APPENDIX A

COMMENTARY

A. General
The necessity of a clear bid specification for the purchase of standard classconcrete 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 this standard class concrete pole specification does not prohibit theapplication 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 in this type of application.

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 concrete pole which might otherwise bebeyond the scope of this specification. The owner must be sure that combinedbending and buckling analysis is performed, that cracking strength and zerotension strength is evaluated, and that deflections are properly modeled.

The owner should recognize when the design of a concrete pole may be moreprudently accomplished using the *Guide Specification for Spun, PrestressedConcrete Pole and Concrete Pole Structures*, RUS Bulletin 1724E-206, whichrequires the actual loading conditions to be specified. In using Bulletin1724E-206, the manufacturer assumes full responsibility in designing andmanufacturing a structurally adequate pole.
**Standard Class Pole**
In some cases, utilities prefer to specify certain spun concrete poles to bedesigned according to a standardized loading criteria, much like the standardclassifications for wood poles.

In utilizing standard class spun concrete poles, a complete structuralanalysis is still required for all structures. All appropriate loading criteriaare considered in the analysis. Once the required concrete pole strength isdetermined, a standard class spun concrete pole which meets the actual loading conditions can be selected. A design example is shown inAppendix C.

This specification was developed to establish a standard classificationsystem and to assist the owner in procuring a standard class concrete pole whichis properly designed for the intended loading criteria.

This guide specification attempts to eliminate ambiguity in specifying andpurchasing standard class concrete 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 concrete pole classifications developed in this specificationgenerally follow the wood pole classification system. However, to avoidconfusion with the wood pole classifications, the concrete 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,WoodPole Specifications and Dimensions, and then wish to order concrete poles whichmeet the wood pole equivalent loadings. Because of the differences in overloadfactors applied to wood poles in comparison to concrete poles, the owner must besure that the overload factors are properly accounted for in the design of theconcrete 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 prestressed concrete pole which is equated byrequired ultimate loading to an ANSI 05.1 standard class wood pole. The equationis made by a ratio of the overload factors applicable for each pole type andloading criteria.

The design and purchase of concrete 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 concrete pole based on theclassifications detailed in Section 4.1.2. 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 concrete pole will result in differencesin buckling analysis, pole deflections, secondary moments, applied wind forces,and so forth.

It is impossible to completely equate the concrete pole and wood pole at allpoints along the pole. The owner must be certain that the concrete pole selectedby equivalency methods will have a strength sufficient for the actualapplication.
**Equivalency Factor (Eq.F)**
The equivalency factor (Eq.F) is defined as the ratio of the concrete poleoverload factor to the wood pole overload factor for a given loading condition.

For example, for ***NESC Grade B district wind loading***, theconcrete pole overload factor is 2.5 and the wood pole overload factor is 4.0.Thus, the equivalency factor will be 2.5/4.0 = 0.625.

The equivalency factor is a useful concept to understand as the ownerrequires a wood pole equivalent under various loading conditions and overloadfactors. Several examples of equivalencies are listed in the following sections.
**Wood Pole Equivalency - 2.5:4 Ratio (0.625 Eq.F)**
For the NESC Grade B district loadings, the NESC allows for an overloadfactor of 2.5 to be applied to a transverse wind load on a concrete pole whileit requires an overload factor of 4.0 to be applied to a transverse wind load ona wood pole. As such, the ultimate strength requirement for the concrete polewill be less than the ultimate strength of the wood pole for the district wind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 concretepole which 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 ultimate loadof 4,500 pounds at 2' from the pole tip based on a simple cantilever. Since theowner had classed the wood pole based on an NESC overload factor of 4.0, theowner wishes to select a concrete 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 2.5/4.0, which equals 2,812 pounds. The 2.5/4.0 ratio (or0.625 Eq.F) adjusts for the difference between wood and concrete overloadfactors for NESC district loads. The owner will then select a standard classconcrete pole which has an ultimate moment capacity based on the horizontal tip loading of at least 2,812 pounds. From Section 4.1.2, the ownerselects a class C-02.8 pole, which has a tip loading of 2,825 pounds.

