Equipment Mounting & Cabling

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Provision for Rack Mounted Equipment

The AETM recommend the provisioning of an equipment rack system to house individual system components, ensuring that an audiovisual system is installed in a professional, operational and serviceable manner.

There are a variety of design considerations associated with the planning and installation of equipment racking, which will be covered in this chapter.

Equipment racking can come in a variety of appropriate forms, depending on the situation and/or preference of an organisation:

Behind Display

Slide out shelves are a suitable solution for situations where a small number of components are required to fit behind a display, or where nearby joinery or racking is not available. Slide-out racks are superior to simply wall-mounting equipment as they allow for simple serviceability of equipment by support technicians, including equipment replacement, they also provide a secure mounting point for locking devices. Care must be taken to ensure that the mounting device does not interfere with a display mounting solution or electrical/communications services that may also be mounted vertically behind the display. Power and data outlets should be mounted in a location that allows simple access by support technicians whilst obscuring their view from passers-by.

Under Table

Simple 2-3RU shelves are often suitable for the mounting of one or two system components under tables. Mounting of gear hard against the underside of the table should be avoided to improve serviceability, and coordination must be

Full or Half-Height Equipment Racks

Lockable, ventilated, purpose designed space must be reserved for the equipment which comprises the audio, video, control and/or lighting sub systems. Provision must be made for power, and data and other building service access to the this rack locationspace and for fitment and maintenance of interconnecting signal cables.

AVIXA F502-01 provides a comprehensive reference for the planning, design and construction of AV equipment racks. Full compliance with this standard is recommended unless excepted by a local organisational standard/guideline.

Minimum Design Considerations for audiovisual Equipment Racks (From AVIXA F502.1):

Planning for the use of this Standard should begin during the project design phase and implemented in conjunction with a fully-developed project documentation package.

Design decisions that should be documented to achieve an agreed-upon outcome prior to building the rack include:

  • Fixed installation or mobile/portable rack – selection of the rack type;*

  • Environmental control of the installation location and resultant thermal management

  • performance requirements of the rack;*

  • Security requirements;*

  • Accessibility of user-accessible AV equipment within the rack and ergonomics;

  • Overall layout of AV equipment within the rack (production of a rack elevation drawing)

  • including thermal management and weight distribution consideration;*

  • Quantity of equipment racks (single/multiple rack installations);*

  • Entry/connection method for site cabling;*

  • Inter-connection method for cabling in multiple rack installations;*

  • Mains voltage power supply delivery arrangements;*

  • Earthing (grounding) and bonding requirements;*

  • Other environmental control factors, such as seismic considerations;

  • The intended final installation location of the rack (if applicable);

  • Spatial considerations and the relationship to the overall physical size of the rack, having

  • regard to access requirements;

  • AV equipment to be housed and the relationship to the overall physical size of the rack;

  • and

  • Acoustic sensitivity of the installation location and resultant acoustic performance

  • requirements of the rack.*

NOTE: At a minimum, a design package provided to users of this Standard should include all items marked with an asterisk (*) above.

Adequate bench space must be allowed for the fitment of control panels, preview monitors, and microphones in addition to user operated equipment such as Visualisers and graphics tablets. This space allowance should be in addition to space for lecturers to place a laptop or portable PC, lecture notes and presentation aids.

While some equipment (such as power amplifiers) are desirably located away from the teaching area because of considerations of fan noise and heat, space must be reserved close to the presentation area for the accommodation of equipment which needs to be accessed to insert media (disks, USB keys, tapes etc.) at the start of a teaching session. This may include PCs, disk players, tape players and recording devices.

Provision must be made to secure this equipment in a way which allows access to loading slots, trays and connectors.

Access for Maintenance

audiovisual equipment in professional use needs to be accessible for routine maintenance operations and also for emergency break-fix should failure or mis-operation occur during a session.

Professional equipment typically has operational controls and mounting screws at the front, while power and signal interconnection is made at the rear. It is important therefore that provision is made for ready access to both the front and rear of equipment racks, as well as one side wherever it is required to service all pieces of equipment or cabling.

A minimum of 600mm distance between rack edge and nearest obstruction is recommended to ensure equitable and appropriate space for technicians to work comfortably and safely.

