1. ------IND- 2012 0528 SI- EN- ------ 20121003 --- --- PROJET
REPUBLIC OF SLOVENIA
MINISTRY OF INFRASTRUCTURE AND SPATIAL PLANNING
TECHNICAL GUIDELINE TSG-N-003:2012
The Minister for Infrastructure and Spatial Planning is issuing this technical
guideline on the basis of the first paragraph of Article 11 of the Construction Act
(102/04-UPB1, 14/05-revised, 92/05-ZJC-B, 93/05 - ZVMS, 126/07, 108/09, 61/10ZRud-1 (62/10 revised), 20/11 Odl.US, 57/12)
LIGHTNING PROTECTION
The Minister for Infrastructure and Spatial Planning
ZVONE ČERNAČ
Number: ……….
Ljubljana, dated …………..
This guideline gives the approval of the Minister for Economy, as the responsible
minister for placing construction products into circulation, number ...................
This technical guideline is included in the list of technical guidelines of the Ministry
of Infrastructure and Spatial Planning that were published in the Official Journal of
the Republic of Slovenia.
5 September 2012
In the process of issuing this technical guideline, all the requirements were met regarding the
Regulation on Notification Procedures in the field of standards, technical regulations and
conformity assessment procedures (Official Journal of the RS, No. 66/00 and 35/05) in the
area that represents the adoption of Directive 98/34/EC of the European Parliament and of
the Council of 22 June 1998 laying down a procedure for the provision of information in the
field of technical standards and regulations and of rules on Information Society services (OJ
No. 204 of 21.6.1998, page 37), last amended by Directive 98/48/EC of the European
Parliament and of the Council of 20 July 1998 amending Directive 98/34/EC laying down a
procedure for the provision of information in the field of technical standards and regulations
and of rules on Information Society services (OJ No. 217 of 5.8.1998, page 18).
Design and layout: IDFL d.o.o.
The Electrotechnical Association of Slovenia prepared the expert content in cooperation with
the professional public and with the Slovenian Chamber of Engineering.
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TABLE OF CONTENTS
0.
INTRODUCTION
5
0.1
MEANING AND FUNCTION OF THE TECHNICAL GUIDELINE “LIGHTNING PROTECTION”
0.1.1 Legal basis for issuing the technical guideline
0.1.2 Regulations on the protection of buildings against lightning - the legal framework of the
guideline
0.1.3 Legal consequences of (not) following this technical guideline
0.2.
REFERENCE DOCUMENTS
0.2.1 Regulations
0.2.2 Standards
0.2.3 Guidelines
0.3
DEFINITIONS
5
5
6
8
10
10
10
11
11
PURPOSE AND FIELD OF USE
13
2.
14
BASIC REQUIREMENTS FOR DESIGN AND IMPLEMENTATION
2.1
GENERAL
2.2
LIGHTNING CURRENT PARAMETERS
2.3.
DAMAGE DUE TO LIGHTNING STRIKES
2.3.1 Causes of the damage
2.3.2 Types of damage
2.3.3. Types of loss
2.4
RISK AND ITS COMPONENTS
2.4.1 Risk
2.4.2 Risk components
2.4.3 Risk assessment
2.4.4 Risk components assessment
2.4.5 Tolerated risk RT
2.4.6 Risk assessment procedure
2.5
DENSITY OF ATMOSPHERIC DISCHARGES INTO THE EARTH
2.6
LPS CLASSES
2.7
EXTERNAL LPS
2.8
DOWN CONDUCTOR SYSTEM
2.9
EARTH-TERMINATION SYSTEM
2.10 IMPLEMENTATION OF AN LPS IN EXPLOSIVE HAZARDOUS AREAS
14
14
15
15
15
15
16
16
16
17
17
17
17
19
19
19
22
23
24
3.
CONDUCTOR MATERIALS
25
4.
PREVENTION OF SPARKING AND PUNCTURES
28
4.1
GENERAL
4.2
EQUIPOTENTIAL BONDING
4.2.1 General
4.2.2. Equipotential bonding of metal installations
4.2.3 Equipotential bonding of external conductor parts
4.2.4 Equipotential bonding of the internal part of the LPS
4.2.5 Equipotential bonding of the supply cables
4.3
Separation distance between the metal parts and the LPS
5.
PROTECTION AGAINST HAZARDS CAUSED BY TOUCH AND STEP VOLTAGE
5.1
5.2
6.
28
28
28
28
29
30
30
30
32
PROTECTIVE MEASURES AGAINST TOUCH VOLTAGE
PROTECTIVE MEASURES AGAINST STEP POTENTIAL
32
32
PROTECTION OF ELECTRICAL AND ELECTRONIC SYSTEMS IN BUILDINGS
6.1
33
GENERAL
33
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6.2
6.3
6.4
6.5
6.6
7.
PROTECTION ZONES
EARTHING AND CONNECTION
MAGNETIC SHIELDING AND TRANSPOSITION
COORDINATED SPD PROTECTION
DESIGNING, CHOOSING AND THE INSPECTION PROCEDURE FOR LEMP PROTECTION
33
33
34
34
34
LPS INSPECTION, TESTING AND METERING
7.1
7.2
7.3
7.4
7.5
35
GENERAL
VISUAL INSPECTION
TESTS
METERING
INSPECTION DOCUMENTATION
35
35
36
36
37
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0.
INTRODUCTION
0.1 Meaning and function of the technical guideline “Lightning
Protection”
0.1.1 Legal basis for issuing the technical guideline
The Minister for Infrastructure and Spatial Planning is issuing this technical guideline on the
basis of the first paragraph of Article 11 of the Construction Act (102/04-UPB1, 14/05 revised
92/05-ZJC-B, 93/05 - ZVMS, 126/07, 108/09, 61/10-ZRud-1 (62/10 revised), 20/11 Odl.US,
57/12).
In the Construction Act, a technical guideline is defined as “a document in which is
determined, for a specific type of building, a more detailed classification of the necessary
requirements, design criteria, chosen levels or classes of construction products or materials
which are permitted to be installed, as well as the method used to install them and the
construction method, whose purpose is to ensure the reliability of the building for the
duration of its life span and, where appropriate, the procedures by means of which it is
possible to ascertain if these requirements have been met” (Item 3.2 of the first paragraph of
Article 3).
The legal nature and use of these technical guidelines are explained in more detail in Article
9 of the Act where it is determined that the construction regulations (these are a type of
implementation regulation issued on the basis of the Act) for specific types of buildings
determine their technical specifications in such a way as to fulfil one, many or all of the
following basic requirements according to their purpose:
- mechanical resistance and stability,
- fire safety,
- hygiene and health protection and environmental protection,
- safe usage,
- noise protection, and
- energy saving and heat conservation.
In the cited statutory provisions it is furthermore determined that the construction regulations
can refer to standards or technical guidelines that concern a specific type of building and
determine their obligatory use, as well as determine that the presumption is valid that a
specific element is in accordance with the requirements of the construction regulation - if it
meets the requirements of the standards or technical guidelines. If a presumption of
conformity is defined in the construction regulations, the construction regulations must also
define the designated decision-making authorities and the procedure which is used to prove
that the project in which the standards or technical guidelines were not followed, but where
the designer used solutions that remained from the previous construction technique used still
ensures at least the same level of safety as a project carried out following the standards or
technical guidelines.
The previously used construction technique is the state which, when the project
documentation or construction was being carried out, represented the developmental level
of the technical capabilities of the construction products, procedures and services that are
based on recognised norms in science, technology and experience in the field of
construction and which at the same time take into account the feasibility of the costs (item
3.1, first paragraph of Article 2).
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5 September 2012
0.1.2 Regulations on the protection of buildings against lightning - the legal
framework of the guideline
The construction regulations which define in more detail parts of the basic requirements “fire
safety” and “safe usage” are the Regulations on the Protection of Buildings Against Lightning
(Official Journal of the RS, No. 28/09,2/12). In these regulations the following requirements
regarding the lightning protection system (hereinafter: lightning protection) are defined. The
system must be able to:
-
dissipate atmospheric discharges into the ground without harmful effects and without
causing hazardous sparking or electric flashovers which could harm people or cause a
fire,
-
limit the failure of electrical, telecommunication and other supply systems,
-
limit the failure of electrical and electronic devices,
-
ensure suitably low touch and step voltages with the appropriate equipotential bonding .
WARNING: This technical guideline covers a significantly larger field than the
statutory validity of the regulations. As is made clear in the third paragraph of
Article 1 of the regulations, some of the criteria in its requirements can also apply
to other facilities - civil engineering works, and not only buildings.
Article 1
(content and use of the regulations)
...
(3) The requirements of these regulations can also be reasonably used for civil
engineering works if the regulations that regulate their basic requirements do not include
equal provisions regarding protection against lightning.
