| Full title | BS EN 50174-3:2013+A1:2017, Information technology. Cabling installation. Part 3: Installation planning and practices outside buildings |
| Publisher | CENELEC (CLC/TC 215). Published in the UK by BSI (committee TCT/7) |
| Current edition | EN 50174-3:2013 (October 2013) with A1:2017 (May 2017). UK consolidated edition published 31 March 2018. Supersedes EN 50174-3:2003 |
| Status | Current. EN confirmed January 2023. BSI lists it as under review, and a revision (prEN 50174-3) is in development |
| Related standards | BS EN 50174-1, BS EN 50174-2, BS EN 50173 series, BS EN 50310, BS 6701, ISO/IEC 14763-2 |
What it covers
BS EN 50174-3 sets requirements and recommendations for the planning and installation practice of information technology cabling outside buildings. It covers metallic and optical fibre cabling. It applies to all types of IT cabling outside buildings, including generic cabling designed to the EN 50173 series.
It is not confined to one set of premises. It covers cabling between buildings on a site, cabling between separate premises and wide area cabling. Its requirements may also be applied to cabling defined as part of a building.
The scope excludes:
- Planning of pathways, spaces and structures in core and access networks owned by access providers, except basic safety, function and environmental objectives
- Cabling installed around or within aerial power supply conductors or their earth conductors
- Cabling on infrastructure carrying power above AC/DC 25 kV
- Free-space transmission such as wireless, radio, microwave and satellite
- Requirements for power supply cabling, although its effect on IT cabling is taken into account
Clause 7 adds site-specific requirements for hazardous or stressful environments. Requirements in Clauses 4, 5 and 6 are subject to Clause 7.
Structure
| Clause or annex | Subject |
|---|---|
| 4 | Planning: safety, documentation, pathways, pathway systems, closures, cabling, spaces and structures, administration |
| 5 | Installation: safety, documentation, installation practices, labelling, testing, contractual acceptance, operation |
| 6 | Segregation: underground cabling, aerial cabling and specific sources of electromagnetic interference (EMI) |
| 7 | Additional practices for hospitals, airports, nuclear areas, chemical manufacturing areas and railways |
| Annex A | EMC and protection: coupling mechanisms, filtering, electrical isolation and surge protective devices (informative) |
| Annex B | Earth potential rise (EPR) and the limit of the hot zone near high voltage installations (informative) |
| Annex C | Application of responsibilities, with a template (informative) |
For conformance, planning must meet Clause 4, installation practices must meet Clause 5, and local regulations, including safety, must be met.
Key technical content
Underground and aerial pathways
Clause 4 covers the design and planning of underground pathways and dedicated aerial pathways. It includes tables for pathway depths below finished surface and for minimum installed clearances above ground for aerial cables. It also includes a table of stacking heights and covers wind vibration dampers on aerial routes.
Cables and closures
The standard references the EN 60794-3 family of outdoor optical fibre cable specifications. These cover duct, directly buried, aerial, lake and river crossing, sewer, gas pipe and drinking water pipe cables. Fibre splice closures are referenced to the EN 50411-2 series. Warning devices for underground cables are referenced to EN 12613.
Segregation
Clause 6 sets separation for underground and aerial IT cabling. Its tables and figures cover:
- Minimum distance between IT cables and earthed electrodes of power systems, in rural and urban environments and to ITU-T K.8
- Minimum clearances and protective measures at crossings with other underground services
- Minimum clearances between aerial IT cabling and overhead power supply cabling
- Separation on supporting structures, including those with lighting devices
Building entry, earthing and surge protection
The standard shows an underground conduit entrance into a building and the use of a galvanic isolation device. Annex A covers filtering, electrical isolation components and surge protective devices. Annex B covers earth potential rise near high voltage installations. Since A1:2017, the standard states that the bonding principles of EN 50310 can be employed in installations outside buildings.
Amendment A1:2017
- New subclause 4.10 on planning of repair
- Changes to definitions
- Technical and editorial corrections to Clauses 4 to 7 and Annexes A and B
- EN 13501-6, EN 61300-3-35, EN 62368-1 and EN 62368-3 added as normative references. EN 50346 and EN 60950 removed
How it relates to other standards
| Standard | Relationship |
|---|---|
| BS EN 50174-1 | Installation specification and quality assurance. Used at the specification phase |
| BS EN 50174-2 | Installation planning and practices inside buildings. Part 3 is its outside-building companion |
| BS EN 50173 series | Generic cabling design standards that Part 3 supports |
| BS EN 50310 | Telecommunications bonding networks. Its principles can be employed outside buildings |
| BS 6701 | UK installation standard written to support the BS EN 50174 series |
| ISO/IEC 14763-2 | International counterpart. Its 2019 edition also covers cabling outside buildings |
What it means in practice
- Use Part 3 for campus links, building-to-building routes, ducts, direct burial and aerial runs. Use Part 2 once the cabling is inside the building.
- Check the specification names the edition. The current text is 2013 with A1:2017, and a revision is in progress.
- Plan separation from power cables, earth electrodes and other underground services at design stage, using Clause 6.
- Where metallic cabling enters a building, consider bonding to EN 50310, galvanic isolation and surge protection.
- Check the outdoor cable type matches the route, for example duct, direct buried or aerial.
Related reading: Armoured vs unarmoured fibre optic cable · Internal vs external data cable.