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EUROPEAN STANDARD
EN 50310

NORME EUROPÉENNE
March 2006
EUROPÄISCHE NORM

ICS 33.100; 35.020; 91.140.50 Supersedes EN 50310:2000


English version


Application of equipotential bonding and earthing
in buildings with information technology equipment



Application de liaison équipotentielle  Anwendung von Maßnahmen
et de la mise à la terre dans les locaux für Erdung und Potentialausgleich
avec équipement de technologie de in Gebäuden mit Einrichtungen
l'information der Informationstechnik





This European Standard was approved by CENELEC on 2005-09-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels


© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50310:2006 E

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EN 50310:2006 – 2 –
Foreword
The first edition of this European Standard has been prepared by CENELEC/TC 215/WG 4, which was
composed of experts of both CENELEC/TC 215 and ETSI/TC EE/WG EE 2 (former ETSI/STC EE 2). The
second edition of this European Standard has been prepared by CENELEC/TC 215/WG 2.
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC
as EN 50310 on 2005-09-01.
The following dates were fixed:
- latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2006-10-01
- latest date by which the national standards
conflicting with the EN have to be withdrawn (dow) 2008-09-01

This standard has been produced within the framework of the following considerations:
a) With the ongoing growth of the liberalised telecommunication market, the increasing advent of private
telecommunication network operators, and the flourishing use of networking computers, the amount
of Information Technology equipment installed in buildings and the complexity of these Information
Technology installations are permanently growing.
b) Information Technology equipment is generally installed either as stand alone equipment (e. g.
personal or network computers, small PBXs), or held in racks, cabinets or other mechanical
structures (e. g. switching systems, transmission systems, mobile base stations).
c) CENELEC/SC 64B „Electrical installations of buildings: Protection against thermal effects“ had
decided during their meeting in November 1997 not to harmonize IEC 60364-5-548:1996 „Electrical
installations of buildings – Part 5: Selection and erection of electrical equipment – Section 548:
Earthing arrangements and equipotential bonding for information technology installations“.
d) This European Standard shall give guidance to Network operators, equipment providers and building
owners to agree on a standardised bonding configuration that facilitates:
– compliance of the Information Technology Equipment installation with functional requirements
including Electromagnetic Compatibility (EMC) aspects of emission and immunity;
– compatible building installation and equipment provisions;
– installation of new equipment in buildings as well as expansion or replacement of installations in
existing buildings with equipment coming from different suppliers;
– a structured installation practice;
– simple maintenance rules;
– contracting on a common basis;
– harmonisation in development, manufacturing, installation and operation.

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– 3 – EN 50310:2006
Content
Introduction.5
1 Scope .8
2 Normative references .8
3 Definitions, abbreviations and symbols.9
3.1 Definitions .9
3.2 Abbreviations .12
3.3 Symbols .13
4 General requirements.13
4.1 Safety from electrical hazards.13
4.2 Signal reference .13
4.3 Electromagnetic compatibility (EMC) .13
5 Requirements on bonding networks .14
5.1 Bonding configurations.14
5.2 Common bonding network (CBN) within a building .14
5.3 Bonding network (BN) within an information technology system.15
5.4 Merging of common bonding network (CBN) and meshed bonding network (MESH-BN) .15
5.5 Bonding and routing aspects of cabling within and between bonding networks.16
5.6 Indication of equipotential bonding conductors.19
6 Requirements for electricity distribution system.19
6.1 DC distribution system of secondary supply.19
6.2 DC distribution system of tertiary supply.19
6.3 AC distribution system and bonding of the protective conductor.19
6.4 AC distribution system from tertiary power supply.20
Annex A (normative) Special national conditions.25
Annex B (informative) Rationale about common bonding network (CBN) co-ordination .25
Annex C (informative) Rationale for the integration of DC distribution systems into
the merging of common bonding network (CBN) and meshed bonding network (MESH-BN) .26
Bibliography.27