Article 4
(ensuring protection against lightning)
(1) All less complex and complex buildings must be fitted with a lightning protection
system of at least level IV which must be designed, implemented and maintained so that:
it dissipates atmospheric discharges into the ground without harmful effects and does
not cause hazardous sparking or electric flashovers which could harm people or cause
a fire,
it limits the failure of electrical, telecommunication and other supply systems,
it limits the failure of electrical and electronic devices and
it ensures suitably low touch and step voltages with the appropriate equipotential
bonding.
(2) Regardless of the previous paragraph, it is not necessary to fit a lightning protection
system in those one- or two-apartment buildings which, following the requirements that
determine the type of building, are classified as less complex or complex buildings.
(3) Regardless of the first paragraph of this article, it is necessary, on the basis of the
diagram or table of the highest values of lightning density from Annex 2, to give a risk
assessment of the probability of lightning strikes and determine the appropriate level of
lightning protection on the basis of this assessment for buildings from Annex 1, which is an
integral part of these regulations. When assessing the risk it is necessary to use the
methodology of risk assessment for lightning strikes from the technical guideline from
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Article 5 of these regulations. In doing so, it is also possible to use more specific data
regarding the density of lightning strikes in the construction location, which is given to the
investor or designer by a legal entity that monitors and handles data of this kind and is
stated in Annex 2 to these regulations.
(4) In buildings with electrical wiring it is necessary to make a common earthing device
which must also enable the functioning of the lightning protection system. The design of the
electrical installations and electrical equipment must ensure the consistency of all the
measures or solutions used (hereinafter: measures) with regard to the electrical wiring and
lightning protection, especially regarding the common elements of the equipotential
bonding, external air termination system with down conductors and the implementation of
the internal lightning protection system.
In the chapter in the regulations where the method of fulfilling the requirements is
determined, the following provisions are the most important for the use of this technical
guideline:
Article 5
(use of the technical guideline)
(1) The minister responsible for construction matters issues the technical guideline TSGN-003 Lightning Protection (hereinafter: technical guideline) which determines the
methodology of risk analysis from Article 4 of these regulations and the recommended
construction measures needed to fulfil the requirements of these regulations.
(2) If the measures that are stated in the technical guideline or in documents to which it
refers are used when designing, implementing and maintaining the lightning protection
system in buildings, a presumption of conformity with these requirements from these
regulations is valid.
Article 6
(use of other measures)
(1) When designing, implementing and maintaining the lightning protection system, instead of
the techniques stated in the technical guideline, it is permitted to use solutions from the
previously used construction techniques which ensure at least the same level of safety as a
project carried out using this technical guideline.
(2) Measures from the previous paragraph apply to the use of the previously used construction
techniques in accordance with the regulations which regulate construction. In this case, the
fulfilment of the requirements is ensured in accordance with Article 12 of these regulations.
(3) Regardless of the first paragraph of this article, it is necessary to use the risk analysis
methodology for lightning strikes from the technical guideline and measures from the technical
guideline stated in Articles 7 and 10 of these regulations.
In the chapter of the regulations where the content of the project documentation is
determined, the following provisions are the most important:
Article 11
(reference to the design basis)
(1) The designer responsible must explicitly state in the technical report of the design of the
project’s electrical installation and electrical equipment as well as in its main folder (in
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Annex 1, in form 0.4, under item “Other Classifications”), if the design has been drawn
up on the basis of the technical guideline or on the basis of Article 6 of these
regulations, so as to be granted the construction permit.
(2) The design from the previous paragraph must include the following with regard to the
lightning protection system:
the protection level of the building,
the safety and separation distances of metal masses,
the layout of the ceiling and appearance of the buildings with the main networks,
an external lightning protection system - air termination system, down conductors and earth
termination system,
an internal lightning protection system - direct galvanised connections with intersections and
planned installations of SPD,
the level of the earthing device’s resistance with the necessary calculations,
the types of earthing devices and metering points (e.g. strip, mesh, foundation earthing
device),
all metal attachments with specific collectors for the equipotential bonding,
the type and position of connections to neighbouring buildings (e.g. water, gas, electricity,
data connections, security),
the system of protection against touch and step overvoltages and
all other necessary information relevant to the installation of the lightning protection system LPS (e.g. isolated system).
Article 12
(inspection obligation)
(1) The inspection of the project in order to obtain a construction permit, apart from the case
stated in the Construction Act (Official Journal of the RS, No. 102/04-UPB1, 14/05-revised,
92/05-ZJC-B, 93/05-ZVMS, 126/07), is obligatory even when the designer plans the lightning
protection system in a less complex building in accordance with Article 6 of these regulations,
and is carried out following the procedure and with the participants who organise the
construction of buildings, as determined in the Act.
(2) The aim of the inspection from the previous paragraph is exclusively to check that
everything in the parts of the design that refer to the electrical installations and electrical
equipment is in perfect order to obtain a construction permit that proves that the submitted
project fulfils the requirements defined by these regulations with regard to the lightning protection
system, just as if the technical guideline and the documents stated within it were used.
(3) In the summary of the inspection report with regard to the regulation that regulates the
project documentation, the inspector responsible enters only those data regarding the inspection
mentioned in the previous paragraph. Signing the inspection only signifies that as far as the
inspection is concerned, it is evident that the project fulfils the requirements of these regulations.
0.1.3 Legal consequences of (not) following this technical guideline
a)
Use of the technical guideline - presumption of conformity
As can be seen from previous items of this introduction, the technical guideline gives the
measures and solutions recommended so as to meet the requirements stated in the
regulations regarding the protection of buildings against lightning. Compliance with these
recommended construction measures is the basis for the establishment of presumptions
regarding the fulfilment of the requirements stated in these regulations. In doing so, it is
necessary to take into consideration that measures regarding the protection of buildings from
lightning strikes are generally related to each other and the final result cannot be dealt with
on the basis of an analysis of each separate measure without taking into account the results
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5 September 2012
of the complete protection concept chosen. This is why the designer responsible must
always make sure that the measures chosen following this technical guideline and in
combination with the measures stated in various reference (supporting) documents work
cohesively together.
The burden of proof with regard to the lack of fulfilment of the requirements in the regulations
falls, in the event of this technical guideline being used, on the relevant state authorities or
the legally determined construction participants who are in charge of the correctness of the
project design (inspectors and supervisors - see the third paragraph of Article 5 of the
regulations). When the design of the project follows the measures from this technical
guideline, during construction and when obtaining the necessary administrative decisions, it
is not necessary to prove adherence to the relevant regulations as it is a presumption on the
basis of the regulations’ provisions.
b)
Designing the project following the previously used construction technique
If the designer responsible decides, in accordance with the regulations, to use (in part or in
whole) the construction measures from the previous construction technique as determined in
Article 6 of the regulations, the same level of safety of the lightning protection system must
be ensured and be visible in the obligatory inspection of the project documentation which
represents the required means of proving that the designer responsible has fulfilled the
required criteria.
When planning a project that arises from the previous construction technique it is also
necessary to take into consideration that measures regarding the protection of buildings from
lightning strikes are generally related to each other and the final result cannot be dealt with
on the basis of an analysis of each separate measure without taking into account the results
of the complete protection concept chosen.
c)
The relationship to the regulation requirements that deal with lightning protection
The content of this technical guideline recommends measures that can exceptionally be
subject to regulation by some mandatory regulations. In relation to the valid regulations, the
technical guideline is written in such a way as to not be in conflict with the regulation
requirements. But in the event that it is discovered that the implementation of a certain
recommended measure would mean a breach of the provisions of the valid regulation, it is
necessary to take into account the mandatory legal requirements.
In Item 0.2.1 the status of the valid regulations is taken from the day of the issuing of this
technical guideline. Amendments connected to the issuing of new regulations and
annulments related thereto must be followed by users in the Official Journal of the Republic
of Slovenia or in the Official Journal of the European Union for legal acts of the EC.
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0.2.
Reference documents1
0.2.1 Regulations
0.2.1.1 The Construction Act (Official Journal of the RS, No. 102/04-UPB1, 14/05-revised,
92/05-ZJC-B, 93/05-ZVMS, 126/07, 108/09, 61/10-ZRud-1 (62/10 revised), 20/11
Odl.US, 57/12),
0.2.1.2 Energy Act (Official Journal of the RS, No. 27/07 EZ–UPB2 – official consolidated
text),
0.2.1.3. Construction Products Act (Official Journal of the RS, No. 52/00),
0.2.1.4. Technical Requirements for Products and Conformity Assessment Act (Official
Journal of the RS, No. 99/04, 17/2011-ZTZPUS-1),
0.2.1.5 Decree on the introduction and application of uniform classification of facilities and
on the designation of facilities of national importance (Official Journal of the RS, No.
