PROJECT 07-03 | JUNE 2012 - Cooperative.com · 2017. 11. 6. · 7.3 Guying Configuration for...

INTRODUCTION AND OVERVIEW

PRACTICES AND PROCEDURES

CODES AND SPECIFICATIONS

CONDUCTOR CHARACTERISTICS

POLE STRENGTH

STRENGTH OF POLE-TOP

ASSEMBLIES

GUYING PRACTICES AND

PROCEDURES

JOINT USE

STAKING FOR UNITPRICE CONTRACTS

SIZING TRANSFORMER AND SERVICE

APPLICATION

DESIGNING FOR EXTRA-LARGE CONDUCTORS

APPENDICES

BIBLIOGRAPHY

GLOSSARY

Acknowledgements About the Authors Legal Notice Addendum

P R O J E C T 0 7 - 0 3 | J U N E 2 0 1 2

appendices

Appendix A: Assembly Numbering, RUS Bulletin 1728F-804, 7.2/12.5-kV Specs

Appendix B: Sag and Tension Tables

Appendix C: Horizontal Pull and Total Guy Load atAngles for 30- to 55-Foot Poles UsingGrade C Construction

Kevin Mara, P.E.

Kevin Mara is the Principal Engineer of Hi-Line Engineering. Mr. Mara’s mainareas of expertise are distribution system planning, power system modelingand analysis, overhead and underground distribution design. He has over 25 years of experience as a distribution engineer and is registered as aProfessional Engineer in 17 states. Mr. Mara performs planning studies,general consulting, underground distribution design, territorial assistance,overcurrent protection schemes, sectionalizing studies, lightning protection,and training services. Mr. Mara received his Bachelor of Science ElectricalEngineering from Georgia Institute of Technology.

Mr. Mara has developed course material for seminars on overhead distributiondesign, underground distribution design, overcurrent protection, NationalElectrical Safety Code, and the application of non-wood pole structures. Inaddition, he has conducted more than 50 training seminars from Florida toAlaska. More than 4,000 people have attended courses instructed by Mr.Mara. Mr. Mara has authored several publications including Field StakingInformation for Overhead Distribution Lines and four chapters of the TVPPATransmission and Distribution Standards and Specifications.

Richard Lovelace, R.F.

Mr. Lovelace is an Executive Consultant and retired Principal of Hi-LineEngineering. His main areas of expertise are overhead distribution design,underground distribution design, contract administration, work orderinspection, right-of-way easement acquisition, vegetation managementplanning, and system evaluation. Mr. Lovelace has over thirty years experiencein the operation and engineering of electric distribution systems. Mr. Lovelacereceived his degree B.S. Degree in Forestry from Auburn University and a B.S.Electrical Engineering from Kennedy Western University. He is also a CertifiedArborist and a Registered Forester in the states of Alabama and Georgia.

continued

about the authors

Braxton J. Underwood, P.E.

Mr. Underwood is a Project Manager at Hi-Line Engineering and has over 10years of experience in the power engineering/consulting. Mr. Underwood’sduties include underground and overhead distribution system design, as well as system modeling, load flow analysis, sectionalizing, and overcurrentprotection.He has completed numerous RUS long range plans, constructionwork plans, substation justification studies, motor analyses, and systemmapping projects. Mr. Underwood has also authored or co-authored severalpublications including Streetlighting Best Practices for APPA and DistributionSystem Arc-Flash Calculation Case Studies for CRN/NRECA.

Mr. Underwood received his Bachelor of Electrical Engineering degree fromAuburn University and he is a registered as a Professional Engineer in thestates of Alabama and Kansas.

Robert C. Dew, Jr., P.E., Regional Manager, Hi-Line Engineering

Mr. Dew has over 34 years of electrical engineering experience, primarily withelectric cooperatives. He is also registered as a Professional Engineer in 16states. In his career, Mr. Dew has prepared over 200 work plans, long rangeplans, and sectionalizing studies for cooperatives from Alaska to Florida. Mr.Dew is a longtime member of the IEEE Rural Power Committee and the NRECAT&D System Planning Subcommittee and is an NESC expert and frequentexpert witness in numerous electric contact cases and territorial affairs. Mr. Dew is currently a Regional Manager for Hi-Line Engineering and manages Hi-Line Engineering’s Indiana Office.

Mr. Dew has an MBA from Butler University and a BS Electrical Engineeringfrom Purdue University. He has also done Post Graduate Work in ElectricalEngineering at Georgia Institute of Technology.

about the authors (cont . )

P R O J E C T 0 7 - 0 3 | J U N E 2 0 1 2

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P R O J E C T 0 7 - 0 3

Prepared by

Kevin J. Mara, P.E.W. Richard Lovelace

Hi-Line Engineering, LLC1850 Parkway Place, Suite 800

Marietta, Georgiawww.hi-line-engineering.com

for

The National Rural Electric Cooperative AssociationCooperative Research Network

4301 Wilson BoulevardArlington, Virginia 22203-1860

Simplified Staking Manual forOverhead Distribution Lines

Fourth Edition

The National Rural Electric Cooperative AssociationThe National Rural Electric Cooperative Association (NRECA), founded in 1942, is the national service organization supportingmore than 900 electric cooperatives and public power districts in 47 states. Electric cooperatives own and operate more than 42 percent of the distribution lines in the nation and provide power to 40 million people (12 percent of the population).

NRECA’s Cooperative Research Network (CRN) harnesses research and development to benefit its electric co-op members infour key ways:

• Improve productivity• Control costs• Increase service excellence• Keep pace with emerging technologies

CRN strives to deliver new products and services best suited to the particular needs of electric co-ops. CRN communicates withits members through its Web site (www.cooperative.com/crn), online and printed reports, newsletters, Web conferences, andseminars.

In addition, CRN staff present at several annual events, including NRECA’s TechAdvantage Conference & Expo, theNRECA/Touchstone Energy “Connect” marketing conference, and Touchstone Energy’s New & Emerging Technologies (NET)Conference. For more information about these events and CRN’s participation, visit the Conferences & Training section ofwww.cooperative.com. For questions about CRN, call 703.907.5843.

© Simplified Staking Manual for Overhead Distribution Lines—Fourth EditionCopyright © 2012 by the National Rural Electric Cooperative Association.Reproduction in whole or in part strictly prohibited without prior written approval of the National Rural Electric CooperativeAssociation, except that reasonable portions may be reproduced or quoted as part of a review or other story about this publication.

Legal NoticeThis work contains findings that are general in nature. Readers are reminded to perform due diligence in applying these findings to their specific needs as it is not possible for NRECA to have sufficient understanding of any specific situation toensure applicability of the findings in all cases.

Neither the authors nor NRECA assumes liability for how readers may use, interpret, or apply the information, analysis, templates, and guidance herein or with respect to the use of, or damages resulting from the use of, any information, apparatus, method, or process contained herein. In addition, the authors and NRECA make no warranty or representation that the use of these contents does not infringe on privately held rights.

This work product constitutes the intellectual property of NRECA and its suppliers, as the case may be, and containsConfidential Information. As such, this work product must be handled in accordance with the CRN Policy Statement onConfidential Information.

Questions

Brian [email protected]

Contents – i i i

contents

Acknowledgments xv

Addendum Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition xvii

Section 1 Introduction and Overview 1Purpose 1Overview 1

Section 2 Field Staking Practices and Procedures 3Examination of Local Conditions 3Practical Structure Location 4Structure Selection 6Mechanics of Staking 6Preparation of Documents 14Staking Equipment, Materials, and Design Aids 15

Section 3 Applicable Codes and Specifications 17National Electrical Safety Code (NESC) 17RUS Specifications and Drawings 35RUS List of Materials 39

Section 4 Conductor Characteristics 41Conductor Tension Limits 41Span Selection 46Conductor Sag 49Maximum Allowable Span Based on the Separation of Conductors 55

Section 5 Pole Strength 59NESC Requirements 59Pole Size 60Ultimate Resisting Moment 65Maximum Wind Span 73Unguyed Line Angle Poles 81Extreme Wind Loading on Unguyed Poles 81Extreme Ice with Concurrent Wind Loading on Unguyed Poles 85

Section 6 Strength of Pole-Top Assemblies 89Crossarm Assemblies 89Strength of Crossarm 90Pin- and Post-Type Insulator Assemblies 97Maximum Permissible Line Angle 115

iv – Contents

contents

Section 7 Guying Practices and Procedures 119Guying Situations 119Forces That Make Guying Necessary 121NESC Requirements 124RUS Requirements 125Line Angle Guying 131Dead-end Guying 134Tap Guying 138Guying Calculations 139

Section 8 Joint Use 151Strength Requirements 151Clearance Requirements 152Joint-Use Construction on Different Utility Distribution Line 153Communication or Cable TV Joint-Use Construction on Existing Cooperative Structures 154

Section 9 Staking for Unit Price Contracts 157Accuracy 157Units 157Contract Specifications 159Staking Sheets 159Stakes 159Sample RUS Form 830 Contract Documents 160

Section 10 Sizing Transformer and Service 167Transformer Loading 167Transformer Sizing 169Voltage Levels 171Voltage Flicker from Starting Motors 173Maximum Service Lengths 174Voltage Drop and Flicker Equations 177

Section 11 Application 179Single-Phase Line Extension for Residential Service 179Three-Phase Line Extension for Industrial Service 183The Staking Package 188

Contents – v

contents

Section 12 Designing for Extra-Large Conductors 189Extra-Large Conductors 189Spans 192Angles 197Weight Spans 204Guys and Anchors 207

Appendix A Assembly Numbering, RUS Bulletin 1728F-804, 7.2/12.5-kV Specs 213

Appendix B Sag and Tension Tables 223

Appendix C Horizontal Pull and Total Guy Load at Angles for 30- to 55-FootPoles Using Grade C Construction 315

Bibliography 355

Glossary 357

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2.1 Uplift on Structure 52.2 Conductor Uplift 52.3 Running a Line Between Control Points Using a Transit 72.4 Location of Pole Stakes Using a Temporary Offset Line 72.5 Use of Range Rods to Establish a Straight Line Between Control Points 72.6 Measuring the Deflection Angle Using a Transit 82.7 Use of a Surveyor’s Chain or Measuring Tape for Measuring a

Deflection Angle 92.8 Use of a Surveyor’s Chain or Measuring Tape for Bisecting a

Deflection Angle 92.9 180° Reverse Compass Scale 102.10 Measuring and Bisecting a Deflection Angle with a Hand

Compass 102.11 Determination of Change in Elevation 112.12 Uplift Factor 132.13 Staking of an Extended Vertical Angle Structure 13

