Following the release of the third amendment to the IET Wiring Regulations Seventeenth Edition (BS 7671:2008), HellermannTyton’s Richard Rands, Product Manager of Fastenings and Fixings, highlights the importance of the changes and outlines the need for greater awareness.
However, as well as installers acknowledging the recent changes to regulations, specifiers also have a level of responsibility to ensure all wiring systems installed are safe. This means that cabling should be supported in such a way that in the event of a fire the system should not collapse, with the emphasis on wiring systems near escape routes – in particular, along corridors and near stairways.
In recent years the dangers and implications of unsafe wiring has been highlighted by several cases, including the tragedy that took place in 2005 which saw two firefighters lose their lives while tackling a fire in a block of flats in Stevenage.
While there were a number of contributing factors to the deaths, one of the firefighters became entangled in electrical cabling that had fallen as a result of the plastic cable trunking in which it was contained melting. The subsequent investigation found that the firefighter had cable insulation stuck on the palm of his glove, indicating that he had been attempting to untangle himself.
In light of this report, and subsequent investigations into other cases where lives have been in danger as a result of loose cabling, BS7671 now applies to all types of wiring systems in a building, including those of distribution circuits and final circuits, safety services, and data and communications services. The sole use of plastic fixings and non-metallic cable ties will no longer comply with the new regulations and rightly so as exposure to fire could result in the melting of trunking and the risk of loose cabling.
Duty of care
“Failure to specify the correct equipment and implement the correct procedure can lead to serious injury, claims of neglect and even fatalities.”
Installers and specifiers therefore have a duty of care to ensure that cabling is not exposed to what really are preventable risks. Failure to specify the correct equipment and implement the correct procedure, as we have learnt, can lead to serious injury, claims of neglect and even fatalities. Understanding of the new rules is therefore crucial and highlights the importance of using appropriate products throughout public buildings, venues, offices and housing, especially near fire exits.
Stainless steel products are ideal for applications that require high strength, reliability and fire resistance. Capable of withstanding temperatures of over 500°C, stainless steel cable ties and mounts comply with the new regulations and can significantly reduce the risk of loose wiring and melting trunking. However, the fixing embedded into the structure also needs addressing, so as well as the actual fastening, the installation of cable mounts and supportive elements also needs to be considered.
There are a wide range of options that decision makers can specify and seeking out products that are, for example, London Underground (LUL) approved for fire safety is one way to ensure safety and reliability. The Metal Ball Locking Tie (MBT) offers a unique self-locking mechanism with low insertion and high tensile strength that has this LUL approval, making them the optimal choice for security.
Other ties including specially designed Metal Fold Locking Ties (MLT) and Metal Punch Lock Tie (MST) offer extremely high resistance to vibration and can provide a reusable solution. Metal Banding for heavy duty applications (AMT) can also be used to ensure in environments where risk is high, security is assured.
It is therefore crucial that for long-term safety the installation is completely fire resistant as cutting corners could potentially put lives at risk.