national wood pole standards44 circumference3effect mg/l= .000264 x fiber strength x circumference 3...

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• Nelson G. Bingel III• ASC O5 Chairman• NESC Chairman

National Wood Pole Standards

President(678) 850-1461nbingel@nelsonresearch.net

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Benefits of Wood as a Utility Pole Material

• Long-Life Span• ~45 years national average without remedial treatment

• Lowest cost• Both initial and full life-cycle costs

• Proven Performance • “Go to” overhead line construction material since the

early 1900’s

• Climb-ability• Ability to service attachments without heavy equipment

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• Supply Chain is Proven• Even in natural disaster events where demand is high, the wood

pole industry has provided poles in required timeline.

• Beneficial Physical Properties• Good insulator, resilience to wind and mechanical impacts

• Easy Maintenance and Modification in service

• “Green”• a treated wood pole has a reduced environmental impact when

compared to other utility pole materials.• A renewable and plentiful resource

“10 Features Often Overlooked About the Extraordinary Wood Pole.”  North American Wood Pole Council. www.woodpoles.org 

Benefits of Wood as a Utility Pole Material

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ANSI

American National Standards Institute

5

ANSI

American National Standards Institute

ANSI accredits the procedures of standards developing organizations

6

ANSI

American National Standards Institute

ANSI accredits the procedures of standards developing organizations

National consensus standards

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ANSI

American National Standards Institute

ANSI accredits the procedures of standards developing organizations

National consensus standards

Openness, balance, consensus and due process

8

American Standards Committee O5 – ASC O5

American Standards Committee O5

USERS

PRODUCERS

GENERAL INTEREST

American National Standards Institute

9

Accredited Standards Committee O5:

Standards for Wood Utility Structures

• Secretariat: AWPA

• Revised: 5 year cycle

• Founded in 1924

National Wood Pole Standards

ASC O5 NESC

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ASC O5 Standards

O5.4 - 2009 Naturally Durable Hardwood Poles

O5.5 - 2010 Wood Ground Wire Moulding

O5.6 - 2010 Solid Sawn Naturally Durable Hardwood Crossarms & Braces

O5.TR.01-2004 Photographic Manual of Wood Pole Characteristics

Glu-Lam CrossarmsPoles

11

http://asco5.org/standards/

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http://asco5.org/standards/

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Scope

Single Pole

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Scope

Single Pole

Simple Cantilever

15

Scope

Single Pole

Simple Cantilever

Transverse

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Scope

Single Pole

Simple Cantilever

Transverse

Groundline

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Maximum Stress Point

Solid, Round, Tapered, Cantilever

Load(Wind Force on Wires, Equip., etc.)

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Maximum Stress Point

Max Stress @ 1.5 Diameter Load Point

Solid, Round, Tapered, Cantilever

Load(Wind Force on Wires, Equip., etc.)

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Maximum Stress Point

Max Stress @ 1.5 Diameter Load Point

Solid, Round, Tapered, Cantilever

Distribution Usually Groundline

Load(Wind Force on Wires, Equip., etc.)

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Maximum Stress Point

Max Stress @ 1.5 Diameter Load Point

Solid, Round, Tapered, Cantilever

Distribution Usually Groundline

Load(Wind Force on Wires, Equip., etc.)

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ANSI O5.1 – Wood Poles

WoodQuality

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ANSI O5.1 – Wood Poles

WoodQuality

ClassLoads

PoleDimensions

FiberStrength

23

Wood Quality

• Allowable knots

24

• Sweep

Wood Quality

25

• Growth Rings

Wood Quality

26

Pole Marking & Code Letters

27

Pole Marking & Code Letters

28

Transverse Wind Loads

Ice

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Class Loads

2 ft Lc

HorizontalClass Load (lb)10 3709 7407 1,2006 1,5005 1,9004 2,4003 3,0002 3,7001 4,500

H1 5,400H2 6,400H3 7,500H4 8,700H5 10,000H6 11,400

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General Class Load Applications

2 ft Lc

HorizontalClass Load (lb)10 3709 7407 1,2006 1,5005 1,9004 2,4003 3,0002 3,7001 4,500

