Contents Page

European foreword 3

1 Modifications to the Introduction 4

2 Modifications to Clause 1, Scope 4

3 Modifications to Clause 2, Normative references 5

4 Modifications to Clause 3, Terms, definitions and abbreviations 5

5 Modifications to Clause 5, Overview of bonding networks 5

6 Modifications to 6.1, Assessment of the impact of the telecommunications bonding network on the interconnection of telecommunications equipment 6

7 Modifications to 7.4.1.2, Installation 7

8 Modification to 7.4.2, Telecommunications bonding network connections 7

9 Modifications to 7.5.2.2, Rack bonding conductors (RBC) for impedance control 7

10 Modification to 7.5.3, Internal connections 7

11 Modifications to 7.6.3 — Bonding conductors for impedance control 7

12 Modification to 7.7 — Documentation 7

13 Modifications to 8.2.4.1 — Telecommunications bonding backbone (TBB) 7

14 Modifications to 8.3.1 — Primary bonding busbar (PBB) 8

15 Modifications to 8.3.4 — Telecommunications bonding backbone (TBB) 8

16 Modification to 8.3.7 — Bonds to structural metal 8

17 Modifications to 9.2.2 — Bonding conductors for impedance control 8

18 Modifications to 10.2.2 — TEBC for impedance control 8

19 Modification to 11.2.1.1 — Requirements 8

20 Modifications to 11.3 — Bonding conductors of a mesh bonding network 8

21 Modification to A.3.2 — Requirements 9

22 Modifications to the Bibliography 9

European foreword

This document (EN 50310:2016/prA2:2026) has been prepared by CLC/TC 215 “Electrotechnical aspects of telecommunication equipment”.

This document is currently submitted to the Enquiry.

The following dates are proposed:

Replace Figure 1 with the following figure:

Replace Table 1 with the following table:

Replace the first paragraph and the list item a) with:

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;

Replace the references “EN 50174‑2:2009” and “EN 50174‑2:2009/A1:2011” with the following:

“EN 50174‑2:2018, Information technology - Cabling installation - Part 2: Installation planning and practices inside buildings”

In 3.1, modify the following terms and definitions and add at the end of the list:

Replace definition 3.1.1 with:

“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]”

Replace definition 3.1.3 with:

“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]”

In definitions 3.1.7 and 3.1.22 delete the words “an item of”.

Delete term and definition 3.1.9 and renumber the following terms accordingly.

In definition 3.1.13 delete the words “within a local area”

Add, at the end of the list, the following new term and definition:

“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.”

Add at the end of the clause the following text:

“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

“

Renumber the following figures and their cross references accordingly.

Replace the 6th paragraph with

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.

Replace the 8th paragraph and Table 2 with

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.

Table 2 — Typical sensitivity of applications to bonding network performance

Applications using	Sensitivity to bonding networking performance
Asymmetric cabling or symmetric cabling (unbalanced applications)	High
Symmetric cabling (screened or unscreened with balanced applications)
Optical fibre cabling	Low

Replace the 2nd paragraph with:

“Telecommunications bonding conductors shall be installed in accordance with the applicable minimum bend radius (installation, operating-static and operating-dynamic). Telecommunications bonding conductors shall not be coiled nor doubled back on themselves.”

Replace the last but one paragraph with:

“Bonding connectors and the fastenings and processes used to connect them to the conductive elements of bonding networks shall be designed to provide and maintain a d.c. contact resistance of ≤100 mΩ.”

Replace in the last paragraph “(with reference to IEC 60950‑1)” with “(with reference to EN IEC 62368‑1)”

In 7.5.2.2.1, amend “n = ROUNDUP(l/6) − 1” to read “n = (l/6) rounded down to the nearest integer”

In 7.5.2.2.2, replace “ROUNDUP” with “round up”

In 7.5.3.1, move the last sentence (starting with “Where screened cables are terminated …”.) after the 3rd paragraph and amend the dated reference to read “… EN 50174‑2:2018, 5.3.6.”