33/03, 25/10),
0.2.1.6 Regulation on the classification of constructions with regard to their complexity
(Official Journal of the RS, No. 37/08, 99/08),
0.2.1.7 Rules on lightning protection systems for buildings (Official Journal of the RS, No.
28/09, 2/12),
0.2.1.8 Rules on requirements for low-voltage electrical installations in buildings (Official
Journal of the RS, No. 41/09, 2/12),
0.2.1.9 Rules on fire safety in buildings (Official Journal of the RS, No. 31/04, 10/05, 83/05
and 14/07),
0.2.1.10 Rules on electrical equipment designed for use within certain voltage limits (Official
Journal of the RS, No. 27/04),
0.2.1.11 Rules on electromagnetic compatibility (EMC) (Official Journal of the RS, No.
132/06),
0.2.1.12 Rules on technical norms for the protection of low-voltage networks and
corresponding substations (Official Journal of the SFRY, No. 13/78),
0.2.1.13 Rules on anti-explosive protection (Official Journal of the RS, No. 102/00 and 91/02,
16/08, 1/11, 103/11),
0.2.1.14 Rules on design documentation (Official Journal of the RS, No. 55/08).
0.2.2 Standards
The design, installation, functioning and maintenance of the lightning protection system
(hereinafter: LPS) is based on the following standards and the standards stated within them,
as well as other documents:
0.2.2.1 SIST EN 62305-1 Lightning Protection - Part 1: General Principles,
0.2.2.2 SIST EN 62305-2 Lightning Protection - Part 2: Risk Management,
0.2.2.3 SIST EN 62305-3 Lightning Protection - Part 3: Physical Damage to Buildings and
Danger to Living Beings,
0.2.2.4 SIST EN 62305-4 Lightning Protection - Part 4: Electrical and Electronic Systems
within the Buildings,
0.2.2.5 SIST EN 62561-1 Lightning Protection System Components (LPSC) - Part 1:
Connecting Component Requirements,
0.2.2.6 SIST EN 62561-2 Lightning Protection System Components (LPSC) - Part 2:
Conductor and Earthing Device Requirements,
1
Reference documents cited in:
 Item 0.2.1 - available on the website: http://zakonodaja.gov.si/,
 Item 0.2.2 - available at the Slovenian Institute for Standardisation,
 Item 0.2.3 - available on the website of the Ministry of Infrastructure and Spatial Planning,
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0.2.2.7 SIST EN 62561-3 Lightning Protection System Components (LPSC) - Part 3:
Sparking Gap Requirements,
0.2.2.8 SIST EN 62561-4 Lightning Protection System Components (LPSC) - Part 4: Clamp
Requirements,
0.2.2.9 SIST EN 62561-5 Lightning Protection System Components (LPSC) - Part 5:
Earthing Device Meter Box and Earthing Device Insulation Compression
Requirements,
0.2.2.10 SIST EN 62561-6 Lightning Protection System Components (LPSC) - Part 6:
Lightning Strike Counter (LSC) Requirements,
0.2.2.11 SIST EN 62561-7 Lightning Protection System Components (LPSC) - Part 7:
Earthing Compound Requirements.
0.2.3 Guidelines
0.2.3.1 Technical guideline TSG-1-001 Fire Safety in Buildings
0.2.3.2 Technical guideline TSG-N-002 Low-Voltage Electrical Installations
0.3
Definitions
(1) Terms from the field of building construction that are not defined in this technical
guideline are defined in the Construction Act, in the Regulations on Protection of Buildings
Against Lightning or in the standard SIST ISO 6707-1.
(2) Terms from the field of protection against lightning that are not defined in this technical
guideline are defined in the Regulations on Protection of Buildings Against Lightning or in
the series of standards SIST EN 62305.
(3) The abbreviations have the following meaning:
LPS - lightning protection system,
LPL - lightning protection level,
LPZ - lightning protection zone,
LEMP - lightning electromagnetic pulse,
SPD - surge protection device,
(4) Lightning - an atmospheric electrical discharge between the clouds and the earth, or
between clouds, which is made up of one or more individual lightning strikes;
(5) Individual lightning strike - an individual electrical discharge of the atmospheric charge
into the earth;
(6) Direct strike - a direct lightning strike into a building;
(7) Indirect strike - an indirect strike next to a protected building or into a supply line
attached to the building;
(8) Supply line - a cable, above-ground line or pipeline which comes into the building from
outside and serves to supply the building with energy, water, gas, data, etc.;
(9) Lightning protection system (LPS) - an interconnected system with which the probability
of damage caused by lightning strikes is lowered. It comprises an external and internal LPS;
(10) Internal LPS - part of the LPS inside the building which consists of the equipotential
bonding (disabling touch and step high-voltage) and the coordinated isolating distances
between parts of the lightning conductor installation itself and parts of the building (disabling
the occurrence of sparks within the building);
(11) External LPS - part of the LPS outside the building which consists of the air termination
system, down conductors and an earth termination system;
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(12) Air termination system - part of the external LPS which consists of connected metal
masts or a mesh of conductors whose purpose is to intercept the lightning;
(13) Down conductors - part of the external LPS system which consists of the connections
between the air and earth termination systems whose purpose is to discharge the electrical
current to the earth electrode system;
(14) Earth termination system - part of the external LPS which consists of one or more
interconnected earth electrodes (various combinations of tapes, rods, etc.) whose purpose is
to discharge the electric current into the earth;
(15) Earthing system - part of the LPS which one or more times intentionally interconnects
the parts of the internal and external LPS to the earth termination system following the
connection set-up concept.
(16) Earth electrode - a conductor placed into the earth with the purpose of discharging and
spreading the lightning current into the earth (e.g. earth rod, horizontal earth electrode, flat
earth electrode, earth electrode mesh, etc.);
(17) Risk - the probable annual loss (human and material/assets) due to lightning strike in
relation to the value (human and material) inside the building which needs to be protected;
(18) Tolerated risk (acceptable risk) - the highest risk value that can still be accepted for the
protected building (human, material, cultural heritage, etc.);
(19) Lightning protection level - the complete set of protective measures defined by the
parameters of the lightning current for a specific type of risk;
(20) Protective zone - the area where only certain electromagnetic effects can occur when
lightning strikes;
(21) LEMP - the effect of the lightning current due to the transfer of the strike current or
voltage wave through the connection or due to the inductive effect of the electromagnetic
field;
(22) Rolling sphere method - a method to assist in planning LPS which determines the area
around a building to protect against direct lightning strikes;
(23) Protection angle method - defining the protection area to within a covered area that
occurs between the exposed points on the down conductors and the reference plane below
the protection angle towards the vertical, in all directions;
(24) Mesh method - a method to define the protection area of the LPS which is similar to a
metal cage;
(25) Surge arrestor - a protective device that, above a certain level, limits the surge effects;
(26) Lightning arrestor - a protective device whose purpose is to protect the electrical
installation and equipment from lightning discharge surge currents.
(27) SPD - a device to protect against lightning discharge surge currents or overvoltage
wave.
(28) Natural components of the LPS - metal roof parts that conduct electrical currents (the
reinforcement in concrete, metal coverings, fences, etc.)
(29) Very complex electrical installations and lightning protection installations are
installations that are placed on and in buildings with explosive hazardous areas, in and on
buildings with their own substation or their own electrical energy source, and in buildings that
are classified with lightning protection level I and II.
(30) Less complex electrical installations and lightning protection installations are
installations that belong to a group of very complex installations of lightning protection.
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PURPOSE AND FIELD OF USE
(1) This technical guideline recommends construction measures for lightning protection
whose aim is to limit the danger to people, animals and property in buildings (see Item 0.1.2)
and in the nearby surroundings. If this guideline is followed, safety is greatly increased as
well as fire safety, which may also be compromised due to lightning strikes.
(2) The way of fulfilling the following requirements is covered in this technical guideline:
 technical specifications for the LPS on and in buildings and their installation,
 technical specifications and other requirements for products intended for connections
within the LPS as well as to be built in,
 the functionality of the LPS during the life span of the building,
 designing, implementation of works and inspections of the LPS.
(3) This technical guideline should not be used for:
 railway systems,
 vehicles, boats, aeroplanes and off-shore platforms,
 underground high-pressure pipelines,
 pipelines, electricity and telecommunication lines that are not connected to other
buildings.
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2.
BASIC REQUIREMENTS FOR DESIGN AND IMPLEMENTATION
2.1
General
(1) The LPS is an integral part of the building and must be compatible with as well as
reasonably connected to all the other installations in the building. The decision regarding the
choice of suitable protection is based on the choice of protection level on the basis of an
acceptable risk for the building which it is necessary to protect from the effects of lightning.
(2) Depending on the risk assessment and the determined tolerated risk, a lightning
protection level is determined (from I to IV). For every protection level there are maximum
and minimum lightning current parameters (see Table 1).
The probability of a lightning current, where the greatest parameter values will not be
exceeded, amounts to 99% for protection level I.
The maximum lightning current values that apply to protection level I are decreased to 75%
at protection level II, and to 50% at protection levels III and IV (linear for I,Q and di/dt, but
quadratic for W/R).
