UNITED STATES DEPARTMENT OF AGRICULTURE

Rural Utilities Service

BULLETIN 1724E-214 

RD-GD-2019-96

SUBJECT: Guide Specification for Standard Class Steel Transmission Poles

TO: RUS Electric Borrowers, Consulting Engineers, and RUS Electric Program Staff 

EFFECTIVE DATE: Date of Approval 

OFFICE OF PRIMARY INTEREST: Engineering Standards Branch, Electric Program 

FILING INSTRUCTIONS: This bulletin replaces RUS Bulletin 1724E-214, "Guide

Specification for Standard Class Steel Transmission Poles" issued March 23, 2017. 

AVAILABILITY: This bulletin can be accessed via the Internet at: 

https://www.rd.usda.gov/publications/regulations-guidelines/bulletins/electric

PURPOSE: This bulletin provides guidance for procuring standard class steel poles for 

transmission applications. 

 April 9, 2019

Christopher A. McLean Date

Assistant Administrator, 

Electric Program

Disclaimer: The contents of this guidance document does not have the force and effect of law and is not 

meant to bind the public in any way. This document is intended only to provide clarity to the public 

regarding existing requirements under the law or agency policies.
Bulletin 1724E-214 

Page ii

ACKNOWLEDGMENTS

The following current and former members of the Transmission Line Subcommittee of the 

National Rural Electric Cooperative Association, Transmission and Distribution Engineering 

Committee provided invaluable assistance in preparing this document: 

Ballard, Dominic, East Kentucky Power Coop., Winchester, KY

Beadle, Bob, North Carolina EMC, Raleigh, NC 

Beckett, Thomas, TL Beckett Consulting Engineers, Marietta, GA

Bertelsen, James, Dairyland Power Cooperative, La Crosse, WI 

Caldwell, Art, Georgia Transmission Corporation, Tucker, GA 

Harvey, Gary, East Kentucky Power Cooperative, Winchester, KY

Johnson, Wilson, USDA, Rural Utilities Service, Electric Program, Washington, DC 

Kahanek, Bil, McCord Engineering, Inc., College Station, TX 

Lukkarila, Charles, Great River Energy, Maple Grove, MN 

McAndrew, Jeremy, South Mississippi Electric Power Assoc., Hattiesburg, MS 

Metro, Patti, National Rural Electric Cooperative Association, Arlington, VA 

Nordin, Bryan, Tri-State Generation & Transmission Association, Inc., Denver, CO 

Ruggeri, Erik, Power Engineers, Hailey, ID 

Shambrock, Aaron, South Central Power Company, Lancaster, OH

Twitty, John, PowerSouth Energy Cooperative, Andalusia, AL 

Woodruff, Paul, Great River Energy, Maple Grove, MN 

Zhang, Chendi, USDA, Rural Utilities Service, Electric Program, Washington, DC 
Bulletin 1724E-214 

Page iii

BLANK PAGE
Bulletin 1724E-214

Page iv

TABLE OF CONTENTS

Instructions............................................................................................................................vii-x

Technical Specifications....................................................................................................... 1-24

1 Scope .....................................................................................................................................1

2 Definitions.............................................................................................................................1

3 Codes and Standards ........................................................................................................... 3

4 Conflicts between Specifications, Drawings, and Reference Documents .......................... 5

5 General Requirements......................................................................................................... 5

6 Shipping and Delivery.........................................................................................................17

7 Drawings and Information to Be Supplied by Manufacturers ............................................17

8 Approvals, Acceptance and Ownership .............................................................................19

9 List of Attachments to This Specification...........................................................................19

Attachment A - Structure Dimensions and Pole Framing Drawings ..................................20

Attachment B - Application Requirements ........................................................................22

Attachment C - Standard Class Steel Pole Bid Summary...................................................24

Appendix A - Commentary

Appendix B - Examples of Drawings

Appendix C - Design Examples

Appendix D - Selected Metric Conversions 
Bulletin 1724E-214

Page v

ABBREVIATIONS

ACA Ammoniacal Copper Arsenate

ACSR Aluminum conductor steel reinforced

ACZA Ammoniacal Copper Zinc Arsenate

ANCO American Nut Company 

AISC American Institute of Steel Construction

ANSI American National Standards Institute

ASCE American Society of Civil Engineers 

ASTM American Society for Testing and Materials

AWS American Welding Society

CCA Chromated Copper Arsenate

DFT Dry Film Thickness

Eq. F Equivalency Factor

HSS High Strength Steel

kV kilovolt

ksi kips (1000 lb.) per square inch

mph miles per hour

LF Load factor

NACE National Association of Corrosion Engineers

NESC National Electrical Safety Code

NEMA National Electrical Manufacturers Association

OHGW Overhead ground wire

psf pounds per square foot

psi pounds per square inch

UNC unified coarse threads

RUS Rural Utilities Service

SSPC Steel Structure Painting Council
Bulletin 1724E-214

Page vi

DEFINITIONS

Borrower – An entity which borrows or seeks to borrow money from or arranges financing with 

the assistance of the Rural Utilities Service through guarantees, lien accommodations or lien 

subordinations.

RUS Form 198 – Equipment Contract.

Rural Utilities Service (RUS) – An Agency of the United States Department of Agriculture, 

under Rural Development.

INDEX:

 Materials and Equipment: Guide Specifications for Standard Class Steel Poles

 Poles: Steel

 Specifications and Standards: Guide Specifications for Standard Class Steel Poles.

 Transmission Facilities: Poles (Steel)
Bulletin 1724E-214 

Page vii

INSTRUCTIONS WHEN USING THE GUIDE SPECIFICATIONS

FOR STANDARD CLASS STEEL TRANSMISSION POLES

1. PURPOSE

The intent of this guide specification is to provide Rural Utilities Service (RUS) Electric 

Program borrowers a basis for procuring standard class steel poles for transmission 

applications. Use of this specification should help eliminate ambiguities that might arise 

in the evaluation process of competitively bid standard class steel poles procurements. 

Borrowers or their engineering representatives will need to complete this specification 

and add documents as appropriate. Modifications to this specification may be necessary 

to consider special applications or preferences of the owner. 

2. SCOPE 

This suggested purchase specification covers the technical aspects of design, materials, 

manufacturing, inspection, testing, and delivery of direct embedded standard class steel 

poles. It is recommended that this specification be limited to single poles that are not 

guyed, not subjected to unbalanced lateral loads, or do not have unusual deflection or 

other special limitations. For applications that consider these items, it is recommended 

that the owner use “Guide Specifications for Steel Single Pole and H-Frame Structures,” 

RUS Bulletin 1724E-204. 

This guide specification does not include contract (front-end) documents or specifications 

for construction. The user of this specification should add these documents, including 

general conditions and any supplemental instructions to the bidders. This specification 

may be expanded to include H-frame structures.

3. INITIAL DESIGN CONSIDERATIONS

There are engineering decisions required of the user of this specification to determine 

which standard class steel poles to specify. Some examples include, but are not limited to: 

• Amount of foundation rotation in contributing to P-delta moments; 

• Location of point of fixity; 

• Embedment depths; 

• Load cases to be considered in addition to those required by the National 

Electrical Safety Code (NESC); and 

• Deflection limitations.

Prior to the selection of a standard class pole, the user should perform the engineering 

required for these types of issues or employ an engineering consultant to do so. See 

Appendix A of this bulletin for a discussion of some of these items. 
Bulletin 1724E-214

Page viii

4. INFORMATION TO BE COMPLETED BY THE OWNER

Users of these specifications should detach the instructions and the Appendices, and add 

or complete the following:

a. Documents and general information to be added to the technical specification:

Front-end documents and general information which need to be added to this

technical specification.

• RUS Form 198, Equipment Contract (Recommended for competitive bidding)

• Supplemental Instructions to Bidders

• General Conditions

When there is competitive bidding, it is recommended that RUS Form 198 be 

used. This form covers Notice and Instructions to Bidders, Proposal, and 

Equipment Contract. For the 2nd item above, Supplemental Instructions, the user 

may want to add such items as Bid Submission, Bid Price and Schedule, Bid 

Acceptance Period, Bid Requirements, and Bid Data. A section on General 

Conditions could include such items as Definition of Terms, Interpretation of Bid 

Documents, Addenda to the Bid Documents, Insurance, Method of Payment (if 

RUS Form 198 is not used), Quantities, and Tabulation of Unit Prices.

b. Requirements to the technical specifications to be added or completed by the owner 

or owner’s representative and supplied to the bidders include:

(1) Configuration requirements and other information (Attachment A of the 

Specification or equivalent):

• Pole Length

• Pole Class

• Pole Framing (Pole attachment requirements)

• Embedment Depths

(2) Strength requirements and standard class designations for steel poles

This specification establishes standard steel pole sizes. The engineer in the 

design process needs to select the appropriate standard class pole from 

Table 1 based on loading requirements and a calculated load 2 feet from 

the top.

Minimum design loads have to meet NESC requirements which are 

appropriate for the loading district, the NESC extreme wind load 

provisions, NESC extreme ice with concurrent wind and any necessary 

extreme ice and wind conditions with the appropriate load factors and any 

local codes. The design loads account for all loading cases, including wind 

on pole and secondary stresses from foundation deflection and rotation, and 

from vertical loads acting on lateral pole deflection (P-delta effect).
Bulletin 1724E-214

Page ix

The American Society of Civil Engineers (ASCE) Guidelines for Electrical 

Transmission Line Structural Loading can be used for developing loads 

produced by climate, accidents, construction and maintenance. 

Calculations need to include the vertical, transverse, and longitudinal loads 

with wind on the structure and the dead weight of the structure for any 

given loading condition applied simultaneously. All loads require 

appropriate load factors.

(3) Application Requirements (Attachment B of the Specification to be 

completed by the owner.)

• Type of pole finish.

• Special Charpy requirements.

• Desired method of surface protection.

• Preference of climbing ladders, steps or stepbolts. Also, quantity of 

removable ladders, steps or step bolts to be supplied with the total order 

of poles should be specified. 

• Location of climbing and /or working ladders or step bolts.

• Ground collar 

• Pole grounding method.

• Delivery schedule, and free on board destination, and owner’s contact. 

• Miscellaneous additional items such as special attachments 

requirements, climbing devices, hot line maintenance requirements 

switch operating mechanisms, location of bolt holes for other 

equipment requirements.

• Pole tests (if required).

5. INFORMATION TO BE COMPLETED BY THE MANUFACTURER

a. The owner or owner’s representative should have the following information 

completed and submitted by each bidder (Attachment C of this specification or 

equivalent).

(1) Design information (Pole Framing Drawing and length). This will 

demonstrate conformance with the design needs.

(2) For each standard class steel pole, provide the diameter at the top, at the 

ground line, and at the bottom, plus the pole taper. This will demonstrate

conformance with the requirements of paragraph 5.a.(2)(c).

(3) For each standard class steel pole, provide the following general 

information: the weight of each pole; the tip load of each pole class; the 

location of the point of fixity; the type of steel according to American 

Society of Testing and Materials (ASTM) number and yield; the pole cross 

sectional shape; and the connection details for multiple piece poles 
Bulletin 1724E-214

Page x

(slip/flange joints). This will demonstrate conformance with the 

requirements of paragraphs 5.a.(1), 5.a.(2), 5.a.(3), and 5.a.(6).

(4) For each standard class steel pole, provide the following calculations at 

the ground line: Moment, Shear, Axial load, and Cross-sectional area. 

This will demonstrate conformance with the requirements of section 5.a. 

(5) For each standard class steel pole, provide the following calculations at 

the point of fixity: Moment, Shear, Axial load, and Cross-sectional area. 

This will demonstrate conformance with the requirements of section 5.a. 

(6) For each standard class steel pole, provide the wall thickness at the pole 

top, ground line, and bottom. This may be provided in catalog form.

