SIST EN 50310:2016/A2:2026

• Abstract:

  This document specifies requirements and provides recommendations for the design and installation of connections (bonds) between various electrically conductive elements in buildings and other structures, during their construction or refurbishment, in which information or telecommunications technology equipment is intended to be installed in order to: a) minimise the d.c. and a.c. potential differences in order to reduce the risk of malfunction of that equipment and interconnecting cabling due to electromagnetic disturbance; b) provide the telecommunications installation with a reliable signal reference – which may improve immunity from electromagnetic interference (EMI). The requirements of this European Standard are applicable to the buildings and other structures within premises addressed by EN 50174-2 (e.g. residential, office, industrial and data centres) but information given in this European Standard may be of assistance for other types of buildings and structures. NOTE Telecommunications centres (operator buildings) are addressed by ETSI/EN 300 253. This European Standard does not apply to power supply distribution of voltages over AC 1 000 V. Electromagnetic compatibility (EMC) requirements and 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 the requirements of these standards and regulations.

• Status: Published
• Public Enquiry End Date: 30-Mar-2026
• Publication Date: 26-Aug-2026
• ICS: 29.120.50 - Fuses and other overcurrent protection devices
• ICS: 35.020 - Information technology (IT) in general
• ICS: 91.140.50 - Electricity supply systems
• Technical Committee: ELI - Electrical and communication installations
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 24-Jul-2026
• Due Date: 28-Sep-2026
• Completion Date: 27-Aug-2026
• Ref Project: EN 50310:2016/A2:2026 - Telecommunications bonding networks for buildings and other structures

• Amends: SIST EN 50310:2016 - Telecommunications bonding networks for buildings and other structures
• Effective Date: 13-Aug-2024

Overview

SIST EN 50310:2016/A2:2026 is a European standard that specifies the requirements and provides recommendations for the design and installation of telecommunications bonding networks in buildings and other structures. Developed by SIST in collaboration with CENELEC, this standard focuses on methods to minimize d.c. and a.c. potential differences, reducing electromagnetic disturbances that could affect telecommunications and IT equipment. It supports the establishment of a reliable signal reference, improving immunity to electromagnetic interference (EMI) in various building types, including residential, office, industrial, and data centers.

This standard is relevant when information or telecommunications technology equipment is installed during either new construction or refurbishment projects. The guidelines assist in supporting proper bonding and grounding to protect the functionality and safety of interconnected telecommunications systems.

Key Topics

• Bonding and Grounding Requirements

  • Guidance for connecting electrically conductive elements to minimize potential differences.
  • Recommendations for integrating bonding networks into building infrastructure at design and installation phases.

• Reduction of Electromagnetic Disturbance

  • Strategies for lowering the risk of malfunction in equipment and cabling due to EMI.
  • Establishment of a reliable signal reference for telecommunications installations.

• Types of Bonding Networks

  • Identification and application of different network types: star, ring, local mesh, and mesh configurations.
  • Selection criteria based on sensitivity and operational requirements.

• Documentation and Compliance

  • Emphasis on comprehensive documentation (technical drawings, layouts, schematics) for bonding systems.
  • Encouragement to use electronic and AIM-compliant documentation platforms.

• Applicable Building Types

  • Application in residential, office, industrial, and data centers, with adaptability for other structures.

• Normative References and Integration

  • Alignment and cross-reference with related standards (for example, EN 50174-2 for cabling installation).

Applications

The implementation of SIST EN 50310:2016/A2:2026 delivers practical value in multiple contexts:

• Commercial Properties: Ensures that office buildings and data centers have robust bonding and grounding, vital for stable telecommunications networks and IT system operations.
• Industrial Facilities: Supports EMI management in environments with high levels of electrical activity, helping to maintain equipment functionality and safety.
• Residential Developments: Increases the reliability of telecommunications services, which is especially important for smart home technologies.
• Data Centers: Provides a foundation for enhanced uptime and operational continuity by mitigating potential differences and EMI.
• Refurbishments and Retrofits: Guidance can be leveraged during system upgrades or rebuilds, minimizing disruptions to ongoing IT services.

