National Wood Pole Standards

1 Wood pole StandardsNelson G. Bingel III NESC Chairman President(678) 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 3 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. Benefits of Wood as a utility pole Material4 ANSIA merican National Standards Institute45 ANSIA merican National Standards InstituteANSI accredits the procedures of Standards developing organizationsNational consensus standardsOpenness, balance, consensus and due process56 ASC O5 CommitteeAmerican Standards Committee O5 USERSPRODUCERSGENERAL INTERESTA merican National Standards Institute67 ASC O5 NESCA ccredited Standards Committee O5: Standards for Wood utility Structures Secretariat: AWPA Revised: 5 year cycle Founded in 1924 National Wood pole Standards78 ASC O5 -2009 Naturally Durable Hardwood -2010 Wood Ground Wire -2010 Solid Sawn Naturally Durable Hardwood Crossarms & Manual of Wood pole CharacteristicsPolesGlu-LamCrossarms89 Single PoleSimple CantileverTransverseGroundline12 Maximum Stress PointMax Stress Diameter Load PointSolid, Round, Tapered, CantileverDistribution Usually GroundlineLoad(Wind Force on Wires, Equip.)

2 , etc.) 1213 ANSI Wood PolesWoodQualityClassLoadsPoleDimensions FiberStrength1314 Wood Quality Allowable knots1415 Wood Quality Sweep1516 Wood Quality Growth Rings1617 pole Marking & Code Letters1718 pole Marking & Code Letters1819 Transverse Wind LoadsIce1920 Class Loads2 ft LcHorizontalClassLoad (lb)103709 7407 1,20061,50051,90042,40033,00023,70014,50 0H15,400H26,400H37,500H48,700H510,000H61 1,4002021 Class Loads2 ft LcTelcoDistributionTransmissionHorizonta lClassLoad (lb)103709 7407 1,20061,50051,90042,40033,00023,70014,50 0H15,400H26,400H37,500H48,700H510,000H61 1,4002122 Strengths are Average Values2223 pole PopulationsWood PolesSteel Poles23P24 LcD2 ftClass 1 4,500 lbClass 2 3,700 lbClass 3 3,000 lbClass 4 2,400 lbClass 5 1,900 lbApplied Bending LoadApplied Bending Load =Lcx D (ft-lb)2425L x D = Bending Moment (ft-lb)76,800 ft-lb2400 lb32 ft40 ft Class 441 ft98,400 ft-lb2400 lb50 ft Class 42526 LcFiber StrengthCompression(psi)Tension(psi)Fibe r StrengthBending Capacity =kxfiber strength xC3(ft-lb)2627 Circumference3 EffectMG/L=.

3 000264 x Fiber Stress x Circumference 326 34 37,120 ft-lb83,010ft-lbCircumference Increase -30%Bending Capacity Increase -123%2728 Circumference3 EffectMG/L= .000264 x Fiber Stress x Circumference 326 34 37,120 ft-lb83,010ft-lbCircumference Increase -30%Bending Capacity Increase -123%80-90% pole s Bending Strength In The Outer 2-3 Of Shell!2829 Table 1 Designated Fiber StrengthGroup AAir SeasoningGroup BBoultonDryingGroup CSteam ConditioningGroup DKiln Drying2930 Table 1 Designated Fiber StrengthSouthern Yellow Pine8,000 psiDouglas fir8,000 psiWestern red cedar6,000 psi3031 pole Species31 Distribution:Southern Yellow PineTransmission:Douglas firWestern red cedarSouthern PineDistribution:Douglas firTransmissionDouglas firWestern red cedar32 Table 1 Designated Fiber Strength1)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 3233 Through-boring34 Oregon State University-Through-Boring Project-3435363637 Through-boring3738 Table 1 Designated Fiber Strength5)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 )The designated fiber strength represents a mean, groundline, fiber strength value with a coefficient of variation equal to 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 38392017 Table 1 to add MOE402017 Table 1 to add MOE412017 Table 1 to add MOE1) 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. 42 Circumference DimensionsTIP6ftG/LBending Capacity =kxfiber strength xC3(ft-lb)4243 Circumference Dimension Tables1) 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. 4344 Annex B: Groundline Stresses4445 Annex B: Groundline StressesMinimum circumferences specified at 6 feet from the butt Were calculated so each species in a given classCan support the class horizontal load applied 2 ft from the tip Bending Capacity =kxfiber strength xC3(ft-lb)Applied Bending Load =Lcx D (ft-lb)4546 pole Dimension Table(in)Southern Pine and Douglas Fir47 pole Dimension Table(in)Southern Pine and Douglas FirApplied Bending Load= Class Load x Distance2,400 lbsx 32 ft =76,800 ft-lbs48 pole Dimension Table(in)Southern Pine and Douglas FirApplied Bending Load= Class Load x DistanceBending Capacity =kx fiber strength x 8000 x =79,401 ft-lbs2,400 lbsx 32 ft =76,800 ft-lbs4940 ft Class 4 PolesDouglas fir(8000 psi)36 1/2 Western Red Cedar (6000 psi)33 1/2 2400 lb4950 Annex B.