(7) For each standard class steel pole provide the pole top deflection due to 

design load.

b. Documentation which the successful bidder needs to supply for approval by 

owner or owner's representative prior to manufacture of the pole include:

(1) Description of pole including geometry, thickness, length, diameter, taper, 

and hole locations.

(2) Complete design/erection reproducible drawings for each pole class.

(3) Anticipated deflection of pole at specified tip load.

(4) Connection and Assembly Details on multiple piece poles.

c. Test reports (as requested by the owner).
Bulletin 1724E-214 

Page xi

BLANK PAGE

Bulletin 1724E-214 

Page 1

SPECIFICATIONS FOR STANDARD CLASS STEEL TRANSMISSION POLES

1. SCOPE: This specification covers the design, materials, welding, inspection, protective 

coatings, drawings and delivery of unguyed standard class, direct embedded, steel 

transmission poles. The poles are to be used in single pole, unguyed situations. 

2. DEFINITIONS

Appurtenance – Any hardware or structural members that are attached to the pole to make 

a complete structure.

Bearing Plate – A plate at the base of the pole that is intended to transfer the vertical loads 

of the pole. 

Charpy Impact – The impact properties of the material which are used to evaluate the 

susceptibility of structural steel to brittle fracture. See ASTM A370 and ASCE 48 for 

details. 

Crook – A localized deviation from straightness that causes the centerline of one section of 

the pole not to align with the centerline of another section of the pole. 

Circumferential Weld /C-weld – A weld perpendicular to the long axis of a structural 

member.

D/t – The ratio of the diameter of a tubular pole to the plate thickness. 

Engineer – A registered or licensed person, who may be a staff employee or an outside 

consultant, and who provides engineering services. Engineer also includes duly authorized 

assistants and representatives of the licensed person.

Ground Collar – An additional steel plate jacket that encapsulates the portion of the buried 

pole immediately above and below the groundline.

Group of Bolt Holes – All of the holes in which an appurtenance will be attached.

Guyed Structure – A structure in which cable supports are used to increase its lateral load 

resistance.

Groundline – A designated location on the pole where the surface of the ground will be 

after installation of a direct embedded pole. The groundline location will be used to locate 

the ground collar and other attachments to the pole. 

Flanged Connection/splice – A bolted type connection. 

Factored Load – The maximum design load that includes the appropriate load factor 

specified.
Bulletin 1724E-214

Page 2

In-Line Face – The face of the pole which “faces” an adjacent structure in the line.

Longitudinal Weld – A weld parallel to the long axis of a structural member.

Manufacturer – The company responsible for the fabrication of the poles. The 

manufacturer fabricates the poles based on the design drawings developed by the structural 

designer, which is the manufacturer’s engineer responsible for the structural design of the 

poles. 

Load Factors (LF) – A multiplier, which is applied to each of the vertical, transverse and 

longitudinal structure loads to obtain a factored load.

Owner – The Rural Utilities Service borrower or owner's representative.

P-delta (P-∆) Moment – A measure of the increase in bending moment resulting from a

structure’s displacement under load.

Pole Height – For this bulletin, this term is used interchangeably with pole length.

Pole Length – The length from the pole top to the bearing plate on the pole bottom. 

Pole Sweep – The measure of deviation from straightness along the length of the pole.

Point of Fixity – The point where the maximum moment occurs. The actual location of 

this point is dependent on the characteristics of soils around the embedded portion of the 

pole. For this specification it will be assumed to be equal to 7 percent of the pole length.

Pole Twist – spiral rotation of a pole section relative to the pole end. It is caused by the 

residual stress in the steel as received from the mill, the clamping force holding the tube 

shells together and the heat applied during the seam welding process.

Slip Connection/splice – A telescoping type connection of two tapered tubular pole 

sections.

Standard Class Pole – A direct embedded steel pole that is designed according to a 

standardized strength and loading criteria established by the owner.

Taper – The change in diameter of a tubular section from its base to its top.

Tip Load – The horizontal load that is applied to the standard class pole at a distance of 2 

feet from the pole top.

Yield Strength – The minimum stress at which a material will start to physically deform 

without further increase in the load or which produces a permanent 0.2 percent 

deformation. This is also known as the elastic limit of the material.
Bulletin 1724E-214

Page 3

Ultimate Moment Capacity – The moment that is developed in the pole at the time the 

yield strength of the pole is realized.

w/t – Ratio of a flat width of a multisided pole to the thickness of the steel plate.

Weathering Steel – Steel that conforms to ASTM A588 or A871. This steel forms a 

natural protective oxide layer on the surface. 

3. CODES AND STANDARDS 

Codes, standards, or other documents referred to in this specification shall be considered as 

part of this specification. The following codes and standards are referenced:

a. American Institute of Steel Construction (AISC), “Specification for the Design, 

Fabrication and Erection of Structural Steel for Buildings,” latest edition. 

b. American Society of Civil Engineers (ASCE) Standard, “Design of Steel 

Transmission Pole Structures,” ASCE 48, latest edition.

c. American Society of Testing and Materials (ASTM), various standards, latest 

revision. Referenced ASTM specifications:

A6/A6M Specification for General Requirements for Rolled Structural Steel 

Bars, Plates, Shapes, and Sheet Piling

A36/A36M Specification for Carbon Structural Steel

A123/A123M Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and 

Steel Products

A143 Practice for Safeguarding Against Embrittlement of Hot-Dip 

Galvanized Structural Steel Products and Procedure for Detecting 

Embrittlement

A153/153M Specification for Zinc Coating (Hot-Dip) on Iron and Steel 

Hardware

A325 Specification for High-Strength Bolts for Structural Steel Joints

A354 Specification for Quenched and Tempered Alloy Steel Bolts, 

Studs, and Other Externally Threaded Fasteners

A370 Test Methods and Definitions for Mechanical Testing of Steel 

Products
Bulletin 1724E-214

Page 4

A384 Practice for Safeguarding Against Warpage and Distortion During 

Hot-Dip Galvanizing of Steel Assemblies

A570/A570M Specification for Steel, Sheet and Strip, Carbon, Hot-Rolled, 

Structural Quality

A572/A572M Specification for High-Strength Low-Alloy ColumbiumVanadium Structural Steel

A588/588M Specification for High Strength Low-Alloy Structural Steel with 

50 ksi Minimum Yield Point to 4 in. Thick

A595 Specification for Steel Tubes, Low-Carbon, Tapered for Structural 

Use

A607 Specification for Steel, Sheet and Strip, High-Strength, LowAlloy, columbium or Vanadium, or Both, Hot-Rolled and ColdRolled

A673/A673M Specification for Sampling Procedure for Impact Testing of 

Structural Steel

A871/A871M Specification for High Strength Low-Alloy Structural Steel Plate 

with Atmospheric Corrosion Resistance

B695 Specification for Coatings of Zinc Mechanically Deposited on Iron 

and Steel

B696 Specification for Coatings of Cadmium Mechanically Deposited

d. American Welding society (AWS), Structural Welding Code, AWS D1.1, latest 

edition.

e. American National Standards Institute (ANSI), National Electrical Safety Code, 

ANSI C2, latest edition.

f. Society for Protective Coatings (SSPC, formerly Steel Structure Painting Council)/ 

National Association of Corrosion Engineers (NACE) Surface Preparations 

Specification, SSPC/NACE SP-6/NACE 3. 
Bulletin 1724E-214

Page 5

4. CONFLICT BETWEEN THIS SPECIFICATION, DRAWINGS, AND 

REFERENCES DOCUMENTS 

In the event of conflict between this specification and the above referenced documents, the 

requirements of this specification shall take precedence. In the case of conflict between 

several referenced documents, the most stringent requirement shall be followed. If a 

conflict exits between this specification or the referenced documents and the attached 

drawings, the attached drawings shall be followed. If clarification is necessary, contact the 

owner.

5. GENERAL REQUIREMENTS

The design, fabrication, allowable stresses, processes, tolerances, and inspection shall 

conform to ASCE Standard, “Design of Steel Transmission Pole Structures” (ASCE 48), 

latest edition, with the following additions and/or exceptions: 

a. Design Requirements

(1) Pole designs shall be prepared for the attached Standard Class design loads. 

The poles shall be designed to meet ASCE 48, “Design of Steel 

Transmission Pole Structures”, design methods. The point-of-fixity shall be 

considered to be located at a distance from the pole bottom that is equal to 7 

percent of the pole length. The pole shall be symmetrically designed such 

that the strength required in any one direction shall be required in all 

directions about the longitudinal axis. 

(2) Using the corresponding values in Table 1, the poles shall be designed for 

the following requirements as illustrated by Figure 1.

(a) The pole shall develop the minimum ultimate moment capacity 

required in Table 1 at a distance of five feet from the pole top.

(b) The pole shall develop the minimum ultimate moment capacity 

above the point-of-fixity that is calculated by multiplying the tip 

load in Table 1 by the distance to the tip load. 

(c) The geometry and taper of the pole shall be uniform throughout their 

entire length (top to butt). 
Bulletin 1724E-214

Page 6

Figure 1

Minimum Ultimate Moment Capacity Diagram along the Pole

(Tip Load X D)

Point-of-Fixity

Owner Defined

Groundline

Pole Butt

5'

D

Pole Top

2'

Load

Tip

By Section 5.1.2.(c)

Strength Governed

Strength Governed

By Section 5.1.2.(b)

Strength Governed

By Section 5.1.2.(a)

Min. 

Ultimate

Moment 

Capacity

(3) The poles shall be designed to withstand the specified tip loading in Table 1 

without exceeding a pole deflection of 15 percent of the pole length above 

the point of fixity when tested in accordance with ASCE 48.

(4) Overall length of poles shall be designed and manufactured in incremental 

lengths of 5 feet.
Bulletin 1724E-214

Page 7

Table 1

Strength Requirements

Standard Class

Designations for

Steel 

Poles

Minimum

Ultimate Moment

Capacity At Five Feet From 

Pole Top

(Ft.–Kip)

Horizontal

Tip Load

Applied 2 Ft from Pole Top

(Lbs.)

S-12.0 96 12,000

S-11.0 88 11,000

S-10.0 80 10,000

S-09.0 72 9,000

S-08.0 64 8,000

S-07.4 57 7,410

S-06.5 50 6,500

S-05.7 44 5,655

S-04.9 38 4,875

S-04.2 32 4,160

S-03.5 27 3,510

S-02.9 23 2,925

S-02.4 19 2,405

S-02.0 15 1,950

(5) Poles shall be designed for the loads generated from handling and erecting 

without causing permanent deformation or damage to the pole when 

handled according to the manufacturer’s instructions. Handling and erecting 

loads shall include but not be limited to, a one-point (tilting) pickup and a 

two-point (horizontal) pickup.

(6) The maximum design unit stress shall be the minimum yield strength as 

stated in applicable ASTM specifications for the particular application and 

types of loads, including load factors.

(7) Minimum plate thickness for all pole components shall be 3/16 inch.

(8) The owner shall provide the pole manufacturer with the load capabilities, 

attachment method, and attachment location of the appurtenances. The pole 

manufacture shall verify that the pole will not have a localized strength 

problem at the attachment point.

(9) All poles shall have bearing plates. Bearing plates shall have diameter not 

more than 2 inches greater than the maximum diameter at the pole butt.

(10) Galvanized poles shall have a drain hole at the bottom. This hole shall not 

be greater than 20 percent of the bottom plate surface area. 
Bulletin 1724E-214

Page 8

(11) Grade and type of steel shall be uniform for the poles.

(12) Ground collars to protect the pole groundline area from corrosive 

environments are required per Attachment B. Length of the ground collar 

shall be as specified in Attachment B.

(13) Ground collars shall have a minimum thickness of 3/16 inch; shall be 

centered at the groundline; and shall not be considered in strength 

calculations. A seal weld shall be provided around the ground collar at the 

top and bottom of the ground collar.

(14) The top of the pole shall be permanently covered with a structural steel 

plate that is bolted or otherwise permanently attached to the pole. The pole 

shall be delivered with the pole cover attached in place. 

