Bsi bs en 50341 2 13 2017

BS EN 50341-2-13:2017

BSI Standards Publication

Overhead electrical lines
exceeding AC 1 kV
Part 2-13: National Normative Aspects
(NNA) for ITALY (based on
EN 50341-1:2012)


BS EN 50341-2-13:2017

BRITISH STANDARD
National foreword
This British Standard is the UK implementation of EN 50341-2-13:2017.
This standard, together with the following list of National Normative
Aspect standards, supersedes BS EN 50423-3:2005 and BS EN 50341-3:2001:
Country
Code
AT
BE
CH
DE
DK
ES
FI
FR
GB
GR
IE

IS
IT
LU
NL
NO
PT
SE
CZ
EE
PL
SK

Origin

Ref

Austrian National Committee
Belgian National Committee
Swiss National Committee
German National Committee
Danish National Committee
Spanish National Committee
Finnish National Committee
French National Committee
British National Committee
Greek National Committee
Irish National Committee
Iceland National Committee
Italian National Committee
Luxemburg National Committee

Nederland’s National Committee
Norwegian National Committee
Portuguese National Committee
Swedish National Committee
Czech National Committee
Estonian National Committee
Polish National Committee
Slovak National Committee

BS EN 50341-2-1
BS EN 50341-2-2
BS EN 50341-2-3
BS EN 50341-2-4:2016
BS EN 50341-2-5
BS EN 50341-2-6
BS EN 50341-2-7:2015
BS EN 50341-2-8
BS EN 50341-2-9:2015
BS EN 50341-2-10
BS EN 50341-2-11
BS EN 50341-2-12
BS EN 50341-2-13:2017
No NNA available
BS EN 50341-2-15
BS EN 50341-2-16:2016
BS EN 50341-2-17
BS EN 50341-2-18
BS EN 50341-2-19:2015
BS EN 50341-2-20:2015
BS EN 50341-2-22:2016

BS EN 50341-2-23:2016

BS EN 50423-3:2005 and BS EN 50341-3:2001 will be withdrawn upon
publication of the rest of the series.
The UK participation in its preparation was entrusted to Technical
Committee PEL/11, Overhead Lines.
A list of organizations represented on this committee can be obtained
on request to its secretary.
This publication does not purport to include all the necessary provisions
of a contract. Users are responsible for its correct application.
© The British Standards Institution 2017.
Published by BSI Standards Limited 2017
ISBN 978 0 580 96535 7
ICS 29.240.20

Compliance with a British Standard cannot confer immunity from
legal obligations.
This British Standard was published under the authority of the Standards
Policy and Strategy Committee on 31 March 2017.

Amendments/ccorrigenda issued since publication
Date

Text affected


BS EN 50341-2-13:2017

EN 50341-2-13

EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM

January 2017

ICS 29.240.20

English Version

Overhead electrical lines exceeding AC 1 kV - Part 2-13:
National Normative Aspects (NNA) for ITALY (based on EN
50341-1:2012)
Lignes électriques aériennes dépassant 1 kV en courant
alternatif - Partie 2-13: Aspects normatifs nationaux (NNA)
pour l'ITALIE (basés sur l'EN 50341-1:2012)

This European Standard was approved by CENELEC on 2016-12-13.
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: Avenue Marnix 17, B-1000 Brussels

© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN 50341-2-13:2017 E


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Contents
European foreword ............................................................................................................... 4
1

2

3

4

Scope .............................................................................................................................. 5
1.1

General ................................................................................................................ 5

1.2

Field of application .............................................................................................. 5

Normative references, definitions and symbols ........................................................... 5

2.1

Normative references .......................................................................................... 5

2.2

Definitions ........................................................................................................... 7

2.3

Symbols ............................................................................................................... 7

Basis of design ............................................................................................................... 7
3.1

Introduction ......................................................................................................... 7

3.2

Requirements of overhead lines.......................................................................... 7

Actions on lines .............................................................................................................. 7
4.1

Introduction ......................................................................................................... 7

4.3

Wind loads ........................................................................................................... 8

4.5

Ice loads ............................................................................................................ 12

4.6

Combined wind and ice or snow loads .............................................................. 13

4.7

Temperature effects .......................................................................................... 13

4.8

Security loads ................................................................................................... 15

4.9

Safety loads ....................................................................................................... 16

4.11 Other special forces .......................................................................................... 16
4.12 Load cases ........................................................................................................ 17
4.13 Partial factors for actions.................................................................................. 18
5

Electrical requirements ................................................................................................ 18
5.6

Load cases for clearances calculation .............................................................. 18

5.8

Internal clearances within the span and at the top of the tower ....................... 18

5.9

External clearances .......................................................................................... 20

5.11 Electric and magnetic fields .............................................................................. 23
6

Earthing systems .......................................................................................................... 24

7

Supports ....................................................................................................................... 24
7.3

Lattice steel towers ........................................................................................... 24

7.5

Wood poles ........................................................................................................ 25

7.10 Maintenance facilities........................................................................................ 25
8

9

Foundations .................................................................................................................. 25

8.1

Introduction ....................................................................................................... 25

8.2

Basis of geotechnical design (EN 1997-1:2004 – Section 2) ............................ 25

Conductors and earth-wires......................................................................................... 26
9.1

Introduction ....................................................................................................... 26

9.2

Aluminium based conductors ........................................................................... 26


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9.3

Steel based conductors ..................................................................................... 26

9.4

Copper based conductors ................................................................................. 26

9.6

General requirements ........................................................................................ 27

10 Insulators ...................................................................................................................... 27
10.7 Mechanical requirements .................................................................................. 27
11 Hardware ....................................................................................................................... 28
11.6 Mechanical requirements .................................................................................. 28
12 Quality assurance, checks and taking-over ................................................................ 28
Annex J ............................................................................................................................... 30
J.4 Buckling resistance of angle in compression (see 7.3.6.4) ........................................ 30
J.5 Design resistance for bolted connections (see 7.3.8) ................................................ 32
J.5.1

General ................................................................................................................... 32


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EN 50341-2-13:2017

European foreword
1.

The Italian National Committee (NC) is identified by the following address:
Italian Electrotechnical National Committee
Via Saccardo 9
20134 Milano
Italy
Phone n°. ++39 02 21006.1
Fax n°.
++39 02 21006210
Committee 11/7 – Overhead electrical lines
E-Mail

2.

