rulers are useful in determining the total square footage of a structure (house, building, etc.) that has been drawn on a set of blueprints (floor plans). @ A regular tape measure (ruler, yard stick, etc.) can be used, but the use of a scale ruler makes the job much easier. © C e n g a g e Learning 2012

Gathering Information Gathering certain information is necessary to accurately

© How many laundry circuits will be installed?

perform load calculations. All the essential data can be identified by simply answering the questions found on the

© If an electric clothes dryer will be installed, what is the volt-ampere load?

load calculation form, either standard or optional. Enter the information on the appropriate line of the load calculation forms provided with this textbook. Q W hat is the dwelling's total square-foot (ft2) area, using the outside dimensions? © W hat fastened-in-place appliances will be installed and w hat is the volt-ampere load of each? How many small appliance branch circuits will be installed?

© W hat household cooking equipment will be installed and what is the volt-ampere load of each? ( ? ) Will there be an air-conditioning system? If so, what is the total volt-ampere load, including the compressor and fan motors? If an electric heating system will be installed, what is the total volt-ampere load, including the strip heat and blower motor? I» «)

®d)

Front Porch 7 ft x 10 ft

© Cengage Learning 2012

1 56

SECTION 2: ONE-FAMILY DWELLINGS

STANDARD METHOD: ONE-FAMILY DWELLINGS Standard Method Load Calculation for One-Family Dwellings 1

General Lighting and Receptacle Loads 220.12 D o n o t include open porches, garages, or unused or unfinished spaces not adaptable f o r fu tu re use.

2

(sq ft using outside dimensions)

Small-Appliance Branch Circuits 220.52(A) A t least two sm all-appliance branch circuits

1500 x

m u st be included. 210.11(C)(1)

(minimum of two)

Laundry Branch Circuit(s) 220.52(B) A t least one laundry branch circuit

(minimum of one)

Add lines 1, 2, and 3

Lines 5 through

8

utilize the demand factors found in Table 220.42.

3000 = (line 4)

-1 1 7 ,0 0 0 = (if 117,000 or less, skip to line 8)

X

(line 5, if more than 117,000)

25% =

X

(line 6) 9

1

1500 x

m u st be included. 210.11(C)(2) 4

1

3x

35% =

(smaller of line 5 or 117,000)

Total General Lighting and Receptacle Load

3000 + (line 7)

(line 8)

1 0 Fastened-In-Place Appliances 220.53

Use the nam eplate rating. D o n o t include electric ranges, c lothes dryers, space-heating equipm ent, o r air-conditioning equipm ent.

220.52(A) E xception «. It a dw elling has m ore than one feeder, a separate load cal­ culation is needed for each. It is n o t necessary to include this step if a feeder does n o t supply small-appliance branch circuits. A load calculation for a feeder supplying smallappliance branch circuits m ust include at least 1500 voltamperes for each 2-w ire circuit Y>220.52(A)«.

© Each small-appliance branch circuit is calculated at no less than 1500 volt-amperes » 220.52(A) . © A dwelling unit must have at least two small-appliance branch circuits » 2 1 0 .1 1 (C )(1 )« . © These loads can be included with the general lighting load and subjected to the demand factors provided in Table 220.42 » 2 2 0 .5 2 (A )« .

2

Small-Appliance Branch Circuits 22 0 .5 2 (A ) A t least two sm all-appliance branch circuits m ust be included. 2 1 0 .1 1(C)(1)

\

1500 x

+ /

(minimum of two)

-

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© Cengage Learning 2012

1 58

SECTION 2: ONE-FAMILY DWELLINGS

Line 3—Laundry Branch Circuits © Laundry branch circuits must be included when calculating a dwelling unit service » 2 2 0 .5 2 (B )« .

© At least one laundry branch circuit is required per dwelling unit » 210.11 (C)(2)« .

( ] ) Each laundry branch circuit is calculated at no less than 1500 volt-amperes »2 2 0.5 2 (B )

{ • ) These loads can be included with the general lighting load and subjected to the demand factors provided in Table 220.42 » 220.52(B) « .

Laundry Branch Circuit(s) 220.52(B) A t least one laundry branch circuit must be included. 210.11(C)(2)

£

1500 x

3000

(minimum of one)

© C e n g a g e Learning 2012

Lines 4 through 8—Applying Demand Factors Found in Table 220.42 © T h e next 117,000 (from 3001 to 120,000) is multiplied by 35% » Table 220.42 « .

© Line 4 is simply the total of lines 1 through 3. ( ] ) Lines 5 through 8 outline the procedure that derates by using demand factors provided in Table 220.42.

O The result found on line 8 has been rounded up from 4047.75 to the next whole number, thus eliminating the decimal.

© Line 5 is the result of subtracting 3000 from the number in line 4. ( J ) The first 3000 (or less) volt-amperes must remain at 100% » Table 220.42 « .

N O T E

Q If line 5 is 117,000 or less, then lines 6 and 7 can be skipped.

Generally, one-fam ily dw elling load calculations will not use lines 6 and 7. (For exam ple, a one-fam ily dw elling w ith a total floor area o f 25,000 ft2, tw en ty small-appliance circuits and ten laundry branch circuits w ill n o t need lines 6 and 7.)

Q If Line 4 is 120,000 or less, then lines 6 and 7 will remain empty. ( ? ) Insert the smaller of line 5 or 117,000.

© 4

\ 4 r fSG>220.53({. H ousehold cooking appliances individually rated in excess o f 1750 watts are derated u n d er 220.55 provisions; see Line 12.

© No derating is allowed when there are only one, tw o, or three fastened-in-place appliances.

1 0 Fastened-ln-Place Appliances 220.53

Use the nam eplate rating. D o n o t include electric ranges, clothes dryers, space-heating equipm ent, o r air-conditioning equipm ent.

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