Should every downlight be fire-rated? Mike Collins, Sales Director at Ovia, provides the answer.
The simple answer to the question of whether every downlight should be fire rated is no, they do not. It all depends on the overall construction of the building and the ceiling into which the downlight is to be installed. However, for all downlights installed into a ceiling Electrical Safety First recommends the use of ‘fire-rated’ downlights fitted with aluminium reflector lamps to ensure fire and excessive heat are kept out of cavities. Legally, any building worked carried out in England and Wales must adhere to the Building Regulations. Fire safety is covered by Approved Document and Part B. Let’s examine the whole area of fire rating, when and why it is required and what the testing requirements are.
Why is fire rating required?
A standard house in the UK usually has two floors, and where there is living space above, the wooden floor construction with plasterboard ceiling must pass stringent fire tests. In these properties, the complete floor/ceiling construction between the two floors must withstand a minimum of 30 minutes of fire to a) prevent rapid fire spread which could entrap occupants of the building, and b) to reduce the chance of fires becoming large, on the basis that large fires are more dangerous, not only to occupants, fire and rescue service personnel, but also to people in the vicinity of the building.
Where there is no living space above, for example loft space, no fire rating is required. However, we would still recommend fire-rated downlights in the event the fire was to spread and affect the roof structure and the safety of the building. The more floors in a building, the longer the fire protection/ compartmentation has to last. In a three-story building with the loft converted to a bedroom, for example, the complete ceiling/floor constructions must comply with a minimum of a 60-minute fire rating to give enough time for the occupants to evacuate in the event of a fire occurring.
Downlights and fire rating
The floors and ceilings will have passed fire testing as a complete structure, but once an aperture for a downlight is made, the fire barrier is compromised. A standard open back downlight allows the fire, vapours and heat to penetrate the floor space and can lead to potential collapse before the required times of 30, 60 or 90 minutes. A fire-rated downlight uses a sealed steel body, together with an exterior intumescent strip around the unit. In the case of a fire, these elements separate the room from the ceiling void, preventing the spread of fire for a period of time. The intumescent material helps stop the fire, heat and vapours from spreading into the void.
Downlights and fire testing
Testing for Ovia products is carried out to strict British Standards and there are a number of building regulations that also cover the testing of downlights.
Recently, NHBC has also required additional testing of all downlights in conjunction with different joist construction types:
● BS 476: Part 21: 1987 – Fire tests on building materials and structures. Methods for determination of the fire resistance of loadbearing elements of construction.
● BS EN 1365-2: 2014 – Fire resistance tests for loadbearing elements. Floors and roofs.
● BS EN 1363-1: 2012 – Fire resistance tests. General requirements.
All our fire tests are carried out by independent testing specialists BRE (Building Research Establishment). BRE Global is a UKAS accredited testing laboratory. They can comprehensively test, predict and assess the fire performance of products and materials to British, European, Marine and International fire-test standards. BRE Global operates one of the largest fire research and testing laboratories in Europe. Their facilities include a state-of-the-art Burn Hall (one of the largest in Europe) capable of staging 10 MW (9m x 9m hood) calorimeter fire tests, and a large custom-built facility for fire resistance tests of floors, walls, beams and columns.
BRE tests our fire-rated downlights under real world conditions. This starts with the construction of the floor to fit the furnace (4.5m x 3.5 m approx.) whilst following the material manufacturer’s construction guidelines for the fire rating required. The joists, floor board and plasterboard are assembled, with the apertures then cut and the downlights fitted. The downlights have to be spaced at recommended distances to give an account of real-life installations in a worst-case scenario.
Temperature monitoring and regulation
Once constructed, weights are added to the floor to simulate the weight of furniture, etc. The floor is lifted into place on the furnace, with the heat thermocouples added to the required elements. The furnace is heated by gas burners, to over 1,000˚C and the furnace temperature is regulated and monitored during the testing. The temperate during the test can exceed 1,000˚C. If more than one layer of plasterboard is fitted (e.g. the 90-minute fire test), the first layer can fall without being deemed a failure. The main contribution to an early failure is a hot joint on the floorboards. This is mainly due to vapours and heat build-up within the floor void exceeding 300˚C where ignition is only required. The test can stop in the event of earlier failure – whether the required time has elapsed or until the floor construction collapses.
Guidelines from NHBC on recessed light fittings have provided the industry with one of its most recent challenges. With the increasing use of I-joists and metal web joists as part of floor construction – around 70% of new build homes feature engineered timbers joists, as opposed to solid timber joists which dominated the market 20 years ago – the National Housebuilding Council (NHBC) updated its technical guidance on recessed light fittings in ceilings to intermediate floors in houses.
As a result, the NHBC now requires test evidence showing that recessed downlights are suitable for a similar I-joists/web joists and plasterboard combination. For many years the market for fire-rated downlights has been the cause of some confusion, with many manufacturers making claims but not always having the technical data to back up these claims. The NHBC guidance on the use of fire-rated downlights makes it very clear that only correctly tested products can be used in the type of floor construction in which they are being fitted. At Ovia we design our products to withstand the rigorous testing that is necessary to meet the requirements of the British Standard governing their safety.
Some manufacturers will state that their products have a 90-minute fire rating. However, that doesn’t always mean that they will meet the requirement for 30 or 60 minute ratings. Each rating has its own test, so they should have passed all three tests to ensure the full rating requirement.
CPD Training
To help contractors understand the issues around testing, Ovia has produced a CPD training module – Downlights and Testing for Fire Rating – which is available for delivery on request. Ovia also has a 20 minute technical Q&A on this subject, available via Facebook, Twitter and YouTube.
To view the Ovia technical Q&A video, click here