The Italian NC has prepared this Part 2-13 (EN 50341-2-13) listing the Italian National
Normative Aspects (NNA) under its sole responsibility and duly passed it through the
CENELEC and CLC/TC 11 procedures.
NOTE: The Italian NC 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 already made in the framework of the
general responsibility of a standards committee under the national laws/regulations.

3. This NNA is normative in Italy and informative for other countries.
4.

This NNA has to be read in conjunction with Part 1 (EN 50341-1). All clause numbers
used in this NNA correspond to those of Part 1. Specific subclauses, which are prefixed
“IT”, are to be read as amendments to the relevant text in Part 1. Any necessary
clarification regarding the application of this NNA in conjunction with Part 1, shall be
referred to the Italian NC who will, in co-operation with CLC/TC 11, clarify the
requirements.

When no reference is made in this NNA 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 this NNA, shall be taken into account in Italy.
However, any boxed value, whether defined in Part 1 or in this NNA, shall not be
amended in the direction of greater risk in a Project Specification.

6.

The national Italian standards/regulations related to overhead electrical lines exceeding
1 kV (AC) are listed in subclause 2.1/IT.1 and 2.1/IT.2.
NOTE: All national standards referred to in this NNA will be replaced by the relevant European
Standards as soon as they become available and are declared by the Italian NC to be applicable
and thus reported to the secretary of CLC/TC 11.


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1

Scope

1.1

General

(ncpt)

IT.1

EN 50341-2-13:2017

New overhead line

This NNA (National Normative Annex) is only applicable to all new overhead
lines equipped with bare conductors, covered conductors or cables, with
voltages above 1kV AC. This standard is not applicable to overhead lines preexisting before its coming into force and shall not be applied to maintenance or
reconductoring; the standard can be applied in case of significant modifications
of existing lines.

1.2
(ncpt)

Field of application
IT.1

Field of application

This standard specifies the general safety requirements, clarifies the actions that
shall be carried out in the project and their relevant combinations, defines the
characteristics of materials, products and any other aspects relevant to safety of
electrical overhead lines as reported in the following clause 2. With reference to
structural safety aspects, in absence of specific indications, and as an
integration to this standard, the dispositions reported in “Norme tecniche sulle
costruzioni” apply (see subclause 2.1).

For what concerns structural aspects this standard applies also to D.C. overhead
lines.
For details concerning the application of this standard to telecommunication
systems involving optical fibres either incorporated in or wrapped around earthwires or conductors or suspended from overhead line supports, reference should
be made to the Project Specifications.

2

Normative references, definitions and symbols

2.1

Normative references

(A-dev)

IT.1

National normative laws, government regulations

List of Law Decrees, Ministerial Decrees, Decrees of the President of the
Minister’s Council:

− In the following text the new Italian Technical Standard, reported in the

Ministerial Decree 14.01.2008 promulgated in force of article 5, subsection 2
of Law Decree 28 May 2004 n. 136 turned into law 27.07.2004 n. 186 and the
articles 52 e 83 of D.P.R. 06.06.2001, n. 380, contained the “Testo Unico
delle disposizioni legislative e regolamentari in materia edilizia” will be
referred as “Norme tecniche sulle costruzioni”.

− Decree of the President of the Ministers’ Council, 23 April 1992.
Limiti massimi di esposizione ai campi elettrico e magnetico generati alla
frequenza industriale nominale (50 Hz) negli ambienti abitativi e nell’ambiente
esterno.
Maximum limits of exposure to power frequency (50 Hz) electric and magnetic
fields in inhabited buildings and external environment.

− Decree of the Ministers of Public Works and of Internal Affairs, 16 January
1996.

Technical standard related to “Criteri generali per la verifica di sicurezza delle
costruzioni e dei carichi e sovraccarichi”.


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− Decree of the President of the Ministers’ Council, 8 July 2003.
“Fissazione dei limiti di esposizione, dei valori di attenzione e degli obiettivi di
qualità per la protezione della popolazione dalle esposizioni ai campi elettrici
e magnetici alla frequenza di rete (50 Hz) generati dagli elettrodotti”.
Prescription of the exposition limits, attention values and quality objectives for
the protection of people from the expositions to electrical and magnetic fields
at power frequency (50 Hz).
(ncpt)

IT.2

National technical standards

List of Standard:

− CEI 103-6 (1997-12)
Protezione delle linee di telecomunicazione agli effetti dell’induzione
elettromagnetica provocata dalle linee elettriche vicine in caso di guasto.
Protection of telecommunication lines against harmful effects produced by power
lines in fault conditions

− CEI 7-1 (1997-09)
Norme per conduttori di rame e leghe di rame per linee elettriche aeree.
Requirements for copper and copper-alloy conductors for electrical overhead
lines.

− CEI 7-2 (1997-09)
Norme per conduttori di alluminio, alluminio-acciaio, lega di alluminio, e lega di
alluminio-acciaio per linee elettriche aeree.
Requirements for all aluminium, aluminium-steel reinforced, all aluminium alloy
and aluminium alloy-steel reinforced conductors for electrical overhead lines.

− CEI 7-6 (1997-04)
Norme per il controllo della zincatura a caldo per immersione su elementi di
materiale ferroso destinati a linee e impianti elettrici.
Requirements for checking hot galvanizing by immersion on ferrous components
used in lines and electrical installations.

− CEI 7-10 (1997-09)
Norme per conduttori di acciaio rivestito di rame a filo unico ovvero cordati
destinati a linee di telecomunicazione ed a linee di trasporto energia.
Requirements for copper clad steel conductors, single wire and stranded, for
telecommunication and power lines.

− CEI 7-11 (1997-09)
Norme per conduttori di acciaio rivestito di alluminio a filo unico e a corda per
linee elettriche aeree.
Requirements for aluminium clad steel conductors, single wire and stranded, for
electrical overhead lines.

− Guida CEI 36 (1997-10)
Resistenza meccanica residua di elementi di catene di isolatori di vetro o di
ceramica per linee aeree dopo il danneggiamento meccanico della parte
isolante.
Residual strength of insulators units of glass or ceramic materials for overhead
lines after mechanical damage of dielectric.