(15) Lifting lugs are optional. The manufacturer shall supply all guidelines for 

handling and erection of poles and arms.

(16) In the design of connections for vangs, brackets, or stiffeners attached to the 

pole shaft, care shall be taken to distribute the loads sufficiently to protect 

the wall of the pole from local buckling.

(17) Weathering steel structures shall be designed to eliminate water and refuse 

traps. The tubular sections shall be sealed from moisture entering the inside 

of the pole. Factory drilled holes shall be plugged to prevent moisture 

intrusion during shipping. Connections shall be designed to reduce the 

effect of pack-out by preventing moisture from entering the joint or by 

designing the connection to allow moisture to easily drain off.

(18) Plastic plugs shall be installed in all nuts welded to the structure and all 

tapped holes.

(19) Pole design and design calculations shall be the responsibility of the 

manufacturer.

(20) Poles shall be designed with the minimum number of joints.

(21) Field welding is not normally permitted. In rare instances, it will be 

permitted to make minor repairs. All welds must be approved by the owner 

and must follow the manufacturer’s direction. 

(22) Flange connections for weathering steel poles shall be designed to avoid 

pack-out.

(23) Application requirements: (See Attachment B of this Specification)
Bulletin 1724E-214

Page 9

b. Materials 

(1) All materials shall comply with the applicable requirements of ASTM 

specifications. Any modifications from ASTM specifications must be 

approved by the owner or the owner’s representative.

(2) Steel utilized for the purposes of making poles shall conform with the 

following ASTM Specifications: ASTM A36, ASTM A570, ASTM A572, 

ASTM 588, ASTM A607, ASTM A871 or ASTM A595, and must be 

qualified to the requirements contained in ASTM A6/A6M-96b.

(3) Structural plate, and weld material, shall conform to ASTM A370 and 

ASCE 48. Plates shall be heat-lot tested in conformance with ASTM A 673 

Charpy V-Notch Impact test for properties of 15 ft-lbs. at –20°F.

(4) For galvanized structures, steel used for the pole shaft and arms shall have a 

silicon content less than .06 percent.

(5) Bolts and nuts shall conform, as applicable to ASTM A307, ASTM A325, 

and ASTM A354. Locknuts or American Nut Company (ANCO) type selflocking nut shall be provided for each bolt. Locknuts shall be the 

galvanized MF type or ANCO type. Other types of nut locking devices 

must be approved by the owner.

c. Fabrication

(1) All welding shall be in accordance with the American Welding Society 

Code AWS D1.1, latest edition. Welders shall be qualified in accordance 

with AWS D1.1 welding procedures.

(2) One hundred percent penetration welds shall be required in, but not limited 

to, the following areas:

• Circumferential welds (C-welds) joining structural members;

• Longitudinal welds in the female portion of the joint within the slip joint 

area plus 6 inches;

• Welds at butt joints with back-up strips; and

• Longitudinal welds within 3 inches of C-welds, flange welds, base 

welds and ends of tubes.

(3) Full penetration, or equivalent 90 percent partial penetration with fillet 

overlay to develop the shaft capacity, shall be used for arm-to-arm brackets, 

vang-to-plate reinforcement, and arm box joints.
Bulletin 1724E-214

Page 10

(4) Quality and acceptability along the entire length of full penetration welds 

shall be determined by visual and ultrasonic inspection. 

(5) All other penetration welds shall have 60 percent minimum penetration. 

Quality and acceptability of all welds other than full penetration welds shall 

be determined by visual inspection, supplemented by magnetic particle, 

ultrasonic, or dye penetrant inspection. 

(6) All weld back-up strips shall be welded continuous for the length of the 

welds. Care shall be exercised in the design of welded connections to avoid 

areas of high stress concentration that could be subject to fatigue or brittle 

fractures.

(7) Field welding shall not be permitted except with owners, or owner’s 

representative’s approval, and the manufacturer’s direction in repairing the 

pole.

(8) All parts of the pole shall be neatly finished and free from kinks or twists. 

All holes, blocks, and clips shall be made with sharp tools and shall be 

clean-cut without torn or ragged edges.

(9) Before being laid out or worked in any manner, structural material shall be 

straight and clean. If straightening is necessary, it shall be done by methods 

that will not compromise the steel.

(10) Shearing and cutting shall be performed carefully and all portions of the 

work shall be finished neatly. Copes and re-entrant cuts shall be finished 

neatly. 

(11) All forming or bending during fabrication shall be done by methods that 

will prevent embrittlement or loss of strength in the material being worked.

(12) Holes for connection bolts shall be 1/8 inch larger than the nominal 

diameter of the bolts. Holes in the flange plates for bolted splices shall be 

1/8 inch larger than the bolt diameter. The details of all connections and 

splices shall be subject to the approval of the owner or the owner’s 

representative.

(13) Holes in steel plates which are punched must be smooth and cylindrical 

without excessive tear out or depressions. Any burrs that remain after 

punching shall be removed by grinding, reaming, etc.

(14) Holes of any diameter may be drilled in plate of any thickness. Care shall 

be taken to maintain accuracy when drilling stacks of plates.

(15) Holes may be made by use of a machine guided oxygen torch. Flame cut 

edges shall be reasonably smooth to minimize stress concentrations. 

(16) Field drilled holes must be approved by the owner. If the manufacturer is 

aware of the owner's intent to field drill holes, the manufacture must supply 

a galvanizing touch-up kit for galvanized poles or a silicon sealant for 

weathering steel poles.
Bulletin 1724E-214 

Page 11

d. Tolerances

Manufacturing tolerances shall be limited to the following:

Pole Length

One piece: ±2 inches, or ±1 inch ±1/8 inch per 10 feet of length, whichever 

is greater (i.e. - 120-foot pole shall have a length of 120 feet ±21⁄2 inches)

Assembled pole with flange connections: same as for one piece

Assembled pole with slip joint connections: The accumulation of the slip 

joint tolerances not to exceed – 6-inch, +12 inch

Pole Diameter -0 inch, +1/4 inch

Pole End Squareness ±1/2 inch per foot of pole diameter 

Pole Sweep 1/8 inch per 10 feet of pole length

Pole Twist

Limit twist to 1°/10' of length, not to exceed 4°/tube segment. Overall 

structure twist shall be limited to 10° for embedded and 6° for base 

plated structures. Connections for all appurtenances to the pole shall 

account for the pole twist and should align vertically. 

Slip Joint tolerances Tolerances per manufacturer’s recommendations and total pole 

length requirements above. See Paragraph 5.g.

Pole Taper See paragraph 5.a.(2)(c) .

Location of Groups of 

Bolt Holes from Top of 

Pole 

±1.0 inches 

(tolerance to dimension A, 

Figure 2)

Location of Centerline 

Between Groups of 

Bolt Holes 

±1.0 inch

(tolerance to dimension B, 

Figure 2)

Location of Holes 

Within a Group of Bolt 

Holes

±1/8 inch 

(tolerance to dimension C, 

Figure 2)

Bolt Hole Diameter See Paragraph 5.c.(12) for hole diameters

Bolt Hole Alignment Not to vary from the longitudinal pole centerline of that group of 

holes by more than 1/16 inch 

Location of 

Identification Plate ±2.0 inch 
Bulletin 1724E-214

Page 12

e. Grounding

(1) A grounding connection shall be welded to the pole shaft, 18 inches above 

the groundline or 6 inches above the ground collar. The grounding 

connection will be either the two-hole National Electrical Manufacturers 

Association (NEMA) pad, or a nut, or a threaded insert installed in the pole, 

or an approved alternative. 

(2) Grounding pad face shall not be painted or covered with other coatings. 

The grounding nut thread and grounding pad threads shall be protected from 

coatings.

(3) Threaded inserts installed for grounding shall be made of Type 316 stainless 

steel and provided with standard 1⁄2 inch, 13 UNC threads (Unified Coarse 

threads). Threads shall be protected from unapproved coatings.

f. Climbing Devices

(1) Design Loads:

(a) Step Bolts and removable steps: The step bolts, removable steps 

and attachment to the pole shall be designed to support a minimum 

of a 300-pound worker and equipment multiplied by a load factor 

as defined in paragraph 5.f.(2). The load shall be at the outer edge 

of the step or bolt.

(b) Removable Ladders: The ladder and each attachment to the pole 

shall be designed to support a minimum of a 300-pound worker 

and equipment multiplied by a load factor as defined in paragraph 

5.f.(2). The load shall be at the outer edge of the step or bolt. 

(2) Load Factor: A load factor of 2.0 shall be applied to the design loads in 

5.6.1. These loads shall be supported without permanent deformation. 

(3) Location: Climbing devices shall start 8 feet above groundline and extend 

to the pole top unless specified by the owner. The climbing device shall be 

spaced such that each step is 1 foot 6 inches apart and orientated to provide 

maximum ease of climbing. They shall be located to avoid interference 

with other attachments.

(4) Finish: Step bolts, removable steps, and removable ladders shall be hot 

dipped galvanized. For weathering steel poles, step bolts may be 

weathering steel.
Bulletin 1724E-214

Page 13

(5) Intent of steps/ladder: This system is intended for climbing the pole and 

working on the structure. It is not intended to replace the worker's fall 

arrest system.

g. Splices

(1) Poles shall be designed with a minimum number of joints. Field welding 

shall not be allowed as part of the design of a new pole. The shaft joints to be 

made in the field shall be slip joints or bolted flange joints. Slip joints shall 

be designed for a nominal lap that will develop the full required design 

strength of the pole at that point. The minimum lap shall meet the 

requirements of ASCE 48. All welds on both sections of the pole, in the area 

of the splice, shall be complete penetration welds for at least a length equal to 

the maximum lap dimension. 

(2) Manufacturer shall verify slip joint fit, through dimensional measurement or 

actual fit-up, before shipment. Joints should not interfere with threaded 

inserts, step nuts, ladder clips, or jacking nuts.

(3) Sufficient jacking lugs and permanent orientation marks shall be provided 

at all slips joints to ensure proper alignment and complete overlap of the 

joint.

(4) The axis of the pole shall not be distorted after the pole is mated. Shims 

shall not be allowed to straighten the pole unless approved by the owner. 

The owner reserves the right to reject a pole based on the improper mating 

of a pole splice.

h. Appurtenances

(1) Appurtenance material shall be supplied by the owner. The owner shall 

provide the pole manufacturer connector and/or member locations, 

orientations, size, types, and strength capacities.

(2) The steel pole manufacturer and the owner shall work together to assure 

design coordination and fit up of all appurtenance connections and members 

to poles. Also refer to paragraph 5.a.(8) of this specification.

i. Finishes

(1) The following finishes are acceptable: Galvanizing, zinc primer combined 

with paint, weathering steel, and a below grade coating.

(a) Galvanizing – All poles and structural components which are hotdip galvanized shall meet all the requirements of ASTM A123 or 

ASTM A153. Measures shall be taken to prevent warping and 
Bulletin 1724E-214

Page 14

distortion according to ASTM A384 and to prevent embrittlement 

according to ASTM A143. Poles made of ASTM A588 steel shall 

not be galvanized due to the high silicon content of the steel. One 

gallon of zinc enriched paint shall be provided with each five poles. 

(b) Zinc Primer and Painting - Poles which are to be painted shall be 

hermetically sealed to prevent corrosion of interior surfaces. After 

shot or sand blasting and cleaning in accordance with the surface 

preparations specification, SSPC/NACE SP-6/NACE 3, a zinc 

primer of 3 mils dry film thickness (DFT) and two coats of finish 

paint, each 3 mils DFT shall be applied to all exterior surfaces in 

accordance with the paint supplier's recommendations. One gallon 

each of primer and finish paint shall be supplied with each five 

poles. A guarantee against flaking or fading of the paint for a 

minimum of 5 years shall be provided. 

(c) Weathering Steel - Steel shall conform to ASTM A588 or A871. 