(3) The LPS must be constructed in such a way that it can dissipate the atmospheric
discharge into the earth without harmful consequences and that living beings are not
harmed, and that electrical flashovers and dangerous sparking do not occur.
(4) A suitable type and place of LPS installation must be chosen in the planning phase of
new buildings, so as to maximize the utilisation of their electrical conductive parts and to
create an effective LPS with the lowest costs, as well as aesthetically integrate it into the
building and surroundings.
(5) The technical characteristics of the LPS must, at the time of the building’s use, ensure
all the designed requirements, taking into account the necessary maintenance in accordance
with this guideline.
(6) After reconstruction, the LPS must fulfil all the technical specifications that it fulfilled
before its reconstruction.
(7) Depending on its position in the building, the LPS consists of an external and internal
LPS.
(8) In individual cases, when an external LPS is not needed, it is only necessary to
construct an internal LPS.
2.2
Lightning current parameters
(1) Mechanical, thermal and electromagnetic effects depend on the peak value of the
lightning current (I), the whole discharge charge (including the short-lasting and long-lasting
lightning strike charge) and the specific energy (W/R).
Table 1: The maximum parameter values of the lightning current depending on the
protection level (more in chapter 8, SIST EN 62305-1:2011)
Lightning current parameter
Lightning protection level (LPL)
Initial positive strike
I
II
III-IV
Peak value of the current I in (kA)
200
150
100
Lightning strike charge Qshort in (C)
100
75
50
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5 September 2012
Specific energy W/R in (MJ/Ω)
10
Time parameters T1/T2 in (µs)
10/350
5.6
2.5
To continue see Table 3 in SIST EN 62305-1:2011
(2) Harmful effects caused by changes in the electromagnetic field depend on the gradient
of the lightning current. For the purposes of design, the average gradient of 30%-90% of the
peak value of the increase in the lightning current is used.
2.3.
Damage due to lightning strikes
2.3.1 Causes of the damage
The lightning current is the basic cause of the damage. Damage can occur due to (see Table
1):
S 1: discharges into the building,
S 2: discharges near the building,
S 3: discharges into the water supply,
S 4: discharges near the water supply,
2.3.2 Types of damage
(1) The lightning current can cause damage that depends on the characteristic
specifications of the specific building (e.g. its construction, contents and use, type of supply
lines and which protective measures against lightning were used).
(2) The three types of typical damage occurring due to lightning strikes are (see Table 2):
D 1: damage to living beings,
D 2: physical damage,
D 3: damage to electrical and electronic systems.
(3) Individual types of damage can be limited to the actual building, to the inside of the
building, to neighbouring buildings and the surroundings (e.g. chemical and radioactive
emissions). Lightning strikes can cause damage to supply lines going into the building
(pipelines, electrical and electronic systems) which can then transfer directly to the actual
building.
2.3.3. Types of loss
Each of the types of damage can, individually or in combination with each other, cause
various types of loss:
L 1: loss of human life,
L 2: loss of services to the public,
L 3: loss of cultural heritage,
L 4: loss of economic value (of the building and its contents, due to the discontinuation of
the supply of public amenities).
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Table 2: Damage and loss within the building with regard to various points of lightning strikes
(SIST EN 62305-1:2011)
POINT OF STRIKE
SOURCE
OF
DAMAGE
TYPE OF
DAMAGE
TYPE OF LOSS
Discharges into
the building
S1
D1
D2
D3
L1, L41
L1, L2, L3, L4
L12, L2, L4
Discharges near
the building
S2
D3
L12, L2, L4
Discharges into
the power lines
S3
D1
D2
D3
L1, L41
L1, L2, L3, L4
L12, L2, L4
Discharges near
the power lines
S4
D3
L12, L2, L4
1. Only for property where animals may perish
2. Only for buildings at risk of explosion and hospitals as well as other buildings where
failures of internal systems may directly threaten human lives.
2.4
Risk and its components
2.4.1 Risk
(1) Risk is the value of average and probable annual losses. There is a typical value for the
building for each type of damage.
(2)
R1:
R2:
R3:
R4:
Risks assessed for buildings are the following:
risk of loss of human life,
risk of loss of services to the public,
risk of loss of cultural heritage,
risk of loss of economic value,
(3) Individual risks must be calculated in accordance with the sources of the damage, types
of damage and types of losses. Individual groups are given in the standards SIST EN 623051 and SIST EN 62305-2.
2.4.2 Risk components
Each risk is the sum of the individual risk components. When calculating the risk, the
individual components of risk can be taken into account with regard to the causes and types
of damage as well as the type of loss:
- taking into account the lightning strikes to the building,
- taking into account the lightning strikes near the building,
- taking into account the lightning strikes into the supply lines of the building,
- taking into account the lightning strikes near the supply lines of the building,
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5 September 2012
2.4.3 Risk assessment
Deciding on the level of protection of the building in the sense of protection against lightning
is carried out in accordance with standards SIST EN 62305-1 and SIST EN 62305-2. The
risk assessment procedure and the cost assessment of the implementation of the protection
take place in the following order:
- gathering data about the building that is in need of protection,
- determining all types of possible damage to the building and to the supply lines,
- evaluation of risk for all types of damages,
- assessment of the need for protection against lightning with comparison of the
individual risks to the tolerated risk RT,
- evaluation of the implementation cost of the protection against lightning with regard
to the costs without protection (see standard SIST EN 62305-2).
2.4.4 Risk components assessment
The risk components that are factored in are:
- the building itself,
- installations in the building,
- contents of the building,
- people in the building as well as those persons who are located up to a distance of
3m from the external walls of the building,
- the building surroundings which could also be in danger,
2.4.5 Tolerated risk RT
(1) The tolerated risk defines the highest value of risk which can still be accepted with
regard to the building in need of protection.
(2) The tolerated risk is, in the case of some types of loss, given a general evaluation,
which can be seen in Table 3.
Table 3 - Accepted tolerated risk RT (SIST EN 62305-2:2012)
Type of loss
RT / year
L1
Loss of human life or permanent injuries (living beings)
10-5
L2
Loss of supply systems intended for people (public services)
10-3
L3
Loss of cultural heritage
10-4
2.4.6 Risk assessment procedure
(1) The procedure of risk assessment is carried out in accordance with the standards SIST
EN 62305-1 and SIST EN 62305-2 and is clearly shown in Figure 1, from which the
evaluation of the necessity to protect against lightning can be seen, namely:
- risk R1, R2, R3 and R4 for the building,
(2) For each of these risks the following must be determined:
- identification of individual components Rx, that comprise the risk,
- evaluation of the identified risk components Rx,
- evaluation of the whole risk R,
- identification of the tolerated risk RT,
- comparison of the whole risk R to the tolerated risk RT.
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5 September 2012
(3) Whenever R ≤ RT, protection against lightning is not necessary.
(4) Whenever R>RT it is necessary to take into account a number of protective measures
against lightning to the degree where the actual risk R will be lower than the tolerated risk
RT.
(5) The types of protective measures and choice of protection levels which enable the risk
of damage R to be reduced can be seen from the standards SIST EN 62305 (3-4), namely:
- SIST EN 62305-3 for the protection against damage to living beings and physical
damage within the buildings,
- SIST EN 62305-4 for the protection of internal devices and electronic systems within
the buildings,
(6) The choice of the most suitable means of implementing the protection against lightning
is made by the designer after evaluating all the partial risks (individual risk components) and
taking into account the combined risk which must be lower than the acceptable (tolerated)
risk RT. In doing so, all technical and economic effects of the various protective measures
must be taken into account (see standard SIST EN 62305-2).
Information on the building to
be protected
Determining all types of possible
damage to the building and to the
supply lines
For each type of damage it is
necessary to determine the tolerated
risk with all its components (R1-R4)
Risk calculation
Assessment of risk with regard to the tolerated risk
RT
Additional
protective
measures
Necessary
further reduction
of risk
YES
NO
The building is safe if it is
within the acceptable limits
of risk
Figure 1: The risk assessment procedure with regard to the necessity for lightning protection
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5 September 2012
2.5
Density of atmospheric discharges into the earth
The density of atmospheric discharges into the earth, expressed as the number of lightning
strikes into the earth per square kilometre per year is determined by metering. The number
of highest lightning density values is given in Annex 2 to the Regulations on the protection of
buildings against lightning.
2.6
LPS classes
(1) With regard to the chosen level of protection against lightning, four classes (I-IV) of LPS
implementations are available, shown in Table 4.
Table 4: The connection between the LPS protection levels and classes (SIST EN 623053:2011)
Lightning protection level (LPL)
LPS class
I
I
II
II
III
III
IV
IV
(2) LPS classes differ from each other by:
 the parameters of the lightning current,
 the radius of the final puncture distance, the size of the air terminal ring and the
protection angle,
 the typical distance between down conductors,
 the separation distances between individual parts between which flashover can
occur,
 the minimal earth electrode length,
(3) The LPS class is chosen on the basis of risk assessment following the standard SIST
EN 62305-2.
