EN 50174-3:2003

STANDARDInformacijska tehnologija – Pokabljenje – 3. del: Načrtovanje inštalacij in tehnike dela zunaj zgradbInformation technology – Cabling installation – Part 3: Installation planning and practices outside buildings©
Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljenoReferenčna številkaSIST EN 50174-3:2005(en)ICS33.040.50; 35.110

EUROPEAN STANDARD
EN 50174-3 NORME EUROPÉENNE EUROPÄISCHE NORM
November 2003 CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2003 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50174-3:2003 E
ICS 33.040.50; 35.110
English version
Information technology -
Cabling installation Part 3: Installation planning and practices outside buildings
Technologies de l'information -
Installation de câblage Partie 3: Planification et pratiques d'installation à l'extérieur des bâtiments
Informationstechnik -
Installation von Kommunikationsverkabelung Teil 3: Installationsplanung
und -praktiken im Freien
This European Standard was approved by CENELEC on 2003-09-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Lithuania, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom.

Foreword This European Standard was prepared by Technical Committee CENELEC TC 215, Electrotechnical aspects of telecommunication equipment, under the framework of the Mandates M/212 on “Telecommunication cables and cabling systems“ and M/239 on “Air traffic management equipment and systems“.
The text of the draft was submitted to the formal vote and was approved by CENELEC as EN 50174-3 on 2003-09-01. The following dates were fixed: - latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement
(dop)
2004-09-01 - latest date by which the national standards
conflicting with the EN have to be withdrawn
(dow)
2006-09-01 This standard comprises three parts. All three parts support the specification, implementation and operation of information technology cabling using both balanced copper and optical fibre cabling components. These components may be combined to provide cabling solutions either in accordance with the design requirements of series EN 50173 or to meet the requirements of one or more application-specific standards (such as EN 50098-1 or EN 50098-2). This part, EN 50174-3, contains detailed requirements and guidance relating to the installation planning and practices outside buildings and is intended to be used by the personnel directly involved in the planning and installation of information technology cabling. It shall be used during the different implementation phases when installing information technology cabling, i.e. during the planning phase, the design phase and installation phase. Annexes designated “informative” are given for information only.
In this standard, Annexes A and B are informative.

– 3 – EN 50174-3:2003 Content Introduction.7 1 Scope .9 2 Normative references.9 3 Definitions and abbreviations.10 3.1 Definitions.10 3.2 Abbreviations.11 4 Safety requirements.12 4.1 Prerequisite.12 4.2 Protection against electric shock.12 4.3 Protection from voltages due to the proximity of high voltage systems.13 4.4 Fire and chemical hazard.13 4.5 Explosive and asphyxiating gases.13 4.6 Optical fibre hazard.13 4.7 Mechanical hazard.13 4.8 Separation requirements for metallic cabling.13 4.9 Closures .13 5 General installation practices for metallic and optical fibre cabling.14 5.1 General .14 5.2 General precautions.15 5.3 Pre-installation practices.15 5.4 Preparation of cable routes.16 5.5 Cabling practices.17 5.6 Cable management systems.18 5.7 Labelling.19 5.8 Installation of closures.19 5.9 Segregation of services.20 5.10 Information technology cabling interconnections between buildings.27 5.11 Pole sharing.27 6 Additional installation practice for metallic cabling.31 6.1 EMC-Considerations.31 6.2 Balanced transmission.31 6.3 Screening.31 6.4 Mains and high voltage power distribution systems (above 1 000 V).31 6.5 Protection against very low frequency fields.31 6.6 Electrical isolation components.31 6.7 Surge protective devices.31 6.8 Protection against lightning.32 6.9 Protection against electrostatic discharge (ESD).32 6.10 Corrosion.33

