Introduction
Choosing the most suitable cable management solutions for a project is essential to ensure cables are adequately supported, contained and protected. The right products will ensure the cables can be routed to the correct place and also improve the experience of building users. When looking at metal products there are several different options including metal trunking, metal tray and wire basket. The installation of these products should also be considered in terms of how the systems will be supported within their environment, with solutions such as threaded rod ladders, wire suspensions or metal strut frameworks.
Physical protection
It is important to consider the environment the cable management will be installed in to assess the likely level of wear and risk of impacts. Regulation 522.6 of the IET Wiring Regulations 18th Edition (BS 7671) provides guidance on protecting cables from a range of ‘external influences’ including mechanical stress such as impact, abrasion, penetration, tension and compression. It states that in environments where medium or high severity impacts can occur – categorised as AG2 and AG3 – the cables should be protected using one or a combination of: the mechanical characteristics of the system; the installation location; and additional protection – such as installing a barrier to prevent impacts.
For commercial, industrial and retail environments, one of the simplest ways to prevent the risk of mechanical stress on the cable installations is to route them out of the way using ceiling mounted metal cable trays and wire baskets. This will prevent the risk of accidental damage and there are a range of options depending on the number and type of cables that need to be supported.
A wire basket, or cable tray product with a slotted design, will make it simple to secure the bundles of cables. Wire baskets also provide a simple solution where cables need to be dropped out at regular intervals along the length of the cable management system. What’s more, using a wire basket with integral couplers can speed up an installation.
It is also important to consider how the cable tray or wire basket will be fixed to the structure of the building. One effective option is metal strut products. Available in either slotted or plain design, metal strut provides a versatile and adaptable way to mount, support and connect cable management systems.
Metal trunking systems are an ideal solution for addressing the risk of using the ‘mechanical characteristics of the system’ due to the enhanced strength and durability. For example, due to the height it is mounted at in the room, dado and skirting trunking may be exposed to frequent or heavy accidental impacts. This is particularly an issue in places such as warehouses or storage areas where materials or equipment are moved regularly. In these situations, a robust steel trunking system may be the best option, especially for retrofit projects.
The greater durability of metal trunking systems should also be considered in lower risk but busy environments where greater wear and tear may be expected. The higher initial cost is often offset by a longer-term reduction in the need for additional maintenance and replacement of damaged sections.
EMI shielding
For some projects there may be a risk of radiated electromagnetic interference (EMI), which may come from a variety of sources, including nearby equipment. However, one of the most common issues is interference caused by a large number of power, data and other service cables being routed together, such as in large offices. The solution is to separate the data and power cables using a material that provides shielding, such as steel or aluminium. While this can be achieved by fitting metal dividers into PVC-U trunking, this does not protect against external sources of EMI, which can include any electrical device nearby. Steel or aluminium trunking systems can provide a more complete level of EMI protection.
Fire Safety
While it has always been important, recent years have seen an increased focus on improving the fire safety of buildings, with changes to both the Building Regulations and Wiring Regulations. As a result, selecting non fire-propagating, low emission products has never been more important. Metal cable management systems have a clear benefit here. By their nature, both aluminium and steel are classified as non-combustible, low smoke zero halogen (LS0H) materials. However, it is also important to consider the properties of the accessories and fittings installed as part of a metal system. Selecting polycarbonate fittings allows the system to maintain its low smoke zero halogen (LS0H) classification.
Furthermore, in the event of a fire, falling and fallen cables can present a serious hazard to those evacuating as well as firefighters moving into and through the building. There have been cases of firefighter fatalities caused by entanglement in fallen cables. Many buildings now contain a vast number of cables due to the technology and connections required.
The 18th Edition of the Wiring Regulations includes enhanced requirements to minimise this risk. In Regulation 521.10.202 of the Wiring Regulations, it states that all cables should be adequately supported using non-combustible fixings to prevent premature collapse in the event of a fire. This means that cables need to be supported using a material with a melting point high enough to sufficiently withstand the heat of a fire – 1000°C for up to 120 minutes. While aluminium has excellent resistance to heat and can withstand temperatures of up to 655ºC, it does not meet the required standard and so, like PVC-U, aluminium products are not acceptable as a sole form of support. Where aluminium trunking or trays are used, cables must be fixed to the fabric of the building, either the wall (within the trunking) or the ceiling, using fire-resistant steel cable clips.
However, customers may want to achieve a higher level of fire safety and as a result it may be worth recommending steel cable management systems due to the higher melting point of between 1200 and 1500°C, depending on the steel’s composition. As long as the cable management is connected to a fire-resistant element of the building’s fabric, then it can effectively protect from the risk of fallen cables.
Metal cable management systems provide a range of benefits, especially where a higher level of durability, impact resistance or EMI shielding is required.
If you want to take a closer look at our range of metal trunking solutions click here.
Related Products
