Securing wires for fire safety

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The 18th edition of the IET Wiring Regulations (BS 7671:2018) Requirements for Electrical Installations will be issued on 2 July 2018 and are intended to come into effect on 1 January 2019. What is new in the updated regulations?

Immediately after the Grenfell Tower fire in London in June 2017, the London Fire Brigade spoke out saying they ‘often witness serious flaws when inspecting buildings’ and ‘critical fire safety systems are often not installed’. As a result, there have been questions about existing building regulations and whether they are good enough to protect people in serious fire events.

One piece of legislation that has been reviewed and will be published in July 2018 is the 18th edition of the IET wiring regulations. The focus of the new legislation is to improve fire prevention and protection throughout buildings in the UK, as well as to safeguard workers and the public.

What is new?

In addition to measures which will prevent a fire starting in the first place, such as a ‘switching device’ in the installation of renewable energy storage systems, and arc fault detection devices in AC final circuits, the most significant change is the way wiring support systems throughout buildings are protected from premature collapse in the event of a fire.

The previous version of the regulations (Amendment 3 to the 17th edition, or BS 7671:2008), stated that fire-resistant fastenings and fixings should be used in all cable installations above escape routes. These are deemed as any points that provide access for people to quickly exit a building to be safe from both fire and smoke.

The intention was to prevent escape routes from becoming blocked by the premature collapse of cabling installations in the event of a fire, where extreme heat has melted their plastic fixings thereby allowing the occupants to exit the building safely.

Fundamentally, the new regulations will improve the safety of occupants in a building in the event of a fire. Photograph: iStock/Dragan Smiljkovic

The latest update now stipulates that this should be extended to include all cabling installations throughout the building. However, this will only apply to wiring systems that could collapse prior to rescue services from entering the building.

So, cables on top of a cable tray, ladder rack or similar, or cables installed within conduit and metal trunking wouldn’t need special consideration. This means that anything that is clipped to the walls, or cables inside plastic trunking, where the lid can ‘pop off’ when there is a heat build-up, will require a fire-resistant fixing. Fundamentally, this will improve the safety of the occupants in a building in the event of a fire and will ultimately save lives.

How can suppliers help?

The main way suppliers can help is by providing products and advice that will help workers choose the right products for their project.

One of the most effective and popular choices is concrete screws. Concrete screws are inserted directly into the concrete without the need for a plastic plug, providing a secure fixing that can withstand a fire. This means they are extremely simple to install as they don’t require many additional tools or fixings, consequently reducing the time it takes to install and increasing efficiencies on site. In addition, concrete screws are very flexible as they can be removed and reused.

In situations where an unexpected change occurs on site, it can dramatically reduce the risk of a costly and time-consuming alteration. Finally, as concrete screws require smaller drill holes, they create a significantly lesser amount of dust. This is increasingly becoming a consideration on site as contractors focus on protecting workers by minimising the risks and also providing PPE.

Another option to consider is stainless steel cable ties. Historically, these have been an unnecessary expense, especially when their plastic cousins are so readily available from all wholesalers. However, as they provide high strength, reliability and fire resistance, they meet the requirements of the new legislation. In the event of a fire they are capable of withstanding temperatures of over 500°C, significantly reducing the risk of cable installations collapsing and causing blockages in escape routes.

It is important to remember that any installation is only as strong as its weakest point, so stainless steel cable ties won’t work if their fixing is still provided using a traditional screw and plastic plug. Therefore, a combination of stainless steel cable ties and concrete screws should be used for cable installations to provide essential support and reassurance.

In my opinion, the reviewed IET wiring regulations are a positive step in addressing safety concerns following the tragic events at Grenfell Tower.

More information available here

Carl Ghinn is managing director at Fixmart


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