After fabrication, poles made of weathering steel shall be cleaned 

of oil, scale, etc., in accordance with the surface preparation 

specification SSPC/NACE SP-6/NACE 3, to ensure uniform and 

rapid formation of the protective oxide layer. 

(d) Coatings for the Embedded Portion of the Pole A minimum 16 mil 

DFT of two component hydrocarbon extended polyurethane coating 

that is resistant to ultraviolet light shall be applied on the exposed 

surface of the embedded portion of the pole. The coating shall 

extend from the butt to 2 inches below the top of the ground collar, 

or 16 inches above groundline. Other coatings shall be approved by 

the owner prior to their use. One-quart container of touch up shall 

be provided with each five poles.

(2) Bolts and nuts with yield strengths under 100,000 psi shall be hot-dip 

galvanized per ASTM A153 and ASTM A143, or mechanically coated with 

zinc in accordance with ASTM B695, Class 50. Bolting materials with 

yield strengths in excess of 100,000 psi shall not be hot-dip galvanized. 

Instead, they shall be painted with zinc enriched paint or mechanically 

coated with zinc per ASTM B695, Class 50. Bolts and nuts made from 

weathering steel do not require a galvanizing coating. 

(3) Compliance with coating thickness requirements shall be checked with a 

magnetic thickness gauge.
Bulletin 1724E-214

Page 15

j. Markings 

(1) Each Pole shall be permanently marked on the pole shaft 60 inches above 

groundline and on the bottom side of the bearing plate with the following 

identifying information, unless specified otherwise by the owner: 

• Manufacturer’s name

• Month and year of manufacture

• Length and class of pole

• Ultimate moment capacity of the pole

• Owner’s name

• Pole weight

(2) The identification information listed above shall be permanently marked on 

the transverse side of the pole. The method of identification shall be 

approved by the owner. The lettering shall be at least 3/4 inch in height. 

(3) Information on the butt of the pole may be with permanent paint applied 

with a 1/2-inch-wide brush. Paint identification markings may not be used 

in any other location.

(4) Each section of a spliced pole shall be marked such that the intended mate 

section can be easily identified. The markings shall be permanent and 

legible and contain at least the following information: 

• Pole Length and Class (each section and total pole); and

• Structure number (if known).

k. Inspection and Testing 

(1) The owner and the owner’s representative shall have free entry at all times 

during fabrication, to all parts of the manufacturer’s plant to inspect any 

part of the production of the poles covered by this specification.

(2) Steel members that are bent or warped or otherwise improperly fabricated 

shall be properly repaired or replaced at the sole discretion of the owner.

(3) The cost of tests made by the manufacturer (except full scale load tests on 

poles), including cost of the certified test reports shall be considered 

included in the bid price. 

(4) The manufacturer shall make tests in accordance with ASTM A370 and 

A673 to verify that the material used in the structures meets the impact 

properties.
Bulletin 1724E-214

Page 16

(5) Mill test reports showing chemical and physical properties of all material 

furnished under this specification shall be maintained by the manufacturer 

for a period of 5 years and shall be traceable to the pole.

(6) All plates over 1-1/2 inches thick shall be ultrasonically tested to assure 

against defects that could lead to lamellar tearing.

(7) Qualification of welders or welding operators will be verified as to 

conformance with the provisions of AWS D1.1.

(8) The manufacturer shall make certified welding reports for each pole. The 

reports covering welding shall include all welds of a pole. Each weld shall 

be clearly identified; and the report shall consist of the method of testing, 

whether the weld is acceptable, the identification of the pole, the date, and 

the name and signature of the inspector.

l. Full Scale Structure Testing

(1) The poles that are to have full-scale load tests performed on them are listed 

in Attachment B. Cost for such test shall be the responsibility of the owner, 

shall be separated from the manufacturer’s bid, and shall be negotiated in 

advance of any test preparation.

(2) Details of the test procedures and methods of measuring and recording test 

loads and deflections shall be specified by the manufacturer prior to testing 

and shall be subject to the review and approval of the owner or the owner’s 

representative.

(3) Deflections shall be recorded in the transverse and longitudinal directions 

when applicable. Deflection measurements shall be taken under the no load 

condition both before and after testing.

(4) Material procurement for test poles shall be identical to material 

procurement procedures for regular production run poles.

(5) A full report listing results shall be submitted after completion of all testing. 

Copies of mill test reports shall be included in the load test report. The 

report shall also include a complete description of the load tests with 

diagrams and photographs.

(6) The owner or the owner’s representative reserves the right to be present 

during testing and shall be notified 2 weeks prior to the start of pole test.
Bulletin 1724E-214

Page 17

6. SHIPPING AND DELIVERY

a. Shipping

(1) Each shipment shall be accompanied by a bill of materials, identifiable by 

pole type and number. Bolts and miscellaneous hardware will be identified 

by the list for match up with the respective pole shaft. All parts that are 

required for any one pole shall be in one shipment, if possible.

(2) The owner and owner’s representative shall be notified prior to shipment 

that such shipment is to take place, and they reserve the right to inspect the 

components prior to shipment. The notification shall give quantities, 

weight, name of common carrier used, and expected time of arrival.

(3) Salt-treated wood blocking and urethane foams shall not be used when 

shipping or storing weathering steel poles.

(4) Transportation and site handling shall be performed with acceptable 

equipment and methods by qualified personnel. The manufacturer shall 

exercise precaution to protect poles against damage in transit.

(5) Handling instructions shall be included with the pole shipment (if special 

handling is required).

b. Delivery

(1) The owner may take delivery at a designated location with the delivering 

carrier’s equipment. The manufacturer shall coordinate with the owner to 

ensure smooth and efficient delivery of poles. 

(2) The owner will provide all labor, equipment, and materials for the 

unloading of poles at the project site. A pole is considered delivered when 

the pole is lifted from the trailer or semitrailer of the delivery carrier.

7. DRAWINGS AND INFORMATION TO BE SUPPLIED BY THE 

MANUFACTURER

a. Information to be supplied with the proposal (See Attachment C)

(1) Pole diameter at the top, groundline, and bottom.

(2) The pole taper of each pole in inches/foot.

(3) The calculated weight of each class and length of pole.

(4) General information about each pole length and class including tip load, 

location of point of fixity, type of steel used for the pole (ASTM number 
Bulletin 1724E-214

Page 18

and yield), cross sectional shape, and connection details of multiple piece 

poles (slip joints/flange joints/welded to be one piece). 

(5) Calculated groundline and point-of-fixity reactions due to the tip loadings 

(including shear, moment, and axial reactions) in order to demonstrate 

conformance with the requirements of 5.1.1 and 5.1.2.

(6) Description of pole shaft cross section including thickness of the plate at 

the bottom, groundline, and at the top.

(7) For each standard class pole, provide pole top deflection using the 

specified tip loading in order to demonstrate conformance with the 

requirements of and 5.1.3.

(8) The cost of each pole by size and length. Also, the total order cost for 

each class and length of pole.

b. Documentation to be supplied for the Owner’s Approval Prior to Fabrication (as 

requested by the owner): Documentation includes final design calculations for 

the pole shaft at 5-foot intervals and will be based upon the pole loading shown in 

Table 1. 

The following information shall be supplied:

• Total shear forces

• Moment

• Design Stress, Allowable stress, and Stress ratio

• Section moduli

• Cross-sectional area

• Deflection at the pole top due to tip load

• Detail drawings for each structure type giving weights of structure

• Bill of materials list (if any)

• Assembly instructions and erection drawings

 (Slip joint lengths and allowable tolerances)

• Special handling instructions (if required)

c. Test Reports (as requested).

• Certified mill test reports for all structural material.

• Certified welding reports for each pole. 

• Impact property test reports showing that the material used in the poles meets 

the impact properties.

• Test reports on coating thickness.

• Report of pole testing, when required, including photographs, and diagrams. 
Bulletin 1724E-214

Page 19

8. APPROVALS, ACCEPTANCE AND OWNERSHIP

a. Final designs must be approved by the owner or owner’s representative before 

material ordering and fabrication. Material ordering and fabrication prior to 

approval will be at supplier’s risk. It is understood that award of this contract does 

not constitute acceptance of design calculations submitted with the bid, if 

corrections are required in the final structure designs due to manufacturer’s errors, 

omissions, or misinterpretations of the specifications, the quoted price shall not 

change. Approval of the drawings and calculations by the owner or the owner’s 

Representative does not relieve the supplier of responsibility for the adequacy of 

the design, correctness of dimensions, details on the drawings, and the proper fit of 

parts.

b. After delivery, the poles will be inspected and shall be free of dirt, oil blisters, flux, 

black spots, dross, teardrop edges, flaking paint or zinc; and in general, shall be 

smooth, attractive, and unscarred. Poles not meeting this requirement shall be 

repaired or replaced by the manufacturer at no additional cost to the owner. Final 

decision to repair rather than replace a pole shall be at the owner’s sole discretion.

c. All final drawings shall become the property of the owner, who shall have full 

rights to reproduce drawings and use them as the owner sees fit.

9. LIST OF ATTACHMENTS TO THIS SPECIFICATION: 

Attachment A, and B to be completed by the engineer. Attachment C to be completed by 

the manufacturer.

• Attachment A, Structure Dimensions and Pole Framing Drawings

• Attachment B, Application Requirements

• Attachment C, Bid Summary
Bulletin 1724E-214

Page 20

Attachment A

Structure Dimensions and Pole Framing Drawings

(To be Completed by the Engineer)
Bulletin 1724E-214 

Page 21

BLANK PAGE
Bulletin 1724E-214

Page 22

Attachment B. Application Requirements

(To be Completed by the Engineer)

1. Type of finish of the pole (indicate by checking one)

Weathering____________________________

Galvanized____________________________

Zinc primer and paint____________________

2. Special Charpy requirements ________________________________________

3. Surface protection desired for embedded portion of the pole (indicate by checking one 

or both)

Polyurethane Coating____________________

Anodes_______________________________

4. Climbing device type (indicate by checking one)

Step Bolts_____________________________

Ladder _____________________________

Removable Steps_______________________

5. Location of climbing device _____________________________________

6. Length of ground collar _____________________________________

7. Grounding plate or nut _____________________________________

8. Delivery schedule _____________________________________

9. Free on board destination ___________________________________

10. Pole test (if required) ______________________________

11. Additional Requirements (below) ____________________________
Bulletin 1724E-214 

Page 23

BLANK PAGE
Bulletin 1724E-214 

Page 24

Attachment C. Standard Class Steel Pole Bid Summary

Standard Class Steel Pole Bid Summary

(Information to be supplied with the bid)

DESIGN INFORMATION

 Pole framing drawing 

 Pole Class

 Pole Length

POLE DESCRIPTION

 Top Diameter

 Groundline Diameter

 Bottom Diameter

 Taper (in/ft)

GENERAL

 Pole Wt/ each

 Tip Load

 Point of Fixity Loc

 Steel (ASTM/yield )

 Cross section shape

 Splice joint type

CALCULATIONS AT THE GROUNDLINE

 Moment

 Shear

 Axial

 Cross Sectional Area

CALCULATIONS AT THE POINT OF FIXITY

 Moment

 Shear

 Axial

 Cross Sectional Area

WALL THICKNESS

 Top

 Groundline

 Bottom

DEFLECTION (Top)

COST SUMMARY

COST/POLE

NUMBER OF POLES

TOTAL COSTS

COMMENTS: TRANSMISSION LINE POLES

ATTACHMENT C 

BID SUMMARY – DESIGN INFORMATION,WEIGHTS,

AND PRICE INFORMATION

(INFORMATION TO BE SUPPLIED 

WITH THE PROPOSAL)
Bulletin 1724E-214 

Page 25

BLANK PAGE

Bulletin 1724E-214 

Appendix A 

Page 1 

APPENDIX A

COMMENTARY

1. General

The necessity of a clear bid specification for the purchase of standard class steel poles is 

very important to the bid evaluation process and the acquisition of structurally adequate 

poles. The specification should contain sufficient requirements and information so that all 

bids can be evaluated equally and so that the manufacturer clearly understands what is 

expected of the manufacturer.

