Cabling system installation practice
Cabling system installation shall be performed in a safe manner.
Personnel undertaking installation works shall be equipped with appropriate personal protection equipment, tools and mechanical aids.
Appropriate barriers and warning signs shall be used to restrict access and draw attention to potential hazards such as open trenches and the like.
Qualifications of Installer
The Structured Cabling System shall be installed only by organisations that are accredited by the manufacturer of the cabling system components and by properly qualified personnel as specified in Contractor Qualifications.
All equipment and cabling shall be installed in full accordance with the manufacturer’s recommendations and instructions.
Cable lengths shall be kept to a minimum by taking the most direct and practical route.
Cable pathways and cable shall be installed to achieve the required separation between communications cabling and other services. Separation shall comply with AS/NZS 3080 Z.A.3.
All cables shall be concealed in walls or ducts except where run on cable trays in equipment rooms. Cables shall be run in neat lines.
All metallic conduit, cable trays, catenaries, boxes, and enclosures shall be permanently and effectively earthed in accordance with the AS/NZS 3000 and AS/NZS 3080.
Cable Support Systems and Pathways
Cable support systems and pathways shall meet the requirements of AS/NZS 3084.
All fixed horizontal cabling shall be concealed from view within the workplace. All cabling shall be installed in conduits, on cable trays, or in ceiling or under-floor cavities. Approved cable fasteners shall be used at intervals as specified in AS/NZS 3084 (ZB220.127.116.11).
It may be necessary to surface-mount cabling within ducting where no cavity exists or where concealment would prove to be inordinately expensive, disruptive or impracticable. Two-compartment duct shall be used to segregate power and data cabling where both services are being run.
All ducting shall be run in an inconspicuous manner. Excess cabling shall not be stored in the duct.
Where cable is run in a false (suspended) ceiling it shall be suspended from fixed non movable structural features, purpose-installed flat cable trays, or from catenary wires. Fixed, non movable features exclude water pipes, sprinkler systems and trunked electrical power.
Cable trays shall be installed in accordance with AS/NZS 3084 ZB3.3.6.
Surface-mounted ducting shall be installed where alternative methods for concealment of cables are not possible. Two-compartment ducting shall be used where necessary to segregate power and data cabling.
Ducting shall be fixed to walls according to the manufacturer’s specification using suitable fixings (e.g. cavity fasteners for cavity walls and masonry anchors for concrete walls). Where no fixing specification is provided, it is suggested that ducting be fixed at approximately 1m intervals when run vertically and approximately 600mm intervals when run horizontally. Fixings shall not cause undue distortion to the ducting when tightened.
Fasteners / Fixings / Ties
Fixings shall be entirely suitable for the situation in which they will be used. Where fixings are to be used externally or exposed to the weather, stainless steel or brass is preferred - plain and cadmium-plated steel will not be accepted. Where fixings are used internally, cadmium-plated steel is acceptable. All fixings, fastenings and supports shall be of adequate strength and size and arranged to ensure the installation against mechanical failure under normal conditions prevailing in ECE Services.
Cables shall be held firmly by the securing device without undue pressure being exerted on the cable sheath.
Cable ties used externally shall be UV resistant.
Internal Catenaries and Above Cable Trays
Internal cabling supported by catenaries or above cable trays shall be installed in accordance with AS/NZS 3084 ZB18.104.22.168 and a main cable route shall be chosen such that the cable path is accessible and conforms to the segregation requirements.
Catenary wires shall be anchored at a maximum of 5m spans. Turnbuckles and steel eyelets shall be used to tighten the catenaries.
A maximum of 24 x 4 pair UTP cables may be tied to a single catenary.
Fire-rated elements and structural members shall not be penetrated without approval from the Building Architect and relevant Fire Authority.
Where ladders or trays pass through ceilings, walls and floors provide neat, close-fitting apertures. At openings through fire rated elements, terminate the ladders or trays both sides of the opening and provide holes for the cables only. All holes shall be fire-stopped with a proprietary product that exceeds the fire resistance of the materials being filled and is installed to the manufacturer’s specifications.
Ducts that pass through walls or floors shall be sealed with an industry-standard duct sealing device to prevent the ingress of water.
Enclosures / Cabinets
All enclosures whether floor or wall mounted shall be installed and mechanically supported to accommodate the load of the enclosure combined with the equipment load specified in Cable Pathways and Enclosures.
Communication enclosures shall be located to achieve maximum operator convenience. The space available for a communications cabinet is to be verified on site. The cabling Contractor shall ensure that enclosures are installed with adequate access for wire termination, equipment installation and maintenance, and patch field alterations.
The vertical footprint for wall-mount enclosures shall not extend above 2m or below 0.5m from the floor. Wall mount locations shall be selected to avoid risk of injury by walking past or rising from beneath the enclosure.
Enclosures shall be installed plumb and square without twists in the frames or variations in level between adjacent racks.
Enclosures shall be bonded to the protective earth system.
Equipment mounting rails at the front of the enclosure shall be set back so that doors may be closed without contacting equipment or connectors or distorting cable bends.
Enclosure Cable Entry
Cabling entering from the floor or ceiling space to enclosures shall be supported and concealed by a vertical cable support system.
