ISO 15206:2010

INTERNATIONAL ISO
STANDARD 15206
First edition
2010-04-01
Timber poles — Basic requirements and
test methods
Poteaux en bois — Exigences de base et méthodes d'essai

Reference number
©
ISO 2010
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ii © ISO 2010 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Symbols and abbreviated terms .6
5 General requirements .7
5.1 Marking.7
5.2 Tree felling and wood preparation.7
5.3 Requirements for pole sizes, tolerances, permissible deviations and damage .7
5.4 Characteristic values .7
5.5 Strength-reducing characteristics.8
5.6 Other characteristics.10
5.7 Untreated wood poles.10
5.8 Preservative-treated wood poles .10
6 Test methods .11
6.1 Length and diameter .11
6.2 Knots and knot clusters.11
6.3 Slope of grain.11
6.4 Rate of growth .11
6.5 Bark pockets and rind galls .12
6.6 Mechanical damage.12
6.7 Fissures, splits and checks.12
6.8 Determination of moisture content.12
7 Evaluation of conformity .12
7.1 General .12
7.2 Initial type testing .12
7.3 Product assessment .13
8 Marking and declarations .13
8.1 Marking (mandatory) .13
8.2 Specific marking and declarations .13
8.3 Marking (optional) .14
Annex A (informative) Commonly used sizes for wood poles .15
Annex B (normative) Scheme for sampling preservative-treated wood poles by taking borings .16
Annex C (normative) Test method for bending properties — Cantilever method .17
Annex D (normative) Test method for bending properties — Four-point method.22
Annex E (normative) Test method for bending properties — Three-point method proof test .28
Annex F (normative) Determination of characteristic values.33
Bibliography.37

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15206 was prepared by Technical Committee ISO/TC 165, Timber structures.

iv © ISO 2010 – All rights reserved

Introduction
This International Standard covers the requirements for grading and assignment of characteristic values that
can be used for the design of timber poles used as cantilevers and/or in compression.
It is the responsibility of the supplier to always ensure that all products supplied are in conformity with the
requirements of this International Standard and any other specification with which they are provided. This
International Standard is intended for the initial determination of the characteristic values for a given
population of poles and additional determination when there is a reason to suspect that the characteristics of a
population have changed.
This International Standard recognizes that there are many different visual strength-grading rules for timber in
use internationally. These have come into existence to allow for
⎯ different species or groups of species,
⎯ geographic origin,
⎯ different dimensional requirements,
⎯ varying requirements for different uses,
⎯ the quality of material available, and
⎯ historical influences or traditions.
Because of the diversity of existing standards for wood poles for overhead lines in use in different countries, it
is impossible to lay down a single set of acceptable visual grading rules.
This International Standard therefore gives the basic principles to be followed when drawing up regional,
national, local or buyer requirements for some characteristics and sets limits for others.
In laying down visual grading rules, two main factors are relevant:
⎯ they shall clearly define and limit the strength-affecting characteristics in poles, such that there is very
high confidence that poles supplied meet the required characteristic strength value;
⎯ the rules and the text are such that they can be easily understood and be suitable for implementation by
grading personnel.
This International Standard is also concerned with the durability characteristics of wood poles for overhead
power and telecommunication lines. It assumes that all such poles are constructed from round timber in which
the finished product comprises either a central core of heartwood surrounded by a zone of sapwood or the
heartwood only. Such assumptions dictate that where sapwood is present, preservative treatment is normally
required in order to provide the poles with sufficient enhanced durability, unless the amount of sapwood
present is such that its loss would not compromise the integrity of the pole during its service life and the
heartwood has sufficient natural durability as required by this International Standard.
Some timber species do not allow an easy differentiation between heartwood and sapwood. Various
standards provide recommendations to address this problem; for example, EN 351-1 and AS 2209:1994
(Appendix D) specify the method of treatment of such timber when preservation is required.

