SIST EN 50341-2-12:2019

SLOVENSKI STANDARD
SIST EN 50341-2-12:2019
01-april-2019
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Overhead electrical lines exceeding AC 1 kV - Part 2-12: National Normative Aspects
(NNA) for ICELAND (based on EN 50341-1:2012)
Ta slovenski standard je istoveten z: EN 50341-2-12:2018
ICS:
29.240.20 Daljnovodi Power transmission and
distribution lines
SIST EN 50341-2-12:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 50341-2-12:2019

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SIST EN 50341-2-12:2019


EUROPEAN STANDARD EN 50341-2-12

NORME EUROPÉENNE

EUROPÄISCHE NORM
December 2018
ICS 29.240.20

English Version
Overhead electrical lines exceeding AC 1 kV - Part 2-12:
National Normative Aspects (NNA) for ICELAND (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 50341-2-12:2018 E

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SIST EN 50341-2-12:2019
EN 50341-2-12:2018 -2/25 - Iceland
Contents
Foreword . 4
1 Scope . 5
1.1 General . 5
2 Normative references, definitions and symbols . 5
2.1 Normative references . 5
2.1 IS.1 National normative laws and government regulations: . 5
3 Basis of design . 5
3.2 Requirements of overhead lines . 5
3.2.2 Reliability requirements . 5
3.2.5 Strength coordination. 6
4 Actions on lines . 6
4.3 Wind loads . 6
4.3.1 Field of application and basic wind velocity . 6
4.3.2 Mean wind velocity . 6
4.3.3 Mean wind pressure . 6
4.4 Wind forces on overhead line components . 6
4.4.1 Wind forces on conductors . 6
4.4.3 Wind forces on lattice towers . 7
4.5 Ice loads . 8
4.5.2 Ice forces on conductors . 8
4.6 Combined wind and ice loads . 9
4.6.1 Combined probabilities . 9
4.6.2 Drag factors and ice densities . 9
4.7 Temperature effects . 9
4.8 Security loads . 9
4.8.1 General . 9
4.8.4 Mechanical conditions of application . 10
4.9 Safety loads . 10
4.9.1 Construction and maintenance loads. 10
4.12 Load cases . 11
4.12.2 Standard load cases . 11
4.13 Partial factors for actions . 12
5 Electrical requirements . 13
5.5 Minimum air clearance distances to avoid flashover . 13
5.6 Load cases for calculation of clearances . 13
5.6.4 Ice loads for the determination of electric clearances . 13
5.8 Internal clearances within the span and at the top of support . 13
5.9 External clearances . 16
5.9.1 General . 16

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5.9.2 External clearances to ground in areas remote from buildings, roads, etc. . 16
5.9.3 External clearances to residential and other buildings . 16
5.9.4 External clearances to crossing traffic routes . 17
5.9.5 External clearances to adjacant traffic routes . 17
5.9.6 External clearances to other power lines and overhead telecommunication lines . 17
5.9.7 External clearances to recreational areas (playgrounds, sports areas, etc.) . 17
5.10.2 Audible noise . 18
6 Earthing systems . 18
7 Supports . 18
7.2 Materials . 18
7.3 Lattice steel towers . 18
7.3.3 Materials . 18
7.3.6 Ultimate limit states. 19
7.3.8 Resistance of connections . 19
7.5 Wood poles . 19
7.5.5 Ultimate limit states. 19
7.7 Guyed structures . 20
7.7.4 Ultimate limit states. 20
7.7.6 Design details for guys . 20
7.9 Corrosion protection and finishes . 21
7.9.2 Galvanising . 21
8 Foundations . 21
8.2 Basis of geotechnical design . 21
8.2.2 Geotechnical design by calculation . 21
8.3 Soil investigation and geotechnical data . 23
9 Conductors and earth-wires . 24
9.1 Introduction . 24
9.6 General requirements . 25
9.6.2 Partial factor for conductors . 25
10 Insulators . 25
10.7 Mechanical requirements . 25
11 Hardware . 25
11.6 Mechanical requirements . 25
12 Quality assurance, checks and taking-over . 25
Annex J Lattice steel towers . 25
J.5 Design resistance of bolted connections . 25
J.5.1 General . 25