3.1 Loading District Map 183.2 Wind Speed Map 193.3 Extreme Ice Loading Map 213.4 Minimum Vertical Clearance at Any Point in the Span 243.5 Unobstructed Climbing Space 263.6 Unobstructed Working Space 263.7 Obstructed Climbing and Working Space 273.8 Application of Clearance Tables 273.9 Clearance Diagrams for Buildings and Other Structures 293.10 Horizontal Clearance with Wind Displacement 323.11 Clearance Envelope for Grain Bins Filled by Permanently

Installed Augers, Conveyors, or Elevators 333.12 Clearance Envelope for Grain Bins Filled by Portable Augers,

Conveyors, or Elevators 333.13 Dimensions of Components, Design Limits, and Bill of Materials 373.14 Pole Framing Guides 38

4.1 Two Spans Between Guyed Deadend Structures 484.2 Sag and Tension Data Request Form 504.3 Sag (Catenary) Curve 524.4 Inclined Span Nomenclature 55

5.1 Wind Force on Conductor 615.2 Pole Moment 655.3 Wind Span 765.4 Transverse Loading on Structure 77

FIGURE PAGE

6.1 Weight Span 906.2 Examples of Longitudinal Unbalances on Crossarms 916.3 Typical Neutral Attachments 976.4 Pin Overload on C2 Pole-Top Assembly 98

7.1 30° Line Angle with Bisect Guy 1207.2 60° Line Angle with Deadend Guys in Both Directions 1207.3 Guying Configuration for Crossing Span Structures 1207.4 Transverse Loading 1217.5 Guy Lead Ratios and Guy Factors 1217.6 Average Guy Attachment Height and Average Guy Lead 1227.7 Lateral Deflection of Pole Due to Short Guy Lead and Vertical Load 1247.8 Sample Guy Attachment Strength Rating, E1-3 Guy Assembly 1267.9 Expanding Anchor Assembly 128 7.10 Plate Anchor Assembly 1287.11 Cone Anchor Assembly 1287.12 Screw Anchor Assembly 1297.13 Swamp Anchor Assembly 1297.14 Log Anchor Assembly 1307.15 Rock Anchor Assembly 1307.16 Wind Span Calculation 1337.17 Multiple Anchor Configurations 1377.18 Sidewalk Guy 1377.19 Guying with Reduced-Tension Spans 1387.20 Overhead Guy 1397.21 Span Lengths and Deflection Angle for Example 7.7 1407.22 Guying Factor Graph 1467.23 Wind Blowing Perpendicular to Tap Line 1497.24 Wind Blowing Perpendicular to Tangent Line 150

8.1 Midspan Vertical Clearance 152

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FIGURE PAGE

9.1 An Example of Special Unit Specification 1589.2 Completed Staking Sheet 1609.3 Sketch of Line 1619.4 Removal Assembly Units List 1629.5 New Assembly Units List 1639.6 Special Unit Descriptions 1649.7 Special Drawing—Bog Shoe Assembly, M31, M31-1 165

10.1 Example of Load Cycle 16810.2 Allowable Service Voltages 17210.3 Range of Observable and Objectionable Voltage Flicker versus Time 173

11.1 Line Extension, Single Phase 18011.2 Line Extension, Three Phase 184

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FIGURE PAGE

2.1 Typical Distribution Line Staking Table 12

3.1 NESC Loading District Ice and Wind Loads 193.2 Horizontal Wind Pressures on Cylindrical Surfaces 203.3 Grades of Construction for Supply Conductors Alone, at Crossing,

or on the Same Structures with Other Conductors 223.4 Common Voltages of Cooperative Systems with Associated

Phase-to-Ground Voltages 223.5 Minimum Basic Vertical Clearance at Supports Between Line Conductors 243.6 Minimum Vertical Clearance at Any Point in the Span from

Distribution Conductors to Underbuild Conductors 253.7 Clearance Between Conductors Bounding the Climbing Space 263.8 Vertical Clearances of Wires, Conductors, and Cables

Above Ground, Rails, or Water 283.9 Basic Clearances of Conductors Passing by But Not Attached

to Buildings, Signs, or Other Installations 303.10 Basic Vertical Clearances of Wires, Conductors, and Cables

Carried on Different Supporting Structures 313.11 Phase and Neutral Clearances from Grain Bin 34

4.1 NESC Tension Limits for ACSR Conductor 424.2 Recommended Tension Limits for ACSR Conductor 434.3 Recommended Tension Limits for AAAC Conductor 434.4 Aluminum Company of America Sag and Tension Data 454.5 Stringing Sag Table 514.6 Time–Sag Table 544.7 Maximum Allowable Final Unloaded Sag for Standard RUS Assemblies

Based on NESC Rule 235B1b 56

5.1 Overload Capacity Factors for Wood Structures 605.2 Extreme Wind Overload Capacity Factors for Wood Distribution

Structures When Installed 605.3 ACSR Conductor Specifications with Transverse NESC District Loadings 625.4 Recommended Minimum Pole Class for One Transformer Installed

on a Single Pole 635.5 Recommended Minimum Pole Class for a Bank of Two Transformers

Installed on a Single Pole 635.6 Recommended Minimum Pole Class for a Bank of Three Transformers

Installed on a Single Pole 645.7 Fiber Stress Ratings of Poles 655.8 Ultimate Resisting Moments of Wood Poles 665.9 Strength Reduction Factors for Wood Poles 695.10 Bending Moment of Wood Poles at Groundline Due to Wind on Pole 705.11 Maximum Wind Spans in Feet: Southern Yellow Pine & Douglas Fir 735.12 Transverse NESC District Loading on TV Cable 78

Tab les – i xTables – ix

tables

TABLE PAGE

5.13 Transverse NESC District Loading on Telephone Cable 785.14 Extreme Loading Coefficients for Wood Poles and Overhead Conductors 82

6.1 Deadend Assemblies for Smaller Conductors 916.2 Overload Capacity Factors for Wood Crossarms 926.3 Strength Reduction Factors for Wood Crossarms 926.4 Strength of Pin- and Post-Type Insulator Assemblies 976.5 Recommended Maximum Permissible Line Angle for

Pin-Type Pole-Top Assemblies 996.6 Maximum Line Angles 1046.7 Overload Capacity Factors for Support Hardware 1166.8 Sine θ/2 for Line Angles 117

7.1 Average Guy Attachment Heights and Corresponding Guy Leads for Typical RUS Distribution Structures 123

7.2 Load Factors (Overload Capacity Factors) for Guys 1247.3 Guy Wire Strength Data 1257.4 Soil Classification for Anchor Design 1277.5 Example of Strength of Guy and Anchor Assemblies 1317.6 Medium Loading District—Three-Phase, 1/0 ACSR Primary and

2 ACSR Neutral 1327.7 Horizontal Pull and Total Guy Load at Deadends 1357.8 Sine θ/2 for Line Angles 141

10.1 Ratings for Single-Phase Overhead Distribution Transformers 16810.2 Daily Peak Loads in Per Unit of Nameplate Rating to Give

Minimum 20-Year Life Expectancy 16910.3 Guide for Sizing Single-Phase Overhead Distribution Transformers

Based on Number of Homes Served 17010.4 Guide for Estimating Load on Transformer Based on Number

of Homes Served 17110.5 Practical Electrical Operating Characteristics of Residential Cooling Units 17310.6 Summary of Voltage Drop Considerations 17410.7 Maximum Service Wire Lengths in Feet Based on Voltage Drop Limits 17510.8 Impedance Values of 600-Volt Triplexed Cable 178

11.1 ALCOA Sag and Tension Data, 2 ACSR 6/1 18111.2 ALCOA Initial Stringing Sag and Tension Table—2 ACSR 6/1 18311.3 ALCOA Sag and Tension Data, 1/0 ACSR 18411.4 ALCOA Initial Sag and Tension Table—1 ACSR 185

x – Tables

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12.1 Extra-Large Conductors 18912.2 Sag Table for a 250-Foot Ruling Span of 795 ACSR under Heavy Loading 19112.3 Conductor Specifications with Transverse NESC District Loadings 19412.4 Maximum Wind Spans in Feet: Southern Pine & Douglas Fir 19512.5 Maximum Permissible Line Angle for Pin-Type Pole Top 19712.6 Maximum Line Angles 19812.7 Maximum Weight Span Limited by Vertical Load on Crossarms 20412.8 Horizontal Pull and Total Guy Load at Dead Ends 20812.9 Heavy Loading District: Three Phase—795 ACSR Primary

and 336 ACSR Neutral 210

Appendix A Assembly Numbering, RUS Bulletin 1728F-804, 7.2/12.5-kV Specs

A.1 From Bulletin 1728-F-804 Exhibit 3. Disposition of Assemblies in Bulletin 50-3 (D 804) 214

Appendix B Sag and Tension Tables

B.1 Light Loading, 4 ACSR, Ruling Span = 250 Feet 225B.2 Light Loading, 4 ACSR, Ruling Span = 300 Feet 226B.3 Light Loading, 4 ACSR, Ruling Span = 350 Feet 227B.4 Light Loading, 2 ACSR, Ruling Span = 250 Feet 228B.5 Light Loading, 2 ACSR, Ruling Span = 300 Feet 229B.6 Light Loading, 2 ACSR, Ruling Span = 350 Feet 230B.7 Light Loading, 1/0 ACSR, Ruling Span = 250 Feet 231B.8 Light Loading, 1/0 ACSR, Ruling Span = 300 Feet 232B.9 Light Loading, 1/0 ACSR, Ruling Span = 350 Feet 233B.10 Light Loading, 3/0 ACSR, Ruling Span = 250 Feet 234B.11 Light Loading, 3/0 ACSR, Ruling Span = 300 Feet 235B.12 Light Loading, 3/0 ACSR, Ruling Span = 350 Feet 236B.13 Light Loading, 4/0 ACSR, Ruling Span = 250 Feet 237B.14 Light Loading, 4/0 ACSR, Ruling Span = 300 Feet 238B.15 Light Loading, 4/0 ACSR, Ruling Span = 350 Feet 239B.16 Light Loading, 336 ACSR, Ruling Span = 250 Feet 240B.17 Light Loading, 336 ACSR, Ruling Span = 300 Feet 241B.18 Light Loading, 336 ACSR, Ruling Span = 350 Feet 242B.19 Light Loading, 477 ACSR, Ruling Span = 250 Feet 243B.20 Light Loading, 477 ACSR, Ruling Span = 300 Feet 244B.21 Light Loading, 477 ACSR, Ruling Span = 350 Feet 245B.22 Light Loading, 556 ACSR, Ruling Span = 200 Feet 246B.23 Light Loading, 556 ACSR, Ruling Span = 250 Feet 247B.24 Light Loading, 556 ACSR, Ruling Span = 300 Feet 248B.25 Light Loading, 740 AAAC, Ruling Span = 200 Feet 249B.26 Light Loading, 740 AAAC, Ruling Span = 250 Feet 250B.27 Light Loading, 740 AAAC, Ruling Span = 300 Feet 251

