The majority of network failures in office environments are caused by problems in the physical layer, usually due to improperly installed cabling that has been left to be connected as and when required, often using patch leads and in some cases not even documented. Treating the cable plant as a designed system with clear definitions of the various subsystems and adhering to established standards to gain an understanding of the designed life-span will generally lead to fewer failures than alternatively dealing with problems after they occur.
What structured actually means in a commercial fitout
There are three levels of a data structured cabling system; work area outlets are connected with horizontal cables to a floor distributor, the floor distributors are connected with backbone cables to a building distributor and so on. This cabling is labelled according to the above defined hierarchy in a strict and constant manner as defined in the TIA-606 standard.
In point-to-point cabling each cable runs back to a patch panel in the most convenient spot. By year three no-one will be able to work out which cable connects which desk and any moves will require a search with a flashlight and a ladder.
The 90 metre rule and why it governs floor planning
For horizontal permanent links, they have a maximum length of 90m or so and then you have to allow for 10m of patch leads at each end of the link. This in turn determines where your communications rooms are to be located and must be fixed up prior to the tenancy layouts being finalised. It is far cheaper to allow for a second communications room in the base design of a finished fitout than to have to retrofit one later.
Where reliability is won or lost
Intermittent faults are perhaps the most costly type of fault as a single test (a link test) may pass but fail under load. The fault may cause dropped video conferencing calls or very slow file access. The helpdesk will work tirelessly to find the problem with the application or service and it is only after many hours or even days that the problem is found to be a faulty cable.
Certification testing is control. On any Adelaide data cabling project worth trusting, always require a permanent link test to the relevant cable category with results reported by outlet. Some common problems with horizontal cabling that result in marginal performance include incorrect shelving height, cable bending, wire damage and poor bonding to structure.
- Untwisting more than 13 millimetres of pair at the termination
- Cable ties pulled tight enough to deform the jacket and alter impedance
- Bend radius breaches behind patch panels and at ceiling transitions
- Mixed-brand connectors and cable within a single channel, which voids most manufacturer warranties
- Power cabling run parallel and close over long distances, inducing noise
Documentation as an operational asset
As-built drawings, a port-to-outlet schedule and the results from the relevant certification tests (i.e. Permanent Link testing to the appropriate cable category for the installed cabling) need to be made available as contract deliverables. These ensure that expensive change orders are detected earlier rather than later.
Designing for expansion rather than reacting to it
The typical planning figure of two outlets per work area is not sufficient in today’s changing office environment. Capacity must be designed for wireless access points, ceiling mounted sensors, access control readers, cameras and meeting room AV. Spare backbone strands should also be provided and the percentage of pathway fill left to complete future pulls should be approximately forty percent.
| Approach | Upfront cost | Cost of a 30 per cent headcount increase | Typical disruption |
| Point-to-point, added as needed | Lowest | High, often full re-cable of affected zones | Repeated after-hours work |
| Structured, minimum provision | Moderate | Moderate, new runs within existing pathways | Single weekend |
| Structured with spare capacity | Highest | Low, mostly patching and outlet activation | Minimal, in-hours |
Specifying for the technologies arriving next
Three key forces are influencing the selection of horizontal cabling for offices. First, Wi-Fi 6E and 7 access points have data rates exceeding that of a single Gigabit Ethernet connection, leading to horizontal cabling of Category 6A or greater for AP drops. Second, with PoE power of up to 90W under the 802.3bt standard, increasing conductor temperature rise in cable bundles of large cross section in closely packed trays needs to be taken into account by appropriate derating. Third, as building services such as lighting and HVAC control systems converge onto the data network, the impact of failure of any cable on the horizontal will increase.
Choosing an installer
The current manufacturer accreditation is important to ensure that a 25 year system warranty is enforceable. Request the Specialist to show sample certification reports and discuss the pathway design of the horizontal cabling, the fire stopping at penetrations, and segregation of data cabling from other electrical services such as power, voice and security installations in data cabling Adelaide services.
Making the business case
Cabling is a minor portion of a fitout but it lasts for the longest time in the communications room. The life of data communications equipment is typically 3 to 5 years but the cabling plant can last for 15 to 20 years or more. When evaluating the cost of proper cabling against doing it cheaper, ensure that you are charging for the correct time to complete the work (labour) and any downtime that may occur by having to re-run cabling that fails at a later time.
