| Full title | BS EN 50174-2:2018, Information technology. Cabling installation. Installation planning and practices inside buildings |
| Publisher | CENELEC; BSI in the UK |
| Part of | EN 50174 series: Part 1 specification and quality assurance, Part 2 inside buildings, Part 3 outside buildings |
| Applies to | Planning and installing all types of information technology cabling inside buildings, copper and optical fibre |
| Works with | BS EN 50173 (cabling design), BS EN 50310 (bonding), BS 6701 (UK installation) |
What BS EN 50174-2 covers
BS EN 50173 sets what finished cabling must achieve; BS EN 50174-2 sets how to plan and install it inside buildings so that it does. It covers pathways and spaces, containment fill, bend radius, fire stopping, cable bundles for remote powering such as PoE, and separation between data cabling and power cabling or other sources of interference.
Separation from power
The minimum separation between data and power cabling is worked out in three steps: find the data cable’s segregation class, read the separation S for that class and the containment, then multiply by the power factor P.
| Segregation class | No containment | Open metallic | Perforated metallic | Solid metallic |
|---|---|---|---|---|
| d | 10 mm | 8 mm | 5 mm | 0 mm |
| c | 50 mm | 38 mm | 25 mm | 0 mm |
| b | 100 mm | 75 mm | 50 mm | 0 mm |
| a | 300 mm | 225 mm | 150 mm | 0 mm |
Most U/UTP cable is class b, and screened Cat5e, Cat6 and Cat6A cables are typically class c. Class d needs a coupling attenuation of 80 dB or more, typical of Cat7 and Cat7A. Where a datasheet does not state the class, ask the manufacturer. Solid metallic containment gives zero separation only where its screening is equivalent to steel conduit with a 1.5 mm wall; stainless steel and aluminium do not qualify. For perforated containment, the top of the cables must be at least 10 mm below the top of the barrier.
Power factor P
| Power circuits | 1-3 | 4-6 | 7-9 | 10-12 | 13-15 | 16-30 | 31-45 | 46-60 | 61-75 | Over 75 |
|---|---|---|---|---|---|---|---|---|---|---|
| Factor P | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 | 2 | 3 | 4 | 5 | 6 |
Circuits are counted as 20 A, 230 V single-phase circuits. A three-phase circuit counts as three, and higher currents count in multiples of 20 A.
Worked example
Cat6 U/UTP (class b) on a perforated metal tray beside eight power circuits: S = 50 mm and P = 0.6, so the minimum separation is 30 mm. A class c screened cable on the same route needs 25 × 0.6 = 15 mm. In solid metallic containment with screening equivalent to 1.5 mm steel conduit, the separation is zero.
Safety separation in the UK
BS EN 50174-2 deals with interference. Electrical safety is separate. BS 6701 adds a safety minimum between telecoms cable and low-voltage power cable:
- 150 mm where nothing separates them;
- 50 mm with a partition that meets BS 7671;
- 50 mm where the power cable is in its own conduit or trunking (bonded to BS 7671 if metallic), is MI or earthed armoured cable, or is a flexible insulated and sheathed cable such as an equipment lead in a cabinet.
Telecoms cabling must not share a compartment with LV cabling that has exposed live terminals. BS 7671 Regulation 528.1 also controls Band I and Band II circuits sharing a wiring system. Where the figures differ, use the larger.
Other planning requirements
- Bend radius: follow the cable manufacturer’s figures during and after installation.
- Containment fill: leave capacity for future cables and avoid crushing the lower layers.
- Remote powering: large bundles of powered cables run warmer; the standard includes guidance on bundles for PoE.
- Fire stopping: restore fire barriers wherever cabling passes through them.
- Other interference sources: fluorescent and neon lamps need 130 mm; check the standard for other equipment on site.
Screened cables need correct bonding. For a fuller guide, read cable shielding explained.