6.11 Protection against radar emission and broadcast emitters.33 7 Additional installation practices for optical fibre cabling.34 7.1 General .34 7.2 Pre-installation procedures.34 7.3 Optical fibre cable practices.34 7.4 Final assembly of closures.34 7.5 Termination practices.34 7.6 Jointing/termination of optical fibres.35 7.7 Optical fibre management.36 8 Additional installation practices for specific sites and services.37 8.1 Hospitals.37 8.2 Airports .37 8.3 Nuclear areas.37 8.4 Explosive areas.38 8.5 Chemical manufacture /areas /plants.38 8.6 Tunnels and bridges including their associated services.38 8.7 Waterways, including rivers, canals, streams (natural or ducted / channelled etc.).38 8.8 Over-ground and underground railways.39 Annex A (informative)
Earth potential rise (EPR).42 Annex B (informative)
Typical examples of protection for information technology cabling.44 Bibliography.46

– 5 – EN 50174-3:2003 List of figures Figure 1 - Relationship between series EN 50174 and other design standards.8 Figure 2 - Examples of areas covered by this document.15 Figure 3 - Example showing the protection of underground information technology cables
when located next to power cables.21 Figure 4 - Distance between information technology cable and high voltage power lines.23 Figure 5 – Example of an underground cable duct entrance for information technology
cables into a building.25 Figure 6 - Example of the use of a galvanic isolation device.27 Figure 7 - Separation distances at the pole.29 Figure 8 - Separation distance at the poles with lighting devices.30 Figure 9 - Clearance not including components of information technology cabling for
standard gauge railways.40 Figure 10 - Clearance not included components of information technology cabling for
protection against falling contact wires.41 Figure A.1 - Definition of hot zone.42 Figure B.1 - Example of connection between inside and outside building.44 Figure B.2 - Example at main frame distributor.44 Figure B.3 - Example of non-equipotential zones.44 Figure B.4 - Example of a hot zone.45

List of tables Table 1 – Minimum installed clearances above ground for aerial cables.17 Table 2 - Minimum clearances between aerial information technology and overhead
power cabling crossing or when running in parallel.20 Table 3 – Minimum distance between buried insulated information technology cables
and earthed electrodes of power systems in rural environment.22 Table 4 - Minimum depth of information technology cabling below the ground surface.22 Table 5 - Minimum clearances and protective measures at crossings between information
technology cables and various underground services.23 Table 6 - Minimum distance between information technology earthing systems and earthed
electrodes of power systems in rural environment.24 Table A.1 – Minimum distance (HV installations less than 25 kV).43 Table A.2 - Minimum distance (HV installations exceeding 25 kV).43

– 7 – EN 50174-3:2003 Introduction The importance of the information technology cabling infrastructure is similar to that of other fundamental building utilities such as heating, lighting and mains power supplies. As with other utilities, interruptions to service can have serious impact. Poor quality of service due to lack of planning, use of inappropriate components, incorrect installation, poor administration or inadequate support can threaten an organisation’s effectiveness. There are four phases in the successful installation of information technology cabling. These are a) design - the selection of cabling components and their configuration, b) specification - the detailed requirement for the cabling, its accommodation and associated building services addressing specific environment(s) identified within the premises together with the quality assurance requirements to be applied,
c) implementation - the physical installation in accordance with the requirements of the specification,
d) operation - the management of connectivity and the maintenance of transmission performance during the life of the cabling. This European Standard is in three parts and addresses the specification, implementation and operational aspects. The design issues are covered in series EN 50173 and / or other application standards. EN 50174-1 is intended to be used by personnel during the specification phase of the installation together with those responsible for the quality planning and operation of the installation. It contains requirements and guidance for the specification and quality assurance of the information technology cabling by defining - aspects to be addressed during the specification of the cabling, - quality assurance documentation and procedures, - requirements for the documentation and administration of cabling, - recommendations for repair and maintenance. EN 50174-2 and this part, EN 50174-3, are intended to be used by the personnel directly involved in the implementation phase of the installation. EN 50174-2 is applicable inside buildings and EN 50174-3 is applicable outside buildings. This part, EN 50174-3, contains detailed requirements and guidance relating to the installation planning and practices by defining 1) planning strategy (road map) and guidance depending on the application and physical environment (climatic, mechanical, electromagnetic, etc.), 2) design and installation rules for metallic and optical fibre cabling depending on the application, electromagnetic environment, physical environment, etc., 3) requirements on satisfactory operation of the cabling depending on the application, electromagnetic environment, physical environment, etc., 4) the practices and procedures to be adopted to ensure that the cabling is installed in accordance with the specification.