INTERNATIONAL STANDARD ISO 15206:2010(E)

Timber poles — Basic requirements and test methods
1 Scope
This International Standard specifies the requirements for grading, test methods, determination of
characteristic values, methods of specifying durability and sizes of single poles manufactured from solid
timber for telecommunications and electrical distribution purposes, either preservative treated or untreated,
under cantilever or compression loading.
It specifies the:
⎯ methods of measuring the sizes of solid wood poles for overhead transmission and telecommunication
lines and permissible deviations that are taken into account for the acceptance of the poles;
⎯ requirements for handling and the characteristics for visual strength grading of softwood and hardwood
poles, as well as the marking requirements;
⎯ methods of test to determine characteristic values for modulus of elasticity and bending strength of any
population of wood poles and moisture content of solid wood poles;
⎯ requirements for durability and preservative treatment of wood poles.
This International Standard is applicable to both softwood and hardwood poles.
This International Standard does not quantify the service life that can be expected from a pole.
NOTE This depends on its geographical location, the associated climate of its service environment and either the
natural durability of the heartwood of the species selected or the combination between selection of species, preservative
type, and requirements of retention and any incised zones.
It is not applicable to poles used as beams.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3166-1, Codes for the representation of names of countries and their subdivisions — Part 1: Country
codes
ISO 21887:2007, Durability of wood and wood-based products — Use classes
AS/NZS 1604.1, Specification for preservative treatment — Part 1: Sawn and round timber
AS 2209:1994, Timber — Poles for overhead lines
AS 2209:1994/Amd.1:1997, Timber — Poles for overhead lines
EN 252, Field test method for determining the relative protective effectiveness of a wood preservative in
ground contact
EN 351-1, Durability of wood and wood-based products — Preservative-treated solid wood — Part 1:
Classification of preservative penetration and retention
EN 599-1, Durability of wood and wood-based products — Efficacy of preventive wood preservatives as
determined by biological tests — Part 1: Specification according to use class
EN 13183-1, Moisture content of a piece of sawn timber — Part 1: Determination by oven dry method
EN 13183-2, Moisture content of a piece of sawn timber — Part 2: Estimation by electrical resistance method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
bark pocket
bark that is partly or wholly enclosed in the wood
3.2
characteristic value
value corresponding to the 5th percentile of the statistical distribution of strength or the mean value of
modulus of elasticity, at a 75 % confidence level
3.3
charge
all the wood treated together in one treatment at one time (one complete treatment cycle)
3.4
crack
separation of wood fibres across the grain
NOTE These can be due to internal strains resulting from unequal longitudinal shrinkage, or the fibres being crinkled
by compression or other external forces
3.5
critical zone
1,6 m length of pole measured from a point 1 m above the nominal ground line to 600 mm below the nominal
ground line
NOTE If the pole is nominated as a stayed pole, an additional zone measured from the top of the pole equivalent to
the length between the nominal ground line and the butt of the pole shall be included.
3.6
decay
rot
decomposition of wood by fungi or other micro-organisms resulting in softening, progressive loss of mass and
strength, and often a change of texture and colour
3.7
direct testing
testing the preservative treatment achieved by the direct measurement of the penetration and retention of
preservative
3.8
double sweep
sweep characterized by two or more bends in one or several planes
3.9
fibre saturation point
FSP
state of a piece of timber when the cell walls are saturated with moisture but no moisture exists in the cell
cavities
2 © ISO 2010 – All rights reserved

3.10
fissure
longitudinal separation of fibres
3.11
grain detector
device for detecting the angle of grain in timber
3.12
growth rate
mean number of growth rings per 25 mm
3.13
heart shake
radial end shake originating at the pith
3.14
incised zone
area of the lateral surface of the pole, which has undergone an incising process as an aid to securing deeper
and more uniform penetration of preservative
NOTE The minimum limit of the incised zone should be 400 mm above and 400 mm below the specified ground line
for the pole in service.
3.15
included sapwood
presence in the heartwood of a complete or incomplete ring, having the colour and the properties of sapwood
3.16
indirect testing
testing the preservative treatment achieved by measurement of a property found to exhibit a correlation
between itself and the penetration and retention of preservative
3.17
kerf
groove or slot formed in wood during the process of sawing
3.18
knot
portion of a branch embedded in wood
3.19
knot cluster
knots located such that no grain recovery is evident between adjacent knots
3.20
knot diameter
dimension of the knot measured on the surface of the pole and perpendicular to the axis of the pole
NOTE The diameter takes the entire knot into account, including the sapwood.
3.21
length
distance from the pole butt to the pole tip
3.22
maximum diameter
largest diameter of the pole at the section of measurement
3.23
minimum diameter
smallest diameter of the pole at the section of measurement
3.24
moisture content
ratio of the mass of the quantity of water in a material to the mass of the dry material
3.25
nominal diameter
3.25.1
nominal diameter
〈pole with 5 % or less ovality〉 theoretical diameter, usually the diameter measured at the nominal ground line
3.25.2
nominal diameter
〈pole with greater than 5 % ovality〉 minimum diameter
3.26
nominal ground line
plane normal to the axis of the pole usually located at a distance of 600 mm plus 10 % of the nominal length
from the butt end
3.27
ovality
difference between the maximum and minimum diameter at a cross-section expressed as a percentage of the
minimum diameter
3.28
pith
innermost part of the pole
3.29
pole
long, round timber for use in a free-standing application
3.30
pole butt
lowermost point of the thicker end of the pole
3.31
pole tip
uppermost point of the narrow end of the pole
3.32
population
group of poles defined by having the same species, source and grade
3.33
resin pocket
cavity that contains or has previously contained resin
NOTE This may be similar to rind galls.
3.34
rind gall
surface wound that has been partially enclosed by the growth of a tree
4 © ISO 2010 – All rights reserved