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EN 50310:2006 – 4 –
Figures
Figure 1 – Schematic relationship between EN 50310 and other standards relevant
for information technology cabling systems .6
Figure 2 – Contextual relationship between EN 50310 and other standards relevant
for information technology cabling systems .7
Figure 3 - Example of a simple common bonding network (CBN) configuration
(installation of network termination e.g. for ISDN basic access).15
Figure 4 - Example of a common bonding network (CBN) configuration for an
information technology installation inside a building .17
Figure 5 - Example of an improved bonding network (CBN/MESH-BN) installation inside a building.18
Figure 6 - TN-S system (taken from HD 384.3 S2:1995).21
Figure 7 - TN-C-S system (taken from HD 384.3 S2:1995) .22
Figure 8 - TN-C system (taken from HD 384.3 S2:1995).22
Figure 9 - TT system (taken from HD 384.3 S2:1995) .22
Figure 10 - IT system (according to HD 384.3 S2:1995 and EN 60990:1999) .23
Figure 11 - Arrangements for the transition from the outdoor electricity distribution system
to the indoor electricity distribution system .24

Tables
Table 1 - Survey of electricity distribution system configurations with respect to EMC .21

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– 5 – EN 50310:2006
Introduction
This standard addresses earthing and bonding of information technology equipment in buildings in
relation to safety, functional and electromagnetic performance, taking into account that the draft does not
specify another earthing and bonding system but selects out of the existing ones (specified in
HD 384/HD 60364 series together with IEC 60364-5-548) the best suitable system to information
technology needs (CBN, MESH-BN, TN-S system).
Information regarding the general principles on earthing for (small) telecommunication installations in
buildings has been published in Recommendation ITU-T K.31.
Depending on the degree of complexity and the size of the information technology installation, different
levels of earthing and bonding are required. Starting from basic requirements on earthing and bonding
this standard defines the refinements necessary to operate information technology equipment. The
underlined concepts of this standard are in harmony with EN 300253. Therefore large information
technology installations in buildings, which may require special care to avoid damage or upset from
electromagnetic sources can make use of the bonding configurations and earthing techniques of
EN 300253.
The specifications of EN 50310 are intended to provide optimum earthing and bonding conditions for
buildings, where information technology installations are to be operated. EN 50310 should be applied at
least in the case of newly constructed buildings and whenever possible in existing buildings (e. g. on the
occasion of refurbishment). EN 50174-2 details the considerations for satisfactory installation and
operation of information technology cabling within the environment of a building operating a low-voltage
electricity distribution system (up to AC 1000 V rms). EN 50174-2 therefore refers, among others, to the
requirements of EN 50310.
Figure 1 and Figure 2 show the schematic and contextual relationships between the standards produced
by TC 215 for information technology cabling, namely this standard on equipotential bonding and earthing
requirements, the generic cabling design standards (EN 50173 series), other application dependent
cabling design standards (e.g. EN 50098 series), cabling installation standards (EN 50174 series) and
testing of installed cabling (EN 50346).

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EN 50310:2006 – 6 –
EN 50098-1: Customer premises EN 50173-2: Information technology -
cabling for information technology - Generic cabling - Office premises
ISDN basic access
EN 50173-3: Information technology -
EN 50098-2: Customer premises Generic cabling - Industrial premises
EN 50173-1: Information technology -
cabling for information technology -
EN 50173-4: Information technology - Generic cabling - General requirements
2048 kbit/s ISDN primary access and
Generic cabling - Homes
leased line network interface
EN 50173-5: Information technology -
Generic cabling - Data centres
EN 50174-1: Information technology -
Cabling installation - Specification and
quality assurance
EN 50174-2: Information technology - EN 50310: Application of equipotential
Cabling installation - Installation bonding and earthing in buildings with
planning and practices inside buildings information technology equipment
EN 50174-3: Information technology -
Cabling installation - Installation
planning and practices outside buildings
EN 50346: Information technology -
Cabling installation -
Testing of installed cabling

Figure 1 – Schematic relationship between EN 50310 and other standards relevant for
information technology cabling systems

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– 7 – EN 50310:2006

Building design Cabling design Planning phase Implementation Operation phase
phase phase phase
EN 50310 EN 50173 series EN 50174-1 EN 50174-1 EN 50174-1
except
EN 50173-4
5.2: Common bonding 4: Structure 4: Specification 6: Documentation 5: Quality assurance
network (CBN) within a considerations
5: Channel 7: Cabling
building
performance 5: Quality assurance 7: Cabling administration
6.3: AC distribution administration
7: Cable requirements 7: Cabling 8: Repair and
system and bonding of
administration maintenance

the protective conductor
8: Connecting hardware

(TN-S)
requirements

9: Requirements for
cords and jumpers
A: Link performance
limits

and and and

EN 50173-4 EN 50174-2 EN 50174-2
4 and 5: Structure 4: Safety requirements 4: Safety requirements