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B.28 Light Loading, 795 ACSR, Ruling Span = 200 Feet 252B.29 Light Loading, 795 ACSR, Ruling Span = 250 Feet 253B.30 Light Loading, 795 ACSR, Ruling Span = 300 Feet 254B.31 Medium Loading, 4 ACSR, Ruling Span = 250 Feet 255B.32 Medium Loading, 4 ACSR, Ruling Span = 300 Feet 256B.33 Medium Loading, 4 ACSR, Ruling Span = 350 Feet 257B.34 Medium Loading, 2 ACSR, Ruling Span = 250 Feet 258B.35 Medium Loading, 2 ACSR, Ruling Span = 300 Feet 259B.36 Medium Loading, 2 ACSR, Ruling Span = 350 Feet 260B.37 Medium Loading, 1/0 ACSR, Ruling Span = 250 Feet 261B.38 Medium Loading, 1/0 ACSR, Ruling Span = 300 Feet 262B.39 Medium Loading, 1/0 ACSR, Ruling Span = 350 Feet 263B.40 Medium Loading, 3/0 ACSR, Ruling Span = 250 Feet 264B.41 Medium Loading, 3/0 ACSR, Ruling Span = 300 Feet 265B.42 Medium Loading, 3/0 ACSR, Ruling Span = 350 Feet 266B.43 Heavy Loading, 4/0 ACSR, Ruling Span = 250 Feet 267B.44 Heavy Loading, 4/0 ACSR, Ruling Span = 300 Feet 268B.45 Heavy Loading, 4/0 ACSR, Ruling Span = 350 Feet 269B.46 Heavy Loading, 336 ACSR, Ruling Span = 250 Feet 270B.47 Heavy Loading, 336 ACSR, Ruling Span = 300 Feet 271B.48 Heavy Loading, 336 ACSR, Ruling Span = 350 Feet 272B.49 Heavy Loading, 477 ACSR, Ruling Span = 250 Feet 273B.50 Heavy Loading, 477 ACSR, Ruling Span = 300 Feet 274B.51 Heavy Loading, 477 ACSR, Ruling Span = 350 Feet 275B.52 Heavy Loading, 556 ACSR, Ruling Span = 200 Feet 276B.53 Heavy Loading, 556 ACSR, Ruling Span = 250 Feet 277B.54 Heavy Loading, 556 ACSR, Ruling Span = 300 Feet 278B.55 Heavy Loading, 740 AAAC, Ruling Span = 200 Feet 279B.56 Heavy Loading, 740 AAAC, Ruling Span = 250 Feet 280B.57 Heavy Loading, 740 AAAC, Ruling Span = 300 Feet 281B.58 Heavy Loading, 795 ACSR, Ruling Span = 200 Feet 282B.59 Heavy Loading, 795 ACSR, Ruling Span = 250 Feet 283B.60 Heavy Loading, 795 ACSR, Ruling Span = 300 Feet 284B.61 Heavy Loading, 4 ACSR, Ruling Span = 200 Feet 285B.62 Heavy Loading, 4 ACSR, Ruling Span = 250 Feet 286B.63 Heavy Loading, 4 ACSR, Ruling Span = 300 Feet 287B.64 Heavy Loading, 2 ACSR, Ruling Span = 200 Feet 288B.65 Heavy Loading, 2 ACSR, Ruling Span = 250 Feet 289B.66 Heavy Loading, 2 ACSR, Ruling Span = 300 Feet 290B.67 Heavy Loading, 1/0 ACSR, Ruling Span = 200 Feet 291B.68 Heavy Loading, 1/0 ACSR, Ruling Span = 250 Feet 292B.69 Heavy Loading, 1/0 ACSR, Ruling Span = 300 Feet 293B.70 Heavy Loading, 3/0 ACSR, Ruling Span = 200 Feet 294B.71 Heavy Loading, 3/0 ACSR, Ruling Span = 250 Feet 295B.72 Heavy Loading, 3/0 ACSR, Ruling Span = 300 Feet 296B.73 Heavy Loading, 4/0 ACSR, Ruling Span = 200 Feet 297B.74 Heavy Loading, 4/0 ACSR, Ruling Span = 250 Feet 298B.75 Heavy Loading, 4/0 ACSR, Ruling Span = 300 Feet 299

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B.76 Heavy Loading, 336 ACSR, Ruling Span = 200 Feet 300B.77 Heavy Loading, 336 ACSR, Ruling Span = 250 Feet 301B.78 Heavy Loading, 336 ACSR, Ruling Span = 300 Feet 302B.79 Heavy Loading, 477 ACSR, Ruling Span = 200 Feet 303B.80 Heavy Loading, 477 ACSR, Ruling Span = 250 Feet 304B.81 Heavy Loading, 477 ACSR, Ruling Span = 300 Feet 305B.82 Heavy Loading, 556 ACSR, Ruling Span = 200 Feet 306B.83 Heavy Loading, 556 ACSR, Ruling Span = 250 Feet 307B.84 Heavy Loading, 556 ACSR, Ruling Span = 300 Feet 308B.85 Heavy Loading, 740 AAAC, Ruling Span = 200 Feet 309B.86 Heavy Loading, 740 AAAC, Ruling Span = 250 Feet 310B.87 Heavy Loading, 740 AAAC, Ruling Span = 300 Feet 311B.88 Heavy Loading, 795 ACSR, Ruling Span = 200 Feet 312B.89 Heavy Loading, 795 ACSR, Ruling Span = 250 Feet 313B.90 Heavy Loading, 795 ACSR, Ruling Span = 300 Feet 314

Appendix C Horizontal Pull and Total Guy Load at Angles for 30- to 55-Foot Poles Using Grade C Construction

C.1 Light Loading District: Single Phase—4 ACSR Primary and Neutral 316C.2 Light Loading District: Single Phase—2 ACSR Primary and Neutral 317C.3 Light Loading District: Single Phase—1/0 ACSR Primary and Neutral 318C.4 Light Loading District: Three Phase—4 ACSR Primary and Neutral 319C.5 Light Loading District: Three Phase—2 ACSR Primary and Neutral 320C.6 Light Loading District: Three Phase—1/0 ACSR Primary and

2 ACSR Neutral 321C.7 Light Loading District: Three Phase—3/0 ACSR Primary and

1/0 ACSR Neutral 322C.8 Light Loading District: Three Phase—4/0 ACSR Primary and

1/0 ACSR Neutral 323C.9 Light Loading District: Three Phase—336.4 ACSR Primary and

4/0 ACSR Neutral 324C.10 Light Loading District: Three Phase—477.0 ACSR Primary and

4/0 ACSR Neutral 325C.11 Light Loading District: Three Phase—556 ACSR Primary and

336 ACSR Neutral 326C.12 Light Loading District: Three Phase—740 AAAC Primary and

336 ACSR Neutral 327C.13 Light Loading District: Three Phase—795 ACSR Primary and

336 ACSR Neutral 328C.14 Medium Loading District: Single Phase—4 ACSR Primary and Neutral 329C.15 Medium Loading District: Single Phase—2 ACSR Primary and Neutral 330C.16 Medium Loading District: Single Phase—1/0 ACSR Primary and Neutral 331C.17 Medium Loading District: Three Phase—4 ACSR Primary and Neutral 332C.18 Medium Loading District: Three Phase—2 ACSR Primary and Neutral 333

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C.19 Medium Loading District: Three Phase—1/0 ACSR Primary and 2 ACSR Neutral 334

C.20 Medium Loading District: Three Phase—3/0 ACSR Primary and 1/0 ACSR Neutral 335

C.21 Medium Loading District: Three Phase—4/0 ACSR Primary and 1/0 ACSR Neutral 336

C.22 Medium Loading District: Three Phase—336.4 ACSR Primary and 4/0 ACSR Neutral 337

C.23 Medium Loading District: Three Phase—477.0 ACSR Primary and 4/0 ACSR Neutral 338

C.24 Medium Loading District: Three Phase—556 ACSR Primary and 336 ACSR Neutral 339

C.25 Medium Loading District: Three Phase—740 AAAC Primary and 336 ACSR Neutral 340

C.26 Medium Loading District: Three Phase—795 ACSR Primary and 336 ACSR Neutral 341

C.27 Heavy Loading District: Single Phase—4 ACSR Primary and Neutral 342C.28 Heavy Loading District: Single Phase—2 ACSR Primary and Neutral 343C.29 Heavy Loading District: Single Phase—1/0 ACSR Primary and Neutral 344C.30 Heavy Loading District: Three Phase—4 ACSR Primary and Neutral 345C.31 Heavy Loading District: Three Phase—2 ACSR Primary and Neutral 346C.32 Heavy Loading District: Three Phase—1/0 ACSR Primary and

2 ACSR Neutral 347C.33 Heavy Loading District: Three Phase—3/0 ACSR Primary and

1/0 ACSR Neutral 348C.34 Heavy Loading District: Three Phase—4/0 ACSR Primary and

1/0 ACSR Neutral 349C.35 Heavy Loading District: Three Phase—336.4 ACSR Primary and

4/0 ACSR Neutral 350C.36 Heavy Loading District: Three Phase—477.0 ACSR Primary and

4/0 ACSR Neutral 351C.37 Heavy Loading District: Three Phase—556 ACSR Primary and

336 ACSR Neutral 352C.38 Heavy Loading District: Three Phase—740 AAAC Primary and

336 ACSR Neutral 353C.39 Heavy Loading District: Three Phase—795 ACSR Primary and

336 ACSR Neutral 354

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Acknowledgments – xv

acknowledgments

This simplified manual on the techniques ofstaking distribution lines is the culmination ofcountless hours of effort by many fine indivi-duals. The manual is now in its third edition,which proves its value to our industry as a reference book and a learning tool.The dedication of the lead author, W. Richard

Lovelace of Hi-Line Engineering, LLC, to this proj-ect made this manual a reality. His diverse expe-riences as a lineman, staking engineer, and an

instructor were invaluable to this project. KevinMara, P.E., provided input and direction to theoriginal edition. He also managed the subse-quent revisions with assistance from MathewPamperin, Braxton Underwood, and Linda Gray.The original undertaking to create this manual

was managed by Robert C. Dew, Jr., P.E., withvaluable technical support provided by John A. Rodgers, P.E., Linda Gray, and Joe L.Thebeau.

