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BSEE-AUG21-P26 Legrand_Layout 1 22/07/2021 15:37 Page 26


BSEE


Fire safety has been a key driving force behind latest regulations in UK electrical installation standards. These regulations guide installation of wiring and cabling systems so that the electrical safety of buildings is improved and the lives of building occupants and emergency services are safeguarded. Mark Williams, Lead Marketing Manager for Legrand’s Cable Management business unit, outlines the changes made in the BS 7671:2018 IET Wiring Regulations 18th Edition, and how building services engineers can create cable pathways whilst adhering to regulations and mitigating the effects of fire.


ENERGY MANAGEMENT


Adhering to latest cable pathway regulations for increased fire safety


Aiming for the best


Electrical installation standards now recognise that any area of a building may become an escape route, particularly as buildings also evolve over time. Such changes represent a response to the dangers posed by cabling installed using non fire-resistant materials in the event of a fire and as recommended by Coroners report into the 2010 fire.


deaths. Since then, updates to the IET Wiring Regulations have incurred substantial changes in installation standards for the electrical industry.


F


Such updates are necessary to protect both the occupants of buildings and the emergency service members helping them in case of emergency. This is particularly pertinent since the introduction of 18th Edition, which recognised that, in the event of the main escape route becoming unusable during a fire, anywhere in the building could become a potential escape route and cable management design must take this into account.


With safety under the microscope and public awareness of fire issues relating to buildings higher than ever, there is more expectation on professionals to understand regulations and deliver their requirements. However, the situation is complicated by overlaps in regulations and standards and so, understanding how these interact with one another is very important to delivering compliant buildings.


The regulatory landscape


Before the latest amendments, there were a few key regulations already in place to ensure fire-safe electrical wiring in buildings. These include: • ‘Fire safety in design, management and use’ BS 9999:2017. This governs the general provision of fire safety measures; the provision of means of escape; and provision of access and facilities for firefighting in building design. It provides best practice guidelines to safeguard the lives of building occupants and firefighters, and remains an important foundation of the regulations. • Construction Products Regulation (CPR) BS EN 50575:2014+A1:2016. The 2016 amendment 1 states that from July 2017 it became obligatory for cables to be accompanied by a DoP (declaration of performance) and include a CE mark. This means cables can be specified for high risk areas based on their ‘Reaction to Fire’ by using their Euroclass, which measures flame propagation, smoke production and density, flaming droplets and acidity of gases when burned.


26 BUILDING SERVICES & ENVIRONMENTAL ENGINEER AUGUST 2021


ollowing on from a fire in a high rise residential building in 2010, the inquest found that plastic trunking had failed in the fire and allowed cables to fall and entrap two firefighters causing their tragic


What’s changed?


In the backdrop of regulatory revisions, BS 7671:2018 IET Wiring Regulations 18th Edition has undergone some changes which affect the specification and installation of cable management systems. Two particular sections affect the cable management installation in terms of material choice and location.


Chapter 42 of this standard addresses protection against thermal effects. It dictates regulation of cabling and cable management in escape routes and areas prone to fire. The changes set out the following required conditions for evacuation in an emergency:


• Cables must not encroach on escape routes (unless they meet the relevant part of the BS EN 60332-3 series and achieve at least 60% light transmittance in accordance with BS EN 61034- 2).


• Cables in escape routes must be as short as practicable.


• Cables encroaching on escape routes must not be installed within arm’s-reach unless they are provided with mechanical protection against damage likely to occur during an evacuation. • Where used cable management systems shall be one (or more) of the following: cable trunking and ducting systems (according to BS EN 50085); cable tray and ladder systems (according to BS EN 61537); and powertrack systems (according to BS EN 61534).


Building on this, Section 521 on ‘types of wiring system’, which is part of Chapter 52 (‘selection and erection of wiring systems’) also features several notes to the regulation:


• Wiring systems hanging across access or egress routes may hinder evacuation and firefighting activities.


• Cables installed in or on steel cable containment systems are deemed to meet the requirements of this regulation.


• This regulation precludes, for example, the use of non-metallic cable clips or cable ties as a sole means of support where cables are clipped directly to exposed surfaces or suspended under cable tray and the use of non-metallic cable trunking as the sole means of support of the cables therein.


• Suitably spaced steel or copper clips, saddles, or ties are examples that will meet the requirements of this regulation or metallic systems.


Read the latest at: www.bsee.co.uk


But the updated regulations also mean more challenges for building designers and specifiers; with more regulation comes greater restrictions on the way cabling systems are selected and installed. Where cables may have previously been installed using a plastic fixing as their sole method of support, it is important to ensure that any wiring system installed is adequately supported against premature collapse. On top of this, supports for cable should be made of materials which are metallic. Now, the fire safety of every area of a building must consider that any part could potentially become an escape route. To support the industry through the changing regulatory landscape, Legrand has worked on training and development programmes for professionals working on residential and commercial developments. Legrand’s CPD – ‘Creating a Cable Pathway Through a Building’ – aims to offer guidance and advice to help engineers create effective, regulation-adherent cable management pathways which meet all of the specific requirements of the building. These regulation updates are indicative of the changes we can expect to see in the industry as the safety of new buildings and their occupants is vastly improved. By considering that any area of a building can become an emergency escape route in the event of fire, cable management design must take account of effects of fire and limit potential for unsupported cable to become a serious hazard.


www.legrand.co.uk/cpd


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