H1 5,400H2 6,400H3 7,500H4 8,700H5 10,000H6 11,400

Telecom Only Poles

Distribution

Transmission

General Industry Use

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Strengths are Average Values

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Wood vs. Steel VariabilityASCE Manual and Reports on Engineering Practice No. 141

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Lc2 ft

Class 1 4,500 lbClass 2 3,700 lbClass 3 3,000 lbClass 4 2,400 lbClass 5 1,900 lb

Applied Bending Load

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Lc

D

2 ft

Class 1 4,500 lbClass 2 3,700 lbClass 3 3,000 lbClass 4 2,400 lbClass 5 1,900 lb

Applied Bending Load

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Lc

D

2 ft

Class 1 4,500 lbClass 2 3,700 lbClass 3 3,000 lbClass 4 2,400 lbClass 5 1,900 lb

Applied Bending Load =Lc x D (ft-lb)

Applied Bending Load

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L x D = Bending Moment (ft-lb)

76,800 ft-lb

2400 lb

32 ft

40 ft Class 4

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L x D = Bending Moment (ft-lb)

76,800 ft-lb

2400 lb

32 ft

40 ft Class 4

41 ft

98,400 ft-lb

2400 lb

50 ft Class 4

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Lc

Fiber Strength

39

Lc

Compression(psi)

Tension(psi)

Fiber Strength

40

Lc

Fiber Strength

Fiber Strength

Compression(psi)

Tension(psi)

41

Lc

Compression(psi)

Tension(psi) Fiber Strength

Bending Capacity =k x fiber strength x C3 (ft-lb)

Fiber Strength

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Circumference3 Effect

MG/L = .000264 x Fiber Stress x Circumference 3

26”34”

37,120 ft-lb83,010 ft-lb

Circumference Increase - 30%

Bending Capacity Increase - 123%

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Circumference3 Effect

MG/L = .000264 x Fiber Strength x Circumference 3

26”34”

37,120 ft-lb83,010 ft-lb

Circumference Increase - 30%

Bending Capacity Increase - 123%

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Circumference3 Effect

MG/L = .000264 x Fiber Strength x Circumference 3

26”34”

37,120 ft-lb83,010 ft-lb

Circumference Increase - 30%

Bending Capacity Increase - 123%

80-90% Pole’s Bending Strength

In The Outer 2-3” Of Shell!

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Table 1 – Designated Fiber Strength

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Table 1 – Designated Fiber Strength

Group AAir Seasoning

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Table 1 – Designated Fiber Strength

Group AAir Seasoning

Group BBoulton Drying

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Table 1 – Designated Fiber Strength

Group AAir Seasoning

Group BBoulton Drying

Group CSteam Conditioning

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Table 1 – Designated Fiber Strength

Group AAir Seasoning

Group BBoulton Drying

Group CSteam Conditioning

Group DKiln Drying

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Southern Yellow Pine 8,000 psi

Douglas fir 8,000 psi

Western red cedar 6,000 psi

Table 1 – Designated Fiber Strength

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Pole Species

52

Pole Species

53

Pole Species

Distribution:Southern Yellow Pine

Transmission:Douglas fir

Western red cedarSouthern Pine

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Pole Species

Distribution:Southern Yellow Pine

Transmission:Douglas fir

Western red cedarSouthern Pine

Distribution:Douglas fir

TransmissionDouglas fir

Western red cedar

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Table 1 – Designated Fiber Strength

56

1) The effects of conditioning on fiber strength have been accounted for in the Table 1 values provided that conditioning was performed within the limits herein prescribed.

Table 1 – Designated Fiber Strength

57

1) The effects of conditioning on fiber strength have been accounted for in the Table 1 values provided that conditioning was performed within the limits herein prescribed.

4) The designated fiber strength represents a mean, groundline, fiber strength value with a coefficient of variation equal to 0.20.

Table 1 – Designated Fiber Strength

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Through-boring

59

Oregon State University-Through-Boring Project-

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60

61

62

Through-boring

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5) Where Douglas-fir (coastal or Interior North) are through-bored prior to treatment, to account for the process, the designated fiber strength shall be reduced 5% to 7600 psi.

1) The effects of conditioning on fiber strength have been accounted for in the Table 1 values provided that conditioning was performed within the limits herein prescribed.