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− CEI EN 50443 (2012-12)
Effetti delle interferenze elettromagnetiche sulle tubazioni causate da sistemi di
trazione elettrica ad alta tensione in corrente alternata e/o da sistemi di

alimentazione ad alta tensione in corrente alternata.
Effects of electromagnetic interference on pipelines caused by high voltage a.c.
electric traction system and/or high voltage a.c. power supply system.

− CEI UNI EN ISO/IEC 17065 (2012-12) (CEI 501-22) ex EN 45011
Valutazione della conformità - Requisiti per organismi che certificano prodotti,
processi e servizi.
Conformity
assessment – Requirements for bodies certifying products,
processes and services.
2.2
(A-dev)

Definitions
IT.1

Reference wind speed V b

In this standard, the reference wind speed is referenced as V b and is in
agreement with Eurocodice 1991-1-4 and “Norme tecniche sulle costruzioni”.
2.3
(A-dev)

Symbols
IT.1

Reference wind speed V b

Vb mean wind speed in agreement with Eurocodice 1991-1-4 and “Norme
tecniche sulle costruzioni”. Reference 4.3 IT1 (A-dev).

3

Basis of design

3.1

Introduction

(ncpt)

IT.1

Design philosophy and approach

The design philosophy of the Italian overhead lines shall be based on the limit
state criterion of Eurocodes 1, 2, 3, 5, 7, 8.
The specific design approach to be used shall be specified in the Project
Specifications.
3.2

Requirements of overhead lines

3.2.2

Reliability requirements

(ncpt)

IT.1

Reliability of overhead lines

In compliance with EN 50341-1 and in accordance with past experiences, the
reliability of overhead lines shall be as follows:
−

Level 1: 50-years return period.

Higher reliability levels can be indicated in the Project Specifications.
4

Actions on lines

4.1

Introduction

(ncpt)

IT.1

Action on overhead lines

Actions on overhead lines are due to the wind load, to the tensile load of
conductors and earth-wires on angle supports, or, in case of breakage of
conductors or earth-wires, to the weight of the components, to the weight of ice


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or snow formations on conductors or earth-wires, to the temperature effects, to
erection and maintenance loads and to seismic events. The combination of the
above actions is made according to the criteria indicated in the following in order
to meet the required reliability of the lines.
Actions on lines due to ice, snow and wind loads with higher values than those
reported in the following paragraphs can be prescribed in the Project
Specification on the base of experimental data due to field observations with
sufficient statistical numerosity.
4.3

Wind loads

4.3.1

Field of application and basic wind velocity

(A-dev)

IT1

Wind load acting on overhead line

Wind load acting on overhead line components is based on the reference wind
speed, defined in the following subclause, by applying factors that take into

account gust wind phenomena, the terrain roughness and the height above
ground.
(A-dev)

IT.2

Reference wind speed

The reference wind speed, V b , is defined as the maximum value, with a return
period of 50 years, of the mean wind speed, in m/s, over a period of 10 min at a
height of 10 m above the ground, on a terrain with exposition category II, as
defined in “Norme tecniche sulle costruzioni” and according to table 4.1 of
EN 50341-1.
The reference wind speed, as a function of site and of altitude above sea level
shall be evaluated according to the specifications in the “Norme tecniche sulle
costruzioni”.
In order to calculate the wind speed for different return periods “Table B.1 Conversion factors for different return periods of wind speed” of EN 50341-1
shall be applied, where:
VT

is the extreme wind speed with return period T;

V 50

is the extreme wind speed with return period of 50 years.

The reference wind speed V b is obtained from maps in 3.3.2 of “Norme
tecniche sulle costruzioni”.
Each zone is characterized by maximum mean wind speed per hour, defined
as follow:

V b = V b,0

for a s ≤ a 0

Vb = V b,0 + k a(a s – a 0)

for a s > a 0

Where a s is the effective height above sea level in [m].
Values for V b,0 , K a and a 0 are reported in Table 3.3.I of “Norme tecniche sulle
costruzioni”. For altitudes a s > 1500 m, except for local conditions, properly
documented and proven, it is assumed a s = 1500 m.
The zoning is represented in Figure 4.3/IT.2 (equivalent to Figure 3.3.1 of
“Norme tecniche sulle costruzioni”).


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Figure 4.3/IT.2
(A-dev)

IT.3

Exposition category of the site

For the evaluation of the terrain roughness of the site and of the necessary
parameters for the calculation of wind action, reference shall be made to “Norme
tecniche sulle costruzioni”.
(A-dev)

IT.4

Exposure coefficient C e

Referring to 3.3.7 of “Norme tecniche sulle costruzioni”, the calculation of the
exposure coefficient C e is made on the base of the following parameters:
- the height above ground of the construction. For overhead lines “z” means the
height above ground of the different components (such as supports, fitting,
insulators, conductors, earth-wires);
-

the terrain topography, with the related topography coefficient C t ;

-

the exposition category of the site.
In the absence of specific analyzes which take into account the wind direction
and the effective roughness and topography of the terrain surrounding the
structure, for heights above ground of the structure no more than z = 200 m,
it is given by the following formulas to be applied based on a comparison
between the height of the structure and z min as defined below:


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

 z   z 
2
C e (z ) = k r ⋅C t ⋅7 + C t ⋅ ln  ⋅ ln 

 z 0   z 0 


C e (z ) = C e (z min )

z ≥ zmin
z < zmin

where:
z

is height above ground of the structure (of the related component),

Ct

is topography coefficient, typically set to 1,

k r , z 0 , z min are coefficients defined as function of exposition category of
site, depending on exposure area and terrain roughness class according

to Table 3.3.II of “Norme tecniche sulle costruzioni”. In particular zmin
indicates the minimum height of the construction for a given exposition
category.
According to 4.2 of EN 1991-1-4, reference is made to exposition category of
site II, whose characteristics are reported in Table 4.3/IT.4, conforming to
Table 3.3.II of “Norme tecniche sulle costruzioni”.
Table 4.3/IT.4 − Characteristics of exposition category II
Exposition category
of the site
II

kr
0,19

z0

z min

[m]

[m]

0,05

4

In Figure 4.3/IT.4 (corresponding to figure 3.3.3 of “Norme tecniche sulle
costruzioni”) the exposition coefficient trend for each exposition category is
indicated as a function of the height of the construction.