3.35
ring shake
fissure following the line of a growth ring
3.36
sample
one or more poles taken from a single population
3.37
sampling unit
single preservative-treated pole taken from a charge
3.38
scribe
cranked rod with a swivel handle and a needle at the tip, set to a slight trailing angle
NOTE This is used as a grain detector by pressing the needle into the timber and drawing it across the surface in the
apparent direction of the grain.
3.39
section of maximum stress
section of pole where the diameter equals 1,5 times the diameter at the point of application of load if this
section is above ground line; otherwise the actual ground-line section
3.40
short crook
local deflection
natural deviation of the axis of the pole occurring on a length less than 1,5 m
3.41
simple sweep
sweep characterized by one bend only
3.42
slope of grain
divergence of the direction of the fibres from the longitudinal axis of the piece
NOTE The slope of grain in poles is usually observed as an inclination of the wood cells on the surface, which is
referred to in some International Standards as spiral growth angle.
3.43
standard size pole
pole of a size 8 m or 10 m long and 180 mm to 220 mm diameter at 1,5 m from the butt end, and used for the
determination of characteristic values
3.44
star shake
two or more heart shakes
3.45
sweep
deviation of the longitudinal axis of round timber from a straight line
3.46
taper
gradual reduction in diameter of a stem along its height or round timber along its length
3.47
theoretical diameter
diameter of a circle with the same circumference as the actual circumference at the section of measurement
4 Symbols and abbreviated terms
d nominal diameter at assumed ground line, in millimetres
g
d nominal diameter at point of load application, in millimetres
q
d nominal diameter at section of maximum stress, in millimetres
max
E modulus of elasticity parallel to grain in bending, in newtons per square millimetre
f bending strength — maximum stress at assumed ground line or point of maximum stress if this is
m
above the assumed ground line, in newtons per square millimetre
I second moment of area of cross-section at point of load application, in millimetres to the fourth

q
power
l pole length measured from butt to tip, in millimetres
l distance from butt to assumed ground line, in millimetres
g
l distance from butt to section of maximum stress or ground line, whichever is the greater, in
g
millimetres
l distance from tip to position of applied load, in millimetres
q
Q applied load, in newtons
s − s movement of load application point parallel to longitudinal axis of the pole during testing, in
a 0
millimetres (see Figure C.2)
t − t deflection at point of load application, in millimetres (see Figure C.2)
a 0
E mean value of modulus of elasticity parallel to direction of grain, in newtons per square millimetre
mean
f characteristic value of bending strength, in newtons per square millimetre

m, k
f sample fifth percentile of bending strength, in newtons per square millimetre
m, 05
k statistical factor
m mean value (the variable is given in parentheses)
m(E) sample mean values of modulus of elasticity, in newtons per square millimetre
m( f ) sample mean value of bending strength, in newtons per square millimetre
m
m( f ) mean of f values
m, 05 m, 05
n number of test poles in a sample
s standard deviation (the variable is given in parentheses)
s(E) sample standard deviation of modulus of elasticity, in newtons per square millimetre
s( f ) sample standard deviation of bending strength, in newtons per square millimetre
m
6 © ISO 2010 – All rights reserved