Based on the method shown in this example, Table A-1 (at the end of thissection) is a tabulation of wood pole equivalencies based on the NESC Grade Bdistrict wind loading.
**Wood Pole Equivalency - 1.1:1.5 Ratio (0.733 Eq.F)**
For the NESC Grade B extreme wind loadings, this specification requires anoverload factor of 1.1 to be applied to a transverse extreme wind load on aconcrete pole. RUS recommends an overload factor of 1.5 to be applied to atransverse extreme wind load on a wood pole. As such, the ultimate strengthrequirement for the concrete pole will be less than the ultimate strength of thewood pole for the NESC extreme wind loading conditions.

For example, the owner designs a transmission line for wood poles based onNESC extreme wind loading conditions. The owner wishes to purchase a concretepole which 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 ultimate loadof 4,500 pounds at 2' from the pole tip based on a simple cantilever. Since theowner had classed the wood pole based on an NESC extreme wind overload factor of1.5, the owner wishes to select a concrete pole meeting the same extreme windloading conditions. To do this, the owner will multiply the required tip loadingof 4,500 pounds by 1.1/1.5, which equals 3,300 pounds. The 1.1/1.5 ratio (or0.733 Eq.F) adjusts for the difference between wood and concrete extreme windoverload factors. The owner will then select a standard class concrete polewhich has an ultimate moment capacity based on the horizontal tip loading of atleast 3,300 pounds. From Section 4.1.2, the owner selects a class C-03.4 pole,which has a tip loading of 3,375 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 - 1:1 Ratio (1.0 Eq.F)**
Occasionally, the owner may wish to order a concrete pole which 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 concrete pole overload factors. In this case, the owner has accountedfor the difference in wood versus concrete overload 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, knowing thatconcrete poles will be utilized, the owner uses the NESC district wind loadoverload factor of 2.5 (applicable to concrete poles) in the calculations. Theowner selects a wood pole Class 1 at a specific location. Thus, the owner wishesto purchase a concrete 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 ultimate load of 4,500 pounds at 2' from thepole tip based on a simple cantilever. Therefore, the owner will require aconcrete pole with an ultimate moment capacity based on the same 4,500 pound tiploading. From Section 4.1.2, the owner selects a Class C-04.7 concrete pole,which has a tip loading of 4,700 pounds.

Based on the method shown in the this example, Table A-3 at the end of thissection 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 concrete overload factors.

For example, the design of a heavy angle or deadend transmission linestructure may be predominantly controlled by the conductor tension rather thanwind on the wire. The NESC specifies an overload factor of 1.65 to be applied toconcrete pole wire tensions and an overload factor of 2.0 to be applied to woodpole wire tensions. The resulting equivalency ratio would be 1.65/2.0, or anequivalency factor of 0.825. From a review of the tables at the end of thissection, Table A-2 has an equivalency factor of 0.733 while Table A-3 has anequivalency factor of 1.0. Rather than developing a new equivalency table forthis special application, the owner might prefer to select a concrete poleequivalency based on the Table A-3 which has an equivalency factor greater thanthe required factor of 0.825.
**Conclusions concerning wood pole equivalencies� The designer may avoid the confusing concept of wood pole equivalency byusing the procedure below to select the standard class pole from Table 2:- Calculate the induced design moment in the pole from applied loads with    overload factors.  
- Determine the equivalent tip load for this moment.  
- Select the pole from the standard class pole from Table 2 of the    Specifications
** 

TABLE A-1WOOD POLE EQUIVALENCYBASED ON 2.5:4 RATIO(0.625 Equivalency Factor)(NESC Grade B District Wind Loading)*(Equivalencies based on approximate groundline strength)*
**Design      Wood Pole Class      Based on 4.0 OCF
**Select      Concrete Pole Class      Based on 2.5 OCF

