EN 50310:2010

SLOVENSKI STANDARD
01-januar-2011
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SIST EN 50310:2006
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Application of equipotential bonding and earthing in buildings with information technology
equipment
Anwendung von Maßnahmen für Erdung und Potentialausgleich in Gebäuden mit
Einrichtungen der Informationstechnik
Application de liaison équipotentielle et de la mise à la terre dans les locaux avec
équipement de technologie de l'information
Ta slovenski standard je istoveten z: EN 50310:2010
ICS:
35.020 Informacijska tehnika in Information technology (IT) in
tehnologija na splošno general
91.140.50 Sistemi za oskrbo z elektriko Electricity supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 50310
NORME EUROPÉENNE
October 2010
EUROPÄISCHE NORM
ICS 29.120.50; 91.140.50 Supersedes EN 50310:2006

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

Application de liaison équipotentielle et de Anwendung von Maßnahmen für Erdung
la mise à la terre dans les locaux avec und Potentialausgleich in Gebäuden mit
équipement de technologie de Einrichtungen der Informationstechnik
l'information
This European Standard was approved by CENELEC on 2010-10-01. 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, Bulgaria, Croatia, 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

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50310:2010 E
Foreword
This European Standard was prepared by the Technical Committee CENELEC TC 215,
Electrotechnical aspects of telecommunication equipment. The text of the draft was submitted to the
formal vote and was approved by CENELEC as EN 50310 on 2010-10-01.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
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) 2011-10-01
– latest date by which the national standards conflicting

with the EN have to be withdrawn
(dow) 2013-10-01
This European Standard supersedes EN 50310:2006.
In the course of the revision of EN 50310:2006, some elements from EN 50174-2:2000 have been
moved to this European Standard for reasons of clarity.
This European 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 and protection against electric shock – 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.

– 3 – EN 50310:2010
Contents
Introduction . 5
1 Scope and conformance . 8
1.1 Scope . 8
1.2 Conformance . 8
2 Normative references . 9
3 Terms, definitions, abbreviations and symbols . 9
3.1 Terms and definitions . 9
3.2 Abbreviations .11
3.3 Symbols .11
4 General requirements .12
4.1 Co-ordination .12
4.2 Safety from electrical hazards .12
4.3 Segregation between information technology cabling and power supply cabling .12
4.4 Main earthing terminal (MET) .12
4.5 Signal reference .12
5 Application of earthing networks .12
5.1 General .12
5.2 Requirements and recommendations .13
5.3 Hierarchy of earthing network performance .13
6 Earthing networks.17
6.1 General .17
6.2 Star earthing networks .20
6.3 Ring earthing networks .21
6.4 Local mesh earthing networks .21
6.5 Meshed earthing networks .23
6.6 SRPP .25
7 Bonding .25
7.1 Equipotential bonding conductors .25
7.2 System Reference Potential Plane (SRPP) .28
7.3 Corrosion .30
8 DC power distribution systems .30
8.1 DC distribution system of secondary supply .30
8.2 DC distribution system of tertiary supply .31
9 Power supply distribution systems .32
Annex A (informative) Rationale about common bonding network (CBN) co-ordination .33
Annex B (informative) Rationale for the integration of DC distribution systems into the
merging of common bonding network (CBN) and meshed bonding network (MESH-BN) .34
Bibliography .35

Figures
Figure 1 – Schematic relationship between EN 50310 and other relevant standards . 6
Figure 2 – Examples of earthing networks .15
Figure 3 – Examples of area-specific earthing networks within premises .16
Figure 4 – Example of a simple common bonding network (CBN) configuration (installation of
network termination) .17
Figure 5 – Example of a common bonding network (CBN) configuration for an information
technology installation inside a building .18
Figure 6 – Example of an improved bonding network (CBN/MESH-BN) installation inside a building .19
Figure 7 – Example of high common impedance and large loop .20
Figure 8 – Example of low common impedance and small loop .21
Figure 9 – Local mesh earthing network .22
Figure 10 – Mesh earthing network (multi-floor).24
Figure 11 – Mesh-BN example .26
Figure 12 – Example of bonding straps .27
Figure 13 – Example of raised floor .29
Figure 14 – Example of installation details for an under floor transient suppression plate .29

Tables
Table 1 – Contextual relationship between EN 50310 and other relevant standards . 7
Table 2 – Survey of DC electricity distribution system configurations with respect to EMC .31
Table 3 – Survey of AC electricity distribution system configurations with respect to EMC .32