Scope

While use of this standard class steel pole specification is not prohibited to poles which are 

guyed, which are subjected to unbalanced lateral loads or which have deflection or other 

special limitations, the owner must be prudent when using this specification in these types 

of applications. 

It is recognized that, with the proper understanding and usage of some computerized 

structural analysis and transmission line design programs, it is possible to select a standard 

class steel pole which might otherwise be beyond the scope of this specification. The 

owner must be sure that combined bending and buckling analysis is performed, and that 

deflections are properly modeled. 

The owner should recognize when the design of a steel pole may be more prudently 

accomplished using the “Guide Specification for Steel Single Pole and H-Frame 

Structures,” RUS Bulletin 1724E-204, which requires the actual loading conditions to be 

specified. In using RUS Bulletin 1724E-204, the manufacturer assumes full responsibility 

in designing and manufacturing a structurally adequate pole. 

Standard Class Pole 

In some cases, utilities prefer to specify certain steel poles to be designed according to 

standardized loading criteria, much like the standard classifications for wood poles. 

In utilizing standard class steel poles, a complete structural analysis is still required for all 

structures. All appropriate loading criteria are considered in the analysis. Once the 

required steel pole strength is determined, a standard class steel pole that meets the actual 

loading conditions can be selected. A complete design example is shown in Appendix C. 

Without considering all the potential reasons for specifying standard class poles, this 

specification is developed in order to establish a standard classification system and to assist 

the owner in procuring a standard class steel pole which is properly designed for the 

intended loading criteria. 
Bulletin 1724E-214

Appendix A

Page 2

This guide specification attempts to eliminate ambiguity in specifying and purchasing 

standard class steel poles. Since it has become a widespread practice in the industry to 

design and manufacture poles which are based on the wood pole classification system of 

the American National Standards Institute (ANSI 05.1), the steel pole classifications 

developed in this specification generally follow the wood pole classification system. 

However, to avoid confusion with the wood pole classifications, the steel pole 

classifications have a unique naming system.

Wood Pole Equivalency

In some cases, the owner may design a transmission line based on wood pole 

classifications as described in ANSI 05.1 and then wish to order steel poles which meet the 

wood pole equivalent loadings. Because of the differences in strength factors applied to 

wood poles in comparison to steel poles, the owner must be sure that the strength factors 

are properly accounted for in the design of the steel poles. 

“Wood pole equivalent” is a term that may be defined in a number of ways. For purposes 

of this commentary, the term “wood pole equivalent” is defined as a standard class steel 

pole which is equated by required factored loading to an ANSI 05.1 standard class wood 

pole. The equation is made by a ratio of the strength factors applicable for each pole type 

and loading criteria.

The design and purchase of steel poles as an equivalent to wood poles can be vague even 

with clear instructions. As such, the owner should be sure that the equivalency is properly 

determined. Once the equivalency is determined, the owner should specify the standard 

class steel pole based on the classifications detailed in paragraph 5.a.(2). In doing this, the 

manufacturer will not be involved in the equivalency process and the ambiguity should be 

eliminated.

The wood pole equivalency is based on the required ultimate moment capacity of the pole 

at the groundline based on embedment depths shown in ANSI 05.1. In obtaining a suitable 

equivalency, the owner must consider factors other than the equivalent groundline 

moment. For example, the differences in material and section properties of the wood pole 

versus the steel pole will result in differences in buckling analysis, pole deflections, 

secondary moments, applied wind forces, etc.

It is impossible to completely equate the steel pole and wood pole at all points along the 

pole. The owner must be certain that the steel pole selected by equivalency methods will 

have strength sufficient for the actual application.
Bulletin 1724E-214

Appendix A

Page 3

Equivalency Factor (Eq.F)

The equivalency factor (Eq.F) is defined as the ratio of the wood pole strength factor to the 

steel pole strength factor for a given loading condition. 

For example, for NESC Grade B district loading, the wood pole strength factor is 0.65 and 

the steel pole strength factor is 1.00. Thus, the equivalency factor will be 0.65/1.00 = 

0.650.

The equivalency factor is a useful concept to understand as the owner requires a wood pole 

equivalent under various loading conditions and strength factors. Several examples of 

equivalencies are listed in the following sections.

Wood Pole Equivalency – 0.65 TO 1.00 Ratio (0.65 Eq.F)

For the NESC Grade B district loadings, the NESC allows for a strength factor of 1.00 to 

be applied to a load on a steel pole while it requires a strength factor of 0.65 to be applied 

to a load on a wood pole. As such, the ultimate strength requirement for the steel pole will 

be less than the ultimate strength of the wood pole for the district loading conditions.

For example, the owner designs a transmission line for wood poles based on NESC district 

wind loading conditions. The owner wishes to purchase a steel pole that is equivalent to a 

Class 1 wood pole. Based on ANSI 05.1, the Class 1 wood pole groundline strength is 

derived by applying a horizontal factored load of 4,500 pounds at 2 feet from the pole top 

based on a simple cantilever. Since the owner had classed the wood pole based on an 

NESC strength factor of 0.65, the owner wishes to select a steel pole meeting the same 

NESC district wind loading conditions. To do this, the owner will multiply the required tip 

loading of 4,500 pounds by 0.65/1.00, which equals 2,925 pounds. The 0.65/1.00 ratio (or 

0.65 Eq.F) adjusts for the difference between wood and steel strength factors. The owner 

will then select a standard class steel pole which has an ultimate moment capacity based on 

the horizontal tip loading of at least 2,925 pounds. From paragraph 5.a.(2), the owner 

selects a class S-02.9 pole, which has a tip loading of 2,925 pounds.

Based on the method shown in this example, Table A-1 of this Appendix at the end of this 

section is a tabulation of wood pole equivalencies based on the NESC Grade B district 

loading.

Wood Pole Equivalency - 0.75 to 1.00 Ratio (0.75 Eq.F)

For the NESC Grade B extreme wind loadings, this specification requires a strength factor 

of 1.00 to be applied to an extreme wind load on a steel pole while the NESC requires a 

strength factor of 0.75 to be applied to an extreme wind load on a wood pole. As such, the 

ultimate strength requirement for the steel pole will be less than the ultimate strength of the 

wood pole for the NESC extreme wind loading conditions.
Bulletin 1724E-214

Appendix A

Page 4

For example, the owner designs a transmission line for wood poles based on NESC 

extreme wind loading conditions. The owner wishes to purchase a steel pole that is 

equivalent to a Class 1 wood pole. Based on ANSI 05.1, the Class 1 wood pole groundline 

strength is derived by applying a horizontal factored load of 4,500 pounds at 2 feet from 

the pole top based on a simple cantilever. Since the owner had classed the wood pole 

based on an NESC extreme wind strength factor of 0.75, the owner wishes to select a steel 

pole meeting the same extreme wind loading conditions. To do this, the owner will 

multiply the required tip loading of 4,500 pounds by 0.75/1.00, which equals 3,375 

pounds. The 0.75/1.00 ratio (or 0.75 Eq.F) adjusts for the difference between wood and 

steel extreme wind strength factors. The owner will then select a standard class steel pole 

which has an ultimate moment capacity based on the horizontal tip loading of at least 

3,375 pounds. From paragraph 5.1.2, the owner selects a class S-03.5 pole, which has a tip 

loading of 3,510 pounds.

Based on the method shown in this example, Table A-2 at the end of this section is a 

tabulation of wood pole equivalencies based on the NESC Grade B extreme wind loading. 

Wood Pole Equivalency – 1 to 1 Ratio (1.0 Eq.F)

The owner may wish to order a steel pole that has the same ultimate strength as a specified 

wood pole class. One common application of this is when the owner designs a transmission 

line using wood pole properties but utilizing steel pole strength factors. In this case, the 

owner has accounted for the difference in wood versus steel strength factors during the 

design of the project.

For example, the owner designs a transmission line for wood poles based on NESC district 

wind loading conditions. However, for steel poles, the owner uses the NESC district 

strength factor of 1.00 (applicable to steel poles) in the calculations. The owner selects a 

wood pole Class 1 at a specific location. Thus, the owner wishes to purchase a steel pole 

which is equivalent in ultimate strength to a Class 1 wood pole. Based on ANSI 05.1, the 

Class 1 wood pole groundline strength is derived by applying a horizontal factored load of 

4,500 pounds at 2 feet from the pole top based on a simple cantilever. Therefore, the 

owner will require a steel pole with an ultimate moment capacity based on the same 4,500-

pound tip loading. From paragraph 5.a.(2), the owner selects a Class S-04.9 steel pole, 

which has a tip loading of 4,875 pounds.

Based on the method shown in this example, Table A-3 is a tabulation of wood pole 

equivalencies based on the ultimate-to-ultimate strength comparison, or 1.0 equivalency 

factor.

Other Wood Pole Equivalencies

Using the wood pole equivalency methods described, the owner can develop equivalency 

tables for other ratios of wood versus steel strength factors. 
Bulletin 1724E-214 

Appendix A 

Page 5 

TABLE A-1 - WOOD POLE EQUIVALENCY

BASED ON 0.65 to 1.00 RATIO

(0.65 Equivalency Factor)

(NESC Grade B District Loading)

(Equivalencies based on approximate groundline strength)

Design

Wood Pole Class 

0.65 Strength Factor

Select

Steel Pole Class 

1.00 Strength Factor

H6 S-07.4

H5 S-06.5

H4 S-05.7

H3 S-04.9

H2 S-04.2

H1 S-03.5

1 S-02.9

2 S-02.4

3 S-02.0

TABLE A-2 - WOOD POLE EQUIVALENCY

BASED ON 0.75 to 1.00 RATIO

(0.75 Equivalency Factor)

(NESC Grade B Extreme Loading)

(Equivalencies based on approximate groundline strength)

Design

Wood Pole Class 

0.75 Strength Factor 

Select

Steel Pole Class 

1.00 Strength Factor 

H6 S-09.0

H5 S-08.0

H4 S-06.5

H3 S-05.7

H2 S-04.9

H1 S-04.2

1 S-03.5

2 S-02.9

3 S-02.4
Bulletin 1724E-214 

Appendix A 

Page 6 

TABLE A-3 - WOOD POLE EQUIVALENCY

BASED on 1:1 RATIO

(1.0 Equivalency Factor)

(Ultimate-to-Ultimate Comparison)

(Equivalencies based on approximate groundline strength)

Design

Wood Pole Class 

Select

Steel Pole Class

H6 S-12.0

H5 S-10.0

H4 S-09.0

H3 S-08.0

H2 S-06.5

H1 S-05.7

1 S-04.9

2 S-04.2

3 S-03.5

2. Design - Section 5

Loads - Paragraph 5.a 

The primary loads for steel poles are weather loads. Weather, construction and 

maintenance loads need to be determined by the owner in order to select the proper 

standard class pole.

Load factors for NESC light, medium, and heavy loading districts should be at least equal 

to those given in the applicable edition of NESC for Grade B construction. The load factor 

for extreme ice and extreme wind is recommended to be at least 1.1.

In addition to using the NESC district loading requirements, the ASCE publication No. 74, 

“Guidelines for Transmission Line Structure Loading,” can be used to provide owners with 

procedures for the selection of design loads and load factors related to climate, accidents, 

construction and maintenance.

Once the design loadings have been determined, a design of the structure should be 

performed by the owner’s engineer or structural designer. It is recommended that a 

nonlinear structural analysis computer program be utilized in order to consider the 

loadings, secondary moments (p-delta effect), and effects of foundation rotations and 

deflections. As a minimum, an approximate method for determining the ultimate moment 
Bulletin 1724E-214

Appendix A

Page 7

capacity should be utilized, such as the methods given in the “Design Manual for High 

Voltage Transmission Lines,” RUS Bulletin 1724E-200.