2.7
External LPS
(1) The purpose of the external LPS is to intercept, dissipate and distribute the lightning
current into the earth. In doing so, there must be no damage to the protected building.
(2) The external LPS consists of the air-termination system, the down conductors and the
earth-termination system which together form a safe path between the point of the lightning
strikes and the earth.
(3) The following are used for the air-termination system:
 the protection angle method,
 the rolling sphere method,
 the mesh method.
(4) All three methods act together to adapt to the geometric dimensions of the building they
are protecting. They are shown in Table 5 and Figure 2.
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Table 5: The maximum value of the radius of the rolling sphere and the size of the mesh,
depending on the LPS class (SIST EN 62305-3:2011)
The protection method
LPS class
The radius of the
rolling sphere r [m]
The size of the mesh
hoop W [m]
I
20
5x5
II
30
10 x 10
III
45
15 x 15
IV
60
20 x 20
The protection angle

[]
see Figure 2
[]
LPS class
Note 1:
Note 2:
Note 3:
This method is not used with heights above these values. In that
case, it is necessary to use the rolling sphere or mesh method due
to possible side-flash.
H is the height of the individual air terminal installation above the
space it is protecting.
The protection angle does not change for H under 2m.
Figure 2: The protection angle of the air terminals with a height of H, depending on the LPS
class (SIST EN 62305-3:2011)
(5) The air-termination mesh can be combined with metal rods and existing metal roof
parts. In doing so, they must be properly galvanically interconnected, as this ensures a more
even distribution of the lightning current when it is dissipated.
(6) Because the roof is made out of fire-proof material, the conductors of the air-termination
mesh can be placed directly onto the surface of the roof.
(7) In places where the roof is not fire-proof, it is necessary to make sure that there is a
suitable distance between the conductors and any flammable materials. A suitable distance
is more than 0.1m and 0.15m for thatched roofs.
(8) The following are included as part of the LPS:
a) metal building coverings under the following conditions:
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5 September 2012




electrical continuity between individual parts must be permanent (soldering,
welding, compression, stitching, screwing or riveting),
the thickness of the metal coverings must not be less than t2, as stated in Table
6, when melting is permitted at the lightning strike point, and ignition cannot
occur below them due to the melting of metal,
the thickness of the metal coverings must not be less than t1, as stated in Table
6, when it is not permitted to melt materials at the point of the lightning strike or
if there are flammable materials below it which could ignite due to the melting of
metals or thermal effects.
when they are not coated with insulation materials,
Table 6: The smallest thickness of metal plates or metal pipes of the external LPS (SIST EN
62305-3:2011)
LPS class
I to IV
Material
Thickness t 1
[mm]
Thickness t 2
[mm]
lead
-
2.0
steel/zinc plated,
rust-proof
4
0.5
titanium
4
0.5
copper
5
0.5
aluminium
7
0.65
zinc
-
0.7
t1 prevents puncturing
t2 only for metal where it is not important to prevent puncturing, thermal damage
or ignition
b) metal parts of the roof construction (e.g. supporting beams, connected to the
reinforcement, etc.) underneath the non-metal roof, if the damage to this nonmetal roof is acceptable,
c) metal parts such as decorative items, tracks, pipes, coverings, etc. with
diameters of no less than the dimensions and measurements of the material
used for the external LPS,
d) metal pipes and water tanks on roofs with the thickness and cross-sections
that fit the dimensions of the external LPS (Table 10);
e) metal pipes and water tanks that hold flammable or explosive mixtures must
be of dimensions that are suitable for the thickness t1 in Table 6.
(9) In the event that the required dimensions are not ensured, it is necessary to include
the pipes and water tanks in the area that needs protection.
(10) Pipelines that transfer flammable or explosive mixtures and are joined with plastic
inserts or flanges must be included in the LPS.
(11) A thin coat of paint, 1mm of asphalt or 0.5mm of PVC is not suitable insulation.
(12) If the roof, roof covering or gutter is made out of copper, it is necessary to bolster the
steel or aluminium conductors so that rainwater does not run from the copper parts onto the
steel or aluminium conductors. If this is not possible, it is necessary to use copper
conductors.
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5 September 2012
(13) At the connection points between the copper and aluminium conductors it is necessary
to provide an insert made from both materials (Al - Cu). Zinc-plated steel and aluminium can
be directly joined (see Table 8).
2.8
Down conductor system
(1) Down conductors conduct the lightning current from the strike point to the earth. They
enable:
 several parallel current paths,
 the shortest length of parallel paths,
 equipotential bonding with the conductive parts of the building.
(2) The distances between the individual vertical down conductors and the individual
horizontal ring connections are shown in Table 7.
Table 7: The distance between the vertical down conductors and the individual horizontal
circular connections depending on the LPS class (SIST EN 62305-3:2011)
LPS class
Distances between down
conductors
[m]
I
10
II
10
III
15
IV
20
(3) Down conductors must establish the shortest possible connection with the earth
electrode, vertically if possible, without changing direction. Down conductors must be as
short as possible and need to be installed near the edges of the building. Down conductors
must be kept as far away as possible from windows, doors, electrical installations and those
metal masses which are not, due to special reasons, connected to the building’s lightning
protection system.
(4) Every 10-20m, the individual vertical down conductors are connected to each other with
a circular horizontal connection. Circular connections begin with a basic connection to the
potential ring in the earth.
(5) The air-termination mesh on the roof and the LPS down conductor system can be, in
some cases, constructed so that they are isolated from the metal parts of the building, if the
separation distance from all other metal parts in the building is maintained. At the point
where they enter the earth, all down conductors must be interconnected with the basic
potential ring, which at the same time represents the main collector for the equipotential
bonding (see standards SIST EN 62305-3 and SIST EN 62305-4).
(6) Whenever it is not possible to ensure a sufficient separation distance between the airtermination mesh with the down conductors and all the metal parts, it is necessary to
construct an uninsulated LPS.
(7) In buildings constructed using reinforced concrete, it is necessary to use the
reinforcement as lightning down conductors and at the same time as protection against
electromagnetic fields. In doing so it is necessary to take into account the continuity of the
galvanized joints and the minimal dimensions in accordance with standard SIST EN 623053. The electrical continuity of the reinforcement rods must be checked by electrically testing
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5 September 2012
in the part between the highest part and floor level. The entire electrical resistance should
not be greater than 0.2 . If that value is exceeded then reinforcement cannot be used as a
lightning down conductor.
(8) The lightning conductors of an uninsulated LPS may be placed:
 on the surface of a wall or into the actual wall if the wall is made out of a nonflammable material,
 at least 0.15m away from the wall, on wall supports which are at a distance from
each other of 2m at the most, on roof supports at a distance of 1.5m from each other,
and on ridge supports at a distance of 1m from each other if the wall is made out of a
flammable material.
(9) Metal masses that go through the building and have a large enough diameter are also
used for down conductors, in accordance with the smallest dimensions for LPS conductors.
(10) Down conductors should not be laid in gutters. Gas lines must not be used as down
conductors.
(11) A metering contact, which it is possible to galvanically separate for metering reasons,
must be made at the point of connection to all the down conductors. When using natural
metal masses and reinforcements such as natural down conductors in combination with
other down conductors, it is also necessary to make a metering point which is not to be
separated due to the multiple parallel connections. In these cases, the isolating metering
point is placed where it is possible to separate it from the down conductor.
(12) Conductors that are connected to each other and to couplings must be made from the
same material. The suitability of the connections of various materials is shown in Table 8. In
the event that incompatible materials are being joined, as seen in Table 8, it is necessary to
use an insert made out of a neutral material with a thickness of at least 2mm.
Table 8: The possibilities of joining different materials depending on their electrochemical
potential
Copper
Zinc-plated steel
Rust-proof
steel
Aluminium
Copper
yes
no
yes
no
Zinc-plated steel
no
yes
yes
yes
Rust-proof steel
yes
yes
yes
yes
Aluminium
no
yes
yes
yes
2.9
Earth-termination system
(1) By distributing the earth electrodes appropriately, the overvoltage decreases when
dispersing the lightning current into the earth, In general, the most suitable is a low earth
resistance, less than 10Ω. When the specific ground resistance is greater than 250Ωm, the
earth resistance must not be greater than 4% of the measured specific resistance of the
ground in Ωm.
(2) From the point of view of lightning protection, as well as of electrical and
telecommunication devices, a united and integrated earthing system of all the connected
earthing electrodes in the buildings is most suitable. Special attention must be given to this
part of the wiring so as to ensure correct functioning.
(3) Specially placed conductors, positioned in the earth, can be used as earth electrodes, in
the following forms:
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5 September 2012




horizontally placed wires and strips (earth strips),
vertical pipes or profiles (earth rods),
vertical plates (earth plates),
metal constructions and meshes as well as pipes in the earth, apart from those which
must be kept separate for special reasons.
