| Full title | BS EN 50310, Telecommunications bonding networks for buildings and other structures |
| Publisher | CENELEC (CLC/TC 215). Published in the UK by BSI (committee TCT/7) |
| Current edition | EN 50310:2016 with A1:2020 and A2:2026. UK consolidated edition BS EN 50310:2016+A2:2026 |
| Status | Current. Supersedes EN 50310:2010 |
| Related standards | ISO/IEC 30129, BS EN 50174-1, BS EN 50174-2, BS 7671, EN 62305-4, ANSI/TIA-607-E |
What it covers
BS EN 50310 sets requirements and recommendations for the design and installation of bonds between electrically conductive elements in buildings and other structures where IT and telecommunications equipment will be installed. It applies during construction or refurbishment.
The 2016 text gives two aims:
- to minimise the risk to the correct function of the equipment and its interconnecting cabling from electrical hazards;
- to provide the telecommunications installation with a reliable signal reference, which may improve immunity from electromagnetic interference.
Amendment A2:2026 rewords the first aim around minimising d.c. and a.c. potential differences, to reduce the risk of malfunction from electromagnetic disturbance.
It applies to the premises covered by EN 50174-2, such as offices, homes, industrial buildings and data centres. Operator telecommunications centres are covered by ETSI EN 300 253. It does not apply to power distribution above AC 1 000 V. Electrical safety and EMC requirements for the power installation are outside its scope and are covered by other standards and regulations.
Structure
| Clause | Title |
|---|---|
| 4 | Conformance |
| 5 | Overview of bonding networks |
| 6 | Selection of the telecommunications bonding network approach |
| 7 | Common features: protective bonding networks, telecommunications entrance facility, components, cabinets, frames and racks, documentation |
| 8 | Dedicated telecommunications bonding network |
| 9 | Local telecommunications bonding networks with protective bonding networks |
| 10 | Local telecommunications bonding networks with dedicated telecommunications bonding networks |
| 11 | Mesh bonded networks, including the supplementary bonding grid and system reference potential plane |
| Annex A (normative) | Maintenance of telecommunications bonding network performance, including periodic activity and galvanic corrosion |
Clause numbers are from the 2016 base text. A1:2020 modified the Introduction, Clauses 2, 3 and 4, subclauses 6.1, 6.2, 6.3.1.1, 6.3.2.1, 6.3.3.1, 7.4.1.2, 11.1 and 11.6, the d.c. resistance requirements in Tables 4 and 5, and the Bibliography.
The two approaches
The standard sets assessment criteria for choosing a bonding configuration, then allows it to be built in one of two ways:
| Approach | What it is |
|---|---|
| Using the protective bonding network | The telecommunications bonding uses the existing protective bonding network provided for electrical safety. A set of conductive structures that combines both functions is a common bonding network. |
| Dedicated telecommunications bonding network | A separate bonding network is provided for the telecommunications infrastructure (Clause 8). |
Where equipment is concentrated, such as an equipment room or data centre, Clause 11 covers mesh bonding. A mesh isolated bonding network is a mesh with a single point of connection to the protective bonding network or to another isolated bonding network.
Key components and terms
| Term | Definition (EN 50310:2016, Clause 3) |
|---|---|
| Main earthing terminal | Terminal or busbar that is part of the installation’s earthing arrangement and connects a number of conductors for earthing |
| Primary bonding busbar | Telecommunications bonding element connected to the main earthing terminal, used to attach backbone bonding conductors and equipment bonding conductors |
| Secondary bonding busbar | Bonding element for systems and equipment in the area served by a distributor |
| Backbone bonding conductor | Bonding connection that interconnects telecommunications bonding backbones |
| Rack bonding busbar | Attachment element within a cabinet, frame or rack |
| Rack bonding conductor | Connects a rack bonding busbar, or equipment within a cabinet, frame or rack, to the telecommunications bonding network in a local area |
| Equipment bonding conductor | Connects a protective bonding network to an item of telecommunications equipment |
| Mesh size | Maximum length of conducting material between two adjacent connection points in the bonding grid |
| System reference potential plane | A conductive plane, the ideal for potential equalisation, approached in practice by horizontal or vertical meshes |
How it relates to other standards
| Document | Relationship |
|---|---|
| ISO/IEC 30129 | International equivalent. EN 50310:2016 transposed ISO/IEC 30129 with minimal editorial changes and took its title |
| BS EN 50174-1 | For a cabling installation to conform to EN 50174-1, the bonding system in the premises must be in accordance with EN 50310 |
| BS 7671 | EN 50310 normatively references HD 60364-4-444 and HD 60364-5-54. In the UK these are implemented in BS 7671 Section 444 and Chapter 54. EN 50310 does not replace the electrical safety requirements of BS 7671 |
| EN 62305-4 | Lightning protection for electrical and electronic systems within structures, normatively referenced |
| ANSI/TIA-607-E | The North American counterpart for bonding and grounding (earthing) of telecommunications in customer premises |
| ANSI/TIA-606 | Since revision C (2017), its bonding identifiers use terms compatible with ISO/IEC 30129, such as primary and secondary bonding busbar |
What it means in practice
- Decide the bonding approach at building design stage. Table 1 of the standard places EN 50310 in the building design phase, before cabling design.
- Identify the main earthing terminal and the primary bonding busbar connected to it. Backbone and equipment bonding conductors attach to the primary bonding busbar.
- Check the bonding of cabinets, frames and racks. Clause 7.5 covers them.
- Record the bonding network. Clause 7.7 covers documentation.
- Plan periodic checks. Annex A is normative and covers maintenance of bonding performance, including galvanic corrosion.
Bonding for telecommunications does not change who is responsible for electrical safety. Protective earthing and bonding remain under BS 7671, and should be coordinated with the electrical designer.
Related reading: BS 7671 Amendment 4: PoE and ICT earthing rules · Cable shielding explained: UTP, F/UTP, U/FTP and S/FTP.