The Third Edition of the Simplified Staking Manual for Overhead Distribution Lines has been updatedbased on changes contained in the 2012 National Electric Safety Code (NESC). The goal of this FourthEdition is to be compliant with the current version of the NESC. This Addendum serves as a catalog ofthese changes, and also includes corrections to several typographical errors.

1. Page 2, left column, first paragraph. The reference to the website was changed fromwww.usda.gov/rus to www.rurdev.usda.gov/UEP_HomePage.html.

2. Page 2, left column, third paragraph. After the sentence, “The third edition is based on the 2007 NESC,” the following sentence was added:

This fourth edition is based on the 2012 NESC.

3. Page 2, right column, second full paragraph. “2007 NESC” was changed to “2012 NESC.”

4. Page 18, right column. The following paragraph was added to the end of the subsection entitled “NESC LOADING DISTRICTS (250)”:

In 2012, the NESC added a fourth loading zone to address the weather conditions on islandssuch as American Samoa, Guam, Hawaii, Puerto Rico, and the Virgin Islands. To apply theloading zone for the islands, it is recom-mended that the Light Loading (Zone 3)be used for facilities located between sealevel and 9,000 feet. For facilities on islands with an elevation of more than 9,000 feet above sea level, use theMedium Loading District (Zone 2).

5. Page 18. Figure 3.1 has been updated toshow the change to the loading zone forHawaii.

6. Page 20, right column, bottom of the secondfull paragraph. The following sentence hasbeen added:

Extreme ice loading does not apply towarm islands, such as Hawaii and American Samoa.

Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition – xvii

Addendum:Updates to the Simplified StakingManual for Overhead DistributionLines—Fourth EditionA

FIGURE 3.1: Loading District Map.

Alaska – HeavyHawaii – Light for elevations below 9,000 feetHawaii – Medium for elevations above 9,000 feet

Zone 1

Zone 2

Zone 3

xvi i i – Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition

A

The information provided in this table applies only to effectively grounded circuits and two-wire grounded circuits. Voltagesshown are phase-to-ground values. The grade of construction for supply conductors, as indicated across the top of the table,must also meet the requirements for any lines at lower levels except, when otherwise noted.

Supply conductors Constant-potential supply conductorsat higher levels 0 – 0.75 kV 0.75 – 22 kV

Conductors, tracks, Open or Cable Open Cableand rights-of-wayat lower levels

Common or publicrights-of-way C C C

Railroad tracks, limitedaccess highways, and navigable waterwaysrequiring waterway permits B B B

Supply conductors0 to 750 VOpen or cable C C C

750 V to 22 kVOpen or cable C C C

Exceeding 22 kVOpen or cable B B B

Communication conductorOpen or cable C B1,2 C

1 The supply conductors need only meet the requirements of Grade C crossing construction if both of the following conditionsare fulfilled: (a) the supply voltage will be promptly removed from the communication plant by deenergization or othermeans, both initially and following subsequent circuit breaker operations in the event of a contact with the communicationplant; and (b) the voltage and current impressed on the communication plant in the event of a contact with the supply conductors are not in excess of the safe operating limit of the communication protective devices.

2 On systems of RUS borrowers, Grade C construction may be used over not more than one twisted pair of parallel-lay communication conductor or communication service drops.

For other exceptions, see NESC Table 242-1.

Adapted from NESC Table 242-1.

TABLE 3.3: Grades of Construction for Supply Conductors Alone, at Crossing, or on the SameStructures with Other Conductors

7. Page 21, right column, second full paragraph. “Note 2” has been changed to “Note 1.”

8. Page 22. Table 3.3 has been replaced with the following table. The 2012 NESC made significantchanges to Table 242, prompting this change.

Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition – xix

A

(All voltages are between the conductors involved except for railway feeders, which are to ground.)

InsulatedConductors usually supply cable3

Open supply line conductors1at upper levels and multi-grounded

neutrals

8.7 to 50 kV

Conductors usually Same Differentat lower levels 0 to 750 V (in.) 0 to 8.7 kV (in.) utility (in.) utilities (in.)

Communication conductors:General 401 40 40 60

Supply conductors:0 to 750 Vmulti-grounded neutrals 165 162 40 60

750 V to 8.7 kV 162 40 60

8.7 kV to 22 kV 40 60

Exceeding 22 kV, but not exceeding 50 kV 404 604

1 See NESC Table 235-5 for exceptions and notations.2 Where conductors are operated by different utilities, a vertical clearance of not less than 40 inches is recommended.3 Multiconductor wires or cables, such as duplex and triplex, which are supported by an effectively grounded bare

messenger or neutral.4 These values do not apply to conductors of the same circuit being carried on adjacent conductor supports.5 No vertical separation at the structure is required between a neutral conductor and a multiconductor cable, such

as duplex and triplex supported by an effectively grounded bare messenger or neutral.

Adapted from NESC Table 235-5.

TABLE 3.5: Minimum Basic Vertical Clearance at Supports between Line Conductors

9. Page 24. Table 3.5 has been replaced with the following table. 2012 NESC changed clearances between insulated supply cables (meeting Rule 230C2) and the neutral conductor. A row in thetable was deleted for simplicity and a change in the column headings deleted a reference to NESCRule 230D, which refers to insulated, non-shield cable. These types of cables are beyond thescope of this Manual.

10. Page 29, right column, end of the first paragraph. The following sentence was added:

Table 3.9 also provides clearances to other supporting structures, which include lighting supports, traffic signal supports, and supporting structures of a second line.

11. Page 30. Table 3.9 has been updated. In the first column, second row, “balconies” was replacedwith “balconies, porches, decks”; the 2012 NESC expanded the description for clarity. A footnotefor flag poles and banners was added. The footnote for “Other Supporting Structures” waschanged to clarify the reference.

xx – Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition

AVoltage (Phase-to-Ground on Effectively Grounded Circuits)

Neutrals, 0 – 750 V 0 – 750 V 750 V – 22 kV Voltage ClassGrounded Insulated OpenGuys Conductors Conductors 12.5/7.2 kV 24.9/14.4 kV 34.5/19.9 kV

Clearance Categories1 (ft) (ft) (ft) (ft) (ft) (ft)

1. Buildings

Horizontal:

Walls,1 projections,1

unguarded windows,1

balconies, porches, decks,and areas accessible to pedestrians 4.5 5.0 5.53 7.52 7.52 7.52

Vertical:

Above or below roofs or projections not accessible to pedestrians1 3.0 3.5 10.5 12.5 12.5 12.5

Above or below roofs or projections accessible to pedestrians1 10.5 11.0 11.5 13.5 13.5 13.5

Above roofs accessible to vehicles but not to truck traffic1 10.5 11.0 11.5 13.5 13.5 13.5

Above roofs accessible to truck traffic1 15.5 16.0 16.5 18.5 18.5 18.5

2. Other Installations Not Classified as Buildings4

Horizontal1 4.5 5.0 5.53 7.52 7.52 7.52

Vertical:1

Over or under catwalks and other surfaces upon which personnel walk 10.5 11.0 11.5 13.5 13.5 13.5

Over or under other portions of such installations 3.0 3.5 6.0 8.0 8.0 8.0

3. Other Supporting Structures

Horizontal5 3.0 3.0 5.03 5.02 5.02 5.02

Vertical5 2.0 2.0 4.5 4.5 4.5 4.5

1 Clearances normally apply on rural distribution systems. See NESC Table 234-1 for exceptions and notations.2 This clearance shall not be less than 4.5 ft with conductors displaced by a 6-psf wind. See Figure 3.10.3 This clearance shall not be less than 3.5 ft with conductors displaced by a 6-psf wind. See Figure 3.10.4 Flag poles and banners are included in this category. The specific clearance is with flag or banner fully extended.5 See NESC Rule 234B for exceptions and notations.

TABLE 3.9: Basic Clearances of Conductors Passing by but Not Attached to Buildings, Signs, or Other Installations

Adapted from NESC Table 234-1 and Rule 234B.

Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition – xxi

A

FIGURE 3.12: Clearance Envelope for Grain Bins Filled by Portable Augers, Conveyors, or Elevators.

V = Height of highest filling or probing port on grain binH = V + 18 ft

Loading Side1.5:1Slope

1.5:1Slope

1.5:1Slope

1.5:1Slope

1.5:1Slope

Nonloading Side

15 ft

Rule 232 Area

Area of SlopedClearance

Flat Top ofClearanceEnvelope

Rule 232 Area

See Rule 232 See Rule 232

18 ft

15 ft

H

H

V

1.5

Follows theGround Slope

Flat

1

11.5

Source: NESC Fig. 234-4(a).

12. Page 32, left column, first partial paragraph. The sentence, “The horizontal distance from the grainto wires and rigid live parts is 15 feet with a probe clearance of 18 feet centered at the probeports in the grain bin” was replaced with the following:

For a grain bin with a permanent auger, the vertical clearance above shall be the same as astructure not classified as a building (see Table 3.9) and will also meet a clearance of 18 feetfor all cables and wires in any direction from the probe ports in the grain bin (see Figure3.11). The horizontal clearance must meet the requirements shown in Table 3.9 and mustalso meet a horizontal clearance of 15 feet for all open supply conductors operating between0 and 22 kV phase to ground. This 15-foot requirement for horizontal clearance does notapply to multi-grounded neutrals.

13. Page 33. Figure 3.12 has been changed. The 2012 NESC added the requirement to follow theslope of the ground and clarify the measure of the 15-foot distance on the non-loading side of the grain bin.

14. Page 35, right column, first full paragraph. In the following sentence, the word “minimum” hasbeen deleted.

The required minimum vertical clearances between conductors when one line crosses another are shown in Table 3.10 on page 31.

The clearances represent safe clearances and have been adapted from Table 233-1, which willallow lesser clearances.

15. Page 41, right column, second to last paragraph. The NESC changed the temperatures to reduceAeolian vibration. The original paragraph, “When the conductor is initially strung and is carryingno wind or ice load, the tension shall not exceed 35% of the ultimate strength of the conductor at atemperature of 60°F. This is referred to as the ‘initial unloaded conduction,’” was edited as follows:

When the conductor is initially strung and is carrying no wind or ice load, the tension shall not exceed 35% of the ultimate strength of the conductor at a temperature of 0°F forheavy loading, 15°F for medium loading, and 30°F for light loading. This is referred to as the “initial unloaded conduction.”

xxi i – Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition

A16. Page 42, left column, first partial paragraph: “loading and at a temperature of 60°F shall not

exceed 25% of the ultimate strength of the conductor” was replaced with the following text:

loading, the tension shall not exceed 25% of the ultimate strength of the conductor at a temperature of 0°F for heavy loading, 15°F for medium loading, and 30°F for light loading. This is referred to as the “final unloaded condition.”