6: Channel 5: General installation 5: General installation
performance practices for metallic practices for metallic
and optical fibre cabling and optical fibre cabling
8: Cable requirements
6: Additional installation 6: Additional installation
9: Connecting hardware
practice for metallic practice for metallic
requirements
cabling cabling
10: Requirements for 7: Additional 7: Additional
cords and jumpers
installation practice installation practice
for optical fibre for optical fibre
A: Link performance
cabling cabling
limits

or (and) and and

EN 50098-1 EN 50174-3 EN 50174-3
or (and) See EN 50174-2 and See EN 50174-2 and

EN 50098-2
8: Additional installation 8: Additional installation
practices for specific practices for specific
sites and services sites and services

or (and) and and

(for equipotential (for equipotential
other application
bonding) bonding)
standards
EN 50310 EN 50310

5.2: Common bonding 5.2: Common bonding

network (CBN) within a network (CBN) within a
building building
6.3: AC distribution
6.3: AC distribution
system and bonding
system and bonding of
of the protective
the protective conductor
conductor (TN-S)
(TN-S)

and

EN 50346
  4: General

requirements
5: Test parameters for
balanced cabling
6: Test parameters for
optical fibre cabling
Figure 2 – Contextual relationship between EN 50310 and other standards relevant for
information technology cabling systems

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EN 50310:2006 – 8 –
1 Scope
1.1 This European Standard applies to the equipotential bonding inside buildings in which information
technology equipment is going to be installed. It contributes to the standardisation of information
technology equipment and co-ordinates with the pre-requirements of the generic installation conditions as
outlined in IEC 60364-5-548 to achieve the following targets:
a) safety from electrical hazards;
b) reliable signal reference within the entire information technology installation;
c) satisfactory electromagnetic performance of the entire information technology installation.
1.2 A defined bonding configuration down to the equipment level – independent of the equipment
supplier – is intended to facilitate
– the installation, operation and maintenance of information technology installations in buildings;
– the interworking between different information technology equipment (interconnected by metallic
links).
The specification of information technology equipment and of the pre-requirements of installation are
subject to agreement of the parties (e. g. the equipment supplier and the purchaser or building owner).
1.3 This standard applies to buildings with information technology equpiment or in which the
installation of information technology equipment is intended. It provides additional information for
architects of buildings and for designers and installers of electrical installations of buildings on some
installation concepts that limit electromagnetic influences. Basic considerations are given here to mitigate
such influences that may result in disturbance. This standard does not apply to buildings which may be
subject to a harsh electromagnetic environment, or rooms containing the generation, transmission or
termination of voltages over AC 1000 V. This standard does not address the specific requirements for
telecommunication centres; these are specified in EN 300253.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 41003, Particular safety requirements for equipment to be connected to telecommunication networks
1) 2)
EN 50083 (series), Cable networks for television signals, sound signals and interactive services ,
EN 50174-2, Information technology – Cabling installation – Part 2: Installation planning and practices
inside buildings
EN 50174-3, Information technology – Cabling installation – Part 3: Installation planning and practices
outside buildings
EN 60079-14, Electrical apparatus for explosive gas atmospheres – Part 14: Electrical installations in
hazardous areas (other than mines) IEC 60079-14:2002)
EN 60446, Basic and safety principles for man-machine interface, marking and identification -
Identification of conductors by colours or numerals (IEC 60446:1999)
———————
1)
Antenna systems are included in the scope of the EN 50083 series.
2)
 EN 50083 series will be gradually transformed into EN 60728 series.