Figure 4.3/IT.4
By multiplying V b by square root of C e it is possible to obtain the peak speed
(extreme wind) at the height of the structure.


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(A-dev)

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EN 50341-2-13:2017

Wind speed at arbitrary height above ground

It is calculated according to clause IT.4 above.
(A-dev)

IT.6

Dynamic pressure of the wind

The dynamic pressure of the wind [N/m 2 ] is:
qb =

ρ Vb2

where
3

the air density is ρ = 1,25 kg/m and
V b is the reference wind speed.
(A-dev)

IT.7

Dynamic wind force on any element of lines

The force value Q w of the wind which blows horizontally or at right angle on any
element of lines is:
Qw = qb ⋅ Ce ⋅ Gx ⋅ Cx ⋅ A
where
qb

is the dynamic pressure of wind.

Ce

is the exposition coefficient according to “Norme tecniche sulle
costruzioni”.

Gx

is the dynamic factor which considers the effects of reduction due to the
not contemporaneousness of the maximum local pressures, as defined
in “Norme tecniche sulle costruzioni”; for what concerns aspects that
are peculiar to overhead lines, reference shall be made to EN 50341-1,
in particular when calculation is referred to wind action on conductors
(or earth-wires), the coefficient G x shall be replaced by the coefficient
G c of EN 50341-1 4.4.1.2.

Cx

is the dynamic factor of drag resistance, which depends on the shape of
the element considered; the following values can be considered:
−

conductors

C = 1,00

−

overhead stranded conductors

C = 1,00

−

overhead cables

C = 1,00

−

cylindrical objects (bars, tubular poles)

C = 0,80

−

bar, tubular poles with more than six sides

C = 1,20

−

bar, tubular poles with six sides

C = 1,40

−

flat surfaces normal to wind direction
(angles, rectangular poles)

C = 1,80

−
−

spherical objects
insulators

C = 0,35
C = 1,20

for additional information on lattice structures, reference shall be made
to EN 50341-1.
A

is the area of considered element, projected on a plane perpendicular
to the wind direction.


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For the definition of height above ground for dynamic pressure of the wind on
conductor calculation reference may be made to subclause 4.4.1.1 of EN 50341-1.
The wind pressure on conductors or earth-wires, which are not right angled to
wind direction, can be calculated considering the actual angle of incidence.
4.5

Ice loads

4.5.1

General

(snc)

IT.1

Ice loads evaluation

The ice or snow loads are valuated as variable loads, characterized by the
return period and thickness which assumes conventionally different values,
having cylindrical shape, depending on the zone, and altitude above sea level,
as specified in the following.
(snc)

IT.2

Ice and snow reference thickness

This clause reports the ice and snow reference thickness (S k ) on conductors and
earth-wires with a return period of 50 years; it is an extreme value of thickness
with which to evaluate the overloads on conductors and earth-wires, assuming a
cylindrical shape with circular cross section sleeve.
For all altitudes, a s , above sea level higher than 1500 m, a s shall be assumed
equal to 1500 m.
Load type 1 (ice)
Regions: Valle d’Aosta, Piemonte, Liguria, Lombardia, Trentino Alto Adige,
Emilia Romagna, Friuli Venezia Giulia, Veneto, Abruzzo and Molise, with altitude
above sea level (a.s.l.) a s > 600 m:
Ice density ρ i = 900 kg/m³
S k = 0 mm

for a s ≤ 600 m

S k = 18 + 16 (a s - 600)/1000 mm

for a s > 600 m

Load type 2 (snow)

Regions: Valle d’Aosta, Piemonte, Liguria, Lombardia, Trentino Alto Adige,
Emilia Romagna, Friuli Venezia Giulia, Veneto e Marche, Abruzzo, Molise,
Toscana (with exclusion of the provinces of Livorno and Grosseto), Umbria,
Lazio (with exclusion of the provinces of Viterbo, Roma and Latina), Campania
(with exclusion of the provinces of Napoli and Caserta), Puglia (with exclusion of
the provinces of Brindisi and Lecce), Basilicata, Calabria (with exclusion of the
province of Reggio Calabria):
Snow density ρ i = 500 kg/m³
S k =24 mm

for a s ≤ 600 m

S k =24 + 20 (a s - 600)/1000 mm for a s > 600 m.
Load type 3 (snow)
Regions: Toscana (provinces of Livorno e Grosseto), Lazio (provinces of
Viterbo, Roma and Latina); Campania (provinces of Napoli and Caserta), Puglia
(provinces of Brindisi and Lecce), Sardegna, Calabria (province of Reggio
Calabria), Sicilia:
Snow density ρ i = 500 kg/m³


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for a s ≤ 600 m

S k = 20 + 15 (a s - 600) /1000 mm
4.5.2

EN 50341-2-13:2017

for a s > 600 m

Ice forces on conductors
IT.1

(snc)

Ice and snow loads on conductors and earth-wires

The ice and snow load I T (N/m) is calculated using the thicknesses and densities
indicated in 4.5, and represents the extreme ice or snow load with return period
T = 50 years.
In order to obtain the ice or snow load for a different return period, Table
4.5.2/IT.1 (corresponding to Table B.2 of EN 50341-1) shall be applied.

Table 4.5.2/IT.1 − Conversion factors for different return periods for ice or snow loads
Return period
T [years]

Extreme ratio
I T /I mm

Conversion factor
C T = I T /I 50

3

1,30

0,37

50

3,51

1,00

150

4,33

1,23

500

5,22

1,49

where:
IT

is the extreme ice or snow load with a return period T;

I mm is the mean value of maximum ice or snow loads in a year;
I 50 is the extreme ice or snow load with a return period of 50 years.