Figure 1 shows the relationships between the standards produced by TC 215 for information technology cabling, namely cabling design standards (EN 50098 series, EN 50173 series), cabling installation standards (EN 50174 series) and equipotential bonding requirements (EN 50310). Building design phase Cabling design phase Planning phase Implementation phase Operation phase EN 50310 5.2: Common bonding network (CBN) within a building 6.3: AC distribution system and bonding of the protective conductor (TN-S)
EN 50173 (series)
or (and)
EN 50098-1
or (and)
EN 50098-2
or (and)
Other application standards EN 50174-1 4: Specification considerations 5: Quality assurance
7: Cabling administration and EN 50174-2 4: Safety requirements 5: General installation practices for metallic and optical fibre cabling 6: Additional installation practice for metallic cabling 7: Additional installation practice for optical fibre cabling and EN 50174-3 and (for equipotential bonding) EN 50310 5.2: Common bonding network (CBN) within a building 6.3: AC distribution system and bonding of the protective conductor (TN-S) EN 50174-1 6: Documentation
7: Cabling administration
and EN 50174-2 4: Safety requirements 5: General installation practices for metallic and optical fibre cabling
6: Additional installation practice for metallic cabling 7: Additional installation practice for optical fibre cabling and EN 50174-3 and (for equipotential bonding) EN 50310 5.2: Common bonding network (CBN) within a building 6.3: AC distribution system and bonding of the protective conductor (TN-S) and EN 50346 4: General requirements 5: Test parameters for balanced copper cabling 6: Test parameters for optical fibre cabling EN 50174-1 5: Quality assurance 7: Cabling administration
8: Repair and maintenance
Figure 1 - Relationship between series EN 50174 and other design standards

– 9 – EN 50174-3:2003 1 Scope This European Standard specifies the basic requirements for the planning, implementation and operation of information technology cabling using balanced copper cabling and optical fibre cabling. This standard is applicable to a) cabling designed to support particular analogue and digital communications services including voice services; b) generic cabling systems designed in accordance with series EN 50173 and intended to support a wide range of communications services. This standard is intended for those involved in the procurement, installation and operation of information technology cabling. Furthermore this standard is addressed to - architects, building designers and builders; - main contractors; - designers, suppliers, installers, maintainers and owners of information technology cabling; - public network providers and local service providers; - end users. This standard is applicable to certain hazardous environments but does not exclude additional requirements which are applicable in particular circumstances, e.g. in the presence of electricity supply and electrified railways. This part of the standard c) sets out requirements for satisfactory installation and operation of information technology cabling outside buildings; it is not restricted to campus areas, d) excludes specific requirements applicable to other cabling systems (e.g. power cabling, coaxial cabling); however, it takes account of the effects other cabling systems may have on the installation of information technology cabling (and vice versa) and gives general advice. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies (including amendments). EN 12613, Plastics warning devices with visual characteristics for underground cables and pipelines EN 41003, Particular safety requirements for equipment to be connected to telecommunication networks EN 50173-1, Information technology – Generic cabling systems – Part 1: General requirements and office areas 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 50310, Application of equipotential bonding and earthing in buildings with information technology equipment
EN 60950-1, Information technology equipment – Safety – Part 1: General requirements (IEC 60950-1:2001, modified) EN 60950-21, Information technology equipment – Safety – Part 21: Remote power feeding (IEC 60950-21:2002) EN 61663-1, Lightning protection – Telecommunication lines – Part 1: Fibre optic installations (IEC 61663-1:1999 + corrigendum Oct. 1999) EN 61663-2, Lightning protection – Telecommunication lines – Part 2: Lines using metallic conductors (IEC 61663-2:2001) HD 384.4.41 S2, Electrical installations of buildings – Part 4: Protection for safety - Chapter 41: Protection against electric shock (IEC 60364-4-41:1992, modified) HD 384.4.47 S2, Electrical installations of buildings – Part 4: Protection for safety – Chapter 47: Application of protective measures for safety – Section 470: General – Section 471: Measures of protection against electric shock (IEC 60364-4-47:1981 + A1:1993, modified) HD 384.4.482 S1, Electrical installations of buildings - Part 4: Protection for safety - Chapter 48: Choice of protective measures as a function of external influences - Section 482: Protection against fire where particular risks or danger exist ITU-T K.33, Limits for people safety related to coupling into telecommunications system from a.c. electric power and a.c. electrified railway installations in fault conditions ITU-T K.50, Safe limits of operation voltages and currents for telecommunication systems powered over the network ITU-T K.51, Safety criteria for telecommunication equipment ITU-T K.53, Values of induced voltages on telecommunication installations to establish telecom and a.c. power and railway operators responsibilities 3 Definitions and abbreviations 3.1 Definitions For the purposes of this European Standard the following definitions apply: 3.1.1 bonding network (BN) set of interconnected conductive structures that provides an “electromagnetic shield” for electronic systems and personnel at frequencies from Direct Current (DC) to low Radio Frequency (RF) NOTE The term "electromagnetic shield" denotes any structure used to divert, block or impede the passage of electromagnetic energy. In general, a BN does not need to be connected to earth, but all BNs considered in the present document will have an earth connection [3.1.2 of EN 300 253:2002]