4) The designated fiber strength represents a mean, groundline, fiber strength value with a coefficient of variation equal to 0.20.

Table 1 – Designated Fiber Strength

64

2017 Table 1 added MOE

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2017 Table 1 added MOE

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2017 Table 1 added MOE

1) The fiber strength and MOE values in Table 1 apply to wood utility poles meeting this standard. The effects of conditioning on fiber strength and MOE have been accounted for ……..

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2017 Table 1 added MOE

1) The fiber strength and MOE values in Table 1 apply to wood utility poles meeting this standard. The effects of conditioning on fiber strength and MOE have been accounted for ……..

7) The Modulus of Elasticity (MOE) represents a mean value.

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TIP

6ft

G/L

Circumference Dimensions

69

TIP

6ft

G/L

Bending Capacity =k x fiber strength x C3 (ft-lb)

Circumference Dimensions

70

Circumference Dimension Tables

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Circumference Dimension Tables

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Circumference Dimension Tables

1) The figures in this column are not recommended embedment depths; rather, these values are intended for use only when a definition of groundline is necessary in order to apply requirements relating to scars, straightness, etc.

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Circumference Dimension Tables

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Annex B: Groundline Stresses

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75

Annex B: Groundline Stresses

Minimum circumferences specified at 6 feet from the butt

Were calculated so each species in a given class

Can support the class horizontal load applied 2 ft from the tip

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Annex B: Groundline Stresses

Minimum circumferences specified at 6 feet from the butt

Were calculated so each species in a given class

Can support the class horizontal load applied 2 ft from the tip

Applied Bending Load =Lc x D (ft-lb)

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77

Annex B: Groundline Stresses

Minimum circumferences specified at 6 feet from the butt

Were calculated so each species in a given class

Can support the class horizontal load applied 2 ft from the tip

Bending Capacity =k x fiber strength x C3 (ft-lb)

Applied Bending Load =Lc x D (ft-lb)

77

78

Pole Dimension Table

(in)

Southern Pine and Douglas Fir

78

79

Pole Dimension Table

(in)

Southern Pine and Douglas Fir

79

80

Pole Dimension Table

(in)

Southern Pine and Douglas Fir

80

81

Pole Dimension Table

(in)

Southern Pine and Douglas Fir

81

Applied Bending Load= Class Load * Distance

76,800 ft-lbs= 2,400 lbs* 32ft

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Pole Dimension Table

(in)

Southern Pine and Douglas Fir

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Applied Bending Load= Class Load * Distance

Bending Capacity =k x fiber strength x C3

79,401 ft-lbs=.000264 x 8000x 33.53

76,800 ft-lbs= 2,400 lbs* 32ft

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40 ft Class 4 Poles

Douglas fir(8000 psi)

Western Red Cedar (6000 psi)

84

40 ft Class 4 Poles

Douglas fir(8000 psi)

Western Red Cedar (6000 psi)

2400 lb

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40 ft Class 4 Poles

Douglas fir(8000 psi)

36 1/2”

Western Red Cedar (6000 psi)

33 1/2”

2400 lb

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Annex B: Groundline Stresses

Note 7

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Annex B: Groundline Stresses

Average circumference tapersin the groundline zone of a pole

Note 7

88

ANSI O5.1 Summary

2 ft Lc

BendingCapacity = k x fiber strength x C3 (ft-lb)

89

ANSI O5.1 Summary

2 ft Lc

BendingCapacity = k x fiber strength x C3 (ft-lb)

Lc

90

ANSI O5.1 Summary

2 ft Lc

BendingCapacity = k x fiber strength x C3 (ft-lb)

All SpeciesSame Length & ClassSimilar Load Capacity

Lc

91

ANSI O5.1 Summary

2 ft Lc

BendingCapacity = k x fiber strength x C3 (ft-lb)

All SpeciesSame Length & ClassSimilar Load Capacity

Lc

= k x fiber strength x C3 (ft-lb)

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ANSI O5.1 Summary

2 ft Lc

BendingCapacity = k x fiber strength x C3 (ft-lb)

All SpeciesSame Length & ClassSimilar Load Capacity

Lc

= k x fiber strength x C3 (ft-lb)= k x fiber strength x C3 (ft-lb)