(snc)

IT.2

Ice or snow loads on helically wound cores

For MV cables, having helically shape that gives stronger torsional rigidity to the
single core and limits ice or snow sleeve increase, with a smooth polyethylene
sheath which facilitates the slipping away of any deposits of ice or snow, for the
ice or snow load, I T , a reduction factor equal to 0,8 shall be used.
4.6
(snc)

Combined wind and ice or snow loads
IT.1

Coincidence of wind and ice or snow loads

In presence of ice or snow thicknesses, the combined wind, ice and snow
actions are defined in Table 4.7/IT.1.
4.7
(snc)

Temperature effects
IT.1

Temperature effects

For the calculation of the tensile load on conductors and earth-wires, and of
related forces transmitted to supports, as well as for geometrical verifications of

height above ground for electrical clearances and insulating distances, the
temperatures below reported shall apply:


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a) EDS temperature (Every Day Stress) is 15°C: in this condition, in absence of
wind, the tensile load of conductors shall not be greater than 25 % of the
breakage load.
On the basis of specific project conditions, to limit wind vibration effects,
special attention should be paid to laying conditions when the parameter
value (the ratio, between the horizontal tension and the mass per linear meter
of conductor = 2000 m ) is exceeded. Criteria and conditions of installation
should be defined in project specifications.
b) The minimum temperature to be considered depends on the following zones
A and B of the Italian territory:
Zone A Territory with an altitude not exceeding 800 m a.s.l. in the central,
southern and insular areas of Italy (zones 3, 4, 5, 6, 9); the minimum
temperature is – 7°C;
Zone B Territory with an altitude exceeding 800 m a.s.l in the central,
southern and insular part of Italy (zones 3, 4, 5, 6, 9) plus all the
territory of northern Italy (zones 1, 2, 7, 8); the minimum temperature
is – 20°C.
c) The extreme wind speed condition temperature is – 7°C.
d) The temperature for the combination of wind and ice or snow loads is – 2°C.

e) Temperature and wind actions are combined, as shown in Table 4.7/IT.1.
Both for icing and snow deposits it can be assumed a temperature of – 2°C.
f) Temperature to be used for verifying the electrical clearances. Both the two
following methods can be applied as follows:
Method of maximum reference temperature
f1) The electrical clearances on cross structures shall be verified at the
maximum reference temperature during normal service indicated in
project specifications for both zone A and zone B of Italian territory.
The maximum temperature during normal service is defined in. 9.1,
9.2.3, 9.3.3 and 9.4.
Method at limit states
f2) The electrical clearances over cross structures shall be verified at
reference temperature of 55°C e 48°C, respectively, for zone A e
zone B of Italian territory and the current carrying capacity at which
the line can be operated is determined by the risk of discharge over
cross structures.
For high thermic limits conductors, reference temperatures and the
current capacity at which the line can be operated shall be defined in
project specifications of f2).
f3) For line with voltages > 45kV, the electrical clearances over cross
structures shall be verified, not only for condition f2, but also for
extreme temperatures at state limit indicated in 9.1, 9.2.3, 9.3.3, 9.4,
with the electrical clearances of 5.9 where the term D el has to be
replaced by D 50Hz_p_e and D pp with D 50Hz_p_p . By this additional
verification the current capacity is determined by the discharge risk
over cross structures.
g) The temperature for checking electrical clearances in conditions of swung
catenary is 55°C and 48°C, respectively, for zone A and zone B of Italian
territory.

The Table 4.7/IT.1 summarizes temperature, wind and ice/snow combinations.


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Table 4.7/IT.1 − Temperature, wind and ice/snow combinations
Condition
of tests
a)

Every Day Stress

b)

Minimum temperature

Temperatures
(°C)

Extreme wind

0

15
Zone A

–7

Zone B

–20

Vb
0,76

c)
d)
e)
f1)

f2)

Wind action

–7

Co-existence of wind and ice
or snow (*) actions

–2

Verification of design
clearances – Method of
maximum reference
temperature

Zone A

75

Zone B

75

Verification of design
clearances – Method at limit
states

Zone A

55

Zone B

48

f3)

Verification of clearances at
extreme temperature
conditions –
Method at limit states

g)

Check of electrical clearances
in conditions of swung
catenary

Ice/snow
0
0

Vb

Vb
0,6 V b

0

Sk

0

0

0

0

96

0

0

Zone A

55

0

0

Zone B

48

(*) This verification is not applicable to zones where S k = 0 (zone where the type 3 load per a s
≤ 600 m is expected).
In zone where the type 1 and type 2 loads can be expected, both verifications are
required.
The temperature values for verifications of f1), f2), f3), g) on high temperature conductors
shall be indicated in project specifications.

In the case of a succession of suspended spans, with uniform loads acting on
the various spans, for the calculation of tensile loads on conductors the concept
of equivalent span can be applied.
4.8
(ncpt)

Security loads
IT.1

Breaking of conductors case

The loads shall be calculated:
- In areas where is expected any ice or snow sleeve formation: in presence of
ice or snow sleeves, with a return period of 3 years, and a wind load due to a
wind velocity set to 0,6 V b , acting on a cylinder having diameter equivalent to
ice or snow overload,
-

In areas where is not expected any ice or snow sleeve formation: in presence
of extreme wind with return period of 3 years.

The following load conditions will be considered:
- On each support of lines with voltages not exceeding 45 kV, the following
members shall be considered separately:
a) members connected to up to four conductors,


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b) members connected to more than four conductors;
- On each support of lines with voltages exceeding 45 kV, the following members shall
be considered separately:
a) members connected to up to six conductors,
b) members connected to more than six conductors and less than eighteen
conductors.

The conductors to be considered broken shall be selected, depending on the
support member concerned, on the basis of the following criterion:
- Each of the member specified in a) shall be checked when one of the
conductors or earth-wires (if any) acting on it are broken;
- Each of the members specified in b) shall be checked when any two
conductors or earth-wires acting on it are broken; however, these two
conductors or earth-wires (if any) shall not both act on the same member
referred to in a).
Within the above indicated limits, the conductors or earth-wires to be considered
broken shall be those which cause the most unfavourable load condition on each
single element of the support structure.
The verification of tangent supports, or of supports with angles not greater than
5°, is not prescribed, in case of lines with voltage ≤45 kV when the supports
show a longitudinal mechanical resistance of the line at least equal to transverse
resistance.
Partial factors for actions are assumed equal to 1 (one) while partial safety
factors for material are assumed equal to 90 % of those indicated in clause 7
(supports), 8 (foundations), 9 (suspended conductors or earth-wires with or
without telecommunication circuits), 10 (insulators) and 11 (line equipment –
overhead line fittings) .
For conductors supported by suspension insulator sets, the differential loads
shall be calculated taking into consideration the swing of the string. For
calculating the actions due to a broken conductor (single o in a bundle) on a
support, the maximum tensile load of the section inside which the supported is
included can be used.
4.9

Safety loads

4.9.1

Construction and maintenance loads

(ncpt)

IT.1

Construction and maintenance loads: partial factor

Construction and maintenance loads shall be indicated
specifications: partial factors shall not be lower than 1,5.

in

the

project

If E is the value of such loads, we obtain E d = 1,5 E.
4.11

Other special forces

4.11.2

Earthquakes

(A-dev)

IT.1

Verifications

The supports of overhead lines shall be verified with respect to seismic actions
taking into account the seismic classification of the Italian territory.
According to EN 50341-1, Annex C.2.4, since the frequency of supports if higher
than that of conductors and earth-wires, dynamic loads from conductors and
earth-wires are negligible and only the masses of supports, foundations,
insulator chains and accessories shall be considered.