– 5 – EN 50310:2010
Introduction
This European Standard specifies requirements and recommendations for connections (bonds) to
earthing networks in buildings in which information technology (IT) equipment is intended to be
installed in order to:
a) minimise the risk to that equipment and interconnecting cabling from electrical hazards,
b) provide the information technology installation with:
– a reliable signal reference;
– adequate immunity from electromagnetic interference carried by the earthing network.
Different minimum requirements are specified depending on the intended use of the building with
regard to information technology.
The requirements of this European Standard are applicable when information technology cabling
installations are planned (including, for example, during the refurbishment of buildings).
This document is intended for:
1) building architects, owners and managers;
2) designers and installers of electrical and information technology cabling installations.
Figure 1 and Table 1 show the schematic and contextual relationships between the standards
produced by TC 215 for information technology cabling, namely:
• installation specification, quality assurance, planning and installation practices (EN 50174 series);
• generic cabling design (EN 50173 series);
• application dependent cabling design (e.g. EN 50098 series);
• testing of installed cabling (EN 50346);
• this European Standard (EN 50310).

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Figure 1 – Schematic relationship between EN 50310 and other relevant standards

– 7 – EN 50310:2010
Table 1 – Contextual relationship between EN 50310 and other relevant standards
Building design Generic cabling Specification Installation Operation
phase design phase phase phase phase
EN 50310 EN 50173 series EN 50174-1 EN 50174-1
except
EN 50173-4
6 Earthing 4 Structure 4 Requirements for 4 Requirements for
networks specifying specifying
5 Channel
installations of installations of
performance
information information
7 Cable
technology technology
requirements cabling cabling
8 Connecting 5 Requirements for
hardware
installers of
requirements information
technology
9 Requirements for
cabling
cords and
jumpers
A Link performance
limits
Planning
phase
and
EN 50173-4 EN 50174-2 EN 50174-2
4 and 5 Structure 4 Requirements for 5 Requirements for
planning the installation of
6 Channel
installations of information
performance
information technology
8 Cable technology cabling
requirements cabling
6 Segregation of
9 Connecting
6 Segregation of metallic
hardware metallic information
requirements information technology
technology cabling and
10Requirements for
cabling and mains power
cords and
mains power cabling
jumpers
cabling
A Link performance
7 Electricity
limits
distribution
systems and
lightning
protection
and and
EN 50174-3 EN 50174-3
and and
(for equipotential (for equipotential
bonding) bonding)
EN 50310 EN 50310
and
EN 50346
4 General
requirements
5 Test parameters
for balanced
cabling
6 Test parameters
for optical fibre
cabling
1 Scope and conformance
1.1 Scope
This European Standard specifies minimum requirements for earthing networks and connections
(bonds) in buildings in which information technology equipment is intended to be installed to protect
that equipment and interconnecting cabling from electrical hazards.
Additionally this European Standard specifies requirements and provides recommendations for
earthing networks and connections (bonds) in order for the information technology installation to
achieve
a) reliable signal reference,
b) adequate immunity from electromagnetic interference carried by the earthing network.
The requirements of this European Standard are applicable to all types of buildings ranging from
residential to large commercial and industrial premises. Operator buildings are addressed by
ETSI EN 300 253.
This European standard specifies an earthing and bonding configuration that is appropriate to specific
mains and other power supply distribution systems.
NOTE For the purposes of this European Standard bonding networks are connected to earth and therefore create an earthing
network.
This European Standard does not:
1) apply to power supply distribution of voltages over AC 1 000 V;
2) address the specific requirements for telecommunication centres (operator buildings); these are
specified in ETSI EN 300 253.
Safety requirements for power supply installation are outside the scope of this European Standard and
are covered by other standards and regulations. However, information given in this European
Standard may be of assistance in meeting these standards and regulations.
1.2 Conformance
In order to conform to this European Standard:
a) the general requirements of Clause 4 shall be met;
b) earthing and bonding networks shall meet the requirements of Clause 5;
c) bonding connections shall meet the requirements of Clause 7;
d) the mains and other power supply distribution systems shall meet the requirements of Clause 8;
e) the installation of information technology cabling shall be in accordance with the EN 50174 series;
f) local regulations, including safety, shall be met.