5 General requirements
5.1 Marking
The manufacturer shall declare the species and ensure that all poles are clearly marked to identify the species,
in accordance with Clause 8.
NOTE Common names are different depending on language version.
5.2 Tree felling and wood preparation
5.2.1 Tree felling
At the time the trees are felled, it is advisable to ensure that the rising sap is low, except for timber which is to
be treated by a sap displacement process. If the trees are felled when the sap is high, it is recommended that
measures be taken to avoid pre-treatment decay or attack by insects.
5.2.2 Handling of untreated wood
The method of handling shall avoid any damage that could alter the mechanical performance and durability of
the pole, as well as the suitability of the pole for preservative treatment. Species permitted for use in poles are
generally specified in the referenced local standards.
5.2.3 Mechanical pre-treatments
Where poles are mechanically pre-treated before preservation, e.g. through incising, testing in accordance
with Clause 6 shall be carried out after the mechanical pre-treatment.
5.3 Requirements for pole sizes, tolerances, permissible deviations and damage
For poles used in structural applications, the minimum diameter of a pole shall be not less than 80 % of the
maximum diameter at any cross-section over a maximum of 80 % of the length of the pole.
The manufacturer shall declare the size of the poles, specified by the overall length, the nominal diameter at
1,5 m from the butt and the nominal diameter at the tip, measured in accordance with 6.1. The permissible
dimensional tolerances are:
⎯ length: −1 % or +2 %;
⎯ diameter: −0 or +40 mm unless otherwise declared by the manufacturer.
NOTE A list of commonly used pole sizes (minimum nominal diameter at 1,5 m from the butt, and length) is given in
Annex A.
5.4 Characteristic values
The manufacturer shall declare structural properties in accordance with 8.2.
5.5 Strength-reducing characteristics
5.5.1 Knots
The maximum dimension of knots, knot holes and knot clusters shall be recorded in the following manner:
a) individual knots or knot clusters — maximum diameter of knots or knot clusters, expressed as a factor of
the circumference of the pole at the point where the knot occurs;
b) multiple knots, etc. — maximum sum of all the knot diameters in any 300 mm length of the pole,
expressed as a factor of the circumference of the pole at the midpoint of the 300 mm length (e.g.
factor = knot diameter in mm/circumference of pole at cross-section in millimetres).
The measurement of the individual knot or knot clusters shall be according to 6.2.
Different limitations on knot sizes may be specified for different portions of the pole, e.g. the top third of poles
over 13 m long could have different knot limitations from the rest of the pole.
5.5.2 Slope of grain
The slope of grain relative to the longitudinal axis shall be measured according to 6.3. Significant changes in
the slope of grain shall not be allowed.
5.5.3 Heartwood
For hardwood poles, the minimum area of heartwood when measured at the butt shall be recorded.
Dimensions in millimetres
1 case 2: multiple knots in any 300 mm length of the pole
2 case 1: individual knots or knot clusters
Figure 1 — Measurement of knots
5.5.4 Rate of growth
If the rate of growth is required, it shall be declared as the minimum number of growth rings per 25 mm when
measured in accordance with 6.4 (i.e. maximum growth rate).
8 © ISO 2010 – All rights reserved

