EN 50174 Specification  

EN 50174

EN 50174 is the European Standard for the planning, implementation and operation of information technology cabling using balanced copper cabling and optical fibre cabling.  It is designed to be used in conjunction with EN 50173.  EN 50174 is published in three parts.

EN 50174-1              Information technology – cabling installation – part 1: Specification and quality assurance

EN 50174-2              Information technology – cabling installation – part 2: Installation planning and practices inside buildings

EN 50174-3              Information technology – cabling installation – part 3: Installation planning and practices outside buildings

EN 50174 calls up many other standards and it is easier to pick them up section by section rather than merely list them.  However the following overview is given:-

EN 50174-1

The organisation of EN 50174-1 is:

Safety

Specification considerations

Quality Assurance

Documentation

Cabling administration

Repair and maintenance

Safety

Under the ‘safety’ heading, the following statements are made:-

External cables with flammable polyethylene sheaths must be jointed to a low flammability cable or encased within non-flammable conduit or trunking within 5 metres of entering a building 

Consideration shall be given to cables having non-corrosive, fire retardant and low smoke/toxic emission properties.

Frames and cabinets shall not be installed in toilet facilities, boiler/plant/machine rooms,  in emergency escape routes,  in ceiling or sub-floor spaces or within cabinets or closures containing fire fighting equipment.

The minimum clearance on all faces of the frames and cabinets that require access shall be at least 1.2 metres.

Pathways

Pathway systems are referenced to :

EN 50085          Cable trunking systems and cable ducting systems for electrical installations – Part 1: general requirements

EN 50086          Conduit systems for electrical installations – Part 1: general requirements

Pathways should not be installed in lightning conductor voids or lift shafts.

Scope of work items

Pre-installation tasks

Civil works – identify and document

Pathways

Earthing and bonding

Building entrance facility

Bill of materials

Survey status

Installation tasks

safety plan

connectivity

programme

in-service date

labeling

testing

documentation

documentation hand-over date

Post installation tasks

Reinstatement definition

Recommended spares

Support services

Administration

Documentation

Final cabling documentation includes:-

site plans identifying locations of cables, pathways, termination points etc.

as-built drawings

evidence of conformance to the specification

other information as required

earthing and bonding details

Administration

‘For simple infrastructures a well-designed paper-based administration system is often adequate.  However it is recommended that the principles of administration outlined in this clause be implemented using a computer based administration system.’

Testing

Annex B refers to a yet un-named standard known as EN 50XXX.  A table lists reduced acceptance tests, standard acceptance tests and compliance tests.  Yet all three fall well short of the IEC 61935 tests invoked in EN 50173.  It would seem better to specify IEC 61935 as the main testing regime, as it is more comprehensive and will be called up by later editions of EN 50173 and ISO 11801.

EN 50174-2

The organisation of EN 50174-2 is:-

Safety requirements

General installation practices for metallic and optical fibre cabling

Additional installation practice for metallic cabling

Additional installation practice for optical fibre cabling

General installation practice

Coaxial cabling for distribution of television and sound signals is covered in EN 50083.

Cable management systems shall comply with:-

Conduit systems to EN 50086

Trunking and ducting systems to EN 50085

Busbar trunking systems to EN 60439-2

Tray and ladder systems to prEN 61537

Service poles to prEN 50085-2-4

Additional installation practice for metallic cabling

This chapter goes on at great length about EMC considerations and the organisation of power and earthing systems.  Screened cables for example, must be effectively earthed with a 360⁰ bonding mechanism. The chapter contains a chart detailing minimum separation distances between power and data cables, and this has always been a major point of concern to installers and end users. 

However the wording of the ‘final’ draft of 2000 has been contested by the UK, and on 10-3-00 a negative vote was returned by the UK with a technical justification.  The original draft  proposed:-

No separation between horizontal data and power required if the parallel run is less than 35 m.

For runs longer than 35 m, separation distances shall apply except for the final 15 m to the outlet.

The separation distances are

In addition, a distance of 130 mm shall be kept from fluorescent lamps.

The UK technical recommendation is to replace the above by; 

The minimum segregation distance between power cables and IT balanced cables for cable lengths of up to 90 m is 75mm

This minimum distance applies to 230 V ac, 20 amp, 50/60 Hz, single phase circuits, with a maximum of ten such power cables.  A three phase 415 V ac circuit would account for three of the former power cables.

Outlet boxes that share power and data circuit must keep 6 mm segregation.

130 mm separation from fluorescent lights is still required.

Segregation is not required when power and data cables are enclosed in separate metal trunking or conduit.

Note that trunking must be continuous, completely enclose the cables, be earthed and made of 1 mm low-carbon steel or 2 mm of aluminium.  Stainless steel is not permitted.  Segregation is not required when the power cables are of a shielded design.

Where power and data cables cross they must do so at right angles and with the aid of a bridge.

EN 50174-3

The organisation of EN 50174-3 is:-

·        Installation practice for metallic cabling

            -proximity to high voltages

            -overhead cabling

            -underground lines

            -interface between internal and external cabling

·        Installation practice for optical fibre cabling

-general precautions

-pre-installation procedures

-preparation of cable routes

One standard invoked is;

ENV 61024-1            Protection of structures against lightning

Much space is devoted to the coexistence of IT cabling with other services and utilities, for IT cables installed above or below ground.  For overhead power lines, for example, the clearance must be at least 0.5 m for less than 1000 volts, with a formula supplied to calculate the distance when the voltage is above 1000 V.

The minimum separation from the earthed metallic parts of the IT system and power earthing systems can be anything from 5 to 200 m!! depending upon soil resistivity.

The minimum depth of buried IT cabling is given for various circumstances, such as at least 0.6 m for pavements and roads.

The clearance between IT cabling and other services such as gas (low pressure, 0.5 m, high pressure, 1.5 m) and water (0.3 m) is also given.

Many rules and design guidelines are given for when the IT cable runs through ‘hot zones’, i.e. areas that can suffer from ROEP, or Rise Of Earth Potential.

The above information is offered as a summary of EN 50174.  It is not a definitive design guide and does not replace study and implementation of the Standard itself.  The publisher accepts no responsibility for inaccuracies or omissions.  To purchase the full Standard go to your national standards body, e.g. British Standards Institution, Nederlands Normalisatie Instituut etc. or CENELEC