By following this standard, property owners, facility managers, electrical engineers, and installers can minimize service disruptions, improve safety, and future-proof facilities for evolving telecommunications needs.

Related Standards

Implementing SIST EN 50310:2016/A2:2026 is often part of a broader approach to telecommunications infrastructure, typically used in conjunction with:

• EN 50174-2:2018 - Cabling installation planning and best practices inside buildings
• EN 50173 series - General requirements for information technology cabling
• EN IEC 62368-1 - Safety requirements for audio/video, information, and communication technology equipment
• EN 50667 - Automated infrastructure management (AIM) systems requirements and applications

Other relevant references include standards for power distribution and electromagnetic compatibility (EMC), though these topics are addressed separately.

---

Keywords: telecommunications bonding network, building grounding, potential equalization, electromagnetic interference mitigation, IT equipment installation, structured cabling standards, telecommunications infrastructure, SIST EN 50310

SLOVENSKI STANDARD
01-oktober-2026
Izenačitev potencialov in ozemljevanje v stavbah z opremo informacijske
tehnologije - Dopolnilo A2
Telecommunications bonding networks for buildings and other structures
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 50310:2016/A2:2026
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
EUROPÄISCHE NORM May 2016
ICS 29.120.50; 91.140.50 Supersedes EN 50310:2010
In accordance with CENELEC/BT Decision D144/010, this consolidated version is purely
informal and is intended to be used by the CENELEC National Committees only.

This document includes Amendment 1, approved by CENELEC on 2019-12-13, and Amendment
2, approved by CENELEC on 2026-06-13
The start and finish of text introduced or altered by amendment is indicated in the text by tags
!" and #$.
English Version
Telecommunications bonding networks for buildings and other
structures
Application de liaison équipotentielle et de la mise à la terre Anwendung von Maßnahmen für Erdung und
dans les locaux avec équipement de technologie de Potentialausgleich in Gebäuden mit Einrichtungen der
l'information Informationstechnik