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The verifications shall be carried out without wind, and the permanent vertical
loads on conductors and earth-wires shall be calculated, in areas where ice or
snow formation is expected, in presence of ice or snow sleeves with a return
period of 3 years.
The following verifications shall be carried out:
-

In areas where ice or snow sleeve formation is expected, it is assumed
the following:
a temperature of – 20°C without ice or snow,
a temperature of – 2°C with ice or snow;

-

In areas where ice or snow sleeve formation is not expected, a
temperature of -7 °C shall be assumed.

In case of supports with separate footings foundations, the verification shall be
carried out considering a different horizontal displacements of the footings;
criteria for defining displacement values should be based on accurate physical
models adequately documented design and related tests. In absence of such
models reference should be done to “Norme tecniche sulle costruzioni”.
4.12

Load cases

4.12.2

Standard load cases

(snc)

IT.1

Standard load cases

The load cases in Table 4.12.2/IT.1 shall be considered.
Table 4.12.2/IT.1 − The normal load cases
Load
case

Load as per

subclause

1a
1b

Extreme wind load
4.4

2a
2b
2c

Conditions

Wind load at minimum temperature
Uniform ice/snow loads on all spans

4.5

Uniform ice/snow loads, transversal bending
Unbalanced ice/snow loads, longitudinal bending
Unbalanced ice/snow loads, torsional bending

2d
3

4.6

Combined wind and ice loads

4a

4.8.2 (a)

Security loads, torsional loads

4b

4.8.3 (b)

Security loads, longitudinal loads

5

4.9.1

Construction and maintenance loads

With reference to figures in subclause 4.2.10.2 of EN 50341-1 § 4.2.10.2 for the
determination of load cases 2b, 2c, 2d, the following reduction factors due to ice
load I T apply:
α = 0,5 α 1 = 0,3

α 2 = 0,7

α 3 = 0,3

α 4 = 0,7

For longitudinal bending scheme, if necessary, and if so indicated in the project

specifications, the case of α 1 =0, α 2 =1 in absence of wind can also be
considered; this load case represents the “slope” condition which should be
applied only to supports placed at the peak of the hills/mountains and which
separate line sections on opposite slopes.
(ncpt)

IT.2

Loading conditions for lines with not self-supporting towers

In case of lines with not self-supporting towers, the following loading conditions
shall apply:


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− with reference to wind load cases 1a and 3 of subclause 4.12.2, a wind
blowing alternatively in the longitudinal and transversal direction with respect
to the axis of the line shall be considered;
− with reference to security load cases in all the section of line equipped with
not self-supporting towers, conductors or conductor bundles or earth-wires (if
any) in which breaking occurs, shall be considered entirely missing. In this
section of line, from time to time the two not self-supporting towers, adjacent
to the span in which breaking occurs, shall be subjected to:
a) opposite longitudinal loads equivalent to pull of the conductors or of the

earth-wires and directed outward of the span;
b) transversal and vertical loads equal to those exerted by the conductors or
conductor bundles or by earth-wires (if any) in which breaking occurs;
c) loads of conductors or conductor bundles or of earth-wires (if any) which
are intact.
The points of application of the loads in a) and b) shall correspond to the
points of attack of the conductors, conductor bundles or of the earth-wires(if
any) in which breaking occurs.
In these conditions it is assumed that wind shall be considered blowing
alternatively both in longitudinal and in transversal direction with respect to
the axis of the line.
The calculation in the above conditions implies taking into account the
stabilising reactions of the conductors and any earth-wires running along not
self-supporting towers which are considered intact.
4.13
(A-dev)

Partial factors for actions
IT.1

Partial factor for wind action

The partial factor for wind action, simultaneously applied to all conductors and
earth-wires, shall be set to 1 (one).
(A-dev)

IT.2

Partial factor for ice or snow action

The partial factor for ice or snow action, simultaneously applied to all conductors
and earth-wires, shall be set to 1 (one).
(A-dev)

IT.3

Partial factor for all external loads in case of earthquakes

The partial factors for all external loads in case of earthquakes shall be set to 1
(one).
5

Electrical requirements

5.6

Load cases for clearances calculation

(A-dev)

IT.1

Load cases for clearances calculation

Clearances shall be calculated with reference to the loading cases 1a and 2a of
subclause 4.12.2 and under temperature conditions of Table 4.7/IT.1.
5.8
(A-dev)

Internal clearances within the span and at the top of the tower

IT.1

Clearances calculations

The clearances, in general, shall be calculated as follows.
In the design of the towers, the following minimum air clearance shall be
maintained:


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Table 5.8/IT.1 − Minimum air clearances
Minimum air clearances

Unit

Minimum distance between conductor within the span among
points susceptible of approach: this spacing is reduced to D pp in
case of points not susceptible of approaching each others

m

k⋅

(f + Ik ) + Dpp

Minimum distance between conductor and earth-wire within the
span

m

k⋅

(f + Ik ) + Del

Minimum clearance between live metal parts and earthed metal
parts with wind speed V = 7,5 m/s

m

k1 ⋅ Del

Minimum clearance between live metal parts and earthed metal
parts of suspension towers with max swing (wind speed with
return period of 3 years)

m

D50Hz _ p _ e

Where:
f

is the sag, in metres, of the conductor at a temperature of +15°C in
still air;

Ik

is the length, in metres, of that part of any insulator set swinging
orthogonal to the line direction; in case of different swinging
amplitudes on both supports of the span, the medium value shall be
assumed;

k

is a coefficient equal to 0,6 for homogeneous aluminium or
aluminium alloy conductors, and equal to 0,5 for the other
conductors;

k1

is a coefficient assumed equal to 0,75;

D pp

is the minimum clearance voltage dependent (phase-phase), in
metres, according to EN 50341-1;

D el

is the minimum clearance voltage dependent (phase-earth), in
metres, according to EN 50341-1.