93

Fiber Strength Values

1965 Publication

Forest Products Lab

Fiber Strength Derivation

93

94

FPL 39 Table 4Final Adopted Fiber Strengths

94

95

FPL 39 Table 4Final Adopted Fiber Strengths

Near 5% Lower Exclusion Limit

Of Actual Average Bending Strength

Of Three Pole Groups

95

96

Newer Test Data That Was Adjusted to Align with FPL 39

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Annex C – Poles <50 ft

9797

Newer Test Data That Was Adjusted to Align with FPL 39Annex C – Poles 50 ft and longer

98

All Adjusted Full Scale Break Tests

ASTM

EPRI

98

99

All Adjusted Full Scale Break Tests

ASTM

EPRI

No Changeto

Previous Fiber Strengths

99

100

Annex AFiber Stress Height Effect

100

101

Annex AFiber Stress Height Effect

Round timbers are known to decrease in ultimate unit strength

with height above ground.

101

102

Actual Pole Dimensions

CA

TX

NY

FL

IL

PA

OH

MI

NJ

GA

NC

VA

MA

IN

WA

TN

MO

WI

MD

AZ

MN

LA

AL

CO

KY

SCOK

OR

CT

IA

MS

KS

AR

UTNV

NM

WV

NE

ID

ME

NH

RI

MT

DE

SD

ND

VT

DC

WY

Sample Locations Coastal Douglas Fir (8)

Coastal DF & Western Red (3)

Northern Red Pine (3)

Southern Yellow Pine (16)

Western Red Cedar (5)

102

103

• Coastal Douglas fir 6,997 poles9 Producers; 11 Locations

• Southern Yellow Pine 6,634 poles11 Producers; 16 Locations

• Western Red Cedar 6,982 poles5 Producers; 9 Locations

• Northern Red Pine 2,266 poles2 Producers; 4 Locations

Pole Circumference Data

103

104

• Coastal Douglas fir 6,997 poles9 Producers; 11 Locations

• Southern Yellow Pine 6,634 poles11 Producers; 16 Locations

• Western Red Cedar 6,982 poles5 Producers; 9 Locations

• Northern Red Pine 2,266 poles2 Producers; 4 Locations

Grand Total 22,859 poles

Pole Circumference Data

104

105

Fiber Stress Height Effect (FSHE)

• Tips average 1.5 to 2 classes larger

• Poles 55 ft and shorter• Maximum stress is usually at G/L– FSHE not applied• Maximum stress for guyed poles may be above G/L– Oversize offsets fiber stress height effect

• Poles 60 ft and taller• If maximum stress is at the G/L, no FSHE• If maximum stress is above ground, tables for

reduction

105

106

O5.4 - 2009 Naturally Durable Hardwood Poles

O5.5 - 2010 Wood Ground Wire Moulding

O5.6 - 2010 Solid Sawn Naturally Durable Hardwood Crossarms & Braces

O5.TR.01-2004 Photographic Manual of Wood Pole Characteristics

Glu-Lam CrossarmsPoles

ASC O5 Standards http://asco5.org/standards/

107

Accredited Standards Committee O5:

Standards for Wood Utility Structures

• Secretariat: AWPA

• Revised: 5 year cycle

• Founded in 1924

National Wood Pole Standards

ASC O5 NESC

108

National Overhead Line Standard

ANSI C2:

National Electrical Safety Code

• Secretariat: IEEE (Institute of Electrical and Electronics Engineers)

• Revised: 5 year cycle

• Established in 1915

NESC

109

NESC Committee Structure

Chairman Vice Chair Secretary-IEEE

25 – 35 MembersMainCommittee

ExecutiveSubcommittee

TechnicalSubcommittees

Chairman Secretary

6 - 10 Members

Chairman Secretary

SC 1 – Coordination; Sections 1,2,3SC 2 – GroundingSC 3 – SubstationsSC 4 – Overhead Lines – ClearancesSC 5 – Overhead Lines – Strength & LoadingSC 7 – Underground LinesSC 8 – Work Rules