5.5.5 Straightness
A single sweep shall be permitted to the extent that a straight line drawn from the centre of the tip to the
centre of the butt shall remain in the pole.
Where double sweep and short crook exist, these shall be declared by the manufacturer.
5.5.6 Bark pockets and rind galls
Bark pockets and rind galls shall be permitted in the first 1 m of length from the butt. Above the first 1 m length
from the butt, bark pockets and rind galls shall be measured according to 6.5. Depth, position and number
shall not exceed those given for mechanical damage. They shall be specified by length, width and depth,
expressed as a percentage of the nominal diameter of the pole at that point.
5.5.7 Mechanical damage
Mechanical damage shall not extend to a depth that will reduce the diameter by more than 5 % of the
diameter at any cross-section when measured in accordance with 6.6. No more than two occurrences of
mechanical damage shall be permitted and no part of these shall be less than 500 mm apart.
5.5.8 Ring and star shake
The tip shall be free from ring shake or star shakes with five or more points. At the butt, one complete ring or
one star shake is acceptable, provided not more than two points extend to within 5 mm from the pole
circumference. If they extend to the circumference, they shall not extend along the pole more than 500 mm
from the butt.
5.5.9 Fissures, splits and checks
Seasoning fissures and splits along the grain are expected and are not recognized as defects, provided they
do not have a depth greater than half the diameter at one point along the pole or do not exceed 50 % of the
length of the pole, when measured according to 6.7.
5.5.10 Damage
Any damage in poles manufactured from trees subjected to snow breakage, frost damage, windfall or forest
fires, shall be limited to ensure that any such poles meet the grading requirements of this International
Standard and are fit for purpose.
5.5.11 Decay and insects
Poles shall be sound and free from decay and attack by insects. Minor insect holes are acceptable provided
these are, either not larger than 1,5 mm in diameter and do not exceed 5 in number, or not larger than 1,0 mm
in diameter and do not exceed 20 in number, evenly distributed in any 100 mm length of the pole.
5.5.12 Included sapwood
No included sapwood in heartwood shall be permitted in hardwood poles.
5.5.13 Cracks
Cracks across the pole and the grain shall not be permitted.
5.6 Other characteristics
5.6.1 Other criteria
Circumstances of specific or regional use may call for additional criteria and limits to be declared by the
manufacturer. These shall only be criteria that affect the strength.
5.7 Untreated wood poles
The natural durability to wood-destroying fungi of the heartwood of a pole shall be described by reference to
the relevant use classes and biological hazards defined in ISO 21887, to ensure that the pole meets its
intended purpose and design life.
5.8 Preservative-treated wood poles
5.8.1 General
The poles shall be free from features which would prevent a proper application of preservative and thus impair
the function of the preservative-treated poles when in service.
All dressing, notching, pre-cutting and boring shall be completed before preservative treatment. Prior to
preservative treatment, the moisture content of the pole shall be at a level appropriate to the wood
preservative and method of treatment used.
Preservative treatment shall be defined in terms of depth of lateral penetration of preservative into the treated
pole and retention of preservative within that treated zone in accordance with the requirements of
ISO 21887:2007, A.3.
The preservative treatment used shall not compromise the performance of the pole in service.
5.8.2 Requirements for wood preservatives
The wood preservatives used shall conform to the performance requirements of Use Class 4 preservatives as
defined in EN 599-1 or AS/NZS 1604.1. For the purposes of this International Standard, determination of
compliance with the performance requirements of EN 599-1 shall include data from the field test EN 252 and
any of the additional local tests given in EN 599-1 applicable to the place of use of the product.
5.8.3 Penetration requirement
The penetration requirement shall be defined in terms of the penetration classes listed in EN 351-1 or the
durability classes noted in AS 2209.
⎯ EN 351-1: for permeable species, full sapwood penetration P8 is required. For resistant species, P7 is
required in any incised zone and P5 is required elsewhere.
⎯ AS 2209: sapwood penetration requirements for timber poles shall range between 12 mm and 20 mm for
hardwoods (depending on the durability class) and be not less than 35 mm for permeable softwoods.
5.8.4 Retention requirement
Following completion of the preservation process, the retention requirement specified by the user for treated
poles shall be equal to or greater than the critical value for End Use Class 4 of the preservative used
(see EN 599-1) or the retention requirements for treatment to Hazard level H5, in accordance with
AS/NZS 1604.1. This critical value shall be calculated from the prescribed biological tests defined in the
relevant national standards.
10 © ISO 2010 – All rights reserved