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SIST EN 50341-2-12:2019
EN 50341-2-12:2018 -4/25 - Iceland
European Foreword
1 The Icelandic National Committee (NC) is identified by the following address:
Rafstaðlaráð
Staðlaráð Íslands
Þórunnartúni 2
105 Reykjavík
Iceland
Tel. +354 520 7150
Fax +354 520 7171
Web http://www.stadlar.is
2 The Icelandic NC has prepared this Part 2-12 of EN 50341-1:2012 listing the Icelandic National
Normative Aspects (NNA), under its sole responsibility, and duly passed it through the CENELEC
and CLC/TC 11 procedures.
Note 1: The Icelandic NC also takes sole responsibility for the technically correct co-ordination of this EN
50341-2-12 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 EN 50341-2-12 is normative in Iceland and informative for other countries.
4 This Part 2-12 has to be read in conjunction with EN 50341-1, hereinafter referred to as Part 1.
All clause numbers used in this Part 2-12 correspond to those of Part 1. Specific subclauses,
which are prefixed “IS”, are to be read as amendments to the relevant text in Part 1. Any
necessary clarification regarding the application of Part 2-12 in conjunction with Part 1 shall be
referred to the Icelandic NC who will, in co-operation with CLC/TC 11 clarify the requirements.
When no reference is made in Part 2-12 to a specific subclause, then Part 1 applies.
5 In the case of “boxed values” defined in Part 1, amended values (if any) which are defined in Part
2-12 shall be taken into account in Iceland.
However, any boxed value, whether in Part 1 or Part 2-12, shall not be amended in the direction
of greater risk in a Project Specification.
6 The national Icelandic standards/regulations related to overhead electrical lines exceeding 1 kV
(AC) are listed in subclause 2.1/IS.1.
NOTE  All national standards referred to in this Part 2-12 will be replaced by the relevant European Standards
as soon as they become available and are declared by the Icelandic NC to be applicable and thus reported to
the secretary of CLC/TC 11.

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1 Scope
1.1 General
1.1 IS.1 Application to new lines
(snc) This Part 2-12 is only applicable to new overhead transmission lines exceeding 1 kV (AC).
If deviations and/or extensions to existing transmission lines are planned, the Icelandic NC
shall be informed and will decide case by case whether ÍST EN 50341 is applicable or not.
2 Normative references, definitions and symbols
2.1 Normative references
2.1 IS.1 National normative laws and government regulations:
(A-dev)
• Lög nr. 146/1996 um öryggi raforkuvirkja, neysluveitna og raffanga.
Act no. 146/1996 on the Safety of Electrical Installations, Consumer Apparatus and
Electrical Materials.
• Reglugerð um raforkuvirki nr. 678/2009, með áorðnum breytingum.
The Electrical Regulation no. 678/2009, with later changes.
• Reglugerð um hávaða nr. 724/2008, með áorðnum breytingum.
The Regulation on noise no. 724/2008, with later changes.
3 Basis of design
3.2 Requirements of overhead lines
3.2.2 Reliability requirements
3.2.2 IS.1 Reliability requirements
(snc) Three reliability levels are used for new transmission lines as shown in the following table:
Table 3.2.2/IS.1 Reliability levels
Reliability level Voltage Transmission lines
Normal lines
≤ 45 kV
1
> 45 kV and ≤ 132 kV Less important lines
Very important lines
≤ 45 kV
Normal lines
2 > 45 kV and ≤ 132 kV
Less important lines
> 132 kV and ≤ 400 kV
< 220 kV Very important lines
3
≥ 220 kV Normal lines
Level 3 shall be used in built up or urban areas for lines ≥ 132 kV
Level of importance shall be defined in Project Specification.