5 Groundline StressesAverage circumference tapersin the groundline zone of a poleNote 75051 ANSI Summary2 ft LcBendingCapacity= kxfiber strength xC3(ft-lb)All SpeciesSame Length & ClassSimilar Load Capacity5152 Fiber Strength Values1965 PublicationForest Products LabFiber Strength Derivation5253 FPL 39 Table 4 Final Adopted Fiber Strengths5354 FPL 39 Table 4 Final Adopted Fiber StrengthsNear 5% Lower Exclusion LimitOf Actual Average Bending StrengthOf Three pole GroupsFor Grade B Construction5455 Annex C Data < 50 ft5556 Annex C Data 50 ft +5657 Full Scale Break Tests02000400060008000100001200014000160 001525354555657585 MORGL (psi)Groundline Circumference (GC) (in)Douglas Fir PolesMean = 8380 psiL5 = 6401 psiMean = 6630 psiL5 = 4825 psiASTMEPRI5758 Full Scale Break Tests02000400060008000100001200014000160 001525354555657585 MORGL (psi)Groundline Circumference (GC) (in)Douglas Fir PolesMean = 8380 psiL5 = 6401 psiMean = 6630 psiL5 = 4825 psiASTMEPRINo ChangetoPrevious Fiber Strengths5859 Annex AFiber Stress Height Effect5960 Annex AFiber Stress Height EffectRound timbers are known to decrease in ultimate unit strength with height above pole Dimensions?

6 ??????????????????????????????????CATXNY FLILPAOHMINJGANCVAMAINWATNMOWIMDAZMNLAAL COKYSCOKORCTIAMSKSARUTNVNMWVNEIDMENHRIMT DESDNDVTDCWYS ample Locations?Coastal Douglas Fir (8)?Coastal DF & Western Red (3)?Northern Red Pine (3)?Southern Yellow Pine (16)?Western Red Cedar (5)6162 Coastal Douglas fir 6,997 poles9 Producers; 11 Locations Southern Yellow Pine6,634 poles11 Producers; 16 Locations Western Red Cedar6,982 poles5 Producers; 9 Locations Northern Red Pine2,266 poles2 Producers; 4 LocationsGrand Total 22,859 polesPole Circumference Data6263 Fiber Stress Height Effect (FSHE) Tips average 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 reduction6364 ASC O5 -2009 Naturally Durable Hardwood -2010 Wood Ground Wire -2010 Solid Sawn Naturally Durable Hardwood Crossarms & Manual of Wood pole CharacteristicsPolesGlu-LamCrossarms6465 ASC O5 NESCA ccredited Standards Committee O5: Standards for Wood utility Structures Secretariat: AWPA Revised: 5 year cycle Founded in 1924 National Wood pole Standards6566 National Overhead Line StandardANSI C2: National Electrical Safety Code Secretariat: IEEE (Institute of Electrical and Electronics Engineers) Revised.

7 5 year cycle Established in 1915 NESC67 NESC Committee Structure67 ChairmanVice ChairSecretary-IEEE25 35 MembersMainCommitteeExecutiveSubcommitte eTechnicalSubcommitteesChairmanSecretary 6 -10 MembersChairmanSecretarySC 1 Coordination; Sections 1,2,3SC 2 GroundingSC 3 SubstationsSC 4 Overhead Lines ClearancesSC 5 Overhead Lines Strength & LoadingSC 7 Underground LinesSC 8 Work Rules68 Purpose of the NESC69B. 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 facilitiesC. This code is not intended as a design specification or as an instruction manual. Purpose of the NESC70 NESC Committee Structure70 ChairmanVice ChairSecretary-IEEE25 35 MembersMainCommitteeExecutiveSubcommitte eTechnicalSubcommitteesChairmanSecretary 6 -10 MembersChairmanSecretarySC 1 Coordination; Sections 1,2,3SC 2 GroundingSC 3 SubstationsSC 4 Overhead Lines ClearancesSC 5 Overhead Lines Strength & LoadingSC 7 Underground LinesSC 8 Work Rules71 Section 24 Grades of ConstructionSection 25 Loadingfor Grade B&CSection 26 Strengthrequirements 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 FactorsOverhead Lines Subcommittee 572 Section 24 Grades of ConstructionSection 25 Loadingfor Grade B&CSection 26 Strengthrequirements 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 FactorsOverhead Lines Subcommittee 5 Section 27 Insulators Electrical Strength Mechanical Strength73 Section 24: Grades of Construction Grade B.