D 50Hz_p_p

is the minimum air clearances (phase-phase) in metres, voltage
dependent, required to prevent a disruptive discharge at power
frequency voltages corresponding to distances of Table 5.5 of EN
50341-1; for overhead lines with voltages ≤ 45 kV, a distance of 0,17
x U n /45 (m) shall be assumed;

D 50Hz_p_e

is the minimum clearance (phase-earth) in metres, voltage
depending, required to withstand power frequency voltage,
corresponding to the distances of Table 5.5 of EN 50341-1; for
overhead lines voltage ≤ 45 kV, a distance of 0,11 x U n /45 (m) shall
be assumed.

These distances are not suitable for performing live works.
In case of supports where the conductors are secured by means of tension
insulators, V-chains on transversal plane, or post insulators, I k shall be assumed
equal to 0 (I k = 0); moreover, for overhead lines voltage ≤ 45 kV equipped with
post insulators, the resulting values from the above formulas shall be reduced by
30 %.
The above mentioned minimum distance formulas shall not apply to spans of
lines where f + I k > 40 m.


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In such cases it is merely necessary that the spacing, in metres, between the
conductors are not less than:
(3,8 + D pp ) m for aluminium or aluminium alloy conductors;
(3,2 + D pp ) m for other conductors.
The previous requirements are not applicable to conductor in bundles or to
single sub-conductors of the same bundle.
For loading case 1a of subclause 4.2.10.2, but with and conductor temperature
of 15°C, the spacing d, in metres, shall not be less than D 50Hz_p_e ; for overhead
lines voltage with voltages ≤ 45 kV, a distance if 0,11 x U n /45 (m) is assumed.
At conductor temperature of 15°C, with a wind speed of 7,5 m/s, the spacing d,
in metres, shall not be less than k 1 x D el with k 1 = 0,75.
The above requirements shall not apply to any insulation spark gaps for coordination.

5.9
(A-dev)

External clearances
IT.1

Height of conductors above ground and non navigable waters

In view both of the risk of discharge and of the possible effects, caused by
exposition to electrical and magnetic fields, the conductors of the lines under the
temperature conditions f) of subclause 4.7 and in loading case 2a of subclause
4.12.2, shall not be vertically spaced, in any points, from the ground or from non
navigable stretches of lagoons and lakes, less than the following:
(5 + D el ) m
and, in any case, not less than 6 metres, where D el is the voltage dependent
minimum clearance (phase-earth) in metres.

The specified clearances refer to intact conductors on all spans and shall be
measured apart from any layer of ice or snow, vegetation and from unevenness
in the ground due to cultivation.
Clearances do not need to be checked in case of conductors breakage or of
unevenly loaded conductors.
The above requirements may not be complied with in case of lines passing over
enclosed land with access reserved for authorised electrical personnel.
In addition to the above verifications, the conductors shall be vertically spaced
from the ground in order to respect the limits of the “Decree of President of
minister’s council 8 July 2003”.
(A-dev)

IT.2

Crossing

For the purpose of this standard, a given structure is crossed when the vertical
projection of at least one of the electrical power line conductors intersects the
structure under the conditions reported in 4.7 f) (with vertical catenary) and g)
(with swung catenary) and in load case 2a of subclause 4.12.2, assuming the
plane of the catenary forming an angle of 30° with the vertical.
(A-dev)

IT.3

Clearances

The conductors and the earth-wires of overhead power lines, under the conditions
reported in 4.7 (with vertical catenary) and g) (with swung catenary) and in load
cases 2 of subclause 4.12.2, with both vertical catenary and catenary forming an

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angle of 30° with respect to the vertical, shall not be spaced, in any points at a
distance less than:
a) (9 + D el ) m from the surface of motorways, trunk roads and provincial roads
(and stretches of these in built-up areas), from the rail surface of railways,
tramways, and terrestrial cable railways and from the normal medium water
level of 2 nd class navigable river (royal Decree n° 823, 8 June 1911 and royal
Decree n° 959, 11 July 1913). This distance is reduced to (7 + D el ) m for lines
with voltage ≤ 45 kV. The height of conductors above lake or lagoon areas
crossed by boats shall be prescribed by the appropriate authority.
b) (6,5 + D el ) m from the rail surface of private terrestrial cable railways used
exclusively for goods transport.
c) (4,4 + D el ) m, with a minimum of 4 m, from the nearest part (or the nearest
possible position of its moving parts) of public or private cableways, ski-lifts
and chair-lifts, cable transporting systems, cantilever wires or simple cable
systems. The requirements shall not apply to supply and telephone lines used
with cableways, which are covered by the following points d) and e).
d) (2 + D pp ) m from the conductors of other electrical power or telephone lines
(being D pp the minimum withstand distance (phase-phase) of the higher
voltage line). This minimum shall be reduced to (1,75 + D pp ) m for earth-wires
or when both the conductors concerned are fixed to the support using pin or
dead end cap and pin insulator arrangement. Where electrical power lines

cross each others, the swing of the upper and lower span shall be taken into
account separately but not simultaneously. Clearance from telephone
conductors shall be (3 + D el ) m (where D el is the voltage dependent minimum
clearance (phase-earth) in metres).
e) (3,5 + D el ) m from the supports of other electrical power or telephone lines.
This minimum may be reduced to (1 + D el ), in case of agreement between the
owners of the two lines. The distance from the electrical traction system
conductors of railways, tramways, trolleybus lines and terrestrial cable
railways shall be of (4,4 + D el ) m. This latter requirement shall not apply to
the clearance between conductors of electrical traction systems and
conductors of electrical power lines placed on railway areas. These
requirements shall apply to the clearances from radio and television receiving
antennas of private users.
f) (3,5 + D el ) m from every position, that can be stood on, of other structures or
of the surrounding land, excluding buildings. This requirement shall apply
even in case of underpasses of bridges and viaducts.
g) (1,5 + D el ) m from every position, that cannot be stood on, of other structures
or of the surrounding land, excluding buildings, and branches of trees.
It is considered that a position can be stood on if a normal person can stand
without difficulty, even if to reach it positions that cannot be stood on have to be
crossed.
The above clearances shall be checked with intact conductors on all spans and
shall be measured apart from any layer of ice or snow, vegetation and on the
unevenness in the ground due to cultivation.
Clearances do not need to be checked in case of conductors breakage or of
unevenly loaded conductors.
The above requirements may not be complied with in case of lines passing over
enclosed land with access reserved for authorized electrical personnel.
(A-dev)