110

Purpose of the NESC

111

B. NESC rules contain the basic provisions, under specified conditions, that are considered necessary for the safeguarding of:1. The Public2. Utility workers (employees and contractors), and3. Utility facilities

C. This code is not intended as a design specification or asan instruction manual.

Purpose of the NESC

112

NESC Committee Structure

Chairman Vice Chair Secretary-IEEE

25 – 35 MembersMainCommittee

ExecutiveSubcommittee

TechnicalSubcommittees

Chairman Secretary

6 - 10 Members

Chairman Secretary

SC 1 – Coordination; Sections 1,2,3SC 2 – GroundingSC 3 – SubstationsSC 4 – Overhead Lines – ClearancesSC 5 – Overhead Lines – Strength & LoadingSC 7 – Underground LinesSC 8 – Work Rules

113

Section 24Grades of Construction

Section 25Loading for Grade B&C

Section 26Strength requirements

• Grades B, C & N (B is the highest)

• Load Factors

• Rule 250B: Combined Ice and Wind District Loading

• Rule 250C: Extreme Wind Loading

• Rule 250D: Extreme Ice with Concurrent Wind Loading

• Strength Factors

Overhead Lines Subcommittee 5

114

Section 24Grades of Construction

Section 25Loading for Grade B&C

Section 26Strength requirements

• Grades B, C & N (B is the highest)

• Load Factors

• Rule 250B: Combined Ice and Wind District Loading

• Rule 250C: Extreme Wind Loading

• Rule 250D: Extreme Ice with Concurrent Wind Loading

• Strength Factors

Overhead Lines Subcommittee 5

Section 27Insulators

• Electrical Strength• Mechanical Strength

115

Section 24: Grades of Construction

• Grade B: (3.85 SF)• Crossing Limited Access Highways• Crossing Railways• Crossing Navigable Waterways

• Grade C: (2.06 SF)• All other standard construction

• Grade N: (Strength shall exceed expected loads)• Mainly used for temporary and emergency construction

116

TRANSVERSEVERTICAL

Section 25 – Loadings for Grade B & C

117

TRANSVERSE

Transverse Loading Usually Governs

VERTICAL

118

Wind Bending Loads On:

118

Calculating Transverse Loads

119

Wind Bending Loads On:WiresIce

119

Calculating Transverse Loads

120

Wind Bending Loads On:WiresIcePole

120

Calculating Transverse Loads

121

Wind Bending Loads On:WiresIcePoleEquipment

121

Calculating Transverse Loads

122

Wind Bending Loads On:WiresIcePoleEquipment

Offset Bending Loads

122

Calculating Transverse Loads

123

Wind Bending Loads On:WiresIcePoleEquipment

Offset Bending Loads

Wire Tension123

Calculating Transverse Loads

124

Section 25: Loading for Grade B & C

• Rule 250B: District Loading Combined Ice and Wind

• Rule 250C: Extreme Wind Loading (60ft Exemption)

• Rule 250D: Extreme Ice With Concurrent Wind Loading(60ft Exemption)

125

NESC District LoadingWinter Storm

126

NESC District Loading

½” Ice – 40 mph½” Ice – 40 mph

¼” Ice – 40 mph¼” Ice – 40 mph

0” Ice – 60 mph0” Ice – 60 mph

Winter Storm

127

NESC District Loading

½” Ice – 40 mph½” Ice – 40 mph

¼” Ice – 40 mph¼” Ice – 40 mph

0” Ice – 60 mph0” Ice – 60 mph40 mph = 4 lbs/sqft

60 mph = 9 lbs/sqft

40 mph = 4 lbs/sqft

60 mph = 9 lbs/sqft

Winter Storm

128

¼” Ice

128

40 mph40 mph

Medium Loading District

129

Wind Load Increase per Wire Sizes

0.75” 1.50” 3.00”

Double wire diameter = Double the load

+100% +200%

2x2x

130

1.25” 2.00” 3.50”+67% +33% +17%

Wind Load Increase With 0.25” Radial Ice

1.50” 3.00”.25” Ice

0.75”

131

0

1

2

3

4

5

6

7

8

9

4ACSR 1/0 336 556

REL

ATIV

E LO

AD

CONDUCTOR (SMALLEST TO LARGEST)