The vertical cable support system shall extend from the cable pathway to the enclosure. In the case of under-floor pathways the vertical cable support system shall extend below the floor level. In the case of above ceiling pathways, the vertical cable system shall extend above the ceiling level.
The vertical cable system shall have a metal construction, colour and finish similar to the enclosure.
Cabling Within Enclosures
All cables shall terminate at the patch panels in the communications enclosures with an excess length of 2m neatly placed out of sight prior to terminating. Excess cable shall not be coiled but shall be formed into a “figure 8” or a “loop back”.
Cables terminating at an enclosure shall be neatly loomed within the enclosure, utilising the cable management system specified in Cable Pathways and Enclosures. Cables shall be loomed between the space on the outside of the mounting rails and the removable door. Cables loomed inside wall mounted cabinets shall be loomed in maximum groups of 12, to allow enough space for mounting active network equipment.
All cabling shall be installed in full accordance with the manufacturer’s recommendations. Cables shall be installed with due skill and care so that:
- maximum permitted hauling tension is not exceeded
- minimum bending radius of the cable is not exceeded
- maximum permitted crush rating is not exceeded
Cable bundles shall not obstruct the installation and removal of equipment within equipment enclosures.
Equipment and patch panels shall be laid out to minimise patch cord length and follow clear paths to avoid patch field obstruction.
Precautions During Installation of Cables
Precautions shall be observed to eliminate cable stress caused by tension in suspended cable runs and tightly strapped bundles.
Care shall be taken not to distort the twists by excessive pulling or bending of cables.
Cable bundles shall not rub on or be unduly compressed against or by any cable tray, building or enclosure penetrations, equipment racking, or other cable support. Grommets or similar forms of protection shall be provided where cables traverse sharp edges.
The weight of vertically installed cabling shall be adequately supported.
Category 6 cables shall be fixed to cable trays and catenary wires using Velcro or elasticised cable ties only, at intervals according to AS/NZS 3084 Table ZB6. At no point shall the cabling rest on the false ceiling, light fittings, or any other services.
Cables shall be neatly grouped together based on their destination and bound at regular intervals.
Where cabling is run in cavity walls, surface-mounted ducting and similar enclosures, the run shall be free from protrusion by screws and similar fasteners.
Cable ties shall be tightened by hand or correctly calibrated tension guns just sufficiently to hold cables together and to fix cables to supports. Care shall be taken to avoid tight twisting of the cable, tearing of the outer jacket, cutting or wearing through due to abrasion of the cable.
Balanced Cabling Installation
The cable between a telecommunication outlet and a horizontal distribution panel or patch panel shall be one continuous length with no intermediate joins, splices or taps. Mid-run joints of cables are not permitted except for the use of consolidation points as outlined in Structured Cabling Systems. The maximum length of the various elements of the balanced cabling shall be in accordance with Cabling System Technical Requirements.
Where two or more cables share a pathway the cables shall be tied together at 1200mm intervals to create a trunk effect.
A loop of cable shall be left in the cable trunking on the approach to each telecommunication outlet to facilitate removal of faceplates and associated RJ45 sockets for servicing and re-termination of the cable, should this be required.
Balanced copper cable bending radius shall not be less that eight times the cable diameter under no load conditions and 16 times the cable diameter under load, i.e. when being pulled through conduits, or as specified by the cabling manufacturer - whichever is greater. Cables shall be anchored immediately before the start and after the finish of the bend.
To preserve the electrical characteristics of the balanced cable, the outer insulation of the cable shall not be stripped back unnecessarily, and shall be left intact up to a point as close as possible to where the individual pairs are terminated to the IDC connector.
Balanced Cable Termination
An RJ45 system shall be utilised. Cable termination on a horizontal distribution panel or patch panel should be undertaken in a manner permitting additional cables to be terminated without unduly disturbing previously installed cables.
Cabling termination to telecommunications outlets, patch cords, work area cords, and patch panels shall be to the “T568A” arrangement in accordance with AS/NZS 3080 Z.A.2.
The connecting hardware shall be installed to the manufacture’s specification and preserve the wire twist as close as possible to the point of mechanical termination to minimise signal impairment. The amount of untwisting in a pair shall be no greater than 13mm for Category 5 cable and no greater than 6mm for Category 6 cable.
Where workbenches are fixed to the wall, outlets may be installed above bench height. Where workbenches are positioned along a wall or benches have data distributed internally, outlets should be located at a minimum of 800mm centres.
Outlets should be distributed along walls at the discretion of the ECE Service. The height of the outlets above the floor will be determined by the type of trunking proposed and other wall fixtures such as radiators.
Telecommunication outlets should be flush mounted wherever practicable. Mounting boxes, similar in style and colour to the flush plate, shall be used where flush mounting of telecommunications outlets is not practicable.
Outlets shall be co-located with power outlets. Two-compartment metal trunking may provide a cost effective solution to this requirement.
Outlets shall be located to avoid being obscured and work area cords being damaged by furniture and office equipment. All cable pairs at the telecommunication outlets and at the distribution panels shall be terminated.
A bend radius (1:8) sufficient to avoid damage to the outlet or work area cords shall be provided.
Balanced cables shall be terminated at the telecommunications outlet using the “T568A” pin assignments and colour codes in accordance with AS/NZS 3080 Z.A.2.
Outlets designated for use by a WLAN access point shall be located to meet the requirement identified in Structured Cabling Systems.