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D-Line – Safely Retaining Cable in Future Fires

Firefighters enter buildings on fire to save life and minimise property damage. They work in intense heat and thick/toxic smoke with very poor visibility. To do this, they wear breathing apparatus and fire resistant clothing for protection.

The problem has been that many types of wiring system have fallen from walls and ceilings at the early stages of a fire leaving cables hanging. These cables have become entangled around the firefighters’ breathing apparatus and/or uniform leaving them trapped and running out of air. This directly caused the deaths of 8 firefighters in the UK between 2005 and 2010.

The evidence from these tragic events has helped to drive a change in legislation.

In January 2015, the Institution of Engineering and Technology published the 3rd amendment to the 17th Edition (BS7671). It states in Chapter 52 (Selection and Erection of Wiring Systems) under section 521.11 that “Wiring systems in escape routes shall be supported in such a way that they will not be liable to premature collapse in the event of fire.” This becomes mandatory for all non-domestic installations from 1st July 2015.

In Note 1, there is particular reference to failure of non-metallic trunking leading to cables hanging across access/egress routes hindering evacuation/fire-fighting activities.

In Note 2 it specifically states this precludes the use of non-metallic clips, cable ties or trunking as the sole means of support. For example, where a non-metallic cable trunking is used, a suitable fire-resistant means of support/retention must be provided to prevent cables falling in the event of fire.

Image courtesy of D-Line

Image courtesy of D-Line

Designers and installers will now have to use non-combustible methods of cable containment and restraint for all cable types (including mains power/switching, data, telecoms, coaxial and TV) in any and all areas of a building that can be considered an escape route. This might include general office/retail space as well as the usual corridors, stairwells, service corridors etc. that typically form part of an escape route. This applies within the UK at present – but fire strikes anywhere, so how are you going to retain cables in future?

The widely used Safe-D clip range manufactured by D-Line (Europe) Limited has been tested by Exova Warrington Fire, confirming compliance to BS5839 part 1 section 26.2e – resistance to fire with mechanical shock and resistance to fire with mechanical shock and water spray – both for 120 minutes. The tests confirmed that Safe-D clips, when containing Enhanced Fire Performance 1.5mm 2 core cables, and subjected to 930°C (+40 -0°C) for 120 minutes at a voltage of 500V rms, enabled the cables to maintain circuit integrity. This is the highest requirement any cable type is liable to ever need, thus more than sufficient for all other cable categories.

Safe-D Clips are manufactured from high temperature steel with a gold passivated finish that withstands mild corrosive elements – in ceiling voids for example. Once fastened directly onto the building structure or fixed within plastic trunking (from 25×16 to 50x50mm), pliable tabs on the Safe-D clip are easily folded to secure two or more cables. Fixing time is at least halved as one Safe-D clip fits 2 or more cables compared to fixing one cable by each P-clip.

The clips comply with BS5266 for installation of emergency lighting – especially in retrospective works that become necessary following reassessment of installations carried out to a previous version/standard.

Given that installation time using these simple, inexpensive clips can be reduced using careful planning, isn’t it worth applying them to all future electrical design plans where appropriate to greatly minimise the risk of fallen cables and the possible consequences in future?

For further information, go to www.d-line-it.co.uk

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