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3.2.5 Strength coordination
3.2.5 IS.1 Strength coordination
(snc) The partial factors γ for the resistance of all structural elements of tension and terminal
M
supports shall be multiplied by the factor 1,1 for voltage ≥ 132 kV. This requirement does not
need to be applied in the load case “Construction and maintenance” and “Security loads”.
4 Actions on lines
4.3 Wind loads
4.3.1 Field of application and basic wind velocity
4.3.1 IS.1 Field of application and basic wind velocity
(snc) The basic wind velocity (Vb,0), terrain category and the directional factor (C ) shall be given
dir
in the Project Specification for each line section. The values can either be according to the
Icelandic National Annex of EN 1991-1-4 or be evaluated by experts using reliable extreme
wind statistic and considering local conditions.
4.3.2 Mean wind velocity
4.3.2 IS.1 Mean wind velocity
(snc) A new terrain category with roughness length z = 0,03 and terrain factor k = 0,182 is
0 r
applicable in addition to terrain categories listed in table 4.1.
4.3.3 Mean wind pressure
4.3.3 IS.1 Mean wind pressure
3
(snc) The air density can be taken as ρ = 1,25 kg/m . The use of other values that take into
account air temperature and atmospheric pressures is optional.
4.4 Wind forces on overhead line components
4.4.1 Wind forces on conductors
4.4.1.1 General
4.4.1.1 IS.1 General
(ncpt) The reference height above ground, h, shall be taken as Method 1 unless the Project
Specification specifies otherwise.
4.4.1.3 Drag factor
4.4.1.3 IS.1 Drag factor
(ncpt) The drag factor for bare stranded conductors shall be derived with Method 1, i.e. C = 1,0
c
unless the Project Specification specifies otherwise.
For the calculation of the conductor tension the span factor shall be based on the ruling
span length unless otherwise specified in the Project Specification.

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4.4.3 Wind forces on lattice towers
4.4.3.1 General
4.4.3.1 IS.1 General
(ncpt) Method 1 and Method 2 can both be used.
4.4.3.2 Method 1
4.4.3.2 IS.1 Wind load for lattice cross-arms
(ncpt) Wind forces on rectangular lattice cross-arms with a ratio of length / height ≥ 12 can be
estimated as follows:
1
2 2
Q = q (h)∙ G ∙ C ∙ A ∙�sinϕ + cosϕ�
Wtc p tc tc tc
3
Where
q (h) is the peak wind pressure;
p
G is the structural factor for lattice cross-arms, the recommended value is 1,0;
tc
C is the drag factor for the lattice cross-arm in a wind perpendicular to the
tc
longitudinal axis of the cross-arm. For angle sections C = 2,8;
tc
A is the effective wind area of the elements of the lattice cross-arm in the front
tc
panel face;
φ is the angle between wind direction and the longitudinal axis of the lattice cross-
arm.

Figure 4.4.3.2/IS.1 Wind load for lattice cross-arm
4.4.3.3 Method 2
4.4.3.3 IS.1 Drag factor for tower members
(ncpt) The drag factor C can be taken lower than 1,6 provided that it gives not less loading than
m
in Method 1. The drag factor C shall nevertheless be ≥ 1,2.
m

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4.5 Ice loads
4.5.2 Ice forces on conductors
4.5.2 IS.1 Characteristic ice load
(ncpt) The reference unit ice load (I ) shall be specified in the Project Specification. It shall be
R
based on a 30 mm single conductor at a height of 10 m above ground. Wet snow icing
shall always be specified and in-cloud icing shall be specified where relevant.
The characteristic ice load (I ) is determined by:
k
I = I ∙ k ∙ k ∙ k
k R d b h
Where
I is the reference ice load (N/m) for a 30 mm single conductor 10 m above ground;
R
k  is the influence of conductor diameter on the ice load;
d
k  is the influence of the number of sub-conductors in a bundle on the ice load;
b
k  is the influence of conductor height above ground on the ice load.
h
The influence of conductor diameter and conductor height above ground on the
characteristic ice load shall be taken as in the following table.
Table 4.5.1/IS.1 Influence of the conductor diameter and height above ground on
the ice load, k and k
h d
Parameter Wet snow icing In-cloud icing
k 1,0 1.0 + (h - 10) ⋅ 0,01 but k ≥ 1,0
h h
kd 1,0 + 5 ⋅ (D – 0,03) but  k ≥ 0,9 and k ≤ 1,1
d d
h is the height of conductor above ground in [m];
D is the conductor diameter in [m].
The ice load can be reduced by the factor kb when the number of sub-conductors in a
bundle is greater than one provided that the sub-conductors are connected with spacers
with regular intervals (<75m).
Table 4.5.2/IS.1 Ice loading reduction for bundle conductors, k
b
Reference ice load
Number of conductors in a bundle
(I )
R
[N/m] 1 (simplex) 2 (duplex) 3 (triplex)
0 – 50 1,0 1,0 1,0
50 – 250 1,0 1,075 – 0,0015 ⋅ IR 1,125 – 0,0025 ⋅ IR
> 250 1,0 0,7 0,5
Extreme ice load (IT) is determined by:
𝐼𝐼 =𝛾𝛾 ∙𝜓𝜓 ∙𝐼𝐼
𝑇𝑇 𝐼𝐼 𝐼𝐼 𝑘𝑘
Values for combined partial (γ) and combination (ψ) factors are given in table 4.13/IS.1 for
ψ ⋅γ .
I I