H6
C-07.1
H5
C-06.2
H4
C-05.4
H3
C-04.7
H2
C-04.0
H1
C-03.4
1
C-02.8
2
C-02.3
3
C-01.9** 

TABLE A-2WOOD POLE EQUIVALENCYBASED ON 1.1:1.5 RATIO(0.733 Equivalency Factor)(NESC Grade B Extreme Wind Loading)*(Equivalencies based on approximate groundline strength)*
**Design      Wood Pole Class      Based on 1.5 OCF
**Select      Concrete Pole Class      Based on 1.1 OCF

H6
C-09.0
H5
C-08.0
H4
C-07.1
H3
C-05.4
H2
C-04.7
H1
C-04.0
1
C-03.4
2
C-02.8
3
C-02.3** 

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      Concrete Pole Class

H6
C-12.0
H5
C-10.0
H4
C-09.0
H3
C-08.0
H2
C-07.1
H1
C-05.4
1
C-04.7
2
C-04.0
3
C-03.4
 
**B. Section 4. Design**Loads (Section 4.1)

The primary loads for concrete poles are weather and erection loads. Commonhandling loads are determined by the manufacturer and included in themanufacturer�s design. Weather, construction and maintenance loads need to bedetermined by the owner in order to select the proper standard class pole.

Overload 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. Overload factors for extreme ice and extreme wind should be atleast 1.1.

In addition to using the NESC district loading requirements, the ASCEpublication, "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 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 capacity should be utilized, such as the methods given inRUS Bulletin 1724E-200, *Design Manual for High Voltage Transmission Lines.*
Once the structural analysis has been completed, the owner�s engineer orstructural designer may select a standard class concrete 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 concrete 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 significant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.
**Pole Tip Strength (Section 4.1.2)

This specification sets minimum ultimate moment capacity requirements nearthe pole tip 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 classification.

Upon a careful study of the ANSI 05.1 wood pole specification, one shouldunderstand that the horizontal loading applied at 2' from the pole tip 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 tip size is specified apart from the horizontalloading requirement

For example, according to ANSI O5.1, a Class 1 wood pole must have acircumference of 27" at the tip. When applied to the Douglas Fir orSouthern Yellow Pine poles with a fiber stress of 8,000 psi, the resulting tip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 tip. The moments are greatly increased whenever a braced pole topassembly is utilized. These moments are not accounted for by applying thehorizontal ultimate loading alone. Therefore, in the design of transmissionpoles, it is critical that a minimum ultimate moment capacity be specified nearthe pole tip. In the absence of a minimum tip strength requirement, a concretepole tip strength can theoretically be negligible.

The minimum pole tip strength required by this specification should besuitable for most transmission line applications. However, the owner must besure that the tip strength is properly evaluated, especially when working withwood pole equivalencies and braced structures.
**Point of Fixity (Section 4.1.2)

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. 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, which is equal to 7% 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% of the pole length + 2'.

The reinforcing steel required at the point of fixity is required to continueto the pole butt. However, due to the loss of prestressing steel strength nearthe pole butt, the ultimate moment capacity near the pole butt will be reduced.
**Tip Loading (Section 4.1.2)

The tip loading is used to develop a required ultimate moment capacitydiagram at any point along the pole from 2' below the pole tip 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 ultimate 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 ultimate moment requirements for standardconcrete pole sizes.
**Pole Deflection (Section 4.1.3 and 4.1.4)

Although significant horizontal pole deflection limitations are considered tobe beyond the scope of this standard class concrete 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 concrete 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% of the poleheight above the point of fixity when the tip load specified in Section 4.1.2 isapplied under a horizontal testing procedure under short term loadingconditions. Long term loading will cause continued deflection due to the plasticdeformation of the concrete.