– 11 – EN 50174-3:2003 3.1.2 campus premises containing one or more buildings
[3.1.11 of EN 50173-1:2002] 3.1.3 hot zone area around a high voltage installation (e.g. substation, transformer, pylon) whose earth potential rise in normal operation or when an earth fault occurs, is over the limits given in ITU-T K.53 for typical fault situations 3.1.4
rural area area which has a low density of local metallic structures in direct electrical contact with soil
NOTE In a rural environment the earthing systems of the substations have their own earth electrodes which are not normally connected together. 3.1.5
urban area area which contains a high density of local metallic structures in direct electrical contact with soil such as water pipes, cables with bare metal sheaths, tracks of tramways or underground or overground traction systems and earth-terminations and structures of buildings, masts and foundations 3.2 Abbreviations AC alternating current BN bonding network CBN common bonding network CMS cable management system DC direct current EMC electromagnetic compatibility EPR earth potential rise ESD electrostatic discharge
GDT gas discharge tube
HV high-voltage LV low-voltage
MOV metal oxide varistor
PEC parallel earthing conductor SPD surge protective device TVS transient voltage suppressor

4 Safety requirements 4.1 Prerequisite This clause only deals with general safety requirements, however, all other clauses in this document contain specific safety requirements. Provisions shall be taken to make all concerned persons present in the campus aware of a) the locations and boundaries of hazardous areas outside buildings, b) the procedures to be adopted when working in or in proximity to these hazardous areas, c) fire precautions. It is assumed that mains power cabling is installed in accordance with the requirements of relevant international or regional standards, national or local regulations. All the installed cable shall comply with the relevant product safety requirements.
The requirements of EN 50174-2:2000, Clause 4, shall apply. 4.2 Protection against electric shock 4.2.1 Active equipment requirements Only equipment that incorporates safe signal circuitry complying with EN 60950-1, EN 60950-21, EN 41003, ITU-T K.50 and ITU-T K.51 shall be connected to information technology cabling. Equipment connected shall comply with the requirements for protection against electric shock of the relevant product safety standards. The connection of active equipment to information technology cabling shall not introduce hazards for users or operators of the system. 4.2.2 Cabling components Conductors with hazardous voltages shall not be accessible at any entry and distribution points. The coexistence of power and information technology cables requires proper insulation for the information technology cabling components (e.g. connecting hardware, cable, terminals) or other protection measures to achieve adequate protection from indirect contact. The requirements of HD 384.4.41 S2, HD 384.4.47 S2 and HD 384.4.482 S1 or relevant national or local regulations shall apply. Connection of the main earthing terminal (MET) (as close as possible to the building entrance point), or of a local earth with a low resistance (if outside the premises) to the following is necessary: a) metallic cable screen(s) at both ends; if high unbalance currents are expected, due to different earthing potential, precautions should be taken to limit such currents; b) conductive parts of the entry, distribution and termination points, including metallic cabinets, covers and other metallic parts of the cable management system; c) protection devices installed on line conductors of information technology cables, i.e. at exposed sites. The above earthing shall be realised by low impedance bonding. The electrical continuity of the metallic screen shall be maintained.