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4.5.2 IS.2 Ice on structures and insulators
(snc) No ice is considered on structures or insulators in case of wet-snow icing.
In case of in-cloud icing, ice shall be applied to tower members, guys and insulators by
assuming the ice load as 0,8 ⋅ I The ice shape can be assumed to have a constant
R.
thickness around the profile cross section.
4.6 Combined wind and ice loads
4.6.1 Combined probabilities
4.6.1 IS.1 Combined probabilities
(snc) The wind velocity in a combined wind and ice load (V ) shall be determined based on
Comb
extreme wind velocity on site with a reference return period of 50 years (V ) by:
50
V = V ∙ �γ ∙ψ
Comb 50 W W
The ice load (IComb) in the combination of wind and ice load shall be determined based on
the characteristic ice load (Ik) by:
I =γ ∙ψ ∙ I
Comb I I k
Values for combined partial (γ) and combination (ψ) factors are given in table 4.13/IS.1 for
ψ ⋅γ and ψ ⋅γ .
W W I I
4.6.2 Drag factors and ice densities
4.6.2 IS.1 Drag factors and ice densities
(snc) The drag factor and ice density for icing shall be taken in accordance with the following
table.
Table 4.6/IS.1 Drag factors and ice density for icing
Ice type Wet snow In-cloud icing
Drag factor, C 1,0 1,1
ic
3
Density, ρ [kg/m ] 700 500
i
4.7 Temperature effects
4.7 IS.1 Temperature effects
(snc) The following temperature values shall be used unless otherwise specified in the Project
Specification:
extreme wind condition, 0°C;
wet snow icing condition, 0°C;
in-cloud icing condition, -5 °C.
4.8 Security loads
4.8.1 General
4.8.1 IS.1 General
(snc) A security load should generally not be considered for supports at less than 132 kV or for
wood poles supports at 132 kV.

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4.8.4 Mechanical conditions of application
4.8.4 IS.1 Torsional and longitudinal loads
(snc) The following security load cases can be applied for supports at voltage ≥ 132 kV (though
not for wood poles supports at 132 kV) unless otherwise specified in the Project
Specification.
Security loading for suspension supports
All conductors in normal condition (without wind or ice). Longitudinal force A applied
K
to one phase conductor or earth wire attachment point at a time. Irrespective of
weather conditions, the longitudinal force is defined as:
A = β · T
K S 0
Security loading for tension supports
All conductors in condition of uniform icing (wet snow icing or in-cloud icing) without
wind. Unbalanced longitudinal force, AK, applied to one phase conductor or earth
wire attachment point at a time. The unbalanced force is based on one-sided release
of static tension.
AK = βT · T0
Where:
AK is unbalanced force based on one-sided release of conductor or earth wire
tension. Value of AK shall not be greater than the conductor or earth wire
force in the weather condition;
β is the reduction factor for the conductor tension in suspension supports;
s
β is the reduction factor for the conductor tension in tension supports;
T
T is the initial horizontal tension in a single sub-conductor or earth wire at 0°C
0
temperature.
Table 4.8/IS.1 Reduction factor β for longitudinal security loading on supports
Conductor βs βT
Simplex 1,0 2,0
Phase conductor Duplex 1,5 3,0
Triplex 2,0 4,0
Earth wire 1,3 2,0
4.9 Safety loads
4.9.1 Construction and maintenance loads
4.9.1 IS.1 Construction and maintenance loads
(snc) Tension supports shall be designed for construction and maintenance loads taking into
account the working procedure for the conductor installation.
If documented working procedures are not available, tension supports shall be designed to
resist conductor installation loading in any order without temporary strengthening, including
the following two load cases in weather conditions that may occur during construction work:
Load case 1: Stringing of tension support, before clipping in:
One phase conductor/earth wire at a time is being pulled down at a 45° angle from
vertical over a stringing wheel. Other conductors are either assumed not present, or
already clipped in, in one section only (zero load in other sections)

