18th Edition - Are You Compliant?

Clip & Comply to 18th Edition Regulations

The requirement of IET’s 18th Edition, Chapter 52, that cables must be supported against their premature collapse in the event of fire, is for many stakeholders a long-awaited stipulation to address a critical fire-safety issue, but has others wondering ‘why?’ and ‘how?’ Such queries we put to D-Line, the Newcastle-based cable management experts, who invented the first fire-rated clips for use either direct-to-surface or in pvc trunking installations.

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Keep reading to find out more!

Can D-Line summarise the background to this new requirement?

Of the twelve firefighters killed at work between 2005 and 2015 in UK, two-thirds were victims of fatal cable entanglements - those deaths wouldn’t have occured if cables had been supported with fire- safety in mind. In temperatures up to 900ºC, plastic systems could not prevent cables dropping ‘to make impenetrable webs’, ‘molten sheaths that stuck…’ and made death-traps amidst ‘heat like jet- engines’ in ‘zero-visibility’. Coroners reports describe the horrific consequences of cable entanglements. In July 2015 an amendment to 17th Edition required non-combustible fixings to be used for all new surface cable installations on ‘escape routes’. Because fires occur wherever, the 18th Edition has extended the requirement to all new cable installations… a potential life-saving development.

To clarify, must all new cable installations be secured in noncombustible ways?

Yes. Note, steel fixings and containment-systems can typically withstand temperatures exceeding 1000ºC for at least 2 hours; intended to afford sufficient time to evacuate densely populated buildings. Installations relying on common plastics will melt at approximately 150ºC. In fires, PVC wall-plugs, plastic clips and ties, and plastic cleats fitted direct-to-surface, all cause cables to drop by offering inadequate support. Similarly, every length of surface-mounted PVC trunking and conduits needs to be secured by non-combustible fixings, so long after they disintegrate the cables will remain in-situ.

Are all metallic clips suitable for use?

Not necessarily. While mild-steel is suitable, almost half of metals will melt at lower than 500ºC. Surety is best proved by tests. British fire-test labs test fixings up to 970ºC for 2 hours, applying vibrations to installations and water sprays too, to simulate fire conditions in accordance with BS5839pt1 benchmark. For peace-of-mind and to ensure fit-for-purpose, stakeholders should beware of untested products and alloys of variable compositions from batch productions that can offer no performance guarantees. Aside the heightened awareness of fire-safety generally, at D-Line we trust a legacy of lives lost can be that standards are at least respected.

How should non-combustible fixings be installed?

Cables should be secured in accordance with cable manufacturers guidelines. For horizontal cable installations the rule-of-thumb is generally 300mm spacings for cables up to 8mm diameter, and 400mm for vertical installations. Bigger cables can sometimes be spaced wider. It is important to note that wider-than-recommended spacings compromise cable integrity, and cable performance is fundamental to the regulations. From specially commissioned testing we know D-Line Safe-D products can be fully-loaded re cable weight, and spaced on both walls and ceiling planes at 500mm centres, while still holding cables securely. However tempting, the wider spacings can increase risk of cables sagging, which over the time of a fire increases risk of short-circuits… when power to alarms and lights might be critical. Consideration must be given not only to surface clip capabilities, and for due diligence only fire-tested certified fixings should be used as part of a complementary fire-rated cable management ‘system’.

Are such fire-rated cable management systems available?

D-Line offer a full range of innovative and market-leading solutions, available from all leading wholesalers. All are fully tested for compliance with BS5839pt1 and to satisfy new 18th Edition regulations, in conjunction with D-fixing screws also. These screws have subtly-domed heads that optimize space within the Safe-D Clips, and 40mm length that embeds to offer exceptional pull-load resistance and load-bearing. D-Line’s range is ideal for direct-to-surface fixing or for installation in pvc trunkings up to 50mm wide. All are user-friendly, exceptionally quick-to-install, with value-added features, and very competitively priced.