– 13 – EN 50174-3:2003 Stays and struts used on poles used for information technology cabling should be suitably insulated when required e.g. when passing power cables, and also when using a metallic catenary wire to ensure the safety of the public from hazardous voltages reaching accessible portions of the stay wire. Connecting hardware selected for information technology cabling shall not be interchangeable with the sockets or plugs used for mains power distribution. Further requirements are set out in EN 50174-2:2000 (Clause 4, subclauses 6.7, 6.8 and Annex A). 4.3 Protection from voltages due to the proximity of high voltage systems This standard gives installation rules for the following situations: a) proximity of information technology and power cables / overhead lines; b) proximity of information technology cables and power earthing systems; c) proximity of information technology and power earthing systems. See 5.9 and Annex A. 4.4 Fire and chemical hazard The choice of cables shall be made according to the national regulation relating to the Construction Product Directive (see also EN 50174-2:2000, Clause 4). 4.5 Explosive and asphyxiating gases The requirements of EN 50174-2:2000, 4.4, shall apply. 4.6 Optical fibre hazard The requirements of EN 50174-2:2000, 4.5, shall apply. 4.7 Mechanical hazard The hazard is mainly related to the mechanical stability of aerial cables. For proper installation national regulations shall be followed in placing the poles and evaluating the maximum permitted span length. For further details see Clause 5. 4.8 Separation requirements for metallic cabling Cable and installation requirements for crossing of underground cables and overhead clearances are set out in 5.9 as well as in EN 50174-2:2000, 6.5 (segregation of circuits), where safety and EMC aspects are taken into account. 4.9 Closures Closures providing facilities for the termination and (or) distribution of both information technology cables and mains power cables shall be designed to provide separate covers for the two cabling types. Alternatively, a single overall cover is allowed provided that the mains power cabling remains protected to prevent electric shock after removal of the cover. This applies for example to a closure containing separate termination points for information technology and mains power cabling, but not for termination points where the power supply is provided within the information technology cabling termination point.

Where both information technology cabling and mains power cabling are contained within a closure then: a) if the closure is metallic, it shall be earthed in accordance with the relevant wiring regulations for protective earth; b) the compartment in the closure shall have a barrier (either conducting or non-conducting) between the two cable types. If compartment barriers are conductive, they shall be earthed in accordance with the relevant wiring regulations for protective earth; c) the front covers on the closure shall allow separate access to the information technology cabling and the mains power cabling and shall be retained such that the use of a tool is necessary to gain access thereby preventing inadvertent connection between the mains power and the information technology cabling; d) the entry for the information technology cables and the mains power cables shall be separate and the separation of the cables shall conform to the requirements of Clause 5. 5 General installation practices for metallic and optical fibre cabling 5.1 General The installation practices take into account safety hazards and interference with other outside plant. General EMC requirements and guidance are given in Clause 6. Metallic and optical fibre cabling in outside plant can be installed underground or overhead according to the different possible situations. Generally, but particularly for underground installation, the cable management system should allow for the installation of additional cables in the future without risk of damage. Additional installation guidelines for optical fibre cabling are given in Clause 7. The requirements within this standard do not cover a) any additional requirements for the information technology cables installed in hazardous or stressful environments e. g. electricity supply and electric railway locations (see Clause 8), b) coaxial cabling and components used within cable distribution systems for television and audio signals (according to EN 50083 series). Examples of areas covered by this standard are shown in Figure 2.