– 9 – EN 50310:2010
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 and/or a cable distribution system
1)
EN 50083 series , Cable networks for television signals, sound signals and interactive services
EN 50162:2004, Protection against corrosion by stray current from direct current systems
EN 50174-1, Information technology – Cabling installation – Part 1: Installation specification and
quality assurance
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, Explosive atmospheres – Part 14: Electrical installations design, selection and erection
(IEC 60079-14)
EN 60728 series, Cable networks for television signals, sound signals and interactive services
(IEC 60728 series)
EN 60950-1, Information technology equipment – Safety – Part 1: General requirements
(IEC 60950-1, mod.)
EN 61140, Protection against electric shock – Common aspects for installation and equipment
(IEC 61140)
EN 62305-4, Protection against lightning – Part 4: Electrical and electronic systems within structures
(IEC 62305-4)
HD 60364-4-41, Low-voltage electrical installations – Part 4-41: Protection for safety – Protection
against electric shock (IEC 60364-4-41:2005, mod.)
HD 60364-4-444, Low-voltage electrical installations – Part 4-444: Protection for safety – Protection
against voltage disturbances and electromagnetic disturbances (IEC 60364-4-44:2007, mod.)
HD 60364-5-54:2007, Low-voltage electrical installations – Part 5-54: Selection and erection of
electrical equipment – Earthing arrangements, protective conductors and protective bonding
conductors (IEC 60364-5-54:2002, mod.)
3 Terms, definitions, abbreviations and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
bond
connection to provide equipotential between objects
———————
1)
Being partly replaced by EN 60728 series.

3.1.2
bonding network
BN
set of interconnected conductive structures that provide equipotential
3.1.3
bonding ring conductor
earthing bus conductor which forms a closed conducting ring
NOTE Normally the bonding ring conductor, as part of the bonding network, has multiple connections to the common bonding
network that improves its performance.
3.1.4
common bonding network
CBN
means for effective bonding and earthing inside a telecommunication building
3.1.5
earthing network
bonding network that is connected to earth
3.1.6
isolated bonding network
IBN
bonding network that has a single point of connection to either the common bonding network or
another isolated bonding network
NOTE All IBNs considered here will have a connection to earth through the single point of connection.
3.1.7
meshed bonding network
MESH-BN
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.
[ETSI EN 300 253:2002, 3.1.2, mod.]
3.1.8
meshed isolated bonding network
MESH-IBN
meshed bonding network that has a single point of connection to either the common bonding network
or another isolated bonding network
3.1.9
mesh size
maximum length of conducting material between two adjacent connection points that create the grid of
the bonding network
3.1.10
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
[ETSI EN 300 253:2002, 3.1.2]
– 11 – EN 50310:2010
3.1.11
system reference potential plane
SRPP
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 of 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 facilities signalling with reference to a common potential.
[ETSI EN 300 253:2002, 3.1.2]
3.2 Abbreviations
For the purposes of this document, the following abbreviations apply.
3L Three-phase live power supply conductor
AC Alternating Current
BN (Earthing) Bonding Network
CATV Community Antenna TeleVision
CBN Common Bonding Network
d.c., DC Direct Current
EMC ElectroMagnetic Compatibility
EMI ElectroMagnetic Interference
IBN Isolated Bonding Network
IT Information Technology
L Live power supply conductor
LPS Lightning Protection System
MESH-BN Meshed Bonding Network
MESH-IBN Meshed Isolated Bonding Network
MET Main Earthing Terminal, bar or busbar
N Neutral power supply conductor
PE Protective Earth conductor
SRPP System Reference Potential Plane
TSP Transient Suppression Plate
3.3 Symbols
For the purposes of this document, the following symbols apply.
Bonding connection
Neutral conductor (N)
Protective earth conductor (PE)

4 General requirements
4.1 Co-ordination
The basic purposes of earthing networks in relation to information technology equipment are:
a) safety: touch voltage limitation and earth fault return path;
b) electromagnetic interference (EMI): a single potential reference and voltage equalisation,
screening effect.
The design of earthing networks for information technology infrastructures inside and between
buildings shall be co-ordinated with all parties directly involved in the management of safety and EMI
(e.g. power supply, CATV, railways, tramways, lightning protection, etc).
4.2 Safety from electrical hazards
Equipment attached to information technology (IT) cabling shall be in accordance with EN 60950-1 or
EN 41003, as appropriate. The installation of protective earth conductors (PE) and equipotential
bonding conductors shall be in accordance with HD 60364-4-41, HD 60364-5-54 and EN 61140
(requirements for installations in buildings).
4.3 Segregation between information technology cabling and power supply cabling
See EN 50174-2.
4.4 Main earthing terminal (MET)
Each building shall be provided with a designated MET.
The entrance facilities for metallic information technology cables shall be placed as close as possible
to either the MET or designated points providing connections to the MET.
In order to minimize surge voltages and effects of surge currents in the building, the screens of all
cables entering the building shall be bonded to the MET via a low-impedance path, i.e. by the shortest
possible connection (see Figure 4, 5 and 6).
4.5 Signal reference
In order to maintain a good signal reference, emphasis should be placed on proper equipotential
bonding of both the information technology and the electricity distribution systems. Signalling via earth
return shall be avoided.
5 Application of earthing networks
5.1 General
This European Standard specifies requirements for earthing and bonding networks for all buildings
intended to accommodate information technology equipment within which it is recognised that:
a) stray currents inevitably propagate in an earthing network;
b) it is impossible to remove all sources of disturbances at a site;
c) ground loops are inevitable (see 6.2.2);