The owner should recognize that the actual pole deflection for an applicationwill be less than the specified deflection limit of 15% of the pole height. Withthe standard class pole, all of the loading is applied near the pole tip. In atypical transmission line application, the actual horizontal loading will besome distance from the pole tip. As such, the actual deflection at the conductorunder short term ultimate loading conditions can be expected to be less than 10%of the height above ground.

This specification also limits the allowable pole deflection to 5% of thepole height above the point of fixity when 40% of the tip load specified in Section 4.1.2 is applied under a horizontal testingprocedure under long term loading conditions. This 40% loading approximates theunfactored NESC loading conditions as is discussed in the commentary on crackingstrength.

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% 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 concrete pole properties areinput into the program. Another option would be to ask the pole manufacturer toprovide the analysis.

If the owner has special deflection limitations, it is recommended that RUSBulletin 1724E-206, *Guide Specification for Spun, Prestressed Concrete Poleand Concrete Pole Structures*, 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.
**Cracking Strength (Section 4.1.5)

Cracking strength is defined as the point at which the concrete just beginsto separate due to exceeding the tensile strength of the concrete on the tensionface of the pole.

To minimize the potential for corrosion of the reinforcing steel, it isdesirable to avoid cracking under the unfactored NESC district loadingconditions, or any other service loads specified by the owner. Under thisstandard class concrete pole specification, these service loads are notspecified, but are considered to be 40% of the specified ultimate loads.

For concrete poles designed within the limits of this specification, thepredominant pole loading will be transverse wind loads. The service load isdetermined based on the ratio of the transverse overload factor. The NESCoverload factor applied to district wind loads is 2.5. As such, the service loadwill be equal to the ultimate load divided by 2.5, or 40% of the ultimate load.

For typical concrete pole designs, initial cracking occurs at about 40-55percent of the ultimate strength of the pole. Therefore, the requirement for thecracking strength to be at least 40% of the required ultimate strength shouldnot cause the pole to be stronger than when considering ultimate strength alone.

Since it may be theoretically possible to have a cracking strength at lessthan 40% of the ultimate strength, it is not desirable to do so. By requiringthe cracking strength to exceed 40% of the required ultimate strength, the owneris assured of an adequate cracking strength for the standard class concretepole.
**Zero Tension Strength (Section 4.1.6)
The zero tension strength is defined as the moment at which a crack that waspreviously created by exceeding the cracking moment strength will open again.Under this condition, an applied moment will not cause any tensile stress in theconcrete.

It is important to avoid open cracks in situations of significant unbalancedlateral loading and in extremely corrosive environments in order to protect thesteel reinforcing. Typical structures with permanent unbalanced lateral loadsare unguyed angle and unguyed deadend structures. While the design of thesestructure types is generally outside the recommended scope of thisspecification, this specification does require a minimum zero tension strengthfor all pole classes.

It has been demonstrated that the zero tension strength will typically be 70%to 85% of the cracking strength. With a minimum cracking strength of 40% ofultimate, 70% of this value would be equal to 28% of ultimate. Thus, it isnatural for all spun concrete poles to have a zero tension strength of at least28% of ultimate. As such, this specification requires the standard classconcrete pole to have a zero tension strength exceeding 28% of the requiredultimate strength.

For situations where the owner wishes to select a standard class pole basedon a minimum zero tension strength, this specification may be utilized. Atypical situation where the owner may wish to do this is when the owner uses atransmission line design computer program in which zero tension strength valuesare input for each pole type.