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– 9 – EN 50310:2006
EN 60950-1, Information technology equipment – Safety – Part 1: General requirements
(IEC 60950-1:2001, modified)
EN 61140, Protection against electric shock – Common aspects for installation and equipment
(IEC 61140:2001)
EN 300253, Environmental Engineering (EE) – Earthing and bonding configuration inside
telecommunication centres
HD 384.3 S2, Electrical installations of buildings – Part 3: Assessment of general characteristics of
installations (IEC 60364-3:1993, modified)
HD 384.4.41 S2, Electrical installations of buildings – Part 4: Protection for safety – Chapter 41:
Protection against electric shock (IEC 60364-4-41:1992, modified)
3)
HD 384.5.54 S1 , Electrical installations of buildings – Part 5: Selection and erection of electrical
equipment – Chapter 54: Earthing arrangements and protective conductors (IEC 60364-5-54:1980,
modified)
IEC 61024 (series), Protection of structures against lightning
IEC 61312 (series), Protection against lightning electromagnetic impulse
3 Definitions, abbreviations and symbols
3.1 Definitions
For the purposes of this document, the following terms and definitions apply.
NOTE 1 The definitions with respect to earthing and bonding are taken from series IEC 60050. Furthermore, definitions specific to
information technology installations given in EN 300253:2002 are used. Reference to these standards is indicated, where
appropriate, in square brackets. These definitions are reproduced here to assist the reader of this standard.
NOTE 2 The concept of the various electricity distribution systems (TN-S, TN-C, TT and IT) is introduced in detail in HD 384.3 S2.
3.1.1
bonding mat
essential means to provide a SRPP by a discernible, nearly regular mesh structure
NOTE The bonding mat may be located either below or above a collection of equipment constituting a system block.
[EN 300253:2002, 3.1.2]
3.1.2
bonding network
BN (abbreviation)
set of interconnected conductive structures that provides an „electromagnetic shield“ for electronic
systems and personnel at frequencies from direct current (DC) to low radio frequency (RF)
NOTE The term „electromagnetic shield“ denotes any structure used to divert, block or impede the passage of electromagnetic
energy. In general, a BN need not be connected to earth but all BNs considered in the present document will have an earth
connection.
[EN 300253:2002, 3.1.2]
3.1.3
bonding ring conductor
BRC (abbreviation)
an earthing bus conductor which forms a closed connected ring. Normally a BRC has multiple
connections to the CBN and therefore improves its quality
———————
3)
Intended to be superseded by HD 60364-5-54 (at draft stage).

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EN 50310:2006 – 10 –
3.1.4
common bonding network
CBN (abbreviation)
principal means for effective bonding and earthing inside a building with information technology
equipment
NOTE It is the set of metallic components that are intentionally or incidentally interconnected to form the principal BN in a building.
These components include: structural steel or reinforcing rods, metallic plumbing, alternating current (AC) power conduit, protective
conductors (PE), cable racks and bonding conductors. The CBN is connected to the earthing network.
[EN 300253:2002, 3.1.2 mod.]
3.1.5
DC-C system
system where the DC power return conductors are connected to the Common Bonding Network (CBN),
ensuring simultaneously the supply and protection functions
NOTE The DC-C system is also called a "2 wire system"
[EG 201147:1998, 3.1]
3.1.6
DC-I system
system where the current return function and the grounding of the equipment are separated
NOTE The DC-I system is also called a "3 wire system"
[EG 201147:1998, 3.1]
3.1.7
DC return conductor
(+) conductor of the –48 V or –60 V secondary DC supply
[EN 300253:2002, 3.1.2]
3.1.8
(local) earth
part of the Earth which is in electric contact with an earth electrode and whose electric potential is not
necessarily equal to zero
[IEC 60050-826:2004, 826-13-02; IEC 60050-195:1998, 195-01-03]
NOTE The concept „Earth“ means the planet and all its physical matter.
3.1.9
earth electrode
conductive part, which may be embedded in the soil or in a specific conductive medium, e. g. concrete or
coke, in electric contact with Earth
[IEC 60050-826:2004, 826-13-05; IEC 60050-195:1998, 195-02-01 mod.]
3.1.10
earthing conductor
conductor which provides a conductive path, or part of the conductive path, between a given point in a
system or in an installation or in equipment and an earth electrode or an earth-electrode network
[IEC 60050-826:2004, 826-13-12; IEC 60050-195:1998, 195-02-03 mod.]
3.1.11
earth-electrode network
part of an earthing arrangement comprising only the earth electrodes and their interconnections
[IEC 60050-826:2004, 826-13-06; IEC 60050-195:1998, 195-02-21]