– 13 – EN 50310:2010
d) when an external magnetic field affects the site, e.g. a field produced by lightning, potential
differences are induced in the loops and currents flow in the earthing system and the efficacy of
the earthing network inside a building depends largely on the countermeasures taken outside the
building;
e) currents flowing in a non-equipotential earthing network may generate electromagnetic
disturbances that affect equipment.
5.2 Requirements and recommendations
With reference to Figure 2, this European Standard recommends the implementation of a Type D,
meshed, earthing network meeting the requirements and recommendations of 6.5. However, this
European Standard addresses a range of alternative earthing networks, some of which are not
compatible with, or do not support the easy implementation of, a meshed earth network. These are
also shown in Figure 2 and described as follows:
a) Type A: Star earthing network;
b) Type B: Ring earthing network;
c) Type C: Local mesh earthing network.
The minimum requirements for each type of earthing network are specified in Clause 6 as follows:
1) Type A: Star – see 6.2.1;
2) Type B: Ring – see 6.3.1;
3) Type C: Local mesh – see 6.4.1 and 6.6;
4) Type D: Mesh – see 6.5.1 and 6.6.
In addition, this European Standard provides recommendations for the improvement of these earthing
networks to protect information technology equipment and interconnecting cabling from electrical
hazards. The recommended improvements for each type of earthing network are specified in Clause 6
as follows:
– Type A: Star – see 6.2.2;
– Type B: Ring – see 6.3.2;
– Type C: Local mesh – see 6.4.2;
– Type D: Mesh – see 6.5.2.
5.3 Hierarchy of earthing network performance
Earthing networks are considered to be hierarchical as follows:
a) an earthing network meeting the requirements of Type A is improved by the application of the
recommendations appropriate to that type of earthing network;
b) a Type B earthing network provides better protection than a Type A earthing network and is
improved by the application of the recommendations appropriate to that type of earthing network;
c) a Type C earthing network provides better protection than a Type B earthing network and is
improved by the application of the recommendations appropriate to that type of earthing network;
d) a Type D earthing network provides better protection than a Type C earthing network and is
improved by the application of the recommendations appropriate to that type of earthing network.

For some applications, for example, in broadcast buildings, star and local mesh earthing networks
have advantages.
The solution applied in a particular building should follow a detailed risk assessment that takes the
following into consideration:
1) the purpose of the building or specific areas of the building (noting that different parts of a building
may justify the use of different earthing network and additional bonding solutions as shown in
Figure 3);
2) the cost (noting that subsequent improvements applied to an earthing network are more
expensive than the initial installation of solution of a higher hierarchical level).

– 15 – EN 50310:2010
Earthing Name Minimum requirements Recommended improvements
network (thickened lines show additional bond
type connections)
A Star
See 6.2.1 See 6.2.2
or
B Ring
See 6.3.1
See 6.3.2
Local
C
mesh
BBoonndd c coonnnecnecttiiononss at at al alll mmeesshh i inntteerrsseeccttiioonnss
anand bed betwtweeeen n memesshh aanndd equ equiippmmeenntt
See 6.4.1
See 6.4.2
Figure 2 – Examples of earthing networks

Earthing Name Minimum requirements Recommended improvements
network (thickened lines show additional bond
type connections)
D Mesh
BBoond cnd coonnnecnecttiioonnss at at aallll m meesshh iinntteerrssecectitiononss
andand b beettwweeneen m meesshh and and eqequuiipmpmenentt

See 6.5.1
BBoond cnd coonnnnececttiioonnss at at aallll m meesshh iinntteerrssecectitiononss
andand b beettwweeneen m meesshh and and eqequuiipmpmenentt