The NESC changed the temperatures to reduce Aeolian vibration.

Grade B Grade C

Vertical 1.50 1.90

Transverse (Wind) StrengthAt Crossings1 2.50 2.20Elsewhere 2.50 1.75

Transverse (Wire Tension) StrengthAt Crossings1 1.65 1.30Elsewhere 1.65 1.30

Longitudinal StrengthIn General 1.10 No requirementAt Deadends 1.65 1.30

1 “At crossings” is when a supply line crosses another supply line or communication line.See NESC Rule 241C.

TABLE 5.1: Overload Capacity Factors for Wood Structures. Adapted from NESC Table 253-1.

Grade B Grade C Extreme IceExtreme Wind Extreme Wind With Wind

Vertical 1.0 .87 1.0

Transverse (Wind) StrengthAt Crossings1 1.0 .87 1.0Elsewhere 1.0 .87 1.0

Transverse (Wire Tension) StrengthAt Crossings1 1.0 .87 1.0Elsewhere 1.0 .87 1.0

Longitudinal StrengthIn General 1.0 .87 1.0At Deadends 1.0 .87 1.0

1 “At crossings” is when a supply line crosses another supply line or communication line.See NESC Rule 241C.

TABLE 5.2: Extreme Wind Overload Capacity Factors for WoodDistribution Structures When Installed. Adapted from NESC Rule 253-1.

17. Page 60. Footnotes have been added to explain the term “at crossings” in Table 5.1and Table 5.2.

18. Page 65, left column, last paragraph. Theparagraph was replaced due to a change in NESC Rule 261A2a, which adopted themethodology contained in ANSI O5.1-2008.

This paragraph was deleted:

The strength of the pole is referred toas the ultimate resisting “moment” of thewood pole. If the fiber strength and thedimensions of the pole are known, thenthe ultimate resisting moment of the woodpole can be calculated. (A complete dis-cussion of how to perform these calcula-tions can be found in Chapter V-4 of RUSBulletin 160-2, dated April 1982.)

This paragraph was inserted:

The strength of the pole is referred toas the ultimate resisting “moment” of thewood pole. If the fiber strength and thedimensions of the pole are known, thenthe ultimate resisting moment of thewood pole can be calculated. (A com-plete discussion of how to perform thesecalculations can be found in Chapter V-4of RUS Bulletin 160-2, dated April 1982.)NESC Rule 261A2a requires poles towithstand loads at the maximum stresspoint. For unguyed wood poles less than60 feet in length, the maximum stresspoint will be at groundline, as shown inTable 5.8. For unguyed poles withlengths equal to or longer than 60 feet,ANSI O5.1-2008 Wood Poles —Specifica-tions & Dimensions shows de-rating thestrength of the poles by as much as 15%.

Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition – xxiii

A19. Pages 66–68, Table 5.8 was changed as shown on the following pages. The change was required

due to a change in NESC Rule 261A2a, which adopted the methodology contained in ANSI O5.1-2008. Ultimate resisting moments for poles greater than 55 feet, that had been included in thistable, have been eliminated.

Southern Yellow PineDouglas Fir

(Fiber Stress – 8,000 psi)

MinimumPole Circumference Groundline Resisting Extreme Ice withLength ANSI at Top Circumference Moment Grade B Grade C Concurrent Wind(ft) Class (in.) (in.) (ft-lb)

30 5 19.0 27.7 44,900 29,185 38,165 33,675

30 6 17.0 25.2 33,800 21,970 28,730 25,350

30 7 15.0 23.7 28,100 18,265 23,885 21,075

35 4 21.0 31.5 66,000 42,900 56,100 49,500

35 5 19.0 29.0 51,500 33,475 43,775 38,625

35 6 17.0 27.0 41,600 27,040 35,360 31,200

40 3 23.0 36.0 98,500 64,025 83,725 73,875

40 4 21.0 33.5 79,400 51,610 67,490 59,550

40 5 19.0 31.0 62,900 40,885 53,465 47,175

40 6 17.0 28.5 48,900 31,785 41,565 36,675

45 3 23.0 37.3 109,600 71,240 93,160 82,200

45 4 21.0 34.8 89,000 57,850 75,650 66,750

45 5 19.0 32.3 71,200 46,280 60,520 53,400

45 6 17.0 29.8 55,900 36,335 47,515 41,925

50 2 25.0 41.6 152,000 98,800 129,200 114,000

50 3 23.0 38.6 121,500 78,975 103,275 91,125

50 4 21.0 36.1 99,400 64,610 84,490 74,550

50 5 19.0 33.7 80,800 52,520 68,680 60,600

55 1 27.0 45.9 204,200 132,730 173,570 153,150

55 2 25.0 42.9 166,700 108,355 141,695 125,025

55 3 23.0 40.0 135,200 87,880 114,920 101,400

* See Table 5.9.

TABLE 5.8: Ultimate Resisting Moments of Wood Poles

Continued

De-Rated Strength*

xxiv – Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition

APonderosa Pine

Western Red Cedar



30 5 19 30.2 43,600 28,340 37,060 32,700

30 6 17 28.2 35,500 23,075 30,175 26,625

30 7 15 26.2 28,500 18,525 24,225 21,375

35 4 21 34.5 65,000 42,250 55,250 48,750

35 5 19 32.0 51,900 33,735 44,115 38,925

35 6 17 30.0 42,800 27,820 36,380 32,100

40 3 23 39.5 97,600 63,440 82,960 73,200

40 4 21 36.5 77,000 50,050 65,450 57,750

40 5 19 34.0 62,300 40,495 52,955 46,725

40 6 17 31.5 49,500 32,175 42,075 37,125

45 3 23 41.3 111,600 72,540 94,860 83,700

45 4 21 38.3 89,000 57,850 75,650 66,750

45 5 19 35.8 72,700 47,255 61,795 54,525

45 6 17 32.8 55,900 36,335 47,515 41,925

50 2 25 46.0 154,200 100,230 131,070 115,650

50 3 23 43.0 125,900 81,835 107,015 94,425

50 4 21 39.6 98,400 63,960 83,640 73,800

50 5 19 37.1 80,900 52,585 68,765 60,675

55 1 27 50.8 207,700 135,005 176,545 155,775

55 2 25 47.8 173,000 112,450 147,050 129,750

55 3 23 44.3 137,700 89,505 117,045 103,275

* See Table 5.9.

TABLE 5.8: Ultimate Resisting Moments of Wood Poles (cont.)

Continued

De-Rated Strength*

Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition – xxv

ANorthern White Cedar



30 5 19 34.8 44,500 28,925 37,825 33,375

30 6 17 32.3 35,600 23,140 30,260 26,700

30 7 15 29.8 27,900 18,135 23,715 20,925

35 4 21 39.5 65,100 42,315 55,335 48,825

35 5 19 37.0 53,500 34,775 45,475 40,125

35 6 17 34.0 41,500 26,975 35,275 31,125

40 3 23 45.0 96,200 62,530 81,770 72,150

40 4 21 42.0 78,200 50,830 66,470 58,650

40 5 19 39.0 62,600 40,690 53,210 46,950

40 6 17 36.0 49,300 32,045 41,905 36,975

45 3 23 47.2 111,000 72,150 94,350 83,250

45 4 21 43.7 88,100 57,265 74,885 66,075

45 5 19 40.7 71,200 46,280 60,520 53,400

45 6 17 N/A N/A N/A N/A N/A

50 2 25 52.9 156,300 101,595 132,855 117,225

50 3 23 48.9 123,500 80,275 104,975 92,625

50 4 21 45.4 98,800 64,220 83,980 74,100

50 5 19 42.5 81,100 52,715 68,935 60,825

55 1 27 58.0 206,000 133,900 175,100 154,500

55 2 25 54.6 171,900 111,735 146,115 128,925

55 3 23 50.6 136,800 88,920 116,280 102,600

* See Table 5.9.

TABLE 5.8: Ultimate Resisting Moments of Wood Poles (cont.)

De-Rated Strength*

xxvi – Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition

A

Wire Coefficient KGW2, Span Length, S (ft)

Height Above Groundline1 Structure Coefficient, KGS2 S

30. Page 224, right column, third paragraph, point #3. The phrase “radial thickness of ice as specifiedin Rule 250B” was replaced with “radial thickness of ice as specified in Table 230-1.” This reflectsa change in rules governing clearance of conductors.

31. Page 225 through Page 314, Table B.1 through Table B.90. The footnote has been changed from“2007 NESC” to “2012 NESC.”

32. Page 316 through Page 354, Table C.1 through Table C.39. The footnote has been changed from“2007 NESC” to “2012 NESC.”

33. Page 355. National Electrical Safety Code, ANSI C2, 2007 edition and National Electrical SafetyCode, ANSI C2, 2012 edition were added.

34. Page 362, right column. The definition of Unloaded Conductor Tension has been updated. Thephrase “the tension at 60°F” was changed to “the tension at a temperature of 0°F for heavy loading, 15°F for medium loading, and 30°F for light loading.”

Addendum: Updates to the Simplified Staking Manual for Overhead Distribution Lines—Fourth Edition – xxvii

A

Introduct ion and Over view – 1

Introduction and Overview1In This Section: Purpose Overview

The purpose of this manual is to simplify thestaking of overhead distribution lines. The motivation for this manual is the continued loss,mostly through retirement, of experienced fieldengineers who are specialists in the staking ofdistribution lines. CRN is helping to fill the gapcaused by the loss of these staff members bycreating a good reference document to trainnew staking technicians. In this manual, the

term “staking” is all-encompassing and meansthe complete mechanical design and field layoutof overhead distribution lines.The objective of this manual is to provide a

reference tool for staking technicians that willhelp acquire a basic working knowledge of thecorrect principles and practices of distributionline staking.