NOTE Multiples greater than one may be applied to the critical value to specify higher retentions as a means of
increasing the service life. In the case of established preservatives where a critical value has not yet been determined, the
retention should be specified using service experience as its basis.
5.8.5 Tolerances for preservative-treated charges
5.8.5.1 Penetration tolerances
Sampling for penetration shall be as detailed above (in 5.8.3) and shall be subject to an acceptable quality
level (AQL) of 10 % using inspection level II (see EN 351-2:1995, Table 1 or AS/NZS 1604.1). A lower
percentage AQL may be declared.
5.8.5.2 Retention tolerances
The mean retention in the complete analytical zone shall be equal to or greater than the retention requirement
specified according to 5.8.3.
6 Test methods
6.1 Length and diameter
Length shall be measured using a tape measure. Maximum and minimum diameters shall be measured using
callipers. Alternatively, the theoretical diameter may be calculated from the circumference measured by using
a tape measure.
All measurements shall be made when poles are at or above FSP, determined in accordance with 6.8.
Where one or both ends are not cut square, the minimum length shall be recorded.
NOTE The taper of poles covered by this International Standard is expected to be between 6 mm and 16 mm per
metre.
6.2 Knots and knot clusters
The dimension of a knot or knot cluster shall be measured as the diameter of a knot measured on the surface
of the pole and perpendicular to the axis of the pole. Knot clusters shall be treated as a single knot. The
diameter of an encased knot shall be measured to the sound wood of the pole on either side of the knot.
6.3 Slope of grain
The slope of grain shall be measured over a minimum 1 m length of pole, e.g. a slope of 1 in 8 represents
1/8 metre (125 mm) deviation over a 1 m length along the axis of the pole.
The direction of grain shall be determined by one of the following methods from which the slope of grain shall
be calculated:
a) by taking a line parallel to the surface fissures;
b) through the use of a grain detector (scribe).
6.4 Rate of growth
The rate of growth shall be measured at either the tip or butt of the pole and expressed as the mean number
of growth rings per 25 mm. The measurements shall be made over a radial line, as long as possible,
commencing 50 mm from the pith. For poles that have a theoretical diameter of less than 150 mm,
measurement shall be made over a radial line as long as possible commencing from the circumference.
6.5 Bark pockets and rind galls
The dimensions of each bark pocket and rind gall shall be measured as the overall length, width at the widest
point and depth at the deepest point.
6.6 Mechanical damage
The pole diameter on which the measurement of the damage is based shall be calculated on the nominal
diameter at the cross-section where the damage occurs. To determine the nominal diameter, the nominal
diameter of the sound pole immediately above and below the damage shall be measured and averaged. The
minimum diameter of the damaged cross-section shall be measured and the reduction in diameter determined.
6.7 Fissures, splits and checks
The depth of fissures, splits and checks shall be measured by inserting a 0,2 mm feeler gauge as far as
possible into the fissure.
6.8 Determination of moisture content
6.8.1 For untreated poles, the moisture content of test specimens shall be determined in accordance with
the procedure of EN 13183-1 on a disc of timber cut from the pole. The disc shall be of full cross-section, free
of knots and resin pockets and shall be at least 50 mm in thickness and 300 mm from the tip or butt.
6.8.2 In the case of preservative-treated poles, the determination of moisture content using the above
method shall be restricted to material cut from untreated areas. If the moisture content of treated material is
required, methods appropriate to the specific preservative treatment shall be used. The presence or otherwise
of treatment in the specimens shall be recorded. Moisture content may be determined in accordance with
EN 212.
6.8.3 In the case of ultimate strength tests, the disc shall be cut as closely as possible to the fracture.
6.8.4 For determining the moisture content of a pole prior to treatment or test, the procedures given in
EN 13183-1 may be applied to borings taken in accordance with Annex B (of this International Standard). The
boring sample used for determination of moisture content shall include the full depth of sapwood or the
innermost 75 mm of sapwood, whichever is the lesser. Alternative methods of measurement, such as
electrical resistance moisture meters in accordance with EN 13183-2, may be used provided it can be
demonstrated that the measurements taken relate to measurements taken in accordance with the method
specified in 6.8.1 and 6.8.2.
7 Evaluation of conformity
7.1 General
The conformity of wood poles with the requirements of this International Standard and with the specified
values shall be demonstrated by
⎯ initial type testing, and
⎯ product assessment.
7.2 Initial type testing
Initial type testing shall be performed to show conformity with this International Standard. Tests previously
performed in accordance with the provisions of this International Standard (same product, same
characteristic(s), test method, sampling procedure, system of attestation of conformity, etc.) may be taken into
12 © ISO 2010 – All rights reserved