See 6.5.2
Figure 2 – Examples of earthing networks (continued)
BondBond c connectiononnections s at all mat all meesshh int inteersrsecectionstions
anand betd betwweeeenn m meesshh anand d equequipmipmeentnt

Figure 3 – Examples of area-specific earthing networks within premises

– 17 – EN 50310:2010
6 Earthing networks
6.1 General
It is possible to address bonding configurations at:
a) a building level i.e. a common bonding network (CBN) or a meshed bonding network (MESH-BN);
b) an installation level i.e. merging a CBN and MESH-BN;
c) an equipment level i.e. MESH-BN.
Metallic components (e.g. MET, protective conductors (PE), metallic plumbing, structural steel,
reinforcement rods) shall be used, in accordance with national or local regulations, to construct a basic
CBN. Improved CBN performance is achieved by reducing the impedance and increasing the current
carrying capacity of the CBN by the use of additional conductive components either
1) to create an improved earthing network type (see 5.3)
or
2) implement the recommended improvements as indicated in Figure 2 and as detailed in this
clause for the existing type of earthing network.
For bonding configurations of telecommunication equipment at a building and installation level in a
subscriber's building, ETSI EN 300 253, ITU-T K.27 and ITU-T K.73 provide additional information.
For examples of simple CBN configurations for an information technology installation inside a building
see Figure 4 (for single items of equipment) and Figure 5 (for cabinets containing equipment).

a
Low impedance path; as short as possible (see 4.4).
b
Protective conductor (PE) to be routed in close proximity to signal cables to minimize loop area (see 6.2.2).
c
Functional earthing conductor (FE), e.g. signal earthing conductor, optional for equipment using earth return signalling.
NOTE If Network termination (NT) or Terminal equipment (TE) have non-conducting cases, then the PE is not connected to the
case.
Figure 4 – Example of a simple common bonding network (CBN) configuration
(installation of network termination)

.
a
Optional for equipment using earth return signalling
b
Low impedance path; as short as possible (see 4.4)
c
The MET may be located in the main AC distribution board.
Figure 5 – Example of a common bonding network (CBN) configuration
for an information technology installation inside a building

– 19 – EN 50310:2010
a
Surge protective device (SPD) in main distribution frame (MDF), if necessary
NOTE Although a -48 V supply is detailed, the principles shown may be applied to other DC supplies (voltage and polarity).
Figure 6 – Example of an improved bonding network (CBN/MESH-BN)
installation inside a building

An extension of the information technology installation inside a building, e.g. information technology
systems situated on different floors and interconnected by metallic information technology cabling,
may require such a minimum CBN version to be augmented into a three dimensional grid structure,
approximating a Faraday cage (ETSI EN 300 253:2002, Figure 1).
A system block within an information technology system shall be provided with a bonding network
(BN) of the mesh type as shown in Figure 6. The impact EMI in an exposed location or the need for
information security may require the provision of shielded rooms as an additional requirement to the
CBN.
For a complex information technology installation a system reference potential plane (SRPP) as
shown in Figure 6 may be required to achieve satisfactory performance. Requirements for an SRPP
are specified in 6.6.
NOTE Although Figure 6 details a - 48 V supply, the principles shown may be applied to other DC supplies (voltage and
polarity).
6.2 Star earthing networks
6.2.1 Requirements
For the purposes of safety, the earthing networks shall meet national or local regulations for protective
earth (PE).
Each item of equipment shall be connected to the earth terminal by its own PE conductor as shown in
Figure 2 (minimum requirements, Type A).
6.2.2 Recommendations
Where the equipment served by the star earthing network is interconnected, the following problems
may result where the PE conductors are long or the items of equipment are some distance from each
other:
a) a high common impedance between equipment (see Figure 7);
b) large ground loops (see Figure 7);
c) a poor equipotential state particularly at high frequencies.
This configuration makes electronic equipment more vulnerable to electromagnetic disturbances.
High High
potential potential
difference difference
Disturbed cable
Equipment Equipment Equipment Equipment
No.1 No.2 No.1 No.2
Signal Signal
I
MC
cable cable
PE PE PE PE
High impedance
if Large loop
z z
PE conductor is long
EM field
Figure 7 – Example of high common impedance and large loop
Additional bonding conductors should be connected between the equipment in order to reduce both
the common impedance and the size, and resulting effect, of the relevant ground loop (see reduced
ground loop shown by shaded area in Figure 8). The bonding conductors to be used are specified in
7.1.2.
The recommended improvement for the star earthing network is shown in Figure 2 (Type A).