Purpose

The staking of a distribution line consists of theselection of the various physical components,such as conductors, poles, pole-top assemblies,guys, and anchors, that compose distributionstructures. It includes the proper location andpositioning of stakes to mark the location ofthese structures to provide safe, reliable, andefficient construction of distribution lines.The quality of the design depends on the

staking technician’s knowledge, experience, and degree of skill applied to the job.Tables, illustrations, photographs, and rules

of thumb are provided throughout the manual.All calculations have been simplified to theirfundamental components for ease in under-standing. After learning the fundamentals, moreadvanced applications of both formulas andprinciples are provided so that staking techni-cians can expand the realm of their learning.This manual contains information on a limited

number of conductors. It is assumed that stakingtechnicians will carry into the field similar tablesfor conductors used on their system. It is recommended that the staking technician

study the sections in this manual in the orderpresented after becoming familiar with theNational Electrical Safety Code (NESC); currentRUS specifications and drawings; and RUSInformational Publication 202-1, “List ofMaterials Acceptable for Use on Systems of RUSElectrification Borrowers” (List of Materials), current updates of which are available on theRUS Web site. Additionally, since the second edition of the

Staking Manual was published in 2002, therehave been a number of new RUS bulletins ondistribution system design and construction.Foremost among them is the new Bulletin1728F-804, “Specifications and Drawings for12.5/7.2 kV Line Construction,” dated October

Overview

cSCADA systemsprovide real-time controland monitoring of elec-tric distribution systems.According to IEEE Stan-dard 1402-2000, Guidefor Electric Power Substa-tion Physical and Elec-tronic Security, “the in-troduction of computersystems with online ac-cess to substa tion infor-mation is significant inthat substation relay pro-tection, control, and datacollection systems maybe exposed to the same

2 – Sect ion 1

12005. This new construction specification hasmany changes including assembly numberchanges, upgraded construction and strength of certain assemblies, and new narrow profileassemblies. Additionally, the Appendix contains a number of tables and other design aids for the staking technician. Furthermore, the follow-ing bulletins contain valuable information, calculations, design guides, etc. for the stakingtechnician. These bulletins are available on the RUS Web site, www.rurdev.usda.gov/UEP_HomePage.html, and are listed here asvaluable reference material:

• 1724E-150, Unguyed Distribution Poles—Strength Requirements (7/30/2003)

• 1724E-151, Mechanical Loading onDistribution Crossarms (11/21/2002)

• 1724E-152, The Mechanics of overheadDistribution Line Conductors (7/30/2003)

• 1724E-153, Electric Distribution Line Guys and Anchors (4/25/2001)

• 1724E-154, Distribution Conductor Clearancesand Span Limitations (7/30/2003)

RUS policy requires borrowers to constructtheir lines in compliance with the current NESC,except where local codes and RUS bulletins ordirectives are more restrictive. The cooperativemust conform to the legal safety code of theadministrative authority that has legal jurisdic-tion over the cooperative. The first edition of this manual was based

on the 1993 edition of the NESC. The secondedition was based on the 2002 NESC. The thirdedition was based on the 2007 NESC. This fourthedition is based on the 2012 NESC. Applicabletext, tables, and calculations have been revisedto reflect the changes from previous codes tothe current edition of the NESC.It must be the responsibility of the staking

technician to become well versed in the NESCand other regulations that govern the construc-tion of electric distribution lines so that later editions of the codes can be correctly applied. The staking technician is encouraged to

become familiar with the original text and interpretations of the current edition of theNESC. He/she should be alert to changes thatmay occur from one edition to another. This

Staking Manual is not intended as a replace-ment for the NESC, but as a training aid basedon NESC requirements.The 1990 edition of the NESC was specifically

revised to delete the use of the word “minimum”because the term was often misinterpreted assome kind of minimum number that should beexceeded in practice; such is not the case. Thevalues in the NESC indicate the clearances thatare required for safety purposes. However, inthis manual, the term “minimum clearance” may be used as a descriptive term that a novicestaking technician can easily grasp and under-stand. It should not be confused as overridingthe basic clearances found in the NESC. Many of the tables included in this manual are adapt-ed from the NESC. In some cases constructiontolerances or additional separation have beenadded to the tables to aid novice staking techni-cians who may need the extra margin of clear-ance until they are more confident in theirdesigns.Throughout this manual, there are references

to the 2012 NESC rules, tables, figures, and foot-notes. Where references are made, the stakingtechnician must refer to the entire rule, table, or figure and not just the excerpt.As a final review of Sections 1 through 10,

which are designed as modular learning building blocks, Section 11 is provided to challenge the staking technician’s expertise and to demonstrate the use of the newlyacquired information. The staking technician is given two comprehensive staking situations:

1. A short single-phase line extension to a residential consumer

2. A moderate but challenging three-phase lineextension to an industrial consumer

Extra large conductor considerations anddesign parameters are introduced and explainedin Section 12. Here the staking technician isexposed to the challenges of designing lineusing extra large conductors while using standard RUS distribution materials.Upon completion of this manual, the staking

technician will be familiar with the necessarytools and information that make possible safeand reliable distribution line construction.

www.rurdev.usda.gov/UEP_HomePage.html

Staking is not simply placing wooden stakes inthe ground to mark the location of a proposedpole line. Rather, staking is a complete engineer-ing evaluation of all the conditions surroundingthe choice of each structure and its locationprior to driving the first stake, as well as theplacement of those stakes. A properly staked

line will result in adequate construction at mini-mum costs, while a poorly staked line will resultin substandard construction, unnecessary delays,possible restaking, and invariably higher cost.Technical terms used in this section can gen-

erally be found in the glossary and in subse-quent sections of this manual.

To fully evaluate the conditions affecting the choice and placement of a structure, thestaking technician must consider the followinglocal conditions:

• Terrain• Existing facilities• Right-of-way• Problem consumers or landowners

TERRAINA cursory inspection of the overall topographyalong the proposed route will provide an idea ofenvironmental conditions to be addressed.

EXISTING FACILITIESAn evaluation of the existing poles and assem-blies should be made to determine the following:

• Can the existing structure be reused?• Will replacement of the structure be required?• Can the existing services be integrated intothe new line?

RIGHT-OF-WAYAn examination of the right-of-way along theproposed route should be made to gain the following information:

• The quantity and type of trees and brush tobe cleared or trimmed

• The easements that must be obtained fromproperty owners

• The encroachment permits that must beobtained to locate structures on propertyowned by state or local agencies (highwayrights-of-way), railroads, the gas company,and other utilities

Examination of Local Conditions

Field Staking Pract ices and Procedures – 3

Field Staking Practices and Procedures2

In This Section: Examination of Local ConditionsPractical Structure Location

Structure Selection

Mechanics of Staking

Preparation of Documents

Staking Equipment, Materials and Design Aids

PROBLEM CONSUMERS OR LANDOWNERSIt is desirable that the staking technician deter-mine the location of any potential problem consumers or landowners along the proposedroute of construction prior to the placement ofany stakes. Judgments should be made based on

personal experience, knowledge gained frominquiries of other cooperative employees, orfrom personal contacts with neighboringlandowners. Notes should be made to describeany special procedures necessary to deal effectivelywith these problem consumers or landowners.

4 – Sect ion 2

2

Practical Structure Location

CONTROL POINTSA control point is a point along the route thatdefinitely fixes the location of a structure.On any line, there will be certain points that

will fix the location of structures. Such pointsmay occur at stream crossings, transformer locations, branch tap locations, and angles inthe line.The first control points established are those

where the route obviously changes direction.During both planning and staking, other pointswill be found that will control the lengths of theintermediate line segments. Some of these con-trol points will affect the exact alignment of thepole centerline. They may be due to topograph-ic features, man-made objects, or right-of-waylimitations. Other control points may establishpole locations but not affect alignment. Typical control points include:

• Points required for junction poles or transformers and service taps

• Abrupt changes in topography such as gullies, hills, cliffs, and waterways

• Consumer or landowner requirements such as pole on the property line

• Special clearance problems such as signs,grain bins, or buildings

• Crossings (roads, power lines, railroads, and waterways)

• Changes in direction of the line• Joint-use structures

When actual staking begins, the first step is todetermine, as accurately as possible, all the con-trol points that fix structure locations. Span-by-span staking is then done in segments betweenthese control points.Some of these control points are definitely

fixed, and others allow some leeway that thestaking engineer may use to obtain desired spanlengths. Field conditions often make it necessary

to shift structure locations in a few spans or per-haps increase the height of an occasional poleto obtain the best average span length. Spanselection will be discussed in Section 4,Conductor Characteristics.The use of guyed angle structures increases

the cost of line construction as well as operationand maintenance. Generally, the fewer angles ina line, the more economical it is to build. Inmost cases, it is desirable to avoid a series ofsmall angles. This can be achieved by extendingthe straight line segments as far as possible.

UPLIFTIn laying out a line over rough country, it isdesirable to locate poles on the high points totake advantage of increased ground clearance. If it becomes necessary to locate a pole at a lowpoint in the line, a check should be made todetermine if the conductors will be subjected touplift. During cold weather, conductors will con-tract and approach their minimum sag values.Often this contraction will cause the conductorsto pull up on a pole that is on a lower elevationthan adjoining poles. This upward pull is knownas uplift and is shown in Figure 2.1; it must beconsidered in selecting the height of the structure.Uplift is one of the most frequently found stak-ing errors. Figure 2.2 shows uplift of conductors on an

RUS distribution structure. In staking lines over extremely rough sections

of country, it may be necessary to prepare aprofile of the route to determine uplift. This willrequire determining the elevation of the polesand the preparation of sag templates. This maybest be accomplished by the cooperative engi-neer or a consultant.Where extra-high poles are used at locations

such as crossings, it may be necessary to increasethe height of adjacent poles to prevent conduc-tor uplift. The poles should increase in height to

the maximum height required for the crossingpole and decrease in like manner, assuming thatthe ground beneath the affected spans is fairlylevel. Where sharp breaks occur in the topogra-phy, the pole heights should vary accordingly.This process is called “grading” the line.

ACCESSIBILITYWhen selecting a structure location, the stakingtechnician should consider accessibility to thesite by line construction crews, vehicles, andequipment. Terrain such as swamps, water -courses, deep ditches, and severe slopes willlimit accessibility. When possible, an alternativelocation should be selected to allow betteraccess to the work site. Remember, a contractormay build the line, but the cooperative will havethe responsibility of maintaining it.Another factor affecting accessibility to the

structure is landscaping. A site should be select-ed to avoid damage by vehicles and equipmentto lawns, ornamental plants, fences, and residen-tial driveways.Structure locations should also be selected to

avoid vehicle or equipment travel over or nearseptic tanks or associated septic lines.