(4) If an individual building has more than one earth electrode it is necessary to wire them
together with a conductor placed in the earth. In doing so it is necessary to give priority to
the ring conductor around the protected building. The foundation earth electrode of the
building connects to the circular ring in several places, in accordance with Tables 9 and 10.
If necessary, more than one ring conductor can be installed.
(5) The electrode from the third paragraph must be buried at least 0.5m deep, but it is
recommended to bury it at a depth of 0.8m.
(6) It is not sensible to increase the length of the horizontal electrodes to more than 60m
with the intention of decreasing the electrodes’ resistance.
(7) The earth conductor’s dimensions and materials are shown in Table 11.
(8) To avoid possible interference, the earth resistance of the interconnected electrodes
should be measured at a frequency that is different from the network’s frequency or a
multiple of it.
(9) When installing the horizontal multipoint-star electrodes, where more than one
individual conductor goes in different directions from a single point, the angle between two
neighbouring electrodes should be more than 60o.
(10) It is necessary to join all metal masses that are less than 20m away to the electrode in
the earth, apart from those that are restricted by other regulations (e.g. metal masses in a
cathode protection system).
(11) If the pipes of the plumbing are connected to the earth electrodes, it is necessary to
bridge all the water meters and similar devices which are built-in between the places where
the various metal parts may have different potentials. Cross-sections of these connections
are given in Table 12.
2.10 Implementation of an LPS in explosive hazardous areas
In accordance with standard SIST EN 62305-2, a suitable lightning protection level is chosen
on the basis of the risk evaluation. Protection levels I and II are suitable for all cases where
the contents of the building are especially sensitive to the effects of lightning. Due to the
effects of lightning strikes, substances that pose a threat to human and animal life can be
emitted into the surroundings. The choice of protection level also depends on the explosive
and flammable substances that are present inside the building or one of its parts. The
designer must choose a suitable protection level depending on the information on the
lightning density in the area, the content of the building and the activities that go on there.
A more detailed description of the procedure is given in Annex D to standard SIST EN
62305-3.
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3.
CONDUCTOR MATERIALS
(1) The materials listed in the table may be used for lightning conductors under the
following conditions:
Table 9: LPS materials and conditions for usea(SIST EN 62305-3:2011)
Use
Material
Copper
In the air
Solid
Stranded
In the earth
Corrosion
In concrete
Resistance
Increased
Sulphur
ingredients
Organic
materials
Solid
Stranded
Coated
Solid
Stranded
Coated
Good in many
environments
Can be
destroyed
with
galvanized
joints to
–
Hot zincplated
steelc, d, e
Solid
Strandedb
Solid
Solid
Strandedb
Acceptable in
air, concrete
and neutral soil
High level of
chlorides
Copperplated steel
Solid
Solid
Solid
Good in many
environments
Sulphur
ingredients
Rust-proof
steel
Solid
Stranded
Solid
Stranded
Solid
Stranded
Good in many
environments
High level of
chlorides
Aluminium
Solid
Stranded
Unsuitable
Unsuitable
Good in air with
low
concentrations
of sulphur and
chlorides
Alkaline
solutions
Copper
Leadf
Solid
Coated
Solid
Coated
Unsuitable
Good in air with
a low
concentration
of sulphates
Acid soil
Copper
a
b
c
d
e
f
Copper
–
Rust-proof
steel
The table provides a general framework. In special circumstances under more complex
corrosion conditions, additional research will be needed (see Annex E to standard SIST EN
62305-3:2011).
Stranded conductors are more prone to corrosion than solid materials. Stranded conductors
are also not as resistant at transitions from soil to concrete. That is why it is not recommended
to place stranded zinc-plated steel into the soil.
Zinc-plated steel can also corrode in clay or damp soil.
Zinc-plated steel in concrete should not continue on into the soil due to the danger of steel
corrosion at the point of transitioning from the concrete.
Zinc-plated steel in contact with the reinforcement in the concrete should not be used in
coastal areas where salt may be present in the soil.
The use of lead in the soil is usually forbidden due to environmental requirements.
(2) Types of materials and shapes as well as the smallest cross-section of air-termination
mesh conductors and earth electrodes are shown in Table 10.
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5 September 2012
Table 10: Material, the shape and the smallest cross-section of the air-termination
conductors, air-termination rods, bar earth conductors and down conductorsa (SIST EN
62305-3:2011)
Material
Shape
Cross-section
mm2
Copper
Tin-plated copper
Solid strip
Solid roundb
Strandedb
Solid roundc
50
50
50
176
Aluminium
Solid strip
Solid round
Stranded
70
50
50
Aluminium alloy
Solid strip
Solid round
Stranded
Solid roundc
50
50
50
176
Copper-plated aluminium alloy
Solid round
50
Zinc-plated steel
Solid strip
Solid round
Stranded
Solid roundc
50
50
50
176
Copper-plated steel
Solid round
Solid strip
50
50
Rust-proof steel
Solid stripd
Solid roundd
Stranded
Solid roundc
50
50
70
176
a
b
c
d
The mechanical and electrical specifications as well as resistance to corrosion must all be in
compliance with the requirements of the set of standards SIST EN 62561.
50mm2 (8mm diameter) can be decreased to 25mm 2 (6mm diameter) in special cases when the
mechanical resistance is not a key issue. The distances between the beams should be suitably
adjusted with regard to this.
Suitable for air-termination rods and bar earth conductors. If the mechanical load, e.g. wind
resistance, is not critical, rods with a diameter of 9.5mm and a length of 1m can be used instead
as air-termination rods.
If the thermal and mechanical characteristics are of key importance, these values should be
increased to 75mm 2.
(3) The dimensions of the lightning conductors that are used for the earth-termination
system are shown in Table 11.
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5 September 2012
Table 11: The material, shape and smallest dimensions of the earth electrodesa,e (SIST EN
62305-3:2011)
Dimensions
Material
Copper
Tin-plated
copper
Shape
Stranded
Solid round
Solid strip
Pipe
Solid plate
Mesh platec
Hot galvanised Solid round
steel
Pipe
Solid strip
Solid plate
Mesh platec
Profile
Diameter of
the earthing
rod
mm
Earthing
conductor
mm2
15
50
50
50
20
500 x 500
600 x 600
14
25
78
90
500 x 500
600 x 600
d
Bare steelb
Stranded
Solid round
Solid strip
Copper-plated
steel
Solid round
Solid strip
14f
50
90
Rust-proof steel Solid round
Solid strip
15f
78
100
a
b
c
d
e
f
Earthing
plate
mm
70
78
75
The mechanical and electrical specifications as well as resistance to corrosion must all be in
compliance with the requirements of the set of standards SIST EN 62561.
Must be covered in concrete at a depth of at least 50mm.
The mesh plate made out of a conductor with a combined length of at least 4.8m.
Various profiles with cross-sections of 290mm2 are permitted, a minimal thickness of 3mm, e.g. a
cross profile.
If the foundation earthing system has distribution Type B, the earth electrodes must be correctly
connected to reinforced steel at least every 5m.
In some countries, the diameter may be decreased to 12.7mm.
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4.
PREVENTION OF SPARKING AND PUNCTURES
4.1
General
(1) When the lightning current is transferred from the air-termination system through the
down conductors into the earth-termination system, negative effects may be transferred into
the building through the metal connection and electromagnetic field; these may cause
dangerous sparking and punctures between:
 metal constructions,
 internal connections of various installations,
 external conducting parts and connections from the building to its surroundings,
(2) Sparking inside the building poses a fire and explosion hazard as well as a risk of the
destruction of functioning devices within the building. Then it is necessary to implement
additional protective measures.
(3) Dangerous sparking between various parts of internal devices and installations can be
prevented by:
 equipotential bonding,
 electrical insulation.
4.2
Equipotential bonding
4.2.1 General
(1) Equipotential bonding is achieved by connecting:
 the metal parts in the building,
 metal installations,
 the internal supply installation systems,
 the external conductive parts and installation connections of the buildings.
When establishing equipotential bonding connections it is necessary to take into account
that part of the current can also end through these connections.
(2) Equipotential bonding is carried out with:
 connecting conductors,
 surge protection devices (SPD) where direct connection to the conductors is not
possible,
 sparking gaps, where direct connection to connecting conductors is not permitted.
The choice of method also depends on the specifications of other installations in the building
(electrical, telecommunication, fire, security, etc.).
4.2.2. Equipotential bonding of metal installations
(1) In the event that the external LPS is installed as an insulated implementation,
equipotential bonding is only made at the level of the earth-termination system (a connected
ring of potential around the building). In the case of such implementation, it is necessary to
also follow the fourth and fifth paragraphs of this item.
(2) For external LPSs that are not isolated from internal metal masses, equipotential
bonding is carried out in the following places:
 on the ground floor at the level of the connections of the earthing system and it must
also be constructed in such a way that it is easily accessible for inspection,
 where the insulation requirements are not fulfilled.
