By Hermann Christen, Market Development Manager R&M
Changing technologies, platforms and user habits have resulted into different cable installation and maintenance practices everywhere: from the outside plant, to building access, to in-building systems. R&M would like to share a few key insights into cabling developments and briefly discuss how certain product and technology choices affect cable rollout, handling, and management. First, the company will examine cabling that runs up to a building, and then take a closer look at cabling inside the building…
Cabling outside the building
Last mile solutions: making the right choices
In the ‘last mile’, branching off drop lines from a main fibre line is more challenging than it might appear. The choice of cable installation method depends on many factors. The application determines how the final section of the last mile cable will be fed into the node. For building access, a choice needs to be made between burying cables directly, blowing them into ducts, or using aerial cables. Cable sheathing’ will generally be made of Polyethylene (PE), but the cable construction (beneath the jacket) determines the suitability of a cable for a particular type of rollout. Let’s examine the different types of rollout:
Pulling through ducts
Key mechanical properties for cables to be pulled are tensile strength and dead weight. PE-sheathed cables have excellent surface properties and sliding properties (low frictional resistance) for this type of application.
Placing cable in pre-laid ducts is the most economical installation method. The cables can be blown into the duct tubes: features that determine whether cables are suitable for blowing in are low weight, smooth and low friction cable surface. For this type of cable, tensile strength or crush resistance are not of importance. Cables for blowing should be lightweight, slim, relatively stiff, and have an outer sheath with excellent sliding properties.
Cables can also be ‘direct buried’ in the earth, without ducts. Such cables need to offer a high level of crush resistance and longitudinal water tightness. High Density Polyethylene (HDPE) sheathing is advisable – PE is sufficiently resistant to all chemical influences that direct-buried cables might conceivably be exposed to.
Aerial cables. These are continuously exposed to environmental conditions so requirements are far higher than for buried cables. R&M recommends air cables encased in UV-stable HDPE outer sheathing designed for a temperature range of -25 °C to +70 °C). In aerial drop applications, being all-dielectric and self-supporting are essential.
One of the greatest threats to cabling (installation cables) is rodents. We can distinguish between two levels of cable protection: ‘rodent secure’ and ‘rodent-protected’. Rodent protected cables prevent damage to the cable core in cases of moderate rodent infestation. The company recommends armoured cables with glass roving (e-glass yarn) which protects the cable core. ‘Rodent-protected’ cables provide protection through mechanical resistance for a prolonged period, which is generally adequate, but not unlimited.
Fibre cables can be protected more extensively by adding a layer that ensures rodents aren’t likely to chew their way into the cable core. Steel tape armoured cables are rodent-secure and recommended for outdoor use in ducts and shafts where rodent infestation cannot be prevented. Steel-tape armoured cables are recommended.
Extreme temperatures or chemicals can cause cables to become brittle or less flexible after prolonged exposure or immediately. The cabling sheath may crack, causing rapid deterioration. Fortunately, special sheathing materials can increase resistance to chemical degradation. It is important to know which environmental factors are relevant in different locations and to understand the exact intended usage of cabling and components. In this way, you won’t need to run cable with the most heavy-duty shielding throughout the entire environment. Instead, you can define solutions that offer the best performance where it counts, without compromising in other areas. Important factors to consider include:
- Chemical load (intensity and duration of chemical influence)
- Concentration, exposure and temperature
- Chemical resistance of the material affected
Planning for high density
The use of data-hungry technology solutions will keep expanding, but the backbone can’t be replaced every few years. High density cabling and network infrastructure are essential to meeting current bandwidth demand challenges. Planning needs to take into account imminent demand increases and the need for more ports and fibre cables at access points as well as in and between data centres. You need cables with a very high fibre count that retain the handling attributes of small cables, with minimal termination-related hassle.
Cabling inside the building
Automated asset management
Automated asset management and tracking makes life much easier. Dynamic environments require ongoing, precise and efficient asset management. Changes to a physical network, including switches, servers and patch panels, can be monitored and traced real-time. A system that offers functions for mapping, managing, analysing and planning cabling and network cabinets can also include asset management, planned and unplanned changes and alarms. Such systems improve operational efficiency and facilitate management of passive infrastructure. An integrated hardware and software system automatically detects when cords are inserted or removed and documents the cabling infrastructure, including connected equipment. Everything can be monitored and administrated from a common software tool. The entire infrastructure is represented in a consistent, up to date database, offering precise, real-time information on the current state and future requirements of the data centre. Without this, developing expansion plans and carrying out risk analyses are impossible, let alone complying with legislation and introducing best practices.
Power over Ethernet
PoE has several consequences for cabling choices and handling. Depending on cable diameter, the current 4PPoE standard can produce significant levels of heat. The higher the transmitted power, the more heat is generated. To handle increased temperatures, cable installation conditions (cable type, bundle size, cable duct properties) must be considered and the link length may have to be reduced. Structured cabling standards require the indoor cable to be rated according the Remote Power categories RP 1-RP 3, specifying different levels of PoE support.
During connector mating cycles, connecting hardware is exposed to power discontinuation effects. Unmating connections under load will create sparks that can damage connector contacts. The higher the transmitted power, the greater the risk of damage. It’s important to note that robust mechanical mating of wire contacts in connection modules or plugs is crucial. Loose contacts could lead to power interruption and even to burning of plastic parts. The most reliable connection for RJ45 connections is an IDC contact.
The ‘Digital Ceiling’
An ‘All over IP’ approach can extend data networks through an entire building’s ceiling in a ‘honeycomb’ fashion, making it possible to connect devices to building automation via zones with pre-installed overhead connecting points (service outlets). Real estate managers or tenants can benefit from ‘Plug and Play’ digitisation without barriers, fast and at low cost. All they need to do is plug in network switches, sensors, controls, WLAN access points and other distributed building services.
Single pair ethernet
‘SPE’ will become a key technology in smart buildings. It is the missing link for connecting devices up to sensor/actuator level by means of a standard Internet protocol (IP). It has the potential to replace existing field bus systems and helps with integration of the Internet of Things (IoT) into the LAN and thus accelerates IP expansion right down to the sensor-actuator level. SPE can replace a large part of existing field bus applications. Introduction of smart, converged networks means energy-conserving technologies and applications can be introduced, such as intelligent management of building space, resources and LED lighting.
Don’t forget cable management basics! In spite of numerous changes, the basics of cable management remain unchanged. Bad basic cable management can result in signal interference, damage and failure, resulting in data transmission errors, performance issues and downtime. Always double-check measurements, make sure terminations are of the right quality, test where necessary, always label and colour-code cables, watch out for cramped conduits and make sure no cables or bundles rest upon others.