account. In addition, initial type testing shall be performed at the beginning of the production of a new type of
pole or at the beginning of a new method of production (where this may affect the stated properties).
Poles shall be inspected after they have been dressed and not more than one month prior to preservative
treatment when required. All characteristics in 5.4 shall be subject to initial type testing, where they are
relevant for the poles in question.
Whenever a change occurs in the product, the raw material or supplier of the components, or the production
process, which would change significantly one or more of the characteristics, the type tests shall be repeated
for the appropriate characteristic(s).
Sample sizes for initial type testing shall be in accordance with Annex F.
Initial type testing reports shall be held by the manufacturer for at least 10 years after the date of last
production of the poles to which they relate.
7.3 Product assessment
Product assessment shall consider controls and tests on measuring equipment, raw materials and
constituents, processes, machines and manufacturing equipment and finished components, including material
properties in components, to assess whether or not, the poles placed on the market conform with the declared
performance characteristics.
A product assessment system may be part of a quality management system, for example ISO 9001.
8 Marking and declarations
8.1 Marking (mandatory)
Each pole shall be marked with the following information:
a) the species and origin designated by code letters (the country code shall be in accordance with
ISO 3166-1);
b) the preservative [designated by its reference code (where applicable)] and retention;
c) the pole classification and the year of manufacture.
The information shall be in a form that can readily be interpreted by utility staff working from ground level.
8.2 Specific marking and declarations
The manufacturer shall declare the following:
a) the length of pole (in metres);
b) the nominal diameter at 1,5 m from the butt (in millimetres), or size code;
c) the gauge or depth mark at 3 m from the butt (or as agreed on by the buyer and the manufacturer);
d) the characteristic properties (such as bending strength and modulus of elasticity) to two significant
figures;
e) the minimum diameter at 1,5 m from the butt and the minimum diameter at the tip, determined in
accordance with either Annex C or Annex D.
8.3 Marking (optional)
a) the code of the manufacturer (where applicable);
b) the last two digits of the year of preservation (where applicable);
c) the natural durability class (where applicable);
d) the buyer specification against which the pole is supplied (where applicable).
14 © ISO 2010 – All rights reserved

Annex A
(informative)
Commonly used sizes for wood poles
Length Minimum nominal diameter (at 1,5 m from butt)
m mm
6 120 130 140 150 160 170
7 130 140 150 160 170 180 190 200 210
8 140 150 160 170 180 190 200 210 220
9 150 160 170 180 190 200 210 220 230 240 250 260 270 280
10 160 170 180 190 200 210 220 230 240 250 260 270 280 290
11 170 180 190 200 210 220 230 240 250 260 270 280 290 300
12 190 200 210 220 230 240 250 260 270 280 290 300 310 320
13 210 220 230 240 250 260 270 280 290 300 310 320 330 340
14 230 240 250 260 270 280 290 300 310 320 330 340 350
15 250 260 270 280 290 300 310 320 330 340 350 360
16 260 270 280 290 300 310 320 330 340 350 360 370
17 280 290 300 310 320 330 340 350 360 370 380
18 300 320 340 360 380 400 420
19 330 350 370 390 410 430
20 340 360 380 400 420 440
21 350 370 390 410 430 450
22 370 390 410 430 450
23 400 420 440 460 480
24 420 440 460 480 500
Annex B
(normative)
Scheme for sampling preservative-treated wood poles by taking borings
B.1 General
Borings shall be taken with a sharp increment borer (e.g. Mattson borer), which extracts a core of minimum
diameter 4 mm.
If the poles have been incised, borings shall be taken at a point midway between adjacent incisions.
At the selected point on the surface of each pole, the borer shall be held at right angles to the direction of
grain and directed towards the pith. The borer shall penetrate each pole to a greater depth than the
penetration being measured.
After removal of the borings, borer holes shall be promptly plugged with a tight-fitting wooden plug treated with
a preservative in a similar way to the poles themselves.
One boring shall be taken from each pole where both penetration and retention determinations can be
completed using one boring. However, two borings shall be taken from each pole (i.e. one boring for
penetration and one for retention determinations) where this cannot be achieved.
B.2 Examination of borings
B.2.1 Penetration of preservative
Differentiation of heartwood and sapwood, and the limit of penetration of the preservative, may be apparent
because of colour differences. Where this is not possible, the application of physical or chemical agents is
necessary to reveal the sapwood zone and the penetration of the preservative chemicals.
B.2.2 Retention of preservative
The complete analytical zone associated with the selected penetration class as defined in EN 351-1 shall be
separated from each boring. These shall be combined into a single sample and converted to a form suitable
for quantitative chemical analysis and thus analysed.
16 © ISO 2010 – All rights reserved

Annex C
(normative)
Test method for bending properties — Cantilever method
C.1 Principle
The bottom section of the pole under test is rigidly clamped up to 1,5 m from the butt or the assumed position
of the ground line. A load is applied 150 mm from the tip of the pole in a direction perpendicular to the original
axis of the pole
...