• • • LIGHTING & LIGHTING CONTROLS • • • Fire-rated downlights
Acting as a barrier in ceilings, fire-rated downlights play a crucial role in preventing the spread of fire and smoke in buildings. Chris Anderson, technical manager at Ansell Lighting, clarifies the confusion that can surround these products, providing detailed guidance on their specification and application
W
ith a lack of clear direction given in building regulations, the requirement for fire rated downlights (FRDs) in certain
domestic applications can often be a source of confusion for installers. The UK’s leading charity on fire safety, Electrical
Safety First, recommends FRDs are installed in all ceilings where recessed lights are specified, providing a protective barrier in the event of a fire and slowing down its spread. The reason why is simple. If you consider plaster
board ceilings as an example, they are specified in buildings due to their ability to act as a fire barrier. When a hole is cut into the ceiling to mount a recessed downlight into, the hole acts as a gateway for fire to spread through, compromising the effectiveness of the ceiling. But by choosing to install fire-rated downlights
into the voids, the fire integrity of the ceiling is restored. Fitted with an intumescent pad which swells up
when it reaches a certain temperature, FRD’s seal the hole in the ceiling, slowing down the spread of fire to give occupants more time to escape the building or allowing additional time for the fire to be extinguished. Given this, it seems an obvious finding that FRD’s should be specified in all buildings where recessed lights are installed. However, the decisions do not stop there. When
it comes to FRD’s there are a large number of different products available – all of which are suited to different applications. Ceiling types, their construction (30, 60 or 90 minute), thickness and joist spacing have different
compliance regulations, affecting the type of luminaire required so understanding a building’s fire resistance ratings and the specific requirements relating to different types of ceiling joist is essential during the specification process. Metal web, for example, is a new joist type used
in the UK that combines the lightness of timber with the strength of the Posi Strut steel web. Used only in 30- and 60-minute construction applications, specifications for the relevant fire resistance rating categories are:
30 minute construction • 600mm joist centres • PS9 (225mm x 0.9mm) + TR26 (47mm x 72mm timber)
• 15mm Type A Wallboard plasterboard
60 minute construction • 600mm joist centres • PS10 (253mm x 0.9mm) + TR26 (47mm x 72mm timber)
• 2 x 15mm Type F Fireline plasterboard Typically only seen in domestic dwellings
constructed more than 20 years ago, solid timber joists are used in internal floor and separating constructions for both residential and commercial applications. Specifications for each fire resistance rating category are:
30-minute construction • 600mm joist centres • 220mm x 63mm • 15mm Type A plasterboard
60-minute construction • 600mm joist centres • 220mm x 63mm • 2 x 15mm Type F Fireline plasterboard
90-minute construction • 450mm joist centres • 220mm x 63mm • 2 x 15 mm Type F Fireline plasterboard
I-Joists on the other hand now dominate the
house-building market and are used on new builds across the UK. Specifications for each fire resistance rating category are:
30-minute construction • 600mm joist centres • 220mm x 63mm – 9mm OSB/3 ‘web’ • 15mm Type A Wallboard plasterboard
60-minute construction • 600mm joist centres • 220mm x 63mm – 9mm OSB/3 ‘web’ • 2 x 15mm Type F Fireline plasterboard
90-minute construction • 450mm joist centres • 220mm x 63mm – 9mm OSB/3 ‘web’ • 2 x 15mm Type F Fireline plasterboard
Finding the right luminaire for different ceiling
types can seem complicated which is why our design team has developed a market-first range of FRD’s that comply with every category of joist type and every fire resistance rating, simplifying the specification process completely. Whatever the application, as the Golden Thread
has now become law, it is worth remembering that when it comes to new lighting installations, the onus is on lighting manufacturers to evidence that the FRDs installed in a project are fully compliant. FRDs should come with full documentation of relevant testing, including test house certification numbers, to provide absolute confidence that the downlight will offer maximum protection. Whilst it is down to manufacturers to prove that
their products are fully compliant, the new regulations also call for installers to keep digital records for each project detailing specifications, fire test evidence, certification and other traceable information to ensure that all items have been installed to comply with Building Regulations. Opting to install FRD’s in all areas where
recessed ceiling lights are specified will ensure that legal requirements are met in every case and more importantly, buildings are constructed in the safest manner for occupants.
26 ELECTRICAL ENGINEERING • OCTOBER 2022
electricalengineeringmagazine.co.uk
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