NESC-L

NESC-M

NESC-H

District Loads vs. Wire Size

No ICE

1/4” ICE

1/2” ICE

132

Section 25: Loading for Grade B & C

• Rule 250B: District Loading Combined Ice and Wind

133

Section 25: Loading for Grade B & C

• Rule 250B: District Loading Combined Ice and Wind

Deterministic

134

Extreme Wind– Rule 250C(60 ft. Exclusion)

85 mph = 18.5 lbs/sqft

90 mph = 21 lbs/sqft

130 mph = 43 lbs/sqft

150 mph = 58 lbs/sqft

85 mph = 18.5 lbs/sqft

90 mph = 21 lbs/sqft

130 mph = 43 lbs/sqft

150 mph = 58 lbs/sqft

Summer Storm

135

Extreme Ice with Concurrent Wind –Rule 250D(60 ft. Exclusion)

Winter Storm

Wind Speeds

30 mph

40 mph

50 mph

60 mph

Wind Speeds

30 mph

40 mph

50 mph

60 mph

Radial Ice

0”

0.25”

0.5”

0.75”

1.0”

Radial Ice

0”

0.25”

0.5”

0.75”

1.0”

136

Section 25: Loading for Grade B & C

• Rule 250B: District Loading Combined Ice and Wind

• Rule 250C: Extreme Wind Loading (60ft Exemption)

• Rule 250D: Extreme Ice With Concurrent Wind Loading(60ft Exemption)

Deterministic

137

Section 25: Loading for Grade B & C

• Rule 250B: District Loading Combined Ice and Wind

• Rule 250C: Extreme Wind Loading (60ft Exemption)

• Rule 250D: Extreme Ice With Concurrent Wind Loading(60ft Exemption)

Deterministic

Probabilistic

138

Section 25: Loading for Grade B & C

• Rule 250B: District Loading Combined Ice and Wind

• Rule 250C: Extreme Wind Loading (60ft Exemption)

• Rule 250D: Extreme Ice With Concurrent Wind Loading(60ft Exemption)

Deterministic

Probabilistic

Probabilistic

139

Section 25 Load Cases

• Rule 250 B - Combined Ice & Wind– Light 0” Ice 60 mph– Medium ¼” Ice 40 mph– Heavy ½” Ice 40 mph– Loads to be Factored

• Rule 250 C – Extreme Wind– Poles Taller than 60 feet Above Ground– Wind only (no ice) – Ultimate Load with probability of occurrence

• Rule 250 D – Extreme Ice with Wind– Poles Taller than 60 feet Above Ground– Ice Thickness with Concurrent Wind– Ultimate Load with probability of occurrence

140

Alternate Method

Strength

Load

Storm Load x 4 (B)

Storm Load x 2 (C)>>

Pole Strength

Pole Strength

141

StrengthPole Strength x SF

Pole Strength x SFAlternate Method

Strength

Load

>>

Storm Load x 4 (B)

Storm Load x 2 (C)>>

Pole Strength

Pole Strength

142

StrengthPole Strength x SF

Pole Strength x SFAlternate Method

Strength

Load

>>

Storm Load x 4 (B)

Storm Load x 2 (C)>>

Pole Strength

Pole Strength

LoadStorm Load x LF (B)

Storm Load x LF (C)

143

Grade B Grade Cx Grade CRu

le 2

50B

Vertical Loads 1.50 1.90 1.90

Transverse Loads(wind) 2.50 2.20 1.75

Longitudinal Loads 1.10 No Req. No Req.

250C Wind Loads 1.00 1.00 1.00

250D Ice and Wind

loads 1.00 1.00 1.00

Section 25: Table 253.1-Load Factors

144

Grade B Grade Cx Grade CRu

le 2

50B

Vertical Loads 1.50 1.90 1.90

Transverse Loads(wind) 2.50 2.20 1.75

Longitudinal Loads 1.10 No Req. No Req.