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(3) Connections for equipotential bonding must be made following the most direct and
shortest path.
(4) The smallest cross-sections of the connections for equipotential bonding that connect
the individual metal parts of the LPS, the various equipotential bonding busbars or connect
the equipotential bonding busbars to the earthing system and which can transfer a significant
amount of the lightning current, are shown in Table 12.
Table 12: The smallest dimensions of the conductors which connect the various
equipotential bonding busbars or connect the equipotential bonding busbars to the earthing
system (SIST EN 62305-3:2011)
LPS class
I to IV
Material
Cross-section
[mm2]
Copper
16
Aluminium
25
Copper-plated steel
50
(5) The smallest cross-sections of the connections for equipotential bonding between the
metal parts or the connections of the metal parts to the equipotential bonding busbars and
which do not conduct a significant amount of the lightning current are shown in Table 13.
Table 13: The smallest dimensions of the conductors that connect the internal metal
installations to the equipotential bonding busbars (SIST EN 62305-3:2011)
LPS class
I to IV
Material
Cross-section
[mm2]
Copper
6
Aluminium
10
Copper-plated steel
16
(6) If insulation inserts are in the gas pipes or plumbing within the building, they are bridged
with SPDs that are sized for this specific installation. The same applies to other metal parts
which are not usually connected to the integrated earthing system in the building (e.g. parts
protected with cathode protection).
4.2.3 Equipotential bonding of external conductor parts
(1) It is necessary to carry out the connection of the external metal parts as close as
possible to the entrance of the protected building.
(2) The connecting conductor must have a suitable cross-section and must be able to
conduct the estimated lightning current.
(3) If the direct connection cannot be made, it should be established with a correctly sized
spark gap.
(4) If it is necessary to create equipotential bonding when there is no external LPS, the
earth-termination system of the electrical installation should be used.
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4.2.4 Equipotential bonding of the internal part of the LPS
(1) If the internal conductors are in the form of shielded cables or they are in metal conduits
or tubes, it is necessary to connect the shielding and metal conduits and tubes to the
earthing system of the building.
(2) If the electrical cables and other conductors in the building do not have metal shielding
or are not in metal conduits or tubes, they must be connected to the SPD. In the TN
electrical installation systems, the PE and N conductors must be galvanically connected to
the LPS. In TT electrical installation systems the PE conductors must be galvanically
connected to the LPS.
(3) When implementing overvoltage protection in the building interior, it is necessary to
create a coordinated protection with correctly chosen characteristics of the SPD following the
standard SIST EN 62305-4.
4.2.5 Equipotential bonding of the supply cables
(1) Equipotential bonding of electrical and telecommunication conductors should be
implemented in accordance with Item 4.2.4.
(2) All conductors of each supply line should be connected directly to or through the SPD to
the earthing system of the building. Live conductors should be connected to the
equipotential bonding busbar through the SPD. The PE and N conductors should be
connected directly to the equipotential bonding busbars in TN systems.
(3) If the lines are shielded or in metal conduits, it is necessary to connect the shields or
metal tubes to the earthing system. On the basis of a calculation, the designer decides on
the cross-sections of the metal coatings of the shielded cables and on how many, as well as
on the possibility of connecting them to both ends of the cable’s metal coatings.
(4) The connection of the cable braids and metal shields should be set up where the
connections enter the building. In doing so, the SPD characteristics should be in accordance
with Item 4.2.3 and coordinated in accordance with the third paragraph of Item 4.2.4.
4.3
Separation distance between the metal parts and the LPS
(1) The electrical insulation between the air-termination mesh, the down conductors and
metal parts can in certain cases be achieved with the establishment of a separation distance
between the metal parts in the building and the LPS. The separation distance s in m is
generally determined with the help of the following equation.
s  ki
where:
ki
kc
km
l
kc
l
km
is the coefficient depending on the chosen LPS class (see Table 14)
is the coefficient depending on the lightning current that runs down the airterminal and down conductor (see Table 15)
is the coefficient depending on the electrical insulation material (see Table 16)
is the length of the LPS conductor for which it is necessary to establish the
separation distance to the nearest point of equipotential bonding.
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Table 14: External LPS insulation - coefficient value ki (SIST EN 62305-3:2011)
LPS class
ki
I
0.08
II
0.06
III and IV
0.04
Table 15: Internal LPS insulation - coefficient value kc (SIST EN 62305-3:2011)
Number of down conductors
n
kc
1 (only in the event of an insulated LPS)
1
2
0.66
3 and more
0.44
NOTE
The values in Table 15 are valid for all Type B earth electrode distributions and for
Type A earth electrode distributions under the condition that the earth resistances of
neighbouring earth electrodes do not differ by more than a factor of 2. If the earth resistance of
individual earth electrodes differs by more than a factor of 2, then kc = 1 is used.
Table 16: External LPS insulation - coefficient value km (SIST EN 62305-3:2011)
Material
km
Air
1
Concrete, brick, wood
0.5
NOTE 1 When there are several insulation materials, it is common practice to take into account
the lower km.
NOTE 2 When other insulation materials are used, the instructions on installation and the
coefficient value km should be given by the manufacturer.
(2) When integrating lines or external conductive parts into the building, it is necessary to
ensure direct equipotential bonding or a connection through the spark gap or SPD.
(3) In buildings with a continuous connection of metal masses, a connected reinforcement
mesh, a metal construction, it is not possible to achieve a separation distance and so a
galvanic connection of all metal masses into a united and combined earthing system is
required.
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5.
PROTECTION AGAINST HAZARDS CAUSED BY TOUCH AND
STEP VOLTAGE
5.1
Protective measures against touch voltage
(1) Due to the lightning current being discharged into the earth, touch overvoltages can
occur outside the building. This danger can be reduced to an acceptable level if:
 no person is within a distance of 3m of any down conductors under normal
functioning conditions,
 the natural system of metal masses is made up of a number of connected parallel
paths and connected with reinforcement and to the construction of the building that
has good electrical conductivity (a system of at least 10 down conductors),
 the transitional resistance of the surface layer of the floor within 3m of the down
conductor is not less than 100k.
(2) If none of the conditions from the previous paragraph of this item have been fulfilled, it is
necessary to do the following to protect people against touch overvoltage:
 insulate the LPS down conductors,
 install physical barriers and warnings to reduce the possibility of touching the LPS
down conductors.
(3) In the event of unexpected dangers of touch overvoltage and not fulfilling the conditions
stated in the first paragraph, the designer should determine the necessary additional
measures and, if necessary, the inspection of dangerous differences in potentials.
5.2
Protective measures against step potential
(1) Too high a step potential is reduced to an acceptable level, if:
 no person is within a distance of 3m of any down conductors under normal
functioning conditions,
 a system of at least 10 down conductors is installed,
 the transitional resistance of the surface layer of the floor within 3m of the down
conductor is not less than 100k.
(2) A layer of insulating material, for example 5cm of asphalt or 15cm of gravel, usually
decreases the danger of step potential to an acceptable level.
(3) If none of the conditions from the first paragraph are fulfilled, it is necessary, as a result
of excessive step potentials, to carry out the following:
 create equipotential bonding by modifying the density of the earth-termination system
meshes,
 install physical barriers and warnings within a 3m radius around the LPS down
conductors to reduce the possibility of touching them.
(4) In the event of predicted or determined dangers of excessive step potentials and
unfulfilled requirements from paragraph (1), the designer determines the necessary
additional measures and, if necessary, the inspection of the origins of dangerous differences
in potential.
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6.
PROTECTION OF ELECTRICAL AND ELECTRONIC SYSTEMS
IN BUILDINGS
6.1
General
(1) Atmospheric discharges at their point of discharge and the nearby surroundings
represent a high-energy occurrence. The discharge releases hundreds of megajoules of
energy, which is why it is sensible to install additional protection for some of the more
important electric and electronic equipment.
(2) LEMP poses a constant threat to electrical and electronic equipment, and it works:
- by ohm and induced overvoltage transferred to electrical and electronic devices and
their connections,
- with the effects of the radiation from electromagnetic fields to the devices
themselves.
(3) The connecting mechanisms can vary as follows:
- resistor connections (e.g. the galvanic connection of the earth-termination system to
various connecting lines),
- connections through the electromagnetic field (e.g. wiring hoops),
- electromagnetic assemblies (e.g. through transmitters, antennas).
(4) Overvoltage effects can arise outside and inside a building:
- external effects to buildings arise when atmospheric discharges strike connected
supply lines or in their vicinity. They can also be transferred through electrical and
electronic connecting systems,
- internal overvoltages in the building arise when lightning strikes directly into the
building or its vicinity.
(5) A lightning strike can cause various types of damage (D1, D2, D3), as defined in SIST
EN 62305-2. Protective measures against the effects of LEMP are dealt with in standard
SIST EN 62305-4 and following it reduces the damage to electric and electronic systems.
