On the face of it, data cable installation is not a difficult job. The designers give you a map of the cable runs, specifies the cables that are to be used in the data runs and the associated trays and so‑on, and how they are to be terminated at both ends. In a Structured Cabling environment, the drawings show cable labelling information.
The use of Structured Cabling is intended to ensure that common acceptable standards are applied to cable installations, both at design time and installation time. This, among other things is intended to reduce the possibility of error during installation.
So why do data cable installations, even Structured Cabling installations go wrong?
Here are four common errors than are often seen in Data Cabling installations.
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Design Errors
Often IT design engineers create their design from plans of a new or refurbished site to be cabled without visiting the site or talking with the architect and builders. This can be a big mistake. Unless the plans are the “as-built” plans, they are probably incorrect, omitting any late alterations requested during a site walk-about. They often do not show the detail of any other potential problems that might affect their cable routes or choice of cables and accessories, for example other service runs.
There have been cases where the designers are unaware of physical problems that prevent cables following the planned route. Drains, electrical cables, underground obstructions can be major problems.
As a result, when the installers come to site, they find they cannot lay the cables as indicated on the site plans. Delays, certainly, compromise probably, and increased implementation costs will occur.
A case in the UK some years ago. The installation was a network cabling installation in a prison built in the Napoleonic era. Because they had not visited the site, the designers had not realised that the walls were solid granite about 1 metre thick. Instead of a few days cabling it took several months because of the time taken to core drill holes in the granite. Many cables had to be rerouted and the network redesigned at considerable cost to the installer.
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Cable labelling
On large sites, particularly blown fibre sites with lots of different cables and cable runs, correct and complete labelling is an absolute necessity. Unless you know the start and end points of a cable, firstly connecting it correctly, and secondly managing the equipment at each end becomes virtually impossible. There are cable management software tools available, but they depend on accurate labelling to be truly effective.
An installer has been known to put the wrong cable-id on the patch panel at either end, or a different identifier on the blown fibre tube containing the cable. Sometimes both or all three.
Again, delays while the incorrect labelling is rectified, possible rework, and frustration.
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“It’ll be ok”, aka “They won’t notice”.
Sometimes an installer, sparticularly when under pressure will accept a piece of work that normally would require rework because it does not meet cabling standards. Perhaps the cable bends too much, perhaps the cable twists at the connector are a little too short or too long. Perhaps an ethernet cable length exceeds the 90meter limit for structured cabling by a meter or so. The installer says “It’ll be all right” and moves on to the next piece of work.
These failings can result in an immediate problem requiring an immediate fix. One particularly frustrating problem is the shoddy work generating an intermittent problem that degrades network performance or drops it completely once in a while. These can be difficult to isolate and take a lot of detective work.
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Upsetting users
Communications with users must be part of an installation programme. It is generally not acceptable for IT technicians to just turn up in someone’s office area and start work. Noise and dust usually accompany installations. Disrupting a user’s workplace without advance warning is not good practice.
All in all, most installations proceed without a hitch, giving the users a new network providing improvements in speed, usability and reliability. The four errors set out above can all be minimised with proper planning and communications with the users. Get the design correct first, all the rest should easily fall into place.