250C Wind Loads 1.00 1.00 1.00

250D Ice and Wind

loads 1.00 1.00 1.00

Section 25: Table 253.1-Load Factors

145

Section 26: Strength Factors

Grade B Grade CRu

le 2

50B Metal Structures 1.0 1.0

Wood Structures 0.65 0.85

250C

& 2

50D

Metal Structures 1.00 1.00

Wood Structures 0.75 0.75

Table 261‐1

146

Section 26: Strength Factors

Grade B Grade CRu

le 2

50B Metal Structures 1.0 1.0

Wood Structures 0.65 0.85

250C

& 2

50D

Metal Structures 1.00 1.00

Wood Structures 0.75 0.75

Fiber Strength (ANSI)× Strength Factor (NESC)=

Allowable Stress of Pole

Table 261‐1

147

Section 26: Strength Factors

Grade B Grade CRu

le 2

50B Metal Structures 1.0 1.0

Wood Structures 0.65 0.85

250C

& 2

50D

Metal Structures 1.00 1.00

Wood Structures 0.75 0.75

Fiber Strength (ANSI)× Strength Factor (NESC)=

Allowable Stress of Pole

Table 261‐1

148

StrengthPole Strength x SF

Pole Strength x SFAlternate Method

Strength

Load

>>

Storm Load x 4 (B)

Storm Load x 2 (C)>>

Pole Strength

Pole Strength

LoadStorm Load x LF (B)

Storm Load x LF (C)

149

StrengthPole Strength x .65

Pole Strength x .85Alternate Method

Strength

Load

>>

Storm Load x 4 (B)

Storm Load x 2 (C)>>

Pole Strength

Pole Strength

LoadStorm Load x 2.5 (B)

Storm Load x 1.75 (C)

150

StrengthPole Strength x .65

Pole Strength x .85Alternate Method

Strength

Load

>>

Storm Load x 4 (B)

Storm Load x 2 (C)>>

Pole Strength

Pole Strength

LoadStorm Load x 2.5 (B)

Storm Load x 1.75 (C)

3.85 2.06

151

Section 24: Grades of Construction

• Grade B: (3.85 SF)• Crossing Limited Access Highways• Crossing Railways• Crossing Navigable Waterways

• Grade C: (2.06 SF)• All other standard construction

• Grade N: (Strength shall exceed expected loads)• Mainly used for temporary and emergency construction

Equate the 

Total Storm Load 

to a 

Single Horizontal Load 

applied 

2 feet from the tip. 

900 lb

900 lb Storm Loadx 3.85 (Grade B)

Class 1 4500 lbClass 2 3700 lbClass 3 3000 lbClass 4 2400 lbClass 5 1900 lb

= 3465 lb

NESC ANSI O5.1

Load < Strength

Grade B

155

900 lb Storm Loadx 2.06 (Grade C)

= 1854 lb

NESC ANSI O5.1

Load < Strength

Grade C

Class 1 4500 lbClass 2 3700 lbClass 3 3000 lbClass 4 2400 lbClass 5 1900 lb

156

157

Length

158

ClearanceLength

159

ClearanceLength

Class

160

Clearance

Capacity

Length

Class

161

Clearance

Capacity

Length

Class

Class 1 4,500 lbClass 2 3,700 lbClass 3 3,000 lbClass 4 2,400 lbClass 5 1,900 lb

162

Online Courses – MOOC’s

MOOC #1 NESC Overview

MOOC #2 2017 Changes

163

Technical Subcommittees

SC1 - Coordination between technical subcommittees Sections 1, 2 and 3

SC2 - Grounding Methods - Section 9

SC3 - Electric Supply Stations - Sections 10-19

SC4 - Overhead Lines - Clearances - Section 20-23

SC5 - Overhead Lines - Strength and Loading -Sections 24-27

SC7 - Underground Lines - Sections 30-39

SC8 - Work Rules - Sections 40-43

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Online Courses – MOOC’s

MOOC #1 NESC Overview

MOOC #2 2017 Changes

MOOC #3 Grounding Methods

MOOC #4 Electric Supply Stations

MOOC #5 Overhead Lines – Clearances and S&L

MOOC #6 Underground Lines

MOOC #7 Work Rules

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Released !!!!

166

Tables & Equations

Home Page Table of Contents

NESC Mobile App

167

Search the NESC Search IEEE

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168

• Nelson G. Bingel III• ASC O5 Chairman• NESC Chairman

National Wood Pole Standards

President(678) 850-1461nbingel@nelsonresearch.net