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 50310:2016 E
EN 50310:2016+A2:2026 (E)
Contents
European foreword . 4
Introduction . 6
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviations . 9
3.1 Terms and definitions . 9
3.2 Abbreviations .12
4 Conformance .12
5 Overview of bonding networks .13
6 Selection of the telecommunications bonding network approach .15
6.1 Assessment of the impact of the telecommunications bonding network on the
interconnection of telecommunications equipment .15
6.2 Telecommunications bonding networks .17
6.3 Telecommunications bonding network performance .18
6.3.1 General . 18
6.3.2 Requirements . 18
6.3.3 DC resistance measurements . 19
7 Common features .20
7.1 General .20
7.2 Protective bonding networks .20
7.2.1 Protective bonding network conductors (PBNCs) . 20
7.2.2 Main earthing terminal (MET) . 20
7.3 Telecommunications entrance facility (TEF) .20
7.4 Telecommunications bonding network components .21
7.4.1 Telecommunications bonding network conductors . 21
7.4.2 Telecommunications bonding network connections . 21
7.5 Cabinets, frames and racks .22
7.5.1 External connections to a bonding network . 22
7.5.2 Rack bonding conductors . 23
7.5.3 Internal connections . 24
7.6 Miscellaneous bonding connections .25
7.6.1 General . 25
7.6.2 Bonding conductors for d.c. resistance control. 25
7.6.3 Bonding conductors for impedance control . 25
7.7 Documentation .26
8 Dedicated telecommunications bonding network .26
8.1 General .26
8.2 Components .27
8.2.1 Primary bonding busbar (PBB) . 27
8.2.2 Secondary bonding busbar (SBB) . 28
8.2.3 Bonding conductors for d.c. resistance control. 28
8.2.4 Bonding conductors for impedance control . 30
8.3 Implementation .31
8.3.1 Primary bonding busbar (PBB) . 31
8.3.2 Secondary bonding busbar (SBB) . 32
8.3.3 Telecommunications bonding conductor (TBC) . 33
8.3.4 Telecommunications bonding backbone (TBB) . 33
8.3.5 Backbone bonding conductor (BBC) . 33
8.3.6 Bonds to continuous conductive pathway systems . 33
8.3.7 Bonds to structural metal . 33
EN 50310:2016+A2:2026 (E)
9 Local telecommunications bonding networks in conjunction with protective bonding
networks .34
9.1 Bonding for local distribution .34
9.1.1 Star protective bonding networks . 34
9.1.2 Ring protective bonding networks . 35
9.2 Telecommunications bonding conductors .36
9.2.1 Bonding conductors for d.c. resistance control. 36
9.2.2 Bonding conductors for impedance control . 37
9.3 Bonding for areas of telecommunications equipment concentration .37
10 Local telecommunications bonding networks in conjunction with dedicated
telecommunications bonding networks .38
10.1 Bonding for areas of telecommunications equipment concentration .38
10.1.1 Requirements . 38
10.1.2 Recommendations . 38
10.1.3 Cabinets, frames and racks . 38
10.2 Telecommunications equipment bonding conductors (TEBC) .38
10.2.1 TEBC for d.c. resistance control . 38
10.2.2 TEBC for impedance control . 38
10.2.3 Implementation . 38
11 Mesh bonded networks .39
11.1 General .39
11.2 Mesh bonding alternatives.40
11.2.1 Local mesh bonding (MESH-IBN) networks . 40
11.2.2 MESH-BN . 42
11.3 Bonding conductors of a mesh bonding network .42
11.3.1 Requirements . 42
11.3.2 Recommendations . 43
11.4 Bonding conductors to the mesh bonding network .43
11.5 Supplementary bonding grid (SBG) .44
11.6 System reference potential plane (SRPP) .44
11.6.1 General . 44
11.6.2 Access floors . 44
11.6.3 Transient suppression plate (TSP) . 45
Annex A (normative) Maintenance of telecommunications bonding network performance .47
A.1 General .47
A.2 Periodic activity .47
A.2.1 Schedule .47
A.2.2 Implementation .47
A.2.2.1 Protective bonding network .47
A.2.2.2 Dedicated bonding network .47
A.3 Causes of performance deterioration .48
A.3.1.1 Assessment of results .47
A.3.2 Galvanic corrosion .48
A.3.3 Requirements .48
Bibliography .49

