SIST EN 50341-2-20:2019

SLOVENSKI STANDARD
SIST EN 50341-2-20:2019
01-april-2019
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Overhead electrical lines exceeding AC 1 kV - Part 2-20: National Normative Aspects
(NNA) for ESTONIA (based on EN 50341-1:2012)
Ta slovenski standard je istoveten z: EN 50341-2-20:2018
ICS:
29.240.20 Daljnovodi Power transmission and
distribution lines
SIST EN 50341-2-20:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 50341-2-20:2019

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SIST EN 50341-2-20:2019


EUROPEAN STANDARD EN 50341-2-20

NORME EUROPÉENNE

EUROPÄISCHE NORM
December 2018
ICS 29.240.20 Supersedes EN 50341-2-20:2015
English Version
Overhead electrical lines exceeding AC 1 kV - Part 2-20:
National Normative Aspects (NNA) for ESTONIA (based on EN
50341-1:2012)

This European Standard was approved by CENELEC on 2018-11-26.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN 50341-2-20:2018 E

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Contents
European foreword .6
0 Introduction .7
0.7 Language .7
1 Scope .7
1.1 General .7
1.2 Field of application .7
2 Normative references, definitions and symbols .8
2.1 Normative references.8
3 Basis of design . 10
3.2 Requirements of overhead lines . 10
3.2.2 Reliability requirements. 10
3.2.3 Security requirements . 11
3.2.5 Strength coordination . 11
3.2.6 Additional considerations . 11
3.3 Limit states . 11
3.3.3 Serviceability limit states . 11
3.4 Actions . 11
3.4.2 Classification of actions by their variation in time . 11
4 Actions on lines . 12
4.1 Introduction . 12
4.3 Wind loads . 12
4.3.1 Field of application and basic wind velocity . 12
4.3.2 Mean wind velocity . 12
4.3.3 Mean wind pressure . 12
4.3.5 Wind forces on any overhead line component . 12
4.4 Wind forces on overhead line components . 13
4.4.1 Wind forces on conductors . 13
4.4.2 Wind forces on insulator sets . 13
4.4.3 Wind forces on lattice towers . 14
4.4.4 Wind forces on poles . 14
4.5 Ice loads . 14
4.5.1 General . 14
4.5.2 Ice forces on conductors . 14
4.6 Combined wind and ice loads . 14
4.6.1 Combined probabilities . 14
4.6.2 Drag factors and ice densities . 15
4.7 Temperature effects . 15
4.8 Security loads . 15
4.8.4 Mechanical conditions of application . 15

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4.9 Safety Loads . 15
4.9.1 Construction and maintenance loads . 15
4.9.2 Loads related to the weight of linesmen . 16
4.10 Forces due to short-circuit currents . 16
4.11 Other special forces . 16
4.11.1 Avalanches, creeping snow . 16
4.11.2 Earthquakes . 16
4.11.3 Floating of ice, accidents of vessels . 16
4.11.4 Mining out areas . 17
4.12 Load cases . 17
4.12.1 General . 17
4.12.2 Standard load cases . 17
4.13 Partial factors for actions . 18
5 Electrical requirements . 19
5.1 Introduction . 19
5.2 Currents . 19
5.2.1 Nominal current . 19
5.2.2 Short-circuit currents . 19
5.3 Insulation co-ordination. 19
5.4 Classification of voltages and overvoltages. 19
5.4.1 General . 19
5.5 Minimum air clearance distances to avoid flashover . 20
5.5.1 General . 20
5.6 Load cases for calculation of clearances. 21
5.6.2 Maximum conductor temperature . 21
5.6.3 Wind loads for determination of electric clearances . 21
5.6.4 Ice loads for determination of electric clearances . 22
5.6.5 Combined wind and ice loads . 22
5.8 Internal clearances within the span and at the top of support . 22
5.9 External clearances . 22
5.9.1 General . 22
5.9.2 External clearances to ground in areas remote from buildings, roads, etc. . 23
5.9.3 External clearances to residential and other buildings . 23
5.9.5 External clearances to adjacent traffic routes. 25
5.9.6 External clearances to other power lines or overhead telecommunication lines. 25
5.9.7 External clearances to recreational areas (playgrounds, sports areas, etc.) . 26
5.9.8 External clearances to line crossing pipelines or adjacent pipelines, including gas and oil
pipelines . 30
5.9.9 Overhead lines adjacent to aerodromes. 31
5.10 Corona effect . 32