IT.4

Clearances to buildings

In view of the risk of discharge and of the possible effects caused by exposition
to electrical and magnetic fields, the conductors of the lines, under the


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conditions reported 4.7 f) (with vertical catenary) and g) (with swung catenary)
and in load case 2a of subclause 4.12.2, shall not be spaced, in any points, from
buildings, less than the following distances:
(4,0 + Del) m with vertical catenary;
(2 + Del) m with catenary forming an angle of 30° with respect to the vertical.
In addition to the above mentioned verifications, the clearances shall respect the
limits of the “Decree of President of minister’s council 8 July 2003”.
(A-dev)

IT.5

Angle at which electrical power lines cross structures

When an electrical power line crosses a railway or tramway on its own land,
excluding dead-end and works sidings, a public terrestrial cableway, ski-lift or

chair-lift or a trunk road or motorway, the angle between the power line and the
centre-line of the track, cableway or road shall not be less than:
15° for lines with voltages > 45 kV;
30° for lines with voltages up to and including 45 kV.
The above prescriptions shall not apply in case of crossings in built-up areas.
In exceptional cases, when the angle cannot be maintained within the above
mentioned limits because of particular local conditions, the owner or licensor of
the structure crossed may grant an exception to the above mentioned
requirement.
When structures other than those listed above are crossed, the angle shall be
subjected to any limitations.

(A-dev)

IT.6

Crossing of underground electrical power or telephone cables

The requirements of this standard shall not be applied to the line spans which
over pass other underground electrical power or the telephone cables.
(A-dev)

IT.7

Particular requirements for lines with not self supporting towers

Under the conditions reported into the load cases 1a and 3 of subclause 4.12.2,
with both vertical catenary and catenary forming an angle of 30° with respect to
the vertical, the conductors and the earth-wires shall not be spaced less than the
minimum distances reported in 5.9/IT.1, IT.3 and IT.4 from the ground, from not

navigable waters, from the crossed installations and the buildings.
(A-dev)

IT.8

Clearances to supports

These clearances are indicated on the base of experience acquired in
construction and maintenance of overhead lines and on the base of legislative
requirements; different values can be adopted in particular cases upon
agreement of the competent Authorities and Agencies involved.
Supports of electric lines and relevant foundations shall not be horizontally
spaced, in any point, above ground surface, less than:
a) 6 m from the nearest rail of railways and tramways on its own land, outside
inhabited areas, excluding dead-end and works sidings, with a minimum of 3
m from the edges of trenches and 2 m from the base of raised.
b) 4 m from the nearest rail of terrestrial cable railways, from the nearest contact
conductor of trolleybus lines (outside inhabited areas), from the nearest part
(or the nearest possible position of its moving parts) of public or private


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cableways, ski-lifts and chair-lifts for public or private people transportation
service (with the exclusion of supply and telephone lines used with

cableways).
c) 2 m from the nearest rail of railways and tramways, on its own land or on
roads, inside inhabited areas and for dead-end and works sidings also
outside inhabited areas, from the nearest contact conductor of trolleybus lines
inside inhabited areas, from the nearest part (or the nearest possible position
of its moving parts) of public or private cableways, ski-lifts and chair-lifts,
cable transporting systems, cantilever wires or simple cable systems.
d) 15 m from the edge (article 3 point 10 of law decree 30/04/1992 n. 285 and
following modifications and integrations) of main communication roads, this
distance can be reduced to the height of the support (above ground) in case
of lines ≤ 45 kV.
e) 25 m from the edge of state roads.
f) 7 m from the edge of provincial roads outside inhabited areas; this distance
can be reduced to 2/5 of the height of the support (above ground) in case of
lines up with voltages ≤ 45 kV. Smaller distances can be adopted inside
inhabited areas, even with the installation on sidewalks, upon agreement with
the board owner of the road.
g) 3 m from the edge of communal roads outside inhabited areas. Smaller
distances can be adopted inside inhabited areas, even with the installation on
sidewalks, upon agreement with the board owner of the road.
Moreover supports, relevant foundations and earth electrodes, shall not be
spaced, in any point, less than:
h) 6 m from gas pipeline with maximum service pressure ≥ than 25 atmospheres,
this minimum distance is reduced to 2 m in case the pipeline, in the area of
approaching the electrical line, is contained inside a robust protection tube,
whose extremities are equipped with vents at a distance ≥ 6,5 m from
supports and relevant auxiliary parts.
i) 2 m from gas pipelines with maximum service pressure < 25 atmospheres,
this minimum distance is reduced to 1,5 m in case the pipeline, in the area
where it approaches the electrical line, is contained inside a robust protection

tube, whose extremities are equipped with vents at a distance ≥ 2,5 m from
supports and relevant auxiliary parts.
No clearance requirement is given for lines in cables, with voltage
≤ 45 kV, for public illumination lamps from “vicinali” roads. In case of overhead
line structures supporting also public illumination lamps, and as an exception to
points d), e), f) and g) of this subclause, the distances prescribed by the
execution and implementation regulation of the new Rules of the road
(legislative decree 30 April 1992, n. 288 and subsequent modifications or
integrations), related to vertical traffic signs, apply.
Support shall not be spaced from conductors of other electrical or
telecommunication lines less than the distances reported in 5.9 IT.3 e). Between
supports of electrical lines and telecommunication lines conductors distances
reported in 5.9 IT.3 e) apply.
In case of line supports holding public illumination lamps, the above distances of
points h) and i) can be reduced upon agreement with the boards owner of the
pipeline.
5.11
(A-dev)

Electric and magnetic fields
IT.1

Maximum limits of exposure to power frequency electric and