Since the early 80’s when structured cabling was introduced, patch cords have changed very little. From Cat5 through to current day Cat6A and beyond, the humble patch cord has been produced using predominantly 24AWG & 26AWG* stranded copper cable. (Typically 5.5-5.7mm diameter). This is in line with standards such as ANSI/TIA-568.C.2 & ISO 11801 which define performance and recommend the copper conductor diameter of patch cable to be 22-26AWG. (Note a smaller AWG number is a larger diameter)
As the demand for data network points increased, congestion challenges arose in the Telecommunications Rooms (TR) and patch field management became increasingly important. Mitigating the congestion of patch fields was made possible by introducing horizontal and vertical rack cable managers and increasing rack U space. The introduction of the angled panel was another innovation to aid patch field management. These measures were effective for the typical enterprise network where the TR was located in the office building. However, times have changed and over the past 10 years virtualisation has seen large scale migration of data networks, storage and servers away from the office and concentrated into data centres, creating yet higher densities of cabling and patching. In addition, network devices such as core switches and blade servers have increased in computing power requiring higher speed 10G connections. The increased diameter of shielded Cat6A patch cables, coupled to a higher density of connections has exacerbated the problem. Additionally, increased power loads dictate increased cooling and the need to avoid restricting airflow with cables. These factors all add up to a headache for network designers whilst moves and changes becomes more problematic. Nowadays you may need slim fingers to be able to relocate a patch connection!
One recently introduced solution is the development of smaller diameter 28AWG patch cords. A few innovative network cabling manufacturers have pioneered development and testing of these small diameter cords. When bundled they can have a dramatic effect on the overall diameter. Combined with slim line plugs this alleviates the problems of congested patch managers, improves airflow and enables higher density patch panels e.g. 48 way in 1U may be used without the need of special tools for patching. When applied to a congested data centre this can make all the difference in ensuring that existing space is optimised to the full. The area that can benefit most are network switches i.e. switch harnesses and one to one switch to panel links.
Link, Channel and de-rating factors
There are of course some limitations to the use of smaller diameter cords but the benefits usually far outweigh these. Higher attenuation means that a higher de-rating factor will need to be applied when designing the cabling system. If using PoE, PoE+ or proposed PoE++, bundle size is limited due to heat dissipation. This is more likely to be encountered in offices than data centres where PoE is more applicable. Cords using 28AWG copper fall short of the recommendations in ANSI/TIA-568-C.2 & ISO11801: Typically a 24AWG patch lead will have a de-rating factor of 1.2. which increases to 1.9 with 28AWG patch cords. This translates for example to a channel with a 90m permanent link and 6m of patch cords i.e. a 96m channel overall. In the majority of offices and data centres this would be more than adequate length.
It is fair to say that using small diameter patch leads can free up much needed space in a congested network cabinet but design principles should always be applied before implementation. Small diameter patch cables are available in Cat5e, Cat6 and Cat6A, meaning that most existing installations can benefit from retrofitting them. Networks Centre supply a full range of small diameter patch cords. Call 01403 754233 for more details.