Once the structural analysis has been completed, the owner’s engineer or structural 

designer may select a standard class steel pole which has the ultimate moment capacity 

greater than the design loading requirements. Consideration should be given for strength 

requirements at all points along the pole, not just at the groundline.

P-Delta Moment

Prior to selecting a standard class steel pole, the owner should determine the effect of the 

secondary moments due to the vertical loadings, including the effect of the pole weight, 

during the transmission line design process.

Whenever there is a transverse or longitudinal load, the pole will deflect in the direction of 

the load. As a result, the vertical load is no longer in its original position. The vertical 

load moves over as the pole deflects, causing additional moments in the pole. Also, the 

pole weight can place secondary moment loads in the pole. The additional stress caused 

by this secondary moment is dependent on the magnitude of the vertical load and deflected 

shape of the pole. Many pole designs, particularly tall poles, have to be calculated for the 

position of equilibrium of forces in the fully displaced position. The solution typically 

takes many iterations. A full nonlinear analysis will consider the change in orientation of 

the loads relative to the displaced positions of the structural members. 

As a minimum, an approximate method for determining the effect of the secondary 

moments should be utilized, such as the method given in the RUS Bulletin 1724E-200.

Foundation Rotation and Deflection

Although significant foundation rotation and deflection criteria are considered to be 

beyond the scope of this standard class steel pole specification, some allowances can be 

made for these effects. They should be considered during the owner’s analysis of the 

actual loading conditions to apply to the steel pole. Typically, this type of analysis is 

accomplished by nonlinear structural analysis techniques. 

Once the structural analysis has been completed (including foundation rotations and 

deflections, p-delta effect, etc.), the owner may select a standard class steel pole that has 

the ultimate moment capacity greater than the design loading requirements.

Longitudinal Loads

It is recommended that RUS Bulletin 1724E-204 be utilized whenever the longitudinal 

loads may result in a significant unbalanced lateral loading condition.
Bulletin 1724E-214

Appendix A

Page 8

Because steel poles are flexible structures, there may be a reduction in induced moments in 

a pole under some types of longitudinal loads due to the restraining effect of the overhead 

ground wires. Traditionally, static longitudinal loads are specified due to the complexity 

of calculating the influence of structure flexibility.

Guyed Poles and Guy Wires

It is generally beyond the scope of this standard class steel pole specification to consider 

guyed poles and guy wires in the design of the structure. It is recommended that RUS 

Bulletin 1724E-204 be utilized instead.

It is generally agreed that a steel pole has less buckling strength than an equivalently 

classed wood pole. Wood poles are solid wood and the material in the heart of the pole 

can resist buckling. Standard class steel poles however, are thin walled, hollow structures 

with limited buckling strength. The forces resulting from the attachment of the guy wires 

to the standard class steel pole needs to be carefully analyzed by a structural engineer. The 

steel pole and guy wire(s) must be designed as a system. 

Any time a steel pole structure is guyed, the guy type, size, modulus of elasticity and guy 

slope or angle has to be determined by the owner and properly modeled in the analysis of 

the steel structure. The load in the guy wire should be limited to 65 percent of its ASTM 

rated breaking strength under actual factored loading conditions, as is required by RUS 

Bulletin 1724E-204. The steel pole and guy wire(s) must be designed as a system. The 

guy modulus of elasticity can increase from a minimum value at the time of manufacture, 

to a maximum value that results from periodic stretching and relaxing during the load 

cycles. Ranges from 19,000 ksi to 28,000 ksi have been stated. The ASCE steel pole 

specification (ASCE 48) has suggested the engineer use a guy wire modulus of elasticity of 

23,000 ksi whenever it is not specified.

The owner should use caution in using this equivalency method of sizing standard class 

steel poles and its usage should be prudently influenced by the owner’s experience in 

similar applications where actual design loadings were utilized under similar guying 

conditions. However, a typical situation where the owner may wish to use this 

specification for guyed poles is when the owner uses a transmission line design computer 

program, or other structural analysis program, in which minimum strength values are input 

for each pole type and the program is capable of combined bending and buckling analysis 

of guyed steel poles.

Point of Fixity - Paragraph 5.a.(1)

Point of fixity for this specification is defined as the location on the pole where maximum 

moment occurs. Maximum moment is calculated by the pole designer using the loadings 

provided by the owner and multiplying those loadings by the appropriate moment arms. 

The existing soil and backfill has to be able to support the pole with these bending 

moments applied. The location of this point of fixity could be at or below the groundline.
Bulletin 1724E-214

Appendix A

Page 9

The exact location is theoretical and depends on the soil condition and backfill used to 

support the pole.

For the standard class pole, the point of fixity should remain at the same location on the 

pole, regardless of the embedment depth the owner may specify for a given application. 

Otherwise, the required pole strength could vary as the location of the point of fixity 

varies. Within the scope of this standard class pole specification, the point of fixity is 

arbitrarily considered to be located at a distance from the pole butt that is equal to 7 

percent of the pole length. This value seems to work quite well over a range of pole 

lengths and is approximately the same value as a point of fixity located at 1/3 of the 

distance below the groundline based on an embedment depth of 10 percent of the pole 

length + 2 feet. 

Pole Top Strength (Paragraph 5.a.(2)(a)

This specification sets minimum ultimate moment capacity requirements near the pole top 

for each standard pole classification. The similar ANSI 05.1 requirement is generally 

overlooked, misunderstood or not considered by manufacturers and others who seek to 

standardize pole sizes based on the wood pole classifications. 

Upon a careful study of the ANSI 05.1 wood pole specification, one should understand that 

the horizontal loading applied at 2 feet from the pole top is for the purpose of determining 

a required groundline ultimate moment capacity for any length pole of the given class. 

However, the minimum required wood pole top size is specified apart from the horizontal 

loading requirement 

For example, according to ANSI 05.1, a Class 1 wood pole must have a circumference of

27 inches at the top. When applied to the Douglas Fir or Southern Yellow Pine poles with 

a fiber stress of 8,000 psi, the resulting top strength is calculated as 41.5 ft-kips for the 

Class 1 wood pole. 

Because the conductors and shield wire supports are typically located on crossarms away 

from the pole axis, significant moments can be generated in the pole near the top. The 

moments are greatly increased whenever a braced pole top assembly is utilized. These 

moments are not accounted for by applying the horizontal factored loading alone. 

Therefore, in the design of transmission poles, it is critical that a minimum ultimate 

moment capacity be specified near the pole top. In the absence of a minimum top strength 

requirement, a steel pole top strength can theoretically be negligible.

The minimum pole top strength required by this specification should be suitable for most 

transmission line applications. However, the owner must be sure that the top strength is 

properly evaluated, especially when working with wood pole equivalencies and braced 

structures.
Bulletin 1724E-214

Appendix A

Page 10

Tip Loading (Paragraph 5.a.(2)(b)

The tip loading is used to develop a required ultimate moment capacity diagram at any 

point along the pole from 2 feet below the pole top down to the point-of-fixity. This 

ultimate moment capacity is determined by multiplying the tip load by the moment arm 

based on a simple cantilever. As a result, the required factored moment diagram is linear 

in shape. This same method may be utilized in structural analysis and automated 

transmission line design computer programs to develop an array of factored moment 

requirements for standard steel pole sizes.

Pole Deflection - Paragraph 5.a.(3)

Although significant horizontal pole deflection limitations are considered to be beyond the 

scope of this standard class steel pole specification, some allowances can be made for these 

effects. They should be considered during the analysis of the actual loading conditions 

applied to the steel pole. Typically, this type of analysis should be accomplished by 

nonlinear structural analysis techniques. Since the electrical clearances must be assured in 

the operation of transmission lines, deflections must remain within an acceptable range. 

This specification limits the allowable pole deflection to 15 percent of the pole height 

above the point of fixity when the tip load specified in paragraph 5.a.(2) is applied under a 

horizontal testing procedure.

The owner should recognize that the actual pole deflection for the application will be less 

than the specified deflection limit of 15 percent of the pole height. With the standard class 

pole, all of the loading is applied near the pole top. In a typical transmission line 

application, the actual horizontal loading will be some distance from the pole top. As 

such, the actual deflection at the conductor under short term factored loading conditions 

can be expected to be less than 10 percent of the height above ground.

The NESC requires that electrical clearances be maintained under a wind loading of 6 psf. 

It is expected that the deflection of a standard class pole under this 6 psf loading condition 

will be less than 3 percent of the height above ground.

For situations where the owner wishes to know the deflection for a standard class pole, the 

owner should use a suitable structural analysis computer program in which the actual 

design loading conditions and steel pole properties are input into the program, or the owner 

should ask the pole manufacturer to provide the analysis. 

If the owner has special deflection limitations, it is recommended that RUS Bulletin

1724E-204 be utilized instead of this specification. In doing so, there will be little doubt as 

to what the actual pole deflections will be under all loading conditions.
Bulletin 1724E-214

Appendix A

Page 11

Minimum Plate Thickness - Paragraph 5.a.(7)

The intent of this guide is not to limit new technology. Use of plate thickness less than 

3/16 inch may be possible. However, consensus from the committee members and based 

on current designs by the manufacturers, transmission size poles will normally require at 

least a plate thickness of 3/16 inch. If mild corrosion occurs, the percentage of reduced 

strength will be less the greater the wall thickness of the steel plate. Having the minimum 

plate thickness of 3/16 inch will also improve strength for mounting of davit arms and guy 

attachments. If an owner does decide to purchase poles with a wall thickness less than 

3/16-inch, extra care should be taken in the field to avoid damage to the pole during 

storage, handling, and installation. Small nicks in the galvanizing or other protective 

coating could exaggerate future problems. Also, minor misalignments or poor fit of 

hardware during construction could cause a major problem. Ground collars on thin wall 

poles should be considered a necessity. Other sections of this commentary explain why 

poles purchased with this guide should not be used in guying situations, unless an engineer 

experienced with guyed steel structures oversees the design. This is especially true for 

poles of wall thickness less than 3/16 inch. 

Ground Collars - Paragraphs 5.a.(12) and 5.a.(13)

Attachment B of the specification is set up to allow the owner to alter the requirement for a 

ground collar by putting “not required” on line 6. Ground collars are recommended for 

direct embedded weathering steel poles, but they are sometimes optional with galvanized 

steel poles. If ground collars are used, a length of 4 feet or greater is recommended.

The intent of ground collars on standard class steel poles is similar to the preservative of 

wood poles. The preservative protects the wood against rot and fungus attack. Similarly, 

the ground collar protects the steel pole from corrosion and mechanical damage.

The ground collar does not prevent nicks. The ground collar does provide nonstructural 

steel that can be sacrificed to corrosion. Corrosion can be due to many outside causes over 

which the owner has no control. A short list of potential causes includes road salt, 

fertilizer, poor/corrosive soil, and galvanic corrosion from pipeline crossings or 

underground electric lines. The ground collar also protects the pole from mechanical 

damage that may occur during construction or later by right-of-way crew or by property 

owners.

Whereas some utilities feel that galvanized poles with polyurethane coating do not need 

additional corrosion and mechanical protection, they do feel that weathering steel poles 

need additional protection to the patina and polyurethane coating. Some manufacturers 

claim that poles that are galvanized and the embedded portion coated with polyurethane 

coating (paragraph 5.i.(1)), do not require a ground collar. If nicks do occur to a 

galvanized pole, the galvanizing will act like a sacrificial anode and protect the nicked 

steel.
Bulletin 1724E-214

Appendix A

Page 12

ASCE 48 states that bare weathering steel should not be used below grade due to the 

potential problems from corrosion. Some utilities add a round collar to all weathering steel 

poles. Still other utilities in dry climates with non-corrosive soils may not use ground 

collars. However, since the polyurethane coating can be nicked during construction, it is 

recommended that round collars be used on all weathering steel poles.

Charpy Requirements - Paragraph 5.b.(3)

Charpy test is a notch-bar impact test used to compare notch sensitivities of materials. The 

impact values cannot be converted into energy figures for use directly in engineering 

design. The impact value from the notch-bar impact test is used only as a comparison test. 