OPERATIONAL RELIABILITY AND CONVENIENCEWhen selecting a route for the rebuild of anexisting line, the staking technician must deter-mine whether to rebuild the line in place ormove to a more desirable location.Relocating the line may provide for increased

reliability and convenience in operating the circuit.Factors affecting reliability and convenience

of operation include the following:

• Lines located in areas visible from roads allow for efficient and low-cost maintenanceinspections and the ability to swiftly locatedamaged structures and conductors.

• Lines located close to roads allow ease ofmaintenance and repair.

• Lines relocated from heavily wooded areas toalong road rights-of-way or other open areasprovide for reduced clearing and trimmingcosts as well as limiting danger to the conductors from limbs and trees.

F ie ld Staking Pract ices and Procedures – 5

2

FIGURE 2.1: Uplift on Structure.

FIGURE 2.2: Conductor Uplift.

Cold Curve Conductor, No Ice, No Wind,at Minimum Temp.

Uplift on This Pole

Uplift Is Eliminated bythe Use of a Taller Pole

When Possible, Pole MayBe Left Out Altogether



Shift This Pole as Much as Possible to Even Up Spans

It is the staking technician’s responsibility to select a route and specify structures that will result in the construction of a safe and reli-able distribution pole line for the lowest possi-ble cost. Factors directly affecting the cost of aline include:

• Size and quantity of poles• Types of assemblies• Span lengths• Quantity of guyed structures• Construction methods (energized or deadwork and/or accessibility)

Also, as seen above, the choice of structurelocation or line route adopted by the stakingtechnician has a significant influence on operat-ing and maintenance costs.When staking any distribution line, the techni-

cian must be aware of the cost of larger polesand angled construction versus smaller polesand straight-line construction. Also, as the areasbecome more populated, joint use becomesmore prevalent with telecommunication, cableTV, and possibly other utilities competing forspace on the cooperative’s poles. When stakinga new line or rebuilding an old line, joint usemust be carefully evaluated.

6 – Sect ion 2

2

Structure Selection

Mechanics of Staking

The final step in staking a distribution pole lineis the selection of the appropriate structure tosupport the conductors.Factors to be considered in determining the

structure include:

• Conductor size and type• Pole height and class• Type of pole-top assembly• Sizes and types of guys and anchors

The size of conductors should be determinedfrom the cooperative’s two-year work plan orlong-range plan, or by the cooperative engineeror a consultant. Once the size and type of con-ductor are established, it will control the selec-tion of the design tension and ruling span of the pole line. (Design tension and ruling span are discussed in Section 4, ConductorCharacteristics.)These factors combined will then form the

basis for the selection of poles, assemblies, guys,and anchors.

Poles must be chosen to provide adequate clear-ance and strength in supporting the conductors.Pole-top assemblies are selected on the basis

of conductor size and type and the configurationand voltage class of the circuit.Sometimes right-of-way restrictions may dic-

tate selection of the pole-top assembly, such asuse of vertical-type construction.Guys and anchors are used to provide lateral

support to prevent the structures from over-turning. Selection of these guys and anchorsdepends on the amount of unbalanced pull onthe structure, the length of the guy lead, thetype of pole-top assembly, and the soil type inwhich the anchor is installed.These factors regarding structure selection are

discussed in the following sections of this manu-al. Each item is considered a building block inthe total distribution pole line design package.It is important that the staking technician

understand each of these items in order toassemble these building blocks into a safe, reli-able, and efficient distribution pole line.

Actual staking requires procedures such as run-ning straight lines, measuring distances, andmeasuring line angles. The staking technician

should have a working knowledge of these pro-cedures and accurately apply them when layingout and setting stakes for a distribution pole line.

STAKING BETWEEN CONTROL POINTSAn engineer’s transit should be used to run the line between control points. As shown inFigure 2.3, the transit may be set up and leveledover one of the control points (A), if the otherpoint is visible. By taking a “foresight” on arange rod placed vertically at the other controlpoint (B), the line is established. A rodman thenproceeds from the transit position toward theother control point (B), and the transit operatorlines the rodman in at points along the linewhere poles are to be placed. A stake markedwith the pole number should be driven at eachpole location.If neither control point can be seen from the

other, the transit may be set up at some interme-diate point. This point may be on the top of aknoll midway along the centerline where rangerods set at each control point are visible. Thetransit is set up on a point estimated to be onthe centerline. A backsight is taken on one ofthe control points and then the telescope isreversed on its vertical axisand a foresight is taken onthe point ahead. A check isthen made to determine theextent to which the transitis left or right of the center-line. By repeating the aboveprocedure one or moretimes, the transit is finallyplaced on line. This processis sometimes called “bustin’in.” Once the transit loca-tion is established, interme-diate stakes can then be setby the rodman proceedingalong the centerline betweenthe control points. The tran-sit operator lines the rodmanin at eachpole location.There may

be some sec-tions of linebetween con-trol pointswhere it isdifficult to

line in range rods because of brush, trees, crops,or other obstacles. In such instances it may benecessary to run a parallel line along the edgeof a traveled road or clear area where visibilityis unobstructed. If so, a line may be run as pre-viously described and the structure locationsstaked. As shown in Figure 2.4, the intermediatepole stakes are located by measuring backtoward the span centerline at right angles to thetemporary offset line a distance equal to the off-set. If this method is used, care must be exercisedto make certain that the offset control points (A'and B') are at equal distances measured at rightangles to the original control points (A and B).For short distances and open terrain, range

rods may be used to establish a straight linebetween control points. As shown in Figure 2.5,a range rod is set at each of the two controlpoints A and B. An observer is stationed approx-imately 25 to 50 feet behind point A. A rodmanthen proceeds toward point B and is visuallylined in by the observer.


2

Transit

A

Offset Line

B

Rodman

FIGURE 2.3: Running a Line Between Control Points Using aTransit.

FIGURE 2.5: Use of Range Rods to Establish a Straight Line Between Control Points.

B

Rod

A

RodObserver Rodman

50'

Transit

A90°

90° 90°

90°

15'

15'

15'

15'

B'

B

Offset Line

Span CenterlineIntermediate Pole Stakes

Rodman

FIGURE 2.4: Location of Pole Stakes Using a Temporary OffsetLine.

A'

MEASURING DISTANCE USING ELECTRONIC DEVICESThe staking technician must accurately measurethe span lengths for the line section he or she isstaking. This has traditionally been done using ameasuring wheel or 100-foot tape. Now, tech-nology provides us with laser rangefinders andGPS (the Global Positioning System). Laserrangefinders emit a harmless laser beam thatreflects from a sighted object such as a pole andrecords the distance by determining the differ-ence in the speed of light from its emission to itsreturn. These devicesare especially useful tothe staking technicianif he or she must workalone. Accurate mea-surements can bemade even whendense brush prohibitsusing a measuringwheel or help isunavailable to pull a tape.Laser rangefinders

are available in several configurations. The moreelaborate ones look like pistol-type guns andhave an internal compass. These instruments notonly measure horizontal distances, but can alsoturn angles, measure heights, and calculate thedistance between two points. Simpler devicesmade for hunting and shooting are also veryuseful in staking lines and are less expensive.These rangefinders usually measure distance inyards and in some cases in feet and are limitedto 800 yards maximum or less, based on thereflective properties of the object sighted. The Global Positioning System, another elec-

tronic measuring technology, utilizes a set ofsatellites orbiting the earth that send signals to a GPS receiver and collection device. Using thisinformation, the GPS unit can determine its loca-tion using longitude and latitude coordinates.The accuracy of the location is dependent onthe quality of the receiver and the GPS collec-tion device. Many utilities are staking powerlines using GPS technologies by collecting thecoordinates of the poles and plotting these coor-dinates in mapping or drawing software. Once

plotted, it is possible to accurately measure distances and angles from the drawing.

MEASURING AND BISECTING LINE ANGLESWhen the distribution line changes direction, theangle of change must be accurately measured.The most precise method of measurement isaccomplished by using an engineer’s transit. The line angle measured is called the deflectionangle. This is the angle produced by the changein the direction of the line relative to the contin-uance of the original centerline. See Figure 2.6.

The following steps describe the measure-ment of a line (deflection) angle with a standardopen-type engineer’s transit:

STEP 1: Set transit up at point B.STEP 2: Set the transit horizontal degree scales

to zero and lock down the upper transit plate.

STEP 3: Invert the telescope and back sight on point A and lock down the lowertransit plate.

STEP 4: Plunge (flip) the telescope on the verti-cal axis to the normal position.

STEP 5: Loosen the upper transit plate androtate the telescope on the horizontalaxis until it aligns with point C.

STEP 6: Read the angle from the horizontaldegree scale.

After the angle has been measured, it must bebisected to determine the position of the anchors.The following steps describe the bisecting of

a line angle with a standard open-type engi-neer’s transit:

8 – Sect ion 2

2

Transit Deflection Angle (θ)

A C

B

FIGURE 2.6: Measuring the Deflection Angle Using a Transit.

STEP 1: Divide the measured line angle by 2.STEP 2: Subtract the answer from 90°.STEP 3: Rotate the upper transit plate or tele-

scope on the horizontal axis backthrough the previously turned deflec-tion angle to the degrees calculated inStep 2.

STEP 4: Position a rodman at the desired guylead distance and align the rod with thevertical cross hair.

STEP 5: Set the anchor stake.

Another method for measuring and bisectinga line angle is use of a surveyor’s chain or mea-suring tape as shown in Figure 2.7. This is asimpler method but not as accurate.

The following steps describe the measure-ment of a deflection angle using a surveyor’schain or measuring tape:

STEP 1: From point B (structurelocation), measure 57.5feet ahead along the con-tinuance of the originalcenterline and set a tem-porary point X in linewith points A and B. To provide acceptableaccuracy, the distance of57.5 feet must be used forthis method.

STEP 2: From point B, measure57.5 feet ahead along the

new line route toward the next struc-ture and set a temporary point (Y) inline with points B and C.

STEP 3: Measure the distance d between thetemporary points (X and Y) and readthe line angle (1 foot = 1°).

The angle may be bisected by using a surveyor’s chain or measuring tape as shown in Figure 2.8. The steps are:

STEP 1: From point B, measure an arbitrary dis-tance L back along the original center-line toward the last pole A and set atemporary point X.

STEP 2: From point B, measure the same dis-tance L ahead along the new linetoward the next pole (point C) and seta temporary point Y.

STEP 3: Measure the distance between X and Yalong the inside of the angle.

STEP 4: Divide the total distance by two and seta temporary point Z at the calculatedmidpoint between X and Y. Set a rangerod at point Z.

STEP 5: Proceed to the approximate anchorlocation at a point on the outside angleback of the pole and equal to thedesired guy lead distance (explained inSection 7, Guying Practices andProcedures).