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– 11 – EN 50310:2006
3.1.12
equipotential bonding
provisions of electric connections between conductive parts, intended to achieve equipotentiality
[IEC 60050-826:2004, 826-13-19; IEC 60050-195:1998, 195-01-10]
3.1.13
protective bonding conductor
protective conductor provided for protective-equipotential-bonding
[IEC 60050-826:2004, 826-13-24; IEC 60050-195:1998, 195-02-10]
3.1.14
main earthing terminal
main earthing busbar
terminal or busbar which is part of the earthing arrangement of an installation and enabling the electric
connection of a number of conductors for earthing purposes
[IEC 60050-826:2004, 826-13-15; IEC 60050-195:1998, 195-02-33]
NOTE Abbreviation: MET
3.1.15
meshed bonding network
MESH-BN (abbreviation)
bonding network in which all associated equipment frames, racks and cabinets and usually the DC power
return conductor, are bonded together as well as at multiple points to the CBN
NOTE Consequently, the MESH-BN augments the CBN.
[EN 300253:2002, 3.1.2]
3.1.16
neutral conductor
conductor electrically connected to the neutral point and capable of contributing to the distribution of
electric energy
[IEC 60050-826:2004, 826-14-07; IEC 60050-195:1998, 195-02-06]
NOTE 1 Identification: N
NOTE 2 Definition of „neutral point“ see IEC 60050-826:2004, 826-14-05. The common point of a star-connected polyphase
system is also named „star point“.
3.1.17
PEN conductor
conductor combining the functions of both a protective earthing conductor and a neutral conductor
[IEC 60050-826:2004, 826-13-25; IEC 60050-195:1998, 195-02-12]
3.1.18
power supply
– primary supply: public mains or, under emergency conditions, locally generated AC supply
– secondary supply: supply to the telecommunication equipment, racks or system block, derived from
the primary supply
– tertiary supplies: supplies to the telecommunication equipment, derived from the secondary supply
[EN 300253:2002, 3.1.2]
3.1.19
protective conductor (identification: PE)
conductor provided for purposes of safety, for example protection against electric shock
[IEC 60050-826:2004, 826-13-22; IEC 60050-195:1998, 195-02-09]

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EN 50310:2006 – 12 –
3.1.20
protective equipotential bondig system
PEBS (abbreviation)
equipotential bonding system providing protective equipotential bonding
[IEC 60050-195:1998, 195-02-23]
3.1.21
signalling earth conductor
SE (abbreviation)
conductor referring signalling circuits to earth potential. The signalling functions of such circuits may
include signalling with earth return between different locations. A protective conductor (PE) may serve
simultaneously as an SE if the characteristics of the signalling functions harmonize with the imposed
safety requirements. The CBN (of which the PE is part) can provide the SE function
3.1.22
system
regularly interacting or interdependent group of items forming a unified whole
[EN 300253:2002, 3.1.2]
3.1.23
system block
functional group of equipment depending in its operation and performance on its connection to the same
system reference potential plane, inherent to a MESH-BN
[EN 300253:2002, 3.1.2]
3.1.24
system reference potential plane
SRPP (abbreviation)
conductive solid plane, as an ideal goal in potential equalizing, is approached in practice by horizontal or
vertical meshes
NOTE 1 The mesh width thereof is adapted to the frequency range to be considered. Horizontal and vertical meshes may be
interconnected to form a grid structure approximating to a Faraday cage.
NOTE 2 The SRPP facilitates signalling with reference to a common potential.
[EN 300253:2002, 3.1.2]
3.2 Abbreviations
AC alternating current
BN bonding network
BRC bonding ring conductor
CBN common bonding network
DC direct current
DC-C direct current/common
DC-I direct current/isolated
EMC electromagnetic compatibility
FE functional earthing conductor
L line conductor
3L line conductor (three times)
L+ positive DC conductor
L– negative DC conductor
LPS lightning protection system
MDF main distribution frame
MESH-BN meshed bonding network
MET main earthing terminal or busbar

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– 13 – EN 50310:2006
mod. modified
N neutral conductor
NT network termination
PE protective conductor
PEN conductor combined protective conductor and neutral conductor
SE signal earthing conductor
SPD surge protective device
SRPP system reference potential plane
TE terminal equipment
3.3 Symbols
 neutral conductor (N)
 protective conductor (PE)
 PEN conductor
4 General requirements
4.1 Safety from electrical hazards
Equipment attached to IT cabling shall be in
...