For example, if a type of steel has been found to have good notch toughness in service and 

its impact value is known, it is assumed that other types of steel having the same impact 

value will also have the same notch toughness. The ASCE design standard for steel poles 

has established impact values for the Charpy notch-bar impact test. These values are a 

function of yield stress, plate or bar thickness, and temperature.

Notch-bar impact tests are used to help determine if a normally ductile material might 

behave in a brittle manner. Three main factors that influence if a material will behave in a 

brittle or ductile manner are triaxiality, strain rate, and temperature. Ductile materials tend 

to become more brittle as triaxiality increases, strain rate increases, or temperature 

decreases. Since brittle materials require far less energy for fracture than ductile materials 

of the same strength, one can realize the importance of the Charpy test for steel poles used 

on transmission lines.

The tendency is to reduce temperature requirements of the Charpy test for structures to be 

in service in warm climates such as Louisiana or Florida. This is not recommended. 

However, for locations in which temperatures may be extremely low, lower temperature 

values may need to be specified.

The ASCE design standard specification contains Charpy requirements for structural plate, 

anchor bolts, and weld materials. The material used for making welds is required to meet 

the impact requirements for the lowest toughness requirements of the plates being joined. 

Field Drilled Holes - Paragraph 5.c.(16)

Drilling holes in a pole during construction allows the maximum flexibility in the use of 

poles in unexpected situations. However, the cutting of the pole does affect the corrosion 

protection of the pole. For galvanized poles and painted galvanized poles, a drilled hole 

exposes bare steel to the weather. These holes need to be painted with a zinc rich touch up 

paint similar to described in paragraph 5.i.(1)(a). For poles made from weathering steel

the hole can allow rain or ground water into the pole depending on the hole location. 

Weathering steel poles protect themselves from corrosion by constantly cycling from wet 

to dry. This cycling creates a water tight oxide layer. Inside the pole or under water the 

cycling cannot happen. Therefore, there is no corrosion
Bulletin 1724E-214

Appendix A

Page 13

protection inside the pole. When water enters the pole through the field drilled holes 

corrosion starts. When field drilled holes are anticipated, the inside of weathering steel 

pole should be coated similar to the coating described in paragraph 5.i.(1)(d). If coating 

the inside is not practical then a thick coating of a silicon sealant shall be applied to the 

bolt and hole. Field drilling of painted poles should be avoided if possible. Drilling 

holes in painted poles destroys the water tightness and allows corrosion to start on the 

unprotected carbon steel. If holes cannot be avoided then a thick coating of a silicon 

sealant shall be applied to the bolt and hole. 

Field Drilled Holes (wrong location/drilled in error)

Occasionally a field-drilled hole will end up in the wrong location. A rule of thumb from 

The American Welding Society (AWS) says a defect or hole location is critical if another 

hole is spaced within 2.5 times the diameter of the hole in question. (i.e. two 1 inch holes 

should not be closer than 2 1⁄2 inch edge to edge). A structural analysis of the actual 

conditions will possibly give a different answer. If the location is critical then a field weld 

repair is needed by a certified welder.

If the location is not critical then it can be filled with an automotive type freeze plug and 

painted with touch up paint. The hole should be plugged to keep birds and insects out of 

the pole and to slow or prevent corrosion to the inside of the pole. The above rule of 

thumb does not apply to holes that are drilled at the correct elevation but on the wrong 

face. These poles need to be reviewed by the manufacturer and repaired by a certified 

welder or these poles need to be replaced.

Pole Materials (Galvanized Steel vs. Weathering Steel)

Structural grade steel is a great product for many reasons. However it has one definite 

problem. Mother Nature wants to return it to its natural state of iron ore. Industry has used 

many ways to slow the corrosion process. In 1836 a chemist patented a means for coating 

iron with zinc. That process of hot dip galvanizing remains substantially unchanged today. 

In the 1900's another method was found. By having a relatively high copper content in the 

raw steel a dense patina oxide coating would form on the steel and act as a tight adhered 

barrier preventing future atmospheric corrosion. This steel was largely forgotten until the 

1960's when US Steel started marketing their version of this steel as "COR-TEN". Today 

it is commonly called weathering steel.

The formation of dense patina oxide on weathering steel requires a cycling from wet to dry 

environment - optimally 50 percent wet and 50 percent dry. Departure from the 50/50 ratio 

will slow the oxide formation. Unfortunately, this limitation was not well understood in 

the 1960's and weathering steel was used in locations where water and dirt were trapped. 

The result was the oxide did not form and the corrosion continued as if the steel was 

normal bare steel. In some cases such as highway bridges and lattice towers the corrosion 

caused a problem that was given the name "pack-out". In this case the corrosion takes 

place between two pieces of steel that are bolted together in such a configuration that water 

is trapped and held. The corrosion products swell.
Bulletin 1724E-214

Appendix A

Page 14

Ultimately the forces from the swelling can exceed the strength of the bolts. This can 

cause structural failure. As a result of this problem weathering steel developed a bad 

reputation. However, with prudent attention to details, weathering steel is being used by 

many utilities today.

Both galvanized steel and weathering steel have their advantages. Which is better is a 

question that has not been answered. Weathering steel normally has a cost advantage and 

can be factory welded to make a one-piece pole of any length. The one-piece length of 

galvanized poles is limited to the length of the galvanizing tank. Weathering steel 

becomes a dark brown wood color. A galvanized pole starts out shiny and ends up a dull 

gray. Some people say that weathering steel should not be used in areas of heavy road salt 

or in heavily fertilized farm fields. The weathering steel manufacturers found a number of 

poles in undesirable conditions, tested them and found that the oxide had formed and that 

corrosion was not a problem. This guide makes no judgment as to which material is better 

or gives any guidance in the use of one versus the other. If correctly used both will 

perform very well. If not used as intended, neither will perform as desired. It is 

recommended that the owner contact the pole supplier to select the best material for the 

pole's intended application. 

Painted Poles 

Painted bare steel poles are not recommended. These poles have more construction and 

maintenance expenses than poles with paint over zinc primer or paint over hot dip 

galvanizing. The inside surface of bare steel poles is not protected and the poles can 

corrode from the inside out. Also the outside paint is easily chipped leaving bare steel 

which may quickly corrode. 

Weathering Steel Poles - Paragraphs 5.i.(1)(c) and 5.i.(1)(d)

There are environments where weathering steel is not recommended in a bare, uncoated 

condition because the protective, tight oxide will not form properly. These environments 

include: (1) atmospheres containing concentrated corrosive industrial fumes, (2) marine 

locations subject to salt-water spray or salt-laden fogs, or (3) applications where the steel 

may be continuously submerged in water (salt or fresh) or buried (bare) in soil. Use of 

weathering steel poles near roads that are salted during the winter should be avoided.

In general, weathering steel is intended for and is most often used in a bare, uncoated 

condition. However, those surfaces that will not be exposed to the weather or subjected to 

a wet-dry cycle should be protected from corrosion. Flat, horizontal surfaces are 

particularly vulnerable. Also, in areas where ground cover will grow to a height where it 

will contact the pole and rub the protective weathering steel coat off or in areas where the 

vegetation will keep the pole moist, the steel surface should be protected from corrosion by 

application of a coating. For direct embedded steel poles, the polyurethane coating may 

have to be extended above the top of the ground sleeve to protect the weathering steel pole 

from moisture entrapped by vegetation or rubbing by groundcover.
Bulletin 1724E-214

Appendix A

Page 15

Direct Embedded Poles - Coating General - Paragraph 5.i.(1)(d)

When poles are direct embedded, this specification requires a polyurethane coating to be 

applied to the exterior surface of the embedded portion of the pole. The top edge of the 

coating is not a smooth transition. Water and dirt can get trapped in this area. Therefore, 

we suggest that the transition be located about 2 inches below the top of the ground collar 

where there is extra metal. Some poles get set in areas of high vegetation. These poles 

may require the coating to extend higher on the pole. A full discussion of this is given 

below. 

Bearing Plate, Coatings, Construction in Wet Areas - Paragraph 5.i.(1)(d)

There are many problems associated with setting poles in wet areas and or bad soils. Two 

of these problems are floating poles and bog or swamp shoes. The floating poles can be 

due to the fact that some poles are designed without drain holes in the bearing plate. When 

soil conditions require the use of driller’s mud during the augering process, the pole may 

float and it is impossible to set it in the foundation unless the water is removed from the 

hole, which may cause the sides of the hole to collapse. The pole could be set if there was 

a hole in the bearing plate to allow the fluid into the pole. Galvanized poles are allowed to 

have a drain hole in the bearing plate to facilitate the galvanizing process (paragraph 

5.a.(10)). Weathering steel poles are not normally allowed to have this same hole due to 

absence of corrosion protection inside the pole. Weathering steel poles should not be used 

in areas where water/water table is above the base/bearing plate of a steel pole. The owner 

may want to coat the inside of galvanized poles with a coating similar to that on the outside 

of the pole and described in paragraph 5.i.(1)(d). 

The problem of swamp or bog shoe is the method of attaching the device to the pole. 

Normally this is done by drilling a hole through the pole and using a through bolt. The 

problem is these bolts may be at or below water line. Therefore they let water into the pole. 

This does not cause a major problem for galvanized poles. For weathering steel the steel 

needs to cycle from wet to dry to create the corrosion protection. This cannot happen 

under the above conditions. There are two solutions. One is to have the inside of the pole 

coated as described above, the other is to have the manufacture install a water tight sleeved 

hole at the location of the attachment bolts. 

Structure Testing - Paragraph 5.L

An option is available in the specification for full scale testing of poles. For a 

manufacturer that has been designing and fabricating steel poles with the same processes 

for a good number of years, the need for testing of a steel pole is questionable. Pole testing 

may be appropriate in cases where there are unusual requirements, new fabrication 

techniques or, when new suppliers are used to validate their design.
Bulletin 1724E-214

Appendix A

Page 16

3. MISCELLANEOUS DESIGN INFORMATION

Direct Embedded Poles Near Electric Generating Plants and Substations

Use of direct embedded steel poles should be evaluated for the first two spans outside of a 

substation or generating plant. The large amount of copper used in a substation grounding 

grid may create a galvanic corrosion cell, with the steel of the pole sacrificing itself. 

Anodes or extra subsurface protection may be needed.

Additional Protection

The owner or owner's representative should determine if anodes should protect the 

embedded poles. If it is necessary, requirements for sacrificial anodes and their installation 

should be incorporated in the construction specification.

Electrical Grounding and Polyurethane Coating 

When poles are direct embedded, this specification requires a polyurethane coating to be 

applied to the exterior surface of the embedded portion of the pole. This coating will tend 

to insulate the pole from the ground and as such, supplemental grounding may be 

necessary. 

Ground Rods

Use of copper or copper clad ground wire and rods should be avoided with direct 

embedded poles. Galvanized rods and couplings are suggested. 

4. SHIPPING - Paragraph 6.a.(3)

Lumber treated with salts (Ammoniacal copper arsenate, ACA, Ammoniacal copper zinc

arsenate, ACZA, and Chromated copper arsenate, CCA) to retard “decay or fire” will 

chemically attack the steel. Urethane foam or some foam containing fire retardants

should not be used in packaging and shipping. When these materials become wet, they 

become very corrosive.