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5.10.2 Audible noise . 32
5.10.3 Corona loss . 32
6 Earthing systems . 32
6.1 Introduction . 32
6.1.3 Earthing measures against lightning effects . 32
6.2 Ratings with regard to corrosion and mechanical strength. 32
6.2.1 Earth electrodes . 32
6.2.2 Earthing and bonding conductors . 33
6.4 Dimensioning with regard to human safety . 33
6.4.1 Permissible values for touch voltages . 33
6.4.3 Basic design of earthing systems with regard to permissible touch voltage . 33
7 Supports . 34
7.1 Initial design considerations . 34
7.1.1 Introduction . 34
7.2 Materials . 34
7.2.6 Wood . 34
7.3 Lattice steel towers . 34
7.3.1 General . 34
7.3.6 Ultimate limit states . 34
7.3.8 Resistance of connections . 35
7.4 Steel poles . 35
7.4.8 Resistance of connections . 35
7.5 Wood poles . 35
7.5.3 Materials . 35
7.5.5 Ultimate limit states . 35
7.10 Maintenance facilities. 35
7.10.1 Climbing . 35
7.10.2 Maintainability . 36
7.10.3 Safety requirements . 36
8 Foundations . 36
8.1 Introduction . 36
8.2 Basis of geotechnical design . 37
8.2.2 Geotechnical design by calculation . 37
8.2.3 Design by prescriptive measures . 38
8.2.4 Load tests and tests on experimental models . 38
8.3 Soil investigation and geotechnical data. 38
8.5 Fill, dewatering, ground improvement and reinforcement . 38
8.6 Interactions between support foundations and soil . 38
9 Conductors and earth-wires . 39
9.1 Introduction . 39

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9.2 Aluminium based conductors . 39
9.2.1 Characteristics and dimensions . 39
9.6 General requirements . 40
9.6.2 Partial factors for conductors . 40
10 Insulators . 40
10.2 Standard electrical requirements . 40
10.4 Pollution performance requirements . 40
10.7 Mechanical requirements. 41
10.10 Characteristics and dimensions of insulators . 41
11 Hardware . 42
11.6 Mechanical requirements. 42
12 Quality assurance, checks and taking over . 42
Annex B (informative) Conversion of wind velocities and ice loads . 43
Annex C (informative) Application examples of wind loads – Special forces . 44
Annex E (normative) Theoretical method for calculating minimum air clearances . 45
Annex F (informative) Empirical method for calculating mid span clearances . 46
Annex G (normative) Calculation methods for earthing systems . 47
Annex H (informative) Installation and measurements of earthing systems . 48

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European foreword
1 The Estonian National Committee (NC) is identified by the following address
Estonian Centre for Standardisation
Estonian National High Voltage Committee (HVC)
Akadeemia tee 21/6, 12618 Tallinn, Estonia
Phone: +372 605 5050
Fax: +372 605 5070
E-mail: info@evs.ee
2 The Estonian NC has prepared this Part 2-20 (EN 50341) listing the Estonian National Normative
aspects, under its sole responsibility, and duly passed it through the CENELEC and CLC/TC 11
procedures.
NOTE The Estonian NC also takes sole responsibility for the technically correct co-ordination of this NNA
with EN 50341-1. It has performed the necessary checks in the frame of quality assurance/control. However, it
is noted that this quality control has been made in the framework of the general responsibility of a standards
committee under the national laws/regulations.
3 This revision supersedes EVS-EN 50341-2-20:2015.
The most significant technical changes with respect to the previous edition are:
— requirements for low voltage lines are included;
— telecommunication lines located on common structures with power lines are taken into
account;
— the last amendments of Estonian legal documents are taken into account.
4 This Part 2-20 is normative in Estonia and informative for other countries.
5 This Part 2-20 has to be read in conjunction with EN 50341-1, referred to hereafter as Part 1. All
clause numbers used in this Part 2-20 correspond to those in Part 1. Specific subclauses, which
are prefixed “EE”, are to be read as amendments to the relevant text in Part 1. Any necessary
clarification regarding the application of Part 2-20 in conjunction with Part 1 shall be referred to the
Estonian NC that will, in cooperation with CLC/TC 11, clarify the requirements.
When no reference is made in Part 2-20 to a specific subclause, Part 1 applies.
6 In the case of “box values” defined in Part 1, amended values (if any), which are defined in
Part 2-20, shall be taken into account in Estonia.
However any boxed value, whether in Part 1 or in Part 2-20, shall not be amended in the direction
of greater risk in the Project Specification.
Terms with prepositions “from” and “up to”, denoting boundaries of values, always include the
boundary values itself, as it is common in other Estonian normative documents.
7 The national Estonian standards/regulations related to overhead electrical lines are listed in Clause
2.
NOTE All national standards referred to in this Part 2-20 will be replaced by the relevant European
Standards as soon as they become available and are declared by the Estonian Centre for Standardisation to
be applicable and thus reported to the secretary of CLC/TC 11.