EN 50310:2016+A2:2026 (E)
European foreword
This document (EN 50310:2016) was prepared by the CLC/TC 215, “Electrotechnical aspects of
telecommunication equipment”.
The following dates are fixed:
• latest date by which this document has to be (dop) 2017–04–11
implemented at national level by publication of
an identical national standard or by
endorsement
• latest date by which the national standards (dow) 2019–04–11
conflicting with this document have to
be withdrawn
This document supersedes EN 50310:2010.
In 2012, EN 50310:2010 had been offered to ISO/IEC JTC 1/SC 25 “Interconnection of information
technology equipment” as input to the agreed project to seek global harmonization of the technical
requirements for telecommunications bonding networks. This project, ISO/IEC 30129, has been
finished successfully. Thus, TC 215 decided to transpose ISO/IEC 30129 into the fourth edition of
EN 50310 with minimal editorial changes to fit European needs. In this context, also the title of
EN 50310 has been changed to adopt the title of ISO/IEC 30129.
EN 50310 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 standardized 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,
EN 50310:2016+A2:2026 (E)
– contracting on a common basis,
– harmonization in development, manufacturing, installation and operation.
EN 50310:2016+A2:2026 (E)
Introduction
This European Standard
1) specifies assessment criteria to determine the relevant bonding configurations that are
appropriate,
2) enables the implementation of any bonding configurations that may be necessary by means of
either
– the provision of a bonding network that utilizes the existing protective bonding network for
electrical safety, or
– the provision of a dedicated bonding network for the telecommunications infrastructure.
This standard is intended for
• building architects, owners and managers,
• designers and installers of electrical and telecommunications cabling installations.
Users of this standard should be familiar with all applicable cabling design and installation standards.
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 50700");
• testing of installed cabling (EN 50346);
• this European Standard (EN 50310).
EN 50310:2016+A2:2026 (E)
#
Figure 1 — Schematic relationship between EN 50310 and other relevant standards
$
#
Table 1 — Contextual relationship between EN 50310 and other relevant standards
Building design Generic cabling Specification Installation Operation phase
phase design phase phase phase
EN 50173-2 EN 50174-1
EN 50173-3
Planning phase
EN 50173-4
EN 50173-5
EN 50174-2
EN 50173-6
EN 50174-3
EN 50310 EN 50174-1
EN 50174-4
EN 50173-10 EN 50174-2
EN 50310
EN 50174-3
EN 50173-20
EN 50310
(these ENs
reference general
requirements of
EN 50173-1)
$
EN 50310:2016+A2:2026 (E)
1 Scope
#This document specifies requirements and provides recommendations for the design and
installation of connections (bonds) between various electrically conductive elements in buildings and
other structures, during their construction or refurbishment, in which information or
telecommunications technology equipment is intended to be installed in order to:
a) minimise the d.c. and a.c. potential differences in order to reduce the risk of malfunction of that
equipment and interconnecting cabling due to electromagnetic disturbance;$
b) provide the telecommunications installation with a reliable signal reference – which may improve
immunity from electromagnetic interference (EMI).
The requirements of this European Standard are applicable to the buildings and other structures within
premises addressed by EN 50174-2 (e.g. residential, office, industrial and data centres) but
information given in this European Standard may be of assistance for other types of buildings and
structures.
NOTE Telecommunications centres (operator buildings) are addressed by ETSI/EN 300 253.
This European Standard does not apply to power supply distribution of voltages over AC 1 000 V.
Electromagnetic compatibility (EMC) requirements and 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
the requirements of these standards and regulations.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
1)
EN 50083 series , Cable networks for television signals, sound signals and interactive services
#EN 50174-2:2018, Information technology - Cabling installation - Part 2: Installation planning and
practices inside buildings$
EN 60728 series, Cable networks for television signals, sound signals and interactive services
(IEC 60728 series)
EN 61140, Protection against electric shock - Common aspects for installation and equipment
(IEC 61140)
!
EN 61557-4, Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. -
Equipment for testing, measuring or monitoring of protective measures - Part 4: Resistance of earth
connection and equipotential bonding (IEC 61557-4)
EN 61557-5, Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. -
Equipment for testing, measuring or monitoring of protective measures - Part 5: Resistance to earth
(IEC 61557-5)
"
———————
1)