5. DRAWINGS AND INFORMATION TO BE SUPPLIED BY THE 

MANUFACTURER - Section 7

In order to properly evaluate bids, the specification requires certain information to be 

supplied with the bid. This information may be supplied on the preliminary drawings from 

the Bidder. If the forms in Attachment C are used, one will be able to quickly review the 

information on the sample forms and simultaneously compare the information from the 

different manufacturers.
Bulletin 1724E-214

Appendix B

Page 1

APPENDIX B

EXAMPLES OF DRAWINGS 

(Attachment A of the Specification)

STRUCTURE DIMENSIONS, 

POLE FRAMING DRAWINGS, AND DETAILS
Bulletin 1724E-214 

Appendix B 

Page 2 

Drawing TPS-115 
Bulletin 1724E-214 

Appendix B 

Page 3

Drawing TPFS-115
Bulletin 1724E-214 

Appendix B 

Page 4 

Drawing TM-S1
Bulletin 1724E-214 

Appendix B 

Page 5

Drawing TM-S2
Bulletin 1724E-214 

Appendix B 

Page 6 

BLANK PAGE
Bulletin 1724E-214

Appendix C

Page 1

APPENDIX C. DESIGN EXAMPLES

Example 1: For the TUS-1 pole structure and loading conditions given below, determine the 

standard class steel pole:

General information:

Line voltage: 161 kV

Design by: ACME Engineers

Structure type: TUS-1 Steel Pole Structures

(steel pole with upswept arms)

Geometry of the structure and location of loads:

Distance from Pole Top, Ft.

OHGW 0.25

COND-1 9.00

COND-2 15.00

COND-3 21.00

At Gd. Line-assumed 70.00

Pole-End 80.00

Crossarm Dimensions:

Top arm 8.5 ft

Middle arm 9.5 ft

Bottom arm 9.5 ft

Overall pole length is 80 feet. The above dimensions assume a 10.0 foot 

embedment depth for the steel pole (using standard rule for wood poles 

of 10 percent pole length plus 2 feet). Assume top of the pole has a 

10 inch diameter, and the groundline diameter is 20 inches.

Load Factors (LFs) used in this example:

For NESC Light, Medium, or Heavy Loading District Loads

Vertical Loads 1.50

Transverse. Wind Loads 2.50

Transverse. Wire Tension Load at Line 

Angle

1.65

Longitudinal Loads 1.10

Extreme Wind Loads 1.10

Extreme Ice with Concurrent Wind Loads 1.10

Conductor and OHGW Data:

OHGW: 3/8”HSS

R.B.S = 10,800 lbs

161 kV Conductor: Drake (795 26/7 ACSR)

R.B.S = 31,500 lbs
Bulletin 1724E-214 

Appendix C 

Page 2 

Design Span Information: 

Vertical Span 900 ft.

Horizontal Span 750 ft. 

Line Angle 0 degrees

Load Cases: 

Load Case A: NESC Medium District Loads

Load Case B: 90 mph Extreme Wind Load (1.1 LF applied)

Load Case C: 30 mph with 1 inch ice load (1.1 LF applied) 

Loading Information (summary): 

NESC Medium Loading Data 

Transverse Vertical

Cond. Tension (kips) lb./ft. lb./ft. 

Drake –795 26/7 ACSR 7.91 .5360 1.5162 

OHGW – 3/8 HSS 2.56 .2867 .4626 

Extreme Wind Loading Data (90 mph) 

Transverse Vertical

Cond. Tension (kips) lb./ft. lb./ft. 

Drake –795 26/7 ACSR 6.54 1.9390 1.0940 

OHGW – 3/8 HSS 1.23 .6210 .2730 

Extreme Wind with Concurrent Ice (30 mph wind and 1” ice)

Transverse Vertical

Cond. Tension (kips) lb./ft. lb./ft. 

Drake –795 26/7 ACSR 12.54 .5967 3.7154 

OHGW – 3/8 HSS 5.27 .4532 1.9642
Bulletin 1724E-214 

Appendix C 

Page 3 

Calculate forces and moments at the groundline: (assumes no pole rotation) 

• NESC Medium District Loading

Load Due 

to Wind on 

Wire

(kips) 

Load Due to 

Line Angle 

(kips)

Total 

Transverse 

Load W/LF 

(kips)

Moment 

Arm Feet

Factored Moments 

Ft. kips 

@ Groundline 

OHGW .215 0 .538 69.75 37.5 

COND-1 .402 0 1.005 61.00 61.3

COND-2 .402 0 1.005 55.00 55.3

COND-3 .402 0 1.005 49.00 49.2 

Groundline 0.0 

Total Shear Loads for Wire Loads 3.57 203.4 

Wind on the Pole 0.88 27.2

Moments due to unbalanced vertical Wire Load (8.5 ft arm or 9 ft from 

conductor attachment to center of pole) 

 18.9 

Moment due to deflection for weight of pole and for wires (p-delta moment) 

Approximated, based on 15 percent of the static moment from wire loads, i.e. 

M=.15x203.4 ft kips)

 30.5 

Total Transverse Shear @ Groundline 4.45 --

Total Moments @ Groundline -- 279.9 

Total Groundline Moment for Medium Loading District = 279.9 ft.-kips 

• Extreme Wind Load and Extreme Ice with Concurrent Wind Load

Similar calculations are performed for the extreme wind load and extreme ice with concurrent wind 

loads: 

Total Ground Line Moment for Extreme Wind Load = 418 Ft-Kips

Total Groundline Moments for Extreme Ice with Concurrent Wind Loads = 165ft-kips 

• Conclusions: The Extreme Wind Loading Case controls design.

Determine which “standardized” steel pole design to use:

Distance 2’ from top to groundline = 70’ – 2.0’ = 68'

Load 2’ from the top to 

cause a 332 ft.-kip moment at groundline: = 417 ft-kips/68’ = 6140 lbs. 

Based on the above calculated tip load and from Table 1 of the specification, 

use a S-06.5 pole 

Perform a quick check to verify the assumed embedment depth using RUS Bulletin 

1724E-205, “Design Guide: Embedment Depths for Concrete and Steel Poles”. 
Bulletin 1724E-214

Appendix C

Page 4

Discussion:

Based on the results above, the extreme wind load case controls the design. Results from a computer 

program which uses finite element analysis are summarized in the table below. The results compare 

manual linear calculations with an estimate of secondary moments to the results from a computer 

program which performs a nonlinear analysis. 

The NESC allows the use of span factors and height adjustment factors when considering extreme wind 

loads (refer to RUS Bulletin 1724E-200, Design Manual for High Voltage Transmission Lines, Chapter 

11). From the summary below, several conclusions can be made. The results from manual calculations 

and the computer analysis using finite elements are close, the major difference occurring with the 

estimate of secondary moments in the manual calculations. Also, the use of span factors and height 

adjustment factors will impact the design reactions. When using span factors and height adjustment 

factors, the selected ‘standardized’ steel pole would be:

Load 2 ft from the top to cause a 334. ft kip moment (nonlinear analysis and span and height 

adjustment factors) = 4930 lbs.

Based on the above calculated tip load and from Table 1 of the specification, use a S-05.7 pole

Load Case

Groundline 

Moments based on 

manual 

calculations with 

an estimate of the 

secondary 

moments (15% of 

static moment)

Groundline 

Moments 

based on a 

nonlinear 

analysis

Groundline Moments 

based on a nonlinear 

analysis and using span 

and height adjustment 

factors

Load Case A

NESC Medium Loading

279 276 N.A.

Load Case B

Extreme Wind Load

417 401 334

Load Case C

Extreme Ice with Concurrent 

Wind

163 176 N.A.

In this example, if span factors and height adjustment factors are applied in calculating the unit loads, 

the standard size class steel pole will be reduced by one class.

Example 2: An existing 161 kV single pole line is composed of Douglas Fir wood poles. In several 

locations, steel poles are to replace wood pecker damaged wood poles. The existing damaged poles 

are 80 ft class 1 wood poles with the TUS pole top assembly. Determine which standard size steel 

pole should be used to replace the wood pole. Extreme wind design load is 20.7 psf (90 mph). The 

line is located in the heavy loading district. The conductor is 795 ACSR Drake and the overhead 

ground wire is 3/8" HSS.
Bulletin 1724E-214

Appendix C

Page 5

NESC heavy district loads with an strength factor of .65 and a load factor of 2.5 controlled the design of 

the original wood pole line. However, a quick comparison of the unit loads for the extreme wind and 

the NESC heavy district load with load factors and strength factors for steel, indicates that the extreme 

wind load will control the design of the steel pole.1 Because the extreme wind case controls design of 

the steel replacement pole, the engineer may use Table A-2 for convenience.

Table A-2 indicates that for a class 1 wood pole, a S03.5 may be used. There may be other issues in 

matching classes of wood poles to steel poles that the engineer may need to consider. This example, 

however, shows the importance of determining the loading condition that controls the design of the steel 

pole. If the engineer had assumed that the NESC heavy district load controlled design of the steel pole

replacement since it controlled the design of the wood pole when initially installed, then Table A-1 

would have been mistakenly used and a S02.9 would have been selected as the replacement pole.

Note 1: Unit loads for extreme wind is 1.9113 lbs./ft, or 2.102 with a 1.1 LF and for the NESC heavy district load, the unit 

load is 1.7567 lbs./ft (.7027 times 2.5) with a 2.5 LF.

Bulletin 1724E-214 

Appendix D 

Page 1 

APPENDIX D

SELECTED METRIC CONVERSIONS
Bulletin 1724E-214

Appendix D

Page 2

Selected SI-Metric Conversions

AREA

 To Convert From To Multiply By

circular mil (cmil) square meter (m2) 5.067075 E-10

square centimeter (cm2) square meter (m2) *1.000 E-04

square foot (ft2) square meter (m2) *9.290304 E-02

square inch (in2) square meter (m2) *6.451600 E-04

square kilometer (km2) square meter (m2) *1.000 E+06

square mile (mi2) square meter (m2) 2.589988 E+06

FORCE

 To Convert From To Multiply By 

kilogram force (kgf) Newton (N) *9.806650

kip Newton (N) 4.448222 E+03

pound force (lbf) Newton (N) 4.44822

FORCE PER LENGTH

 To Convert From To Multiply By

kilogram force per

meter (kgf/m) Newton per meter (N/m) *9.806650

pound per foot(lb./ft) Newton per meter (N/m) 1.459390 E+01

DENSITY

 To Convert From To Multiply By

pound per cubic inch (lb/in3) kilogram per cubic 2.767990 E+04

meter (kg/m3)

pound per cubic foot (lb./ft3) kilogram per cubic 1.601846 E+01

LENGTH

 To Convert From To Multiply By

foot (ft) meter (m) 3.048 E-01

inch (in) meter (m) *2.540 E-02

kilometer (km) meter (m) *1.000 E+03

mile (mi) meter (m) *1.609344 E+03

*Exact Conversion
Bulletin 1724E-214

Appendix D

Page 3

Selected SI-Metric Conversions (Cont.)

LOAD CONCENTRATION

 To Convert From To Multiply By 

pound per square inch (lb/in2) kilograms per square meter (kg/m2) 7.030696 E+02

pound per square foot (lb/ft2) kilograms per square meter (kg/m2) 4.788026

ton per square foot (ton/ft2) kilograms per square meter (kg/m2) 9.071847 E+02

PRESSURE

 To Convert From To Multiply By 

kip per square inch (kip/in2) Pascal (Pa) 6.894757 E+06

kip per square foot (kip/ft2) Pascal (Pa) 4.788026 E+04

Newton per square meter (N/m2) Pascal (Pa) *1.000

pound per square foot (lb/ft2) Pascal (Pa) 4.788026 E+01

pound per square inch (lb/in2) Pascal (Pa) 6.894757 E+03

BENDING MOMENT

 To Convert From To Multiply By 

kilogram force meter (kgf-m) Newton meter (N-m) *9.806650

kip-foot (kip-ft) Newton meter (N-m) 1.355818 E+02

pound-foot (lb-ft) Newton meter (N-m) 1.355818

VELOCITY

 To Convert From To Multiply By 

foot per second (ft/s) meter per second (m/s) *3.048 E-01

kilometer per hour (km/h) meter per second (m/s) 2.777778 E-01

mile per hour(mi/h) meter per second (m/s) 4.437030 E-01

meter per hour (m/h) meter per second (m/s) 2.777778 E-04

*Exact Conversion.
Bulletin 1724E-214 

Appendix D 

Page 4 

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