Do You Make These 5 Structured Cabling Mistakes?
Cabling good practice is just good sense.
My career dates way back before structured cabling was conceived. Every manufacturer had their own cabling system. Being a cabling specialist back then meant you had to understand the characteristics of all the different cabling types. There were many different types of multi-core cables, coaxial cables, twin axial cables, quad cables, twisted pair cables and more. I remember scanning through catalogues locating specific cable for some of the specialist work we carried out for the oil industry, City financial businesses and major carriers.
In some cases, I just wanted to squeeze an extra 20 to 30 feet on a standard cable length of 50 feet. The challenge was to achieve this without exceeding the cable characteristic requirements for the interface. The parameters were more familiar to electronics engineers, including: resistance, impedance, capacitance, inductance, however, these parameters were critical for trouble free performance.
With so many standards it wasn’t just about trouble free performance. In the event of an interface problem between two systems connected by a single cable it was vitally important to be able to rule the cable out as a source of the problem. If one of the systems vendors made any claims about the cable being over-length for the standard I could point out the fact that although the cable is over-length, it is in fact within the specification because of the type of cable used. On making the third parties aware of this the question never went any further as everyone agreed the cable was in fact within specification and fit for purpose.
There are some later systems such as Ethernet where it was not possible to extend the length of the cable because propagation time across the media was a major factor in the Ethernet protocol. if any Ethernet segments were over-length they could not be ruled out in any investigation so all segments had to be brought back to within their length specifications before further investigation.
Fast forward to current times and we are rather spoilt as our structured cabling systems are so well defined and to a certain degree de-skilled. We have maximum cable lengths, maximum patch cord lengths, patch panel and outlet standards, cable pathway standards, testing standards and many more. The cabling team just needs to ensure they stick to the system rules rigidly for a professional, trouble free installation.
As data speeds increase sticking to the system rules becomes ever more important. Many of us may know of cabling systems that have been virtually thrown in that appear to work very well. These anecdotal stories could easily lead us into a false sense of security. We are unlikely to know the full details of the installation to make an informed judgement as to why a poorly installed system would still perform as expected.
The poorly installed but apparently working cabling system may comprise relatively short cabling runs and therefore not placing the system under any real stress. The data speeds may be well below the capacity of the cable specification – for example 100Mbps on Cat5e with a capability of 1Gbps will have significant margin for error. There may be an element of luck in that the longer cables in the system are carrying 100Mbps services while the shorter cables are comfortably carrying 1Gbps services.
There could be many other ‘lucky’ combinations yet, I have witnessed many examples of poorly installed systems cited as valid reasons to cut corners on a new structured cabling installation. Cabling system installations may be de-skilled when compared to the early days of data cabling but structured cabling systems still require qualified design and installation technicians to deliver a successful, fully guaranteed system that will support the maximum data speeds for the system on all cables if required.
So, what are the five structured cabling mistakes?
Mistake 1
Thinking of cabling as ‘just cables’ when they are in fact a critical electronic component in the path of your data from one point in your network to another. This may be from a user’s desk top machine to the network switch, the network switch to a server, the network switch to the Internet router, the wireless Access Point to the switch. When you think in these terms it is easy to understand the importance to ensure this vital piece of circuitry is given the best possible chance of matching the life of your building.
Professional cabling installation.
Mistake 2
Never run data cables alongside power cables, even if the cables are screened. If your data cables run alongside in close proximity to power cables, noise from the power cables may be induced into your data cables. Bear in mind noise is any signal other than the signal we want to receive. As load increases and decreases on power cables this can cause a surge or spike that can radiate out of the power cable and into the data cable.
Never underestimate the effects of this noise. I investigated a serious network problem some years ago and found the link LEDs on the network switches were lit even when the workstations were disconnected at the wall outlet. We discovered the main data cable route shared the main route of the power cable serving the data centre. Data cables can cross power cables at 90 degrees even in close proximity but the data and power cables must be separated by a bridge that satisfies electrical regulations and standards.
Mistake 3
It may be tempting to install and commission your cabling without proper testing. However, a proper cable test appropriate to the cabling system is essential for a warranty and for peace of mind. A structured cabling installation is a big investment and it usually has the same lifespan as your building so it is very important to know for sure that your installation has been completed to specification and it can pass data at the stated speeds. In effect, you are simply confirming that you are getting what you paid for.
It may also be tempting to carry out a sample test of a select number of your cables but this also carries some risk. Structured cabling is typically installed in phases. The first phase may be early in a building construction or refurbishment project. Some of the cable routes may be covered and protected but when the cabling technicians are off site between the cable laying and the cable terminating cable may be damaged by other trades. There is also a risk of a cable manufacturing fault that may not be obvious to the eye. To be sure the cables are serviceable and have survived the onslaught of trades people working under floors, above ceilings and in risers, every cable must be tested with a calibrated tester, appropriate to the cabling system (e.g. Cat6, Cat6A, etc.).
If the cables are not tested, you may not discover these problems for months and possibly years when you come to use a cable that has a manufacturing or installation fault. Replacing cables once the building is occupied is obviously a more challenging and costly task.
Cable manufacturing fault. This twisted joint was inside the cable sheath.
Mistake 4
Taking all the above into consideration it can be a seriously false economy choosing very cheap cabling installers. Always check the credentials of your chosen cabling installer and check their references. Ask to speak to some of their customers who have undergone similar projects. Remember that cutting corners at the installation stage may result in problems months or years later. A reputable installer will do everything in their power to ensure your investment is treated with the respect it deserves.
Mistake 5
Allowing your structured cabling patch panels to grow into an unsightly mess carries significant risk to the performance and reliability of your IT systems. There are obvious risks when IT staff need to carry out a patching exercise to add or move a user as pulling a patch cord out of a tangled mess can damage other patch cords or accidentally pull a patch cord out of a socket disconnecting another user or service.
The less obvious problems are when the strain on the patch cords is such that it causes lateral strain on the connectors which can partially disconnect one or more of the conductors in the connection. Overtime, this may damage the patch panel or switch ports making them intermittent and causing problems that are extremely difficult to localise.
Another less obvious problem in large installations is switch ports connected to cables with no user devices on the end. I have seen twice as many switches as were required in some installations because no one bothered to remove patch cords when users were moved or disconnected.
Always keep patch panels and patch cables in a tidy state and always remove patch cables when they are not in use. Use appropriate cable management hardware to support patch cables and follow the patching standards and recommendations appropriate to your structured cabling system.
The moral of the story…
Structured cabling is a big investment and it is long term. If we get this wrong it can be a very costly mistake on many levels. A structured cabling system that is unfit for purpose is unlikely to cause a catastrophic failure (unless the quality is dire). However, it may fail to support our business systems reliably causing a loss in productivity through user down time and at the very least, frustration.
In the worst-case scenario, if structured cabling has to be replaced to restore stability to our business systems the cabling technicians are unlikely to have free access to cable runs now the business is operational. Thus, any remedial works will require significantly more time and effort than the initial installation. The problems could also be exacerbated by cabling routes closed off and covered for aesthetic reasons.
The moral of this story is, it is much more cost effective to install a structured cabling system using good practice first time than it is to remedy a poor installation. This may well seem like I am stating the obvious. But, I have investigated many network issues in the past that have been found to be due to poor structured cabling. A very real problem that is relatively easy to avoid.