[placeholder for two examples - rack built into joinery and another free-standing.]

Where rack frames are mounted in user-accessible joinery/spaces, front and rear access doors should be fitted which are lockable and wide enough to allow removal of individual equipment, as well as the rack without disassembly of the rack or removal of the door. This provision should be extended to side access where deemed required by local AV design personnel.

Where racks are fitted in rooms such as dedicated AV or Communications rooms, space must be large enough for provision to be made to access the front,rear and side of the rack. Room access doors should be lockable and wide enough to allow removal of the rack without disassembly of the rack or removal of the door. Conformance to organisation communications room standards must be adhered to in conjunction with these recommendations.

If audiovisual equipment such as cameras, projectors and speakers are to be fitted to a space with flush plasterboard ceilings, audiovisual maintenance staff from the organisation should be consulted at DD stage to determine the type and location of access hatches required to mount and service this equipment.

Ventilation

Active equipment (including PC based equipment) generates significant heat when in operation and excessive operating temperatures dramatically affect system reliability and service life.

Racks in Joinery Units

Where active equipment is fitted to racks contained in joinery units, the space containing the joinery must be air-conditioned.

The rack space within the joinery must be ventilated with provision to suck in fresh air at the bottom and exhaust hot air at the top. Vents shall be fitted with appropriate mesh to render them vermin proof. Often, forced air ventilation is required, typically using low voltage fans which can operate at very low levels of noise. Two or more fans should be fitted if the active equipment power consumption exceeds 100 watts.

Ventilation provision should be such that the air temperature in the interior of the equipment enclosure (worst case) does not rise by more than 10 degrees Celsius above ambient.

Racks in Communications Rooms

Where active equipment is fitted to racks contained in Communications Rooms, the space containing the racks must be air-conditioned.

It is essential that any joinery, cupboards or rack enclosures are provided with ventilation slots at the bottom (to draw in fresh air) and at the top (to exhaust hot air). Ventilation slots should be covered with expanded metal mesh to render them vermin proof.

Ventilation provision should be such that the air temperature in the interior of the equipment enclosure (worst case) does not rise by more than 10 degrees Celsius above ambient.

General Provisions for Equipment

Unless required to be portable when in use, all equipment shall be firmly secured to minimise the possibility of unauthorised removal. Fastenings and supports shall be adequate to support the load applied with a safety factor of three times the actual weight.

All racks, housings and installed or bench-top equipment shall be level, plumb and square.

Consideration shall be given not only to access and operational efficiency but also to overall aesthetic factors in regard to installed equipment and housings.

Cable Management Standards

Standards

Wiring materials and standards of workmanship shall fully comply with the relevant documents of Standards Australia and the International Organisation for Standardisation (ISO), including subsequent amendments applicable to any part or item forming part of the installation.

Cabling works shall also comply with any relevant requirements of the Electric Supply Authority Regulations, the Australian Communications and Media Authority, the Building Code of Australia, and the Insurance Council of Australia.

Digital Video

Computer chip makers Intel and AMD and computer manufacturers have jointly announced the end of life for analogue computer video (VGA). The announced end for VGA is 2015, however laptops are already appearing with only digital display outputs. Consequently all AV system design must now include digital video infrastructure.

Digital video potentially provides improved image quality, however to be successfully implemented it requires careful attention to cable and signal processing design and meticulous adherence to cable quality, termination, and installation standards.

Some DVI/HDMI installations have been plagued by issues related to the transmission or management of

  • EDID (Extended Display Identification Data)

  • HDCP (High-bandwidth Digital Content Protection)

EDID is an electronic handshaking process where the resolution capability of the display device is communicated to the sending device. The successful transmission and management of EDID information is essential.

HDCP is a copyright protection system that is now incorporated into DVD players, Bluray players and protected computer based media content such as purchased movies. The behaviour of each HDCP protected device can vary depending on the media being viewed and the operating system of the device. In some cases the device can stop working if it detects a non-compliant device attached to the system.

The AETM strongly recommends that HDCP and EDID management be incorporated into the planning, documentation, design and installation of cabling and processing hardware.