The owner should recognize that the zero tension strength for most concretepoles is greater than the minimum required strength of 28% of the ultimatestrength. In fact, the zero tension strength can be as high as 50% of theultimate strength. Thus, for concrete pole applications which must be designedfor the zero tension strength requirements, such as unguyed or unbalancedlateral loadings, it is quite possible for the owner to obtain the concrete poleat a significantly lesser cost by submitting the actual loading conditions tothe manufacturer using RUS Bulletin 1724E-206.
**Foundation Rotation and Deflection**
Although significant foundation rotation and deflection criteria areconsidered to be beyond the scope of this standard class concrete 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 concrete 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 concrete pole which has the ultimate moment capacity greater thanthe design loading requirements.
**Longitudinal Loads**
It is recommended that RUS Bulletin 1724E-206 be utilized whenever thelongitudinal loads may result in a significant unbalanced lateral loadingcondition. In this case, the design of the structure based on zero tensionstrength is emphasized. (Refer to the Commentary regarding Zero TensionStrength.)

Because concrete 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.
**Guy Wires**
It is generally beyond the scope of this standard class concrete polespecification to consider guy wires in the design of the structure. It isrecommended that RUS Bulletin 1724E-206 be utilized instead.

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 concrete poles.

It may also be possible to specify certain types of guyed concrete poles based on wood pole analysis techniques as detailed in RUSBulletin 1724E-200. Once the wood pole class is determined, a standard classconcrete pole could be selected based on an equivalency. In this case, it isrecommended that the 1:1 equivalency ratio be utilized. It is generally agreedthat a concrete pole has a greater buckling strength than an equivalentlyclassed wood pole; therefore, the selected concrete pole class should beadequate for a situation in which a wood pole would normally be specified. Theowner should use caution in using this equivalency method 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.

Any time a concrete 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 concrete structure. As is required by RUSBulletin 1724E-206, the load in the guy wire should be limited to 65 percent ofits ASTM rated breaking strength under actual ultimate loading conditions. Theconcrete 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, which 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 Manual 72) has suggested aguy wire modulus of elasticity of 23,000 ksi be used by the engineer whenever it is not specified.
**Groundline**
The location of the groundline for the standard class pole should bespecified on the owner�s drawings.

While the strength of the standard class pole is not effected by thegroundline location, the proper placement of climbing devices, ground wireclips, cant hole, vent hole, name plate, and so forth, depends upon the locationof the groundline.

In addition, the ultimate moment capacity at the groundline is to be noted onthe manufacturer�s drawings (see Section 7.2.5) and stamped on the pole nameplate (see Section 4.12.1).
**Air Entrainment in Spun Concrete Poles (Section 4.2)

Air entrainment in spun concrete poles is similar to air entrainment innormal concrete except the fabrication processes of pumping, vibrating, andspinning causes a large percentage of the entrained air to migrate out of the concrete. The general effects of airentrainment are to increase workability, decrease density (unit weight),decrease strength, reduce bleeding and segregation, and increase durability. Fora spun concrete pole, the spinning process creates a very dense concrete andcounteracts the air entrainment effects. Since pumping occurs prior to the polebeing spun, the air entrainment effects are present during the fabrication ofspun poles. The percentage of air entrained in a spun concrete pole after it isspun is unknown. However, it is believed poles that have concrete containing anair entrainment agent will have a higher void ratio than those without thisagent. The owner has to be aware that as the percentage of air entrainmentincreases the concrete strength decreases.
**Grounding (Section 4.5)

All internal reinforcing should be bonded electrically to the external poleground wire. This will keep the external ground and internal reinforcingpotential voltage differences lower during lightning events. There have beenreports of step lugs and other materials embedded in the concrete, near or incontact with the reinforcing, being dislodged as a result of lightning. Splicedpoles should have reinforcing on each side of the splice bonded electrically tothe external pole ground wire. This should lower potential voltage differencesof embedded material between each pole section.
**C. Section 5.4 Structure Testing
An option is available in the specification for full scale testing of poles.For a manufacturer, which has been designing and fabricating concrete poles withthe same processes for a good number of years, the need for testing of aconcrete 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.
**D. Section 7 Drawings and Information to be Supplied by the Manufacturer
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. Using the forms in Attachment C will allowquick review of the information and simultaneous comparison of all bidders'information.********************************************