Being partly replaced by EN 60728 series.
EN 50310:2016+A2:2026 (E)
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)
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)
HD 60364-5-54, 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)
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 50174-2 and the following
apply.
#3.1.1
access provider
operator or another entity providing the means to enable external telecommunications service
provision to a subscriber
[SOURCE: EN 50700:2023, 3.1.3]$
3.1.2
asymmetric cabling
cabling within which the cable elements are asymmetric (unbalanced)
#3.1.3
application
system, with its associated transmission and power feeding method that is supported by
telecommunications cabling
[SOURCE: EN 50173-1:2018, 3.1.5]$
3.1.4
backbone bonding conductor
telecommunications bonding connection which interconnects telecommunications bonding backbones
3.1.5
balanced application
application designed and optimized to operate over symmetric cabling
3.1.6
common bonding network
set of interconnected conductive structures that combine the functions of a protective bonding network
and a telecommunications bonding network
3.1.7
equipment bonding conductor
conductor that connects a protective bonding network to #Deleted$ telecommunications
equipment
EN 50310:2016+A2:2026 (E)
3.1.8
main earthing terminal
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
[SOURCE: IEC 60050-826:2004, 826-13-15, modified – The terms “main earthing busbar main”,
“grounding terminal (US)” and “main grounding busbar (US)” have been deleted.]
#Deleted$
3.1.9
mesh size
maximum length of conducting material between two adjacent connection points that create the grid of
the telecommunications bonding network
3.1.10
primary bonding busbar
telecommunications bonding connection element, connected to the main earthing terminal, that is
used to attach telecommunications bonding backbone conductors and equipment bonding conductors
3.1.11
protective bonding network
set of interconnected conductive elements to ensure electrical safety
Note 1 to entry: The protective bonding network meets the protective equipotential bonding system as defined in
IEC 60050–195:1998, 195.
3.1.12
rack bonding conductor
conductor that connects a rack bonding busbar or items of equipment within a cabinet, frame or rack
to the telecommunications bonding network #Deleted$
3.1.13
rack bonding busbar
attachment element within a cabinet, frame or rack or for multiple unit bonding conductors
3.1.14
secondary bonding busbar
telecommunications bonding connection element for telecommunications systems and equipment in
the area, served by a distributor
3.1.15
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 bonding network
[SOURCE: ETSI/EN 300 253:2015, 3.1.2]
3.1.16
system reference potential plane
conductive solid plane, as an ideal goal in potential equalizing, that is approached in practice by
horizontal or vertical meshes
Note 1 to entry: 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 a Faraday cage.
Note 2 to entry: The SRPP facilitates signalling with reference to a common potential.
[SOURCE: ETSI/EN 300 253:2015, 3.1.2]
EN 50310:2016+A2:2026 (E)
3.1.17
symmetric cabling
screened or unscreened cabling within which the cable elements comprise balanced pairs or quads
EXAMPLE Twisted pairs or quads.
3.1.18
telecommunications bonding backbone
conductor installed within telecommunications pathways that interconnects a primary bonding busbar
to its secondary bonding busbars within the building, and that is intended to minimise potential
differences but not intended to serve as a conductor providing a fault current return path
3.1.19
telecommunications bonding conductor
conductor between the primary bonding busbar and the main earthing terminal
3.1.20
telecommunications bonding network
set of interconnected conductive elements that provide functional equipotential bonding for
telecommunications equipment
3.1.21
telecommunications equipment bonding conductor
conductor that connects a primary or secondary bonding busbar to a supplementary bonding network,
a rack bonding conductor or to #Deleted$ telecommunications equipment
3.1.22
telecommunications entrance facility
entrance point where the telecommunications facilities enter the building
Note 1 to entry: The telecommunications entrance facility may also include antenna cable entrances and
electronic equipment serving telecommunications functions.
3.1.23
unbalanced application
application not optimised for transmission over symmetric cabling
3.1.24
unit bonding conductor
conductor that connects the telecommunications equipment within a cabinet, frame or rack to the rack
bonding busbar or to a rack bonding conductor
!
3.1.25
high frequency
frequency of, or greater than, 1 MHz
3.1.26
low frequency
frequency of less than 1 MHz
"
EN 50310:2016+A2:2026 (E)
#
3.1.27
bonding network
BN
set of interconnected conductive structures that mitigate electromagnetic interference for electronic
systems
Note 1 to entry:  This document describes four general types of bonding network: star, ring, local mesh, and