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Load case 2: Stringing of tension support, after clipping in:
For any conductor installation combination in one section (i.e. forward section or
back section), assume zero load on the other side. Other conductors are either
assumed not present, or already clipped in, in one section only (zero load in other
sections)
4.12 Load cases
4.12.2 Standard load cases
4.12.2 IS.1 Standard load cases
(snc) Standard load cases are defined in Table 4.12/IS.1.
Table 4.12/IS.1 Standard load cases
Load Conditions Remark
case
1 Extreme wind load See (a)
2a Uniform ice loads on all spans See (b)
2b Uniform ice loads, transverse bending α=0,3 If relevant
Unbalanced ice loads, longitudinal bending with
2c-1 See (c)
α =0,7 and α = 0,3
2 1
Unbalanced ice loads, longitudinal bending
Applies only to tension
2
2c-2 α2=1,0 and α1= cos θ but α1 ≤ 0,7. θ is the line
supports, see (d)
angle.
Unbalanced ice loads, torsional bending α3=0,3, Applies only to tension
2d
supports if relevant
α4=1,0
Uniform ice loads, reduced ice in one or more
2e If relevant, see (e)
phases
Load case 3a-1 is wet-
Combined wind and ice loads I (strong wind and
3a snow icing and 3a-2 is in-
moderate ice)
cloud icing
Combined wind and ice loads II (moderate wind
3b If relevant
and high ice). In-cloud icing
4 Minimum temperature with/without wind loads If relevant
5 Security loads See paragraph IS 4.8
6 Safety loads, construction and maintenance See paragraph IS 4.9
Note:
a) Wind directions that are critical shall be considered. Normally it is sufficient to consider
the following wind directions: 0°, ±20°, ±45°, ±90°. Directions orthogonal to the forward
span and back span shall also be considered in case of angle support.
In cases where extreme wind on the support part decreases the stress in a particular
member, wind pressure on the critical part in the support shall be reduced to 50%. An
example is a guyed support where an eccentricity at the ends of pinned masts is
introduced to reduce the bending effects due to wind load on the mast.
b) Ice load applies both to wet-snow icing and in-cloud icing where relevant.

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c) An ice load equal to α = 0,7 times the extreme ice load is applied on all conductors in
2
one direction from the cross-arms and the ice load in the other direction is multiplied by
a reduction factor α = 0,3.
1
d) An ice load equal to α = 1,0 times the extreme ice load is applied on all conductors in
2
one direction from the cross-arms. The ice load in the other direction is multiplied by a
2
reduction factor α where α = cos θ but not greater than α = 0,7. The basic ice load
1 1 1
(I ) does not need to be the same in the forward span and back span in case of tension
k
support.
e) Phase(s) with a reduced ice load shall have α=0,5.
4.13 Partial factors for actions
4.13 IS.1 Partial factors for actions
(snc) Partial factors and combination factors for the actions are defined in Table 4.13/IS.1.
Table 4.13/IS.1 – Combined partial factor (γ) and combination factors (ψ) for actions
in the ultimate limit state
Reliability level
Load
1 2 3
Load description
case
ψ ⋅ γ ψ ⋅γ ψ ⋅ γ ψ ⋅γ ψ ⋅ γ ψ ⋅γ
W W I I W W I I W W I I
Extreme wind 1,0 0 1,2 0 1,4 0
1
Ice load 0 1,0 0 1,25 0 1,5
2
Combined wind and ice I.
0,5 k 0,6 1,2⋅k 0,7 1,4⋅k
ws ws
...