STEP 6: Move laterally until alignment with thepole and the point Z range rod isobtained.

STEP 7: Set the anchor stake.


2

d

Distance “d”Equals DeflectionAngle1’ = 1°

A C

B

X

Y

57.5’

57.5’

FIGURE 2.7: Use of a Surveyor’s Chain or Measuring Tape for Measuring a Deflection Angle.

LL

A C

B

X Y

Anchor

Z

FIGURE 2.8: Use of a Surveyor’s Chain or Measuring Tapefor Bisecting a Deflection Angle.

MEASURING AND BISECTING A DEFLECTIONANGLE USING A HAND COMPASSThe staking technician working alone must beable to correctly measure and bisect deflectionangles. The hand compass is a useful tool toperform this task. Using this tool correctly andwithin its limitations can provide accurate anglemeasurements. Angles and bisect readings mea-sured with a good-quality hand compass areusually within one degree of readings madeusing a transit.Obtain a quality survey-grade hand compass.

Less expensive outfitter or army-type compasseswill not do the job as well or as easily as a survey-type compass. Select a compass that has the 180° reverse azimuth scale (Figure 2.9).This feature allows the viewer to read the direc-tion ahead on the scale when making a back-sight. This is readily seen when following thesteps in Figure 2.10. If the compass does nothave a 180° reverse, the viewer must subtract or add 180° to the backsight reading to get the

bearing for the line ahead.The viewer stands at point B and wants to

extend the line from point A to B to point C.The backsight is taken on point A (270°). To get the bearing to point C, 180° must be subtracted from the backsight reading (270° – 180° = 90°). If the compass has thereverse reading on the scale, the computation is unnecessary. Usually, the direct reading is inbold print and the 180° reverse is in lighter print.Figure 2.10 illustrates the procedure and

provides steps for measuring and bisecting lineangles with a 180° reverse-scale survey-gradehand compass. Formulas are provided to calculate the bisect angle from the compassreadings.

10 – Sect ion 2

2

Pole A

Pole C

Pole B

Anchor

∠θ

145°325°

180°

180°

162°

145°

0°

243.5°65.5°

FIGURE 2.10: Measuring and Bisecting a Deflection Angle with a Hand Compass.

A CB

90°270°

270°90°

FIGURE 2.9: 180° Reverse Compass Scale.

STEP 1: Imagine that you are in the center of a large circleencompassing the poles.

STEP 2: Stand at the center (Pole B) and establish a line ofsight between poles B and A.

STEP 3: Take the backsight (BS) on pole A (read the 180°reverse azimuth scale on the compass).

STEP 4: Remain at pole B, rotate your body 180°, and establish a line of sight between poles B and C.

STEP 5: Take the foresight (FS) on pole C (read the directazimuth scale on the compass).

STEP 6: Calculate the line angle: Take the arithmetic difference between the backsight and the foresight(larger number minus the smaller number).

STEP 7: Calculate the bisect azimuth for the guy/anchorusing the above formulas.

STEP 8: Move to the specified guy lead length and line yourbody up with the 180° reverse azimuth scale bisectreading and pole B. Establish the anchor location.

Bisect Angle FormulasBCTRT = FS – (90º + ∠θ/2)BCTLT = FS + (90º + ∠θ/2)

BCTRT = Bisect ∠ right turnBCTLT = Bisect ∠ left turnFS = ForesightBS = Backsight∠θ = Deflection angle

BS = 145ºFS = 162º∠θ = 162º–145º∠θ = 17º RT

BCTRT = FS – (90º + ∠θ/2)BCTRT = 162º – (90º + 17º/2)BCTRT = 162 – 98.5BCTRT = 63.5º

270° 90°

MEASURING CHANGES IN GROUNDELEVATIONSTo properly select pole heights to prevent upliftand excessive downstrain, it may be necessaryfor the staking technician to measure the amountof change in elevation of the ground beneaththe proposed distribution line. This can some-times be done simply by observing the profile ofthe terrain and estimating the rise and fall in feet.However, topography can be deceiving, and theabove “eyeball” method may not provide thedegree of precision necessary for the propergrading of the line.A reasonably accurate method acceptable for

determining changes in grade elevation of proj-ects not requiring a high degree of precision isthe measurement by use of a hand level or cli-nometer. The observer first measures the H.I.(the height of the instrument, hand level, at theobserver’s eye above the ground) with a mea-suring tape. For leveling uphill, adjust the instru-ment to zero and take a sight in the direction oftravel. The point at which a level line of sightstrikes the ground will have the same elevationas the observer’s H.I. For example, if the observ-er’s H.I. is 5 feet, the observed point is 5 feethigher than the ground beneath the observer’sfeet. After identifying this point on the ground,the observer moves to that point and takes

another sight. This procedure is repeated untilthe top of the rise is reached or the final mea-surement is determined for a designated point.More accurate measurements can be obtainedby using a measured staff or range rod as a support for the hand level.If the final level sight is observed to be some

distance above the top of the rise, a range rodmay be set and the final sight taken. Range rodsare painted with alternate orange and whitebands of 1 foot each. Record where the level sightstrikes the range rod. Simply subtract the feetabove the top of the rise from the H.I. to dete r -mine the change in elevation. See Figure 2.11.For leveling downhill, reverse the above pro -

cess. As can be seen, a range rod or other gradu-ated device will be required to level downhill.

USE OF STAKING TABLESThe staking table is a design aid used in thefield staking of overhead distribution lines. Itreduces the time and effort required to stake aline. It serves the same purpose as plotting a planand profile of the span and then applying a sagtemplate curve to determine the height of polesnecessary to provide the required clearance.The staking table gives a range of permissible

maximum span lengths for the span betweentwo identical pole structures. These span lengths

are controlled by the change in ground ele-vation below the conductor. A typical stak-ing table includes ground elevation valuesin feet for both rise and depression, andthey are usually shown as positive or nega-tive numbers.Table 2.1 is an example of a typical distri-

bution line staking table. The base structureis a 35-foot pole with an A1, B1, or C1 pole-top assembly. The controlling conductor isthe 2 ACSR neutral. The midspan clearanceis based on 18 feet plus a 1-foot stakingand construction tolerance. The maximumoperating temperature for the conductor is120°F, and the design tension is 45.3% or1,292 lb. The ruling span is 325 feet. Thetable is based on conductor characteristicsfor the medium loading district.Using 35-foot poles, it can be seen from

Table 2.1 that the span length for a level


2

A

Observer

C

D

B5'

5'

3 1/2'

1 1/2'

FIGURE 2.11: Determination of Change in Elevation.

Change in elevation from point C to point D iscalculated by subtracting the measurementmade on the rod from the observer’s H.I.

5' – 1 1/2' = 3 1/2'

Total change in elevation from point A topoint D is calculated by summing the different sights.

5' + 5' + 3 1/2' = 13 1/2'

12 – Sect ion 2

2PHASE NEUTRAL

Conductor Description No. 2(6/1) ACSR No. 2(6/1) ACSRMax. Operating Temperature 120°F 120°FBasic Ground Clearance 20 feet 18 feetDesign Tension 1292 lb (45.3%) 1292 lb (45.3%)

325-Foot Ruling Span Medium Loading District

For Use With A1.1, B1.11, and C1.11 Type Assemblies(ALL DISTANCES ARE IN FEET)

35-foot Poles 40-foot Poles

Quarter Point Center Span Center Quarter Point Upliftof Span of Span Length of Span of Span Factor

5.4 5.0 244 10.0 10.4 2.05.0 4.5 268 9.5 10.0 2.74.7 4.0 289 9.0 9.7 3.34.4 3.5 309 8.5 9.4 3.94.1 3.0 328 8.0 9.1 4.53.7 2.5 347 7.5 8.7 5.23.4 2.0 365 7.0 8.4 5.83.1 1.5 382 6.5 8.1 6.52.7 1.0 399 6.0 7.7 7.12.4 0.5 415 5.5 7.4 7.82.1 LEVEL 0.0 431 5.0 7.1 8.51.7 –0.5 447 4.5 6.7 9.21.4 –1.0 462 4.0 6.4 9.91.1 –1.5 477 3.5 6.1 10.60.7 –2.0 492 3.0 5.7 11.40.4 –2.5 506 2.5 5.4 12.10.0 –3.0 520 2.0 5.0 12.8

–0.3 –3.5 533 1.5 4.7 13.5–0.6 –4.0 547 1.0 4.4 14.3–1.0 –4.5 560 0.5 4.0 15.0–1.3 –5.0 573 LEVEL 0.0 3.7 15.8–1.7 –5.5 586 –0.5 3.3 16.5–2.0 –6.0 598 –1.0 3.0 17.3–2.3 –6.5 611 –1.5 2.7 18.1–2.7 –7.0 623 –2.0 2.3 18.8–3.0 –7.5 635 –2.5 2.0 19.6–3.4 –8.0 647 –3.0 1.6 20.4–3.7 –8.5 658 –3.5 1.3 21.2–4.1 –9.0 670 –4.0 0.9 21.9–4.4 –9.5 681 –4.5 0.6 22.7–4.8 –10.0 692 –5.0 0.2 23.5

• Table 2.1 includes a 1-foot staking and construction tolerance in addition to the basic clearances. It also includes a 1-footuplift factor tolerance.

• This table may be used for any phase conductor whose maximum temperature is 120°F or less, and whose 60°F final sag in a 325-foot span is less than or equal to 2.7 feet.

TABLE 2.1: Typical Distribution Line Staking Table

ground condition is 431 feet. The other spansrange from 244 feet for a rise at midspan of 5feet to 692 feet for a depression of 10 feet. Thetable also provides the value of rise or depres-sion at the quarter span points that per mits thesame span length. Also shown are the midspanand quarter-span rise and depression values thatpermit the same span length when using thenext longer pole length of 40 feet.The last column in the staking table shows

the uplift factor for the designated span length.It represents values that are minimum midspansags for spans twice the length of the span withwhich the value is associated on the stakingtable, since the sag of a span equals twice itslength. See Figure 2.12. If the center pole is notat midspan, the uplift factor must be interpolated.To do this, find the uplift factors for each of thespans and average the two values to producethe uplift factor for the center pole.Many variables must

be considered in thepreparation of stakingtables. Each coopera-tive should decide onthe basic parametersthat best suit its system and standard construc-tion and request thestaff engineer or consulting engineer to prepare stakingtables accordingly.

MARKING THE ROUTE AND STRUCTURE LOCATIONStakes should be set at each structure locationalong th

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