6.2
Protection zones
Protection against LEMP is based on intentionally chosen zones, intended for controlling the
electromagnetic effects on buildings when lightning strikes. Individual lightning protection
zones successively limit the electromagnetic effects of a lightning strike. In the area of each
individual zone, the LEMP effect is reduced to a low enough level to ensure the undisrupted
functioning of the devices that work in that zone and are intentionally dimensioned to it.
SPDs are installed at the boundaries between each individual protective zone and enable
the reduced electromagnetic effect of the whole or partial lightning current to pass through it.
The general rule is - the higher the protection zone number, the more favourable the
parameters of the electromagnetic environment. The design and method of installation
should be implemented in accordance with Paragraph 4 of standard SIST EN 62305-4.
6.3
Earthing and connection
(1) The success of the earthing and connection is based on the unified earthing system,
which importantly consists of:
- a suitable earth electrode system, which disperses the lightning current into the
earth, and
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suitable galvanic connections which reduce the differences in potential and
simultaneously reduce the influencing magnetic field.
(2) Various means of earthing and connection are shown in Chapter 5 of standard SIST EN
62305-4.
6.4
Magnetic shielding and transposition
Magnetic shielding reduces the penetrating electromagnetic field as well as various internal
overvoltage effects. Appropriate braiding of individual internal conductors in the connection
paths also reduces the amplitude of internal overvoltage strikes to the lowest level possible.
Both methods are very effective in reducing the effects of internal damage to devices.
Magnetic shielding and braiding are shown in more detail in Paragraph 6 of standard SIST
EN 62305-4.
6.5
Coordinated SPD protection
Protection of internal electrical and electronic devices requires a systematic approach with
coordinated installations of surge protection devices (SPD) for both power and signal
connections. Individual characteristics of protective devices depend on the purpose of the
device in need of protection (analogue, digital, DC or AC, low or high frequency). The basic
principle and procedure is shown in Chapter 7 of standard SIST EN 62305-4 and in its
Annexes C and D.
6.6 Designing, choosing and the inspection procedure for LEMP
protection
The design and choice of LEMP protection devices must take place at the same time as the
design of the whole building and before its construction. In doing so, the natural components
of other designed building systems should be used effectively and the most suitable solution
for cabling and the location of individual pieces of equipment should be found. The
procedure described is shown in more detail in Chapter 8 of standard SIST EN 62305-4.
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7.
LPS INSPECTION, TESTING AND METERING
7.1
General
(1) Inspections to ensure the safe functioning of the lightning protection system include a
visual inspection, tests and metering of the installed system, including those parts of the
electrical system that are indivisibly connected to this system.
(2) Inspections of LPS systems constructed in protection zones I and II can only be carried
out by individuals who have acquired the professional qualification NPK (65332730) or are
suitably certified to inspect complex electrical installations and lightning protection systems.
(3) Inspections of LPS systems constructed with protection levels III and IV can only be
carried out by individuals who have acquired the professional qualification NPK (87658650)
or are suitably certified to inspect less complex electrical installations and lightning protection
systems.
7.2
Visual inspection
During a visual inspection it is necessary to check:
1. that the project and designs within it are in accordance with the Regulations on the
protection of buildings against lightning and the corresponding technical guidelines,
2. that documents exist regarding the compliance (declarations of conformity,
certificates) of the chosen materials with regard to the Regulations on the protection
of buildings against lightning and the corresponding technical guidelines,
3. that the implementation of the lightning protection is in an insulated or uninsulated
form,
4. that the LPS is in good working condition and does not show signs of damage,
5. that there are no loose joints and random interruptions of the conductors, joints and
connections,
6. that the lightning conductor installation (metering joint, metering point, numbered
down conductors on the floor plan of the building, the density of the air-terminals and
down conductors) is appropriate for the chosen (designed) protection level of the
lightning conductor installation,
7. that there are no weakened LPS parts due to corrosion, particularly not at the points
of contact with the earth,
8. that all visible earth electrodes and earthing connections are undamaged,
9. that all visible conductors and integral parts of the system are attached to suitable
surfaces and that the mechanical protection parts are not damaged,
10. that the protective measures against the dangers of excessive touch and step
potentials are implemented in the areas where people may be present,
11. that no additional changes have been made to the protected building which would
require additional protective measures,
12. that there are no signs of damage to the LPS or SPD or fuses which protect the
surge protection devices,
13. that the connecting conductors and joints are correctly installed in the building,
14. that the equipotential bonding has been correctly carried out for any new wiring or
additions which have been put in since the last inspection and that tests have been
carried out to check the continuity of these new additions,
15. that the galvanic connections to the neighbouring buildings have been correctly
carried out and that their installations are connected,
16. that the separation distances have been correctly chosen and maintained,
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17. that the connecting conductors, joints and shielding devices, the site of the cable
laying and the surge protection devices have been correctly installed and correctly
connected to the earthing system,
18. that the compatibility of the electrical and lightning conductor installation has been
achieved with regard to the earthing system in the electrical installation (TN, TT, IT),
19. that the compatibility of the electrical and lightning conductor installation is achieved
and maintained with regard to the designed protection zones of the LPS system.
7.3
Tests
The following tests need to be carried out after the visual inspection:
- to establish whether the distances between the air-terminal meshes and the
individual down conductors comply with the chosen protection level of the lightning
conductor installation,
- to establish whether the distances between the various metal parts or parts of the
other installations comply with the calculated separation distances of the project,
- to test the insulation suitability of the insulation inserts and spark gaps which
intentionally separate the various metal installations (gas, installations with cathode
protection, etc.)
- to test the functioning of the surge protection devices which are tested by pressing a
button,
- to carry out a shut-down test of the earth electrodes in the event of significant effects
of corrosion or an unusual increase in the earth resistance of the earth electrode,
which showed considerably higher values before the inspection,
- to test the dimensions of the air-termination system, down conductors and earthtermination system.
7.4
Metering
After completing the visual inspection and tests, the inspection continues with the metering.
Depending on the findings from both previous parts of the inspection (LPS implementation,
surroundings, special requirements), a suitable metering method is chosen that ensures the
required level of accuracy of each measurement. The following measurements need to be
carried out:
- measuring the continuity or the connectivity of the metal parts so that it is a unified
earthing system. In doing so, it is important that the measurements of those metal
parts that will not be visible or accessible in later inspections have already been
tested during construction. When taking these measurements, it is necessary to take
into account the fact that all the earthing devices in the protected building are
connected into one unified earthing system (PEN). In the earthing system of the
electrical installation of the TT system, all the metal parts are connected with
protective earthing (PE), together with the lightning conductor installation. In the IT
systems of electrical installations, the lightning conductor installation is connected to
all the metal parts and the common protective conductor in the IT system,
- measuring the earth resistance of the unified system (resistance of the earthing
system is increased for the resistance from the earth electrode system to the point of
metering in the building). It is necessary to take into account the reference point
outside of the potential effect of the lightning conductor installation of the building
(metering contact - reference earth),
- measuring the earth resistance of individual earth electrodes (separate
measurements). The measurement of the earth resistance is carried out between the
open measuring joint and the earth electrode. The measurement, in the event of
several parallel down conductors, can also be carried out even when the metering
contact is closed, following the ring measurement method.
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-
7.5
the measurement of the continuity of the galvanic connection and joints in order to
prove their low electrical resistance between the connection points,
the measurement of the voltage of the reaction of the surge protection devices or the
idle current (leakage current) of the protection device,
the measurement of the touch and step potential at particularly exposed places
where dangerous differences in potentials are to be expected.
Inspection documentation
(1) The inspector must compile a written report on the completed LPS inspection which
must be kept together with the LPS project and all the previous inspection and maintenance
reports.
(2) The inspector’s report should include the following information:
- the general state of the air-termination conductors and other key components of the
air-termination system;
- the level of corrosion and the effectiveness of the corrosion protection;
- the reliability of the connections and other key components of the LPS;
- the earth resistance of the earth-termination system;
- the earth resistance of the earth electrodes of the individual down conductors and the
connections through the air-termination system and earth electrodes. The individual
lightning conductors must be labelled (in the floor plan, design) so that the
measurements carried out are identically repeated;
- the measurements of the resistance of the lightning conductor installation’s galvanic
connections with other metal parts and metal parts of other installations with regard
to the connection to the LPS (electrical installation, plumbing, central heating, etc.);
- the results of all the completed tests must be presented unambiguously;
- the result of a successfully completed inspection is a report on the inspection with the
findings that, if shortcomings were found, they have been resolved and the lightning
conductor installation as a whole fulfils the requirements of the Regulations on the
protection of buildings against lightning (Official Journal of the RS, No. 28/2009) and
a positive professional evaluation has been given for its safe functioning on the basis
of the results of the completed inspection;
- in the annex it is also necessary to provide a valid certificate on the calibration of the
measuring instrument.
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