8 ( SF) Crossing Limited Access Highways Crossing Railways Crossing Navigable Waterways Grade C: ( SF) All other standard construction Grade N: (Strength shall exceed expected loads) Mainly used for temporary and emergency construction7374 TRANSVERSEVERTICAL74 Section 25 Loadings for Grade B & C75 Wire with IceTransverse Loading Usually Governs76 Wind Bending Loads On:WiresIcePoleEquipmentOffset Bending LoadsWire Tension76 Calculating Transverse Loads77 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)7778 NESC District Loading Ice 40 mph Ice 40 mph0 Ice 60 mph40 mph = 4 lbs/sqft60 mph = 9 lbs/sqft78 Winter Storm79 Ice40 mphMedium Loading District80 Wind Load Increase per Wire 80 Double wire diameter = Double the load+100%+200% +67%+33%+17%Wind Load Increase With Radial .25 82 District Loads vs Wire Size01234567894 ACSR1/0336556 RELATIVE LOADCONDUCTOR (SMALLEST TO LARGEST)NESC-LNESC-MNESC-H82No ICE1/4 ICE1/2 ICE83 Section 25: Loading for Grade B & C Rule 250B: District Loading Combined Ice and Wind 83 Deterministic84 Extreme Wind Rule 250C(60 ft.)

9 Exclusion)85 mph = lbs/sqft90 mph = 21 lbs/sqft130 mph = 43 lbs/sqft150 mph = 58 lbs/sqft84 Summer Storm85 Extreme Ice with Concurrent Wind Rule 250D(60 ft. Exclusion)Winter StormWind Speeds 30 mph 40 mph 50 mph 60 mphRadial Ice0 8586 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)86 DeterministicProbabilisticProbabilistic8 7 Section 25 Load Cases Rule 250 B -Combined Ice & Wind Light0 Ice60 mph Medium Ice40 mph Heavy Ice40 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 occurrence88 StrengthPole Strength x SF pole Strength x SFAlternate MethodStrengthLoad>>Storm Load x4 (B)Storm Load x2 (C)>> pole Strength pole Strength LoadStorm Load xLF (B)Storm Load xLF (C)89 Grade BGrade CxGrade CRule (wind) and Wind 25: Table Factors90 Section 26.

10 Strength FactorsGrade BGrade CRule 250 BMetal & 250 DMetal Strength(ANSI) Strength Factor (NESC)= Allowable Stress of PoleTable 261-19091 StrengthPole Strength x SF pole Strength x SFAlternate MethodStrengthLoad>>Storm Load x4 (B)Storm Load x2 (C)>> pole Strength pole Strength LoadStorm Load xLF (B)Storm Load xLF (C)92 StrengthPole Strength x .65 pole Strength x .85 Alternate MethodStrengthLoad>>Storm Load x4 (B)Storm Load x2 (C)>> pole Strength pole Strength LoadStorm Load (B)Storm Load (C) 24: Grades of Construction Grade B: ( SF) Crossing Limited Access Highways Crossing Railways Crossing Navigable Waterways Grade C: ( SF) All other standard construction Grade N: (Strength shall exceed expected loads) Mainly used for temporary and emergency construction939495 Equate the Total Storm Load to a Single Horizontal Load applied 2 feet from the tip. 900 lb96900 lbStorm Loadx (Grade B)Class 1 4500 lbClass 2 3700 lbClass 3 3000 lbClass 4 2400 lbClass 5 1900 lb= 3465 lbNESCANSI <StrengthGrade B97900 lbStorm Loadx (Grade C)= 1854 lbNESCANSI <StrengthGrade CClass 1 4500 lbClass 2 3700 lbClass 3 3000 lbClass 4 2400 lbClass 5 1900 lb98 IEEE Online Courses MOOC s98 MOOC #1 NESC OverviewMOOC #22017 Subcommittees99 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 40-43100 Online Courses MOOC s100 MOOC #1 NESC OverviewMOOC #22017 ChangesMOOC #3 Grounding MethodsMOOC #4 Electric Supply