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0 INTRODUCTION
0.7 Language
(snc) EE.1 Language
This Part 2-20 is published in English and in Estonian.
1 SCOPE
1.1 General
(snc) EE.1 Application to new lines
In Estonia the standard EN 50341-1 (Part 1) can only be applied using this NNA
(EN 50341-2-20) containing National Normative Aspects for Estonia.
This Part 2-20 applies to all new overhead electric lines with nominal system voltages
exceeding AC 1 kV and also for low voltage (below 1 kV AC) overhead lines performed
by aerial cables. The requirements of the structural design are applicable also for DC
overhead lines, where the electrical requirements are given in the Project Specification.
(ncpt) EE.2 “New overhead line”
A “new overhead line” means a completely new line between two points, A and B. A new
branch line of the existing power line should be considered as a new power line including
the junction support. Specific requirements for junction support should be defined with the
Project Specification.
1.2 Field of application
(ncpt) EE.1 Application to covered conductors and aerial cables
The standard includes requirements for the design and construction of overhead lines
with nominal system voltages up to 45 kV AC equipped with covered conductors and
aerial cables. Additionally, the requirements of the equipment standards and
manufacturers’ instructions shall be followed.
(A-dev) EE.2 Application to mounting of telecommunication equipment
The Standard EVS-EN 50341:2013 is applicable to fixing of structural elements for tele-
communication (antennas, All Dielectric Self Supporting (ADSS) equipment, junction
boxes, etc.), if mounted on power line supports (towers), especially regarding wind forces
and ice loads on such fixed elements. The design and installation should be done under
the due control of the line owner and/or the competent authority. Mounting of
telecommunication equipment on power line supports must be coordinated with the line
owner and stated in the Project Specification.
This standard applies to telecommunication lines only in the case of their common
installation with power lines. This standard does not apply to separately installed
telecommunication overhead lines.
If telecommunication equipment (antennas, dishes, etc.) will be installed in the
transmission line supports, and their size, location or mounting may have major effects on
the loads or design of the structures, the requirements of EVS-EN 1993-3-1/NA:2009
shall also to be taken into account. If such structures include conductive parts, the
requirements on clearances in subclause 5.8 should be applied.

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(ncpt) EE.3 Application to installation of other equipment
Only equipment belonging to the line (electric or telecommunication line) can be installed
on the overhead lines. However, with the permission of the owner of the line, equipment
serving communal services or environmental protection like road signs, warning signs or
warning balls, etc., may also be installed. The installation height of equipment meant to
be installed and maintained by an instructed person shall be such that the work can be
done without climbing the support and the distances of safe electrical work can be
followed. The additional loads due to this equipment on the line supports shall be taken
into account if necessary.
(ncpt) EE.4 Application to existing overhead lines
The Standard EVS-EN 50341:2013 shall not be applied to maintenance, branch lines,
extensions or diversions of existing overhead lines in Estonia, unless specifically required
in the Project Specification.
Overhead lines that meet the mechanical and electrical requirements in force at the time
of their construction can be continually operated if this does not cause obvious danger.
Such lines may be repaired and upgraded according to previously valid requirements.
Thereat repair means replacing a damaged element with a similar new one; renovation
means a more extensive improvement of the line with the aim of extending its life, while
preserving the basic construction of the line.
Any modification of existing lines shall be subject to this standard, but previous norms
and standards can also be used. It shall be made sure that the changes do not have a
significant impact on the line's load. Modification means, for example, the relocation of
some of the supports or the development of the line provided for in the initial design - for
example, adding a circuit or reconductoring on existing supports.
In cases of major revisions of existing lines the degree of application of the Standard
EVS-EN 50341
...