mesh.
$
3.2 Abbreviations
For the purposes of this document, the following abbreviations apply.
a.c. alternating current
BBC Backbone Bonding Conductor
CBN Common Bonding Network
d.c. direct current
EMI ElectroMagnetic Interference
IACS International Annealed Copper Standard
MESH-BN MESH Bonding Network
MESH-IBN MESH Isolated Bonding Network
MET Main Earthing Terminal
PBB Primary Bonding Busbar
PBNC Protective Bonding Network Conductor
RBB Rack Bonding Busbar
RBC Rack Bonding Conductor
SBB Secondary Bonding Busbar
SBG Supplementary Bonding Grid
SRPP System Reference Potential Plane
SPC Single Point Of Connection
TBB Telecommunications Bonding Backbone
TBC Telecommunications Bonding Conductor
TEBC Telecommunications Equipment Bonding Conductor
TEF Telecommunications Entrance Facility
TSP Transient Suppression Plate
UBC Unit Bonding Conductor
4 Conformance
For bonding infrastructures to conform to this European Standard
a) an assessment in accordance with Clause 6 shall be undertaken,
b) based on the results of the assessment any necessary bonding shall be implemented as follows
EN 50310:2016+A2:2026 (E)
1) the backbone and building entrance bonding shall either
– use the protective bonding network provided that it delivers the performance required by
the assessment of Clause 6, or
– conform to the requirements of Clause 8 for a dedicated bonding system,
2) the local bonding shall either
– conform to Clause 9 in line with the requirements of the assessment of Clause 6, or
– conform to the requirements of Clause 10 for a dedicated telecommunications bonding
system in line with the requirements of the assessment of Clause 6,
or
3) a mesh bonding network in accordance with Clause 11,
c) the requirements of Clause 7 shall be applied to all telecommunications bonding networks
implemented,
d) the cross-sectional areas of bonding conductors shall conform to the requirements of Clauses 7 to
11,
e) local regulations, including safety, shall be met.
NOTE The proper implementation of the requirements of this European Standard assumes that electrical
installations, protective bonding networks and protective measures against overvoltages are undertaken in
accordance with the local regulations, as appropriate. ! HD 60364-4-444 contains additional information. "
5 Overview of bonding networks
This European Standard assumes that buildings, or other structures, containing or intended to contain
telecommunications equipment are of vertical extent (where a backbone connects zones of different
floors) and/or horizontal extent (where a backbone connects multiple zones on a floor) and feature, as
follows:
a) one or more entrance facilities,
b) one or more identifiable areas within each zone containing concentrations of telecommunications
equipment (e.g. spaces associated with the generic cabling distributors of standards supported by
EN 50174-2),
c) areas in each zone within which telecommunications equipment is distributed (e.g. locations
associated with the generic cabling outlets of standards supported by EN 50174-2).
For the purposes of this European Standard
1) the term “backbone” refers to connections between the areas of concentrations of
telecommunications equipment and between any given area of concentration and a main earthing
terminal (MET),
2) the term “local” refers to connections between a given area of concentration of
telecommunications equipment and the area of distributed telecommunications equipment which
it serves or other connections within that area.
This is shown schematically in Figure 2 for telecommunications equipment distribution and
telecommunications bonding network terminology.
EN 50310:2016+A2:2026 (E)
Figure 2 – Schematic of telecommunications equipment distribution
and associated bonding connections
The objective of this European Standard is, following the completion of the assessment of Clause 6, to
ensure that backbone and local bonding networks
– minimize d.c. and a.c. potential differences in order to reduce the risk to the correct function of
telecommunications equipment interconnected by metallic cabling,
– have adequate a.c. and radio frequency performance to provide the telecommunications
installation with a reliable signal reference and improved resistance to EMI.
It should be noted that failure to implement correct telecommunications bonding networks can act
against this objective.
#Bonding networks have multiple types with increasing suitability from star to ring to local mesh to
mesh.
Figure 3 shows examples of bonding network types. Requirements and descriptions are detailed in
Clause 9 to Clause 11.
See 9.1.1. See 9.1.2. See 11.2.1. Bond connections at
all mesh intersections
and between mesh
and equipment.
a) Star b) Ring c) Local mesh d) Mesh
Figure 3 — Examples of bonding network types
EN 50310:2016+A2:2026 (E)
$
6 Selection of the telecommunications bonding network approach
6.1 Assessment of the impact of the telecommunications bonding network on the
interconnection of telecommunications equipment