Cable Labeling and Numbering

All connectors, patch leads, audio/video leads, controls, equipment and components, terminal blocks and equipment racks shall be permanently labelled in a format approved by the University. Abbreviations are acceptable only when shown on drawings.

All fixed labels, other than those affixed to cables, shall be permanently engraved in metal or plastic laminate.

All cable numbering and/or identification shall be performed using labels approved by the University. Labels shall be affixed at both ends of each cable. There shall be no unmarked cables at any place in the system.

The proposed cable numbering system shall be submitted to the University for approval to ensure consistency and coordination with the rest of the Campus installations.

Cable Layout and Dressing

All inter-rack and intra-rack cabling shall be neatly laced, dressed and adequately supported.

All exposed cable shall be dressed with heavy duty neoprene heat-shrink tubing

Nylon Cable Management Jacket: The AV Contractor shall organise all signal and power cables which connect equipment racks to adjacent electrical devices. These cables shall be bundled and installed within black nylon woven mesh fabric. This fabric jacket shall be manufactured for such purposes and shall be sized appropriately to the quantities and sizes of cables contained within.

All cables shall be grouped according to the signals being carried to reduce signal contamination. Separate groups shall be formed for the following:

  • Power

  • Control Cables

  • Computer Data Cables

  • Video Cables

  • Audio Cables carrying signals less than -20dbm

  • Audio Cables carrying signals between -20dbm and +20dbm

  • Audio Cables carrying signals more than +20dbm

Each group shall be spaced at a minimum segregation of 50mm or that specified by the then current wiring regulations for that signal type (whichever is greater). In all cases, segregation will be such as to ensure no measurable induced current shall flow in the lower voltage cable as a result of its proximity to a higher voltage cable. Where cables of different signal level must cross they shall do so at an angle of 90 degrees for at least 500mm from the crossing point.

Route all cable and wiring within equipment racks and joinery according to function, separating wires of different signal levels (microphone, line level, amplifier output, AC, intercom, etc.) by as much distance as possible. Neatly arrange and bundle all cable with plastic or Velcro ties according to the requirements of the University.

As a general practice, all power cables, control cables and high level cables shall be run on the right side of an equipment rack as viewed from the rear. All other cables shall be run on the left side as viewed from the rear.

Where there are multiple adjacent equipment racks, the looming shall alternate. For example, as viewed from the rear, all power cables, control cables and high level cables shall be run on the right side. For the next rack, these shall be on the left side and the low level cables on the right. This scheme will alternate from rack to rack, ensuring maximum spacing.

Cable Termination

All cables, except high frequency cables which must be cut to an electrical length, shall be cut to the length dictated by the run. Terminal blocks, boards, strips or connectors, shall be supplied for all cables which interface with racks, cabinets, consoles or equipment modules.

Cables must be of the correct type and manufacturer provided for in the drawings and specifications unless equivalents are approved in writing by the University.

Proper circuit polarity and loud speaker wiring polarity must be observed at all times. Patch panels and connectors shall be wired as follows:

Wire

Connector

Signal

Red or White

Pin#2

Hot or Positive

Black or Blue

Pin #3

Cold or Negative

Shield

Pin #1

Ground or common

No cables shall be wired with a polarity reversal between connectors at either end.

All circuits should be balanced and floating, except as noted in the specification. All system wire, except spare wire, after being cut and stripped, shall have the wire strands twisted back to their original lay and be terminated by approved soldered or mechanical means. No bare wire ends will be accepted.

Heat shrink type tubing shall be used to insulate and dress the ends of all wire and cables including a separate tube for the ground or drain wire.

All solder connections shall be made with rosin-core solder. Temperature controlled soldering irons rated at least 40 watts shall be used for all soldering work. All mechanical connections shall be made with approved crimp plugs of the correct size and type for the connection. Wire nuts are not permitted. Each connector shall be attached with the proper size controlled-duty-cycle ratcheting crimp tool which has been approved by the manufacturer of the connectors.

All use of data cabling whether used for network data or AV signal transmission must comply with the organisation’s data cabling standards for quality, installation and termination. To be accepted the installed cabling must pass the organisation’s approved testing process.