– 21 – EN 50310:2010
Low Low
potential potential
difference difference
Disturbed cable
Equipment Equipment Equipment Equipment
No.1 No.2 No.1 No.2
I
MC
C C
PE PE PE PE
z z
EM field
An additional bonding An additional bonding
conductor (C) reduces the conductor (C) reduces the area
common impedance between of the sensitive loop
equipment
Figure 8 – Example of low common impedance and small loop
6.3 Ring earthing networks
6.3.1 Requirements
For the purposes of safety, the earthing networks shall meet national or local regulations for protective
earth (PE).
Each item of equipment shall be connected to the bonding ring conductor by its own PE conductor as
shown in Figure 2 (minimum requirements, Type B).
6.3.2 Recommendations
Multiple bonding conductors should not be attached to a single connection point (e.g. screw, bolt) due
to the risk of interruption of all connections during maintenance or repair. Bonding connections may
use existing or additional conductors. The bonding conductors to be used are specified in 7.1.2.
The recommended improvement for the ring earthing network is shown in Figure 2 (Type B).
In addition, it is recommended that bonding conductors should be connected between conductive
cable management systems and the bonding ring conductor. The bonding conductors to be used are
specified in 7.1.2.
6.4 Local mesh earthing networks
6.4.1 Requirements
For the purposes of safety, the earthing networks shall meet national or local regulations for protective
earth (PE).
A local mesh requires all metallic parts in a restricted area within a building to be bonded to provide an
electrically continuous earthing network with low impedance and shall include:
a) cabinets, frames and racks;
b) conductive pathway systems;
c) cable screens (the treatment of information technology cabling screens is specified in
EN 50174-2);
d) bonding mats, where appropriate.

This shall be achieved by a combination of the following:
1) the installation of additional bonding conductors;
2) the improvement of finishing and fastening methods for existing bonding conductors.
Figure 9 shows a local mesh earthing network installed within both star and ring earthing networks.
Such earthing networks constitute local mesh isolated bonding networks (MESH-IBN).
There shall be a connection between the local mesh earthing network and the CBN including the main
earthing terminal.
PEPE
LocLocaall m meesshh eaearrtthihinngg netnetwwoorrkk

PEPE
PEPE
LLoocacall m meeshsh
PEPE
eaearrtthhiingng nneettwwororkk
PEPE
BBondiondinngg r riinngg cconduonduccttoror

Figure 9 – Local mesh earthing network
The maximum horizontal mesh size in each area shall be 6 m. The bonding conductors to be used are
specified in 7.1.2.
The pathways of metallic information technology cables within and between local mesh earthing
networks shall be routed along the elements of the CBN.
Specific areas within buildings may be subject to more stringent requirements that require the local
mesh earthing network to be improved either as recommended in 6.4.2 or to provide an SRPP (see
6.6).
6.4.2 Recommendations
The information technology cabling at entry points to a local mesh earthing network should be located
in close proximity.
The electromagnetic interference from a local meshed earthing network reduces significantly as the
mesh size is reduced.
– 23 – EN 50310:2010
There should be multiple connections between the local mesh earthing network and the CBN including
the main earthing terminal.
Bonding connections between equipment and the earthing network should be in accordance with
7.1.5.
6.5 Meshed earthing networks
6.5.1 Requirements
6.5.1.1 General
For the purposes of safety, the earthing networks shall meet national or local regulations for protective
earth (PE).
A mesh requires all metallic parts within large areas within, or all of, building to be bonded to provide a
mesh bonding network (MESH-BN) that provides an electrically continuous earthing network with low
impedance and shall include:
a) cabinets, frames and racks;
b) conductive pathway systems;
c) cable screens (the treatment of information technology cabling screens is specified in
EN 50174-2);
d) bonding mats, where appropriate.
This shall be achieved by a combination of the following:
1) the installation of additional bonding conductors;
2) the improvement of finishing and fastening methods for existing bonding conductors.
There shall be multiple points of connection between the MESH-BN and the CBN including the main
earthing terminal.
Figure 10 shows a mesh earthing network installed in a multi-floor building. For a detailed example of
the implementation principles of the MESH-BN concept see ETSI EN 300 253:2002, Figure 2.

Figure 10 – Mesh earthing network (multi-floor)
The maximum horizontal mesh size in each area shall be 6 m. The bonding conductors to be used are
specified in 7.1.2.
...