Insert a new subclause “7.5.3.2 Recommendations” before the paragraph starting with “The bonding conductors attached…”

Renumber 7.5.3.2 into 7.5.3.3.

In 7.5.3.3, list item b), replace “shall be with “is”.

In 7.6.3.1, amend “n = ROUNDUP(l)−1” to read “n = (l /6) rounded down to the nearest integer”

In 7.6.3.2, amend “n = ROUNDUP(2 × l) – 1” to read “n = (2 x l) rounded down to the nearest integer”

Replace the paragraph with:

“In a bonding system network, connections shall be documented in a set of relevant documents (such as technical drawings, layouts, schematics, termination details, schedules and supporting pictures).

Depending on the complexity of the installation, the use of electronic or AIM system compliant to EN 50667 should be considered.”

In 8.2.4.1.1, amend “n = ROUNDUP(l/6)−1” to read “n = (l/6) rounded down to the nearest integer”

In 8.2.4.1.2, Amend “n = ROUNDUP(l/3) − 1” to read “n = (l/3) rounded down to the nearest integer”

In 8.3.1.1, replace the first paragraph with

“There shall be one PBB associated with each MET in a building. The PBB shall be installed either in the TEF (if an electrical distribution panel for telecommunications equipment is present) or in the space which accommodates a generic cabling building distributor and the associated telecommunications equipment.”

In 8.3.1.2, last paragraph, replace “shall” with “should”

Replace the 2nd paragraph with:

“TBB conductors shall be protected from physical and mechanical damage. The TBB conductors should be installed without splices. If splices are unavoidable, there shall be a minimum number of splices. Splices shall be accessible and located in telecommunications spaces.”

Replace the 3rd paragraph with:

“Structural metal that is bonded to the MET may be used in place of a TBB or a BBC. Before utilizing structural metal in place of a TBB or a BBC, building plans (including as-built drawings as applicable) and specifications shall be reviewed to verify that the structural metal is electrically continuous and its resistivity complies with, or can be modified to be compliant with the bonding requirements.”

In 9.2.2.1, amend “n = ROUNDUP(l/6)−1” to read “n = (l/6) rounded down to the nearest integer”

In 9.2.2.2, amend “n = ROUNDUP(l/3) – 1” to read “n = (l/3) rounded down to the nearest integer”

In 10.2.2.1, amend “n = ROUNDUP(l/6)−1” to read “n = (l/6) rounded down to the nearest integer”

In 10.2.2.2, amend “n = ROUNDUP(l/3) – 1” to read “n = (l/3) rounded down to the nearest integer”

Replace the 2^nd paragraph with

“The MESH-IBN is typically limited to a restricted area within a building such as in areas of concentration of information or telecommunications technology equipment. The MESH-IBN is not typical but can be utilized for a commercial environment. The MESH-IBN is recognized and sometimes utilized in access provider premises.”

In 11.3.1, 3^rd paragraph, amend “n = ROUNDUP(l/6)−1” to read “n = (l/6) rounded down to the nearest integer”.

In 11.3.2, 1st paragraph, replace “mesh earthing network” with “mesh bonding network”.

In 11.3.2, 2nd paragraph, amend “n = ROUNDUP(l/3) − 1” to read “n = (l/3) rounded down to the nearest integer”.

In the 1^st paragraph, replace “EN 60950‑1 contains a table…” with “EN IEC 62368‑1 contains a table…”

Add the following references to the list:

EN 50667, Information technology - Automated infrastructure management (AIM) systems - Requirements, data exchange and applications

EN IEC 62368‑1, Audio/video, information and communication technology equipment - Part 1: Safety requirements

Delete the following references from the list:

EN 50346, Information technology - Cabling installation - Testing of installed cabling

EN 60950‑1, Information technology equipment - Safety - Part 1: General requirements (IEC 60950‑1)