– 15 – EN 50174-3:2003 BuildingBuildingBuildingBuildingPower substationPenetration points of campusIT accessnetworkIT switchCampus Aaccordingto seriesEN 50173Campus Baccordingto seriesEN 50173IT switch NOTE Neither the connection performance nor the media between the entry point and the building entrances are defined in EN 50173-1. Cabling denoted by dotted lines is not within the scope of this standard. Figure 2 - Examples of areas covered by this document
5.2 General precautions All cables and cabling components shall be checked on delivery to ensure that no mechanical damage has occurred during transportation. Documentation supplied shall be checked for compliance with the procurement specification and retained. The components shall be stored in a suitable place until required. Consideration shall be given to security and environmental conditions. The components shall not be unpacked until required for installation. When pulling-in cables, (particularly optical fibre cables) mechanical fuses (or equivalent protection) shall be used to ensure that the maximum tensile loads established by the cable manufacturer are not exceeded. Precautions shall be taken during installation to prevent the ingress of water and other contaminants. 5.3 Pre-installation practices 5.3.1 General The installer shall establish that the routes defined in the installation specification are accessible and available according to the installation programme. The installer shall advise the client of all proposed variations (see EN 50174-1:2000, 4.8.1). The installer shall verify that the physical compatibility and the environmental conditions within the routes and the installation methods to be used are suitable for the design of cable and components to be installed. Where underground installations are envisaged, the installer shall use the best digging methods to minimise any disruption or inconvenience (e.g. traffic, dust, reduced access to buildings and shops, etc.) to the population.

The installer shall identify the proposed locations at which cable drums, reels or boxes are to be positioned during the installation programme and should establish the accessibility and availability of those locations. The installer shall identify proposed locations of cabinets and maintenance holes and should establish their accessibility and availability according to the installation programme. The cabinets and maintenance holes shall be located such that it is possible for subsequent measurements, repair, expansion or extension of the installed cabling to be undertaken with minimal disruption and in safety (see EN 50174-1:2000, 4.6). Should a gas hazard be detected the installer shall inform the site contact nominated by the client and appropriate action shall be agreed and undertaken. The installer shall ensure that all necessary guards, protective structures and warning signs are used to protect the cable, the installation personnel and third parties. Relevant national regulation for safe working practices shall be complied with. 5.3.2 Mechanical and environmental (rodents) Where there is a history of rodent damage special measures may need to be taken. 5.4 Preparation of cable routes 5.4.1 General The requirements of EN 50174-2:2000, 5.4, shall apply. When designing and maintaining information technology cable routes, the regulations related to the prevention of dangerous voltages and any potential disturbances caused by power cables and other heavy current cables shall be taken into consideration (see also 4.1). 5.4.2 Underground cables Underground cables without suitable protection should be drawn into ducts, pipes or other suitable structures to protect them from mechanical, electrolytic or chemical danger.
There are several techniques for installing cabling into ducts or pipes. If draw ropes are used they should be installed prior to the installation of the cable as required. Under no circumstances shall draw ropes be installed concurrently with the cable. Existing draw ropes should be checked for satisfactory function. Cables that are to be laid directly in the ground shall be of suitable mechanical construction for this purpose. Soil conditions should be carefully considered when a cable is buried directly in the ground. However, if subsoil conditions are known to be corrosive, the cable may require additional protection and the cable suppliers should be consulted. Marking tape shall be laid above any directly buried cable (see EN 12613). Laying marking tape above the cable management system is always recommended. When cables with metallic components are buried in rural areas with high risk of lightning strikes, extra protection is strongly recommended (see 6.8). The need for lightning protection shall be considered according to series EN 61663. 5.4.3 Aerial cables The route of the cable shall be designed and built in such a way that damage or unsafe situations caused by overloading the construction are avoided. At the crossing of two or more routes, different cables shall not touch each other in any circumstances.