The requirements applied to a telecommunications bonding network depend upon the intended type of
connectivity between the telecommunications equipment within and between the zones of Figure 2.
!The mesh bonding network of Clause 11 provides the most effective bonding at high frequencies
and can provide effective bonding at low frequencies. It is intended to support the most demanding
requirements of both cabling media and the applications supported over those media (see Table 1). In
addition, it provides the most flexibility in relation to the types and locations of telecommunications
equipment that may be installed (subject to the transmission performance limits of the applications
when using the selected telecommunications cabling).
The installation of such a telecommunications bonding network is most easily implemented during new
construction or refurbishment of a building or structure.
Within an existing building or structure:
a) the cost and complexity of installing a telecommunications bonding network that will support the
requirements of applications operating over asymmetric cabling between any two points in a
building may be prohibitive,
b) the implementation of an all-optical network has no implications for the telecommunications
bonding network but would substantially impact on the cost of transmission and terminal
equipment and may not be viable for all intended applications.
Therefore an assessment has to be made based on a balance between complexity of the
telecommunications bonding network and the type of cabling media and the application supported
over those media between and within the zones described in Figure 2. This assessment has also to
take into consideration the transmission performance requirements of the applications when using the
selected telecommunications cabling.
#Following this assessment, if there are financial or technical justifications for an implementation
other than that of Clause 11, then the bonding networks of Clauses 8, 9 or 10 (as appropriate) should
be considered, taking into account the risk of telecommunications disruption. It is recommended that
the assessment of the bonding system also considers the necessary operational availability of the
telecommunication services and their value added.$
Any bonding approach specified in this standard is enhanced by the installation of power distribution
systems conforming to TN-S as described in the HD 60364 series of standards and, in particular,
HD 60364-4-444."
#The typical comparative sensitivity of the various types of applications supported to a lack of
bonding network performance (d.c. resistance and impedance) is shown in Table 2.
EN 50310:2016+A2:2026 (E)
Table 2 — Typical sensitivity of applications to bonding network performance
Sensitivity to
bonding
Applications using
networking
performance
High
Asymmetric cabling or
symmetric cabling
(unbalanced applications)
Symmetric cabling
(screened or unscreened
with balanced applications)
Optical fibre cabling Low
$
Based upon the outcome of this assessment, the appropriate requirements of this standard shall be
applied to the relevant infrastructures to be used to provide an adequate telecommunications bonding
network as detailed in Table 3.
EN 50310:2016+A2:2026 (E)
Table 3 – Telecommunications bonding network requirements
Transmission
(subject to maximum channel length limits)
Media  Between zones Within a zone
Using the protective d.c. resistance and d.c. resistance and
bonding network impedance control impedance control
requirements of requirements of
Asymmetric cabling or
6.3.1.1 Clause 9
symmetric cabling
(unbalanced
Using a dedicated d.c. resistance and d.c. resistance and
applications)
telecommunications impedance control impedance control of
bonding network requirements of Clause 10
6.3.1.2
Using the protective d.c. resistance d.c. resistance control
bonding network requirements of requirements of
Symmetric cabling
6.3.1.1 Clause 9
(screened or
unscreened with
Using a dedicated d.c. resistance d.c. resistance control
balanced applications)
telecommunications requirements of of Clause 10
bonding network 6.3.1.2
Optical fibre cabling  No requirements No requirements
6.2 Telecommunications bonding networks
Telecommunications equipment is generally connected to a protective bonding network that meets
basic safety requirements in accordance with the HD 60364 series. If the design or measured
performance of the protective bonding network fails to meet the requirements of 6.3 then either
a) supplementary telecommunications bonding solutions shall be employed as defined in Clauses 8,
9, 10 or 11, or
b) restrictions shall apply in relation to the interconnection of telecommunications equipment as
described in Clause 6.
!Where the building or structure has, or will have, lightning protection in accordance with EN 62305
series, the mesh bonded network of Clause 11 can be used in conjunction with the “integrated
lightning protection system” according to EN 62305-4.
