Late afternoon the day before the fateful Grenfell Tower fire, I happened to read the entire building regulations related to the spread of fire; I admit for the first time cover to cover. Although I am very familiar with the practice of how to specify fire rated lighting, I was in search of an answer in black and white in order to satisfy a customer’s question. Not surprisingly I could not pinpoint a satisfactory reply from the regs.
We had supplied a series of ceiling downlighter’s for a project upon which I had advised. It was a complete gutting and upgrade of two semi-detached houses which the client intended to rent out. The downlights were supplied without a certified fire rating and I received a call to say the electricians were refusing to install them.
The project’s architect when asked preferred fire rated downlighters – we advised against them – were we at fault?!
Q: Why did I choose to specify and supply downlighters that were not fire rated?
The building regs explain that fire and the spread of smoke must be contained – they do not currently go as far to say what one should do in a residential house to solve this – regulations are a directive so they must be applied with reasonable judgement. A fire compartment must stop the travel of fire and smoke for up to 1 or 3 hours, any compromise to the compartment – such as a hole in the ceiling for a light fitting – needs to be compensated for if there is a risk of spreading fire to another compartment.
A typical 2-storey house does not have fire doors and fire triggered door closers, which means the whole property is actually one large compartment. The reality is if a ceiling within that compartment is compromised with a hole for a downlight, the fire and smoke would pour out the door of the rooms way before the little hole in the ceiling!
Therefore, unless you are dealing with 3 storey’s where fire doors would likely be required, a singularly occupied 2 storey home does not need fire