– 17 – EN 50174-3:2003 Special consideration shall be given to overhead routes that run parallel to or cross railways, tramways, trolley bus cables, cable railways, cable ways, ski and chair lifts, motor ways, roads and navigable rivers and waterways, etc. The stresses on the cables and poles depend on the span length and the sag. The climatic conditions that can have a major effect on tensions in poles, aerial cables and sag are heat, cold, wind and snow / ice load on cables and poles. Reference shall be made to the national regulations for routes affected by such conditions and the appropriate construction methods utilised. The information technology cable route should be as straight as possible and shall be installed to respect the minimum clearances above ground given in Table 1: Table 1 – Minimum installed clearances above ground for aerial cables Location Clearance Motorway, main roads 6
m Non electric railway 6
m Minor road crossings, areas accessible to vehicular traffic, field path, campus entrance 5,5 m Minimum clearance no traffic crossing 4
m Specific environment, Gardens 3
m NOTE Aerial crossing of motorway, non electric and electrified railways is not recommended. Where pole sharing is allowed, see 5.11. Any information technology cables rising from the ground shall be mechanically protected to a height of at least 2 m. 5.5 Cabling practices Proper installation practices shall be observed for cabling to ensure performance of the cabling system over its life cycle.
Performance specifications for cable and connecting hardware assume the use of proper installation practices and cable management techniques according to manufacturers’ guidelines. If recommended cable handling practices and installation methods are not observed, it is possible that specified transmission capabilities of cabling components cannot be achieved. During cable installation, appropriate techniques shall be followed: a) the cabling components shall be installed in environmental conditions compliant with any relevant standards; b) bend radii shall never be less than the minima specified by the manufacturer/supplier; c) cables shall not be exposed to temperatures exceeding their specified limits after installation, this includes localised effects such as those from hot air blowers or gas burners; d) no forces shall be allowed that cause damage (e.g. through improper fastening or crossovers) to the cable sheath or the cable elements; e) jointing chambers should be positioned at all joints, places where there are severe changes of direction and cabinets;

f) leaving enough spare cable along the route (e.g. at jointing chambers or poles) to facilitate future maintenance is recommended; g) covers of jointing chambers shall be sized according to the maximum foreseeable load; h) all cabling management systems at the entrance into a building shall be sealed to prevent the ingress of dust, water, animals, gas, etc.;
i) if more additional cables are installed in a duct or sub-duct then great care shall be taken to prevent damage to existing cables, when removing or installing cables. 5.6 Cable management systems 5.6.1 Aerial supporting structures (overhead) Supporting structures, e.g. poles, shall be selected to be of dimensions and strength suitable for their length and the load they are intended to carry, taking into account influences due to climatic and soil conditions. The most economical layout will generally be obtained with a span of 50 m. If special supporting structures are used, greater span lengths may be obtained. The deviation from the straight line between poles should not be more than 20 % without using stays or struts. Supporting structures shall be suitably treated to prevent decay. Supporting structures should be checked periodically so that degradation and damage can be detected and corrected if required.
Where necessary stays or struts can be attached to the pole at the resultant load points of the cables or at road crossings. To ensure the safety of the public from hazardous voltages reaching accessible portions of the stays or struts, they shall be suitably insulated when required (e.g. when passing power cables), and also when using a metallic catenary wire. Catenary wires shall not be spliced in the field. 5.6.2 Underground
Except for particular cases (e.g. bridges, thrust boring) underground cable management systems (e.g. pipes, ducts) should be made from suitable non conductive material. All underground cable management systems should be made of a non-porous material. Sections shall be jointed to inhibit ingress of gases, water and foreign materials. 5.6.3 Attachments Attachment of suspension wires or catenary cables to buildings should be permitted only when it is clear that the load on the fixing point will not exceed its design strength and the structure of the building is capable of sustaining the load with a safety factor. Attachment of suspension wires or catenary cables to buildings should be avoided in earthquake zones. 5.6.4 Earthing of cables and cabling management systems Metallic parts (e. g. screens, suspension or catenary wires) and metallic cable management systems should be conne
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