Other lightning protection systems, including the “isolated lightning protection system” according to
EN 62305-3, may be used provided that specific restrictions are applied as agreed between the
planners of the lightning protection system and the bonding network."
Where the requirements of Clause 11 are determined to be inappropriate but an effective
telecommunications bonding network is required then
1) Clause 8 provides requirements and recommendations for the construction of a dedicated
telecommunications backbone bonding network,
2) Clause 9 provides requirements and recommendations for the construction of a local
telecommunications bonding network for connection to protective bonding networks,
3) Clause 10 provides requirements and recommendations for the construction of a local
telecommunications bonding network for connection to a dedicated telecommunications backbone
bonding network.
EN 50310:2016+A2:2026 (E)
6.3 Telecommunications bonding network performance
6.3.1 General
6.3.1.1 Protective bonding networks
!Protective bonding networks can provide adequate performance for the telecommunications
infrastructure. Where a protective bonding network is found not to comply with the requirements of
6.3.2.1 and 6.3.2.2, corrective actions shall be undertaken before decisions are taken in relation to the
implementation of the telecommunications bonding network."
The backbone protective bonding network is considered to connect the primary electrical power
distribution units within each zone to the main earthing terminal (MET).
For a backbone protective bonding network to be considered adequate for a telecommunications
bonding network, it shall meet requirements for impedance of 6.3.2.1 and the d.c. conductor
resistance as detailed in 6.3.2.2.
With each zone, the local protective bonding network shall have one of the forms as described in
Clause 9. The requirements for the supplementary telecommunications bonding networks are
described in Clause 9.
For a local protective bonding network to be considered adequate for a telecommunications bonding
network, it shall meet requirements for impedance of 6.3.2.1 and the d.c. conductor resistance as
detailed in 6.3.2.2.
6.3.1.2 Dedicated telecommunications bonding networks
When the protective bonding network fails to provide adequate performance for the
telecommunications bonding infrastructure or other factors take precedence then a dedicated
telecommunications bonding network shall be installed in accordance with Clause 8 and Clause 10.
For a dedicated backbone bonding network to be considered adequate for a telecommunications
bonding network it shall meet requirements for impedance of 6.3.2.1 and the d.c. conductor resistance
as detailed in 6.3.2.3.
The dedicated bonding network extends from the backbone into each zone via a local
telecommunications bonding network. The requirements for the supplementary telecommunications
bonding networks are described in Clause 10.
For a local bonding network to be considered adequate for a telecommunications bonding network it
shall meet requirements for impedance of 6.3.2.1 and the d.c. conductor resistance as detailed in
6.3.2.3.
6.3.2 Requirements
6.3.2.1 General requirements
The bonding network shall have busbars with sufficient capacity for the attachment of planned
telecommunications equipment and cabling.
If required by the approach taken to the bonding network (see 6.1), adequate impedance performance
of the bonding network requires that
a) the pathways in which the bonding network is installed are close to the pathways in which the
telecommunications network is installed to reduce loop area inductance to improve high
frequency performance,
b) there is sufficient and easy access to add supplemental bonding conductors for impedance
control as described in Clauses 7, 8, 9 and 10 to improve the high frequency performance of the
protective bonding network.
!NOTE The use of multiple bonding conductors as described in Clauses 7, 8, 9, 10 and 11 improves the
impedance by a factor equal to the number of additional connections."
EN 50310:2016+A2:2026 (E)
6.3.2.2 Protective bonding networks
The protective bonding network shall comply with local safety requirements and provide a safe
environment for the telecommunications installers and equipment.
The d.c. resistance between points of a protective bonding network shall meet the requirements of
Table 4.
!
Table 4 — DC resistance requirements for protective bonding networks
Connections between Requirement
maximum
a
mΩ/m
Busbars in electrical distributors with a zone 2,5
Busbars in electrical distributors within adjacent zones 2,5
a
Based on the shortest length between the two points.
"
6.3.2.3 Dedicated bonding networks
The d.c. resistance between points of the telecommunications bonding network shall meet the
requirements of Table 5.
!
Table 5 — DC resistance requirements for dedicated telecommunications
bonding networks
Connections between Requirement
maximum
a
mΩ/m
Any point of the bonding network and the MET 1,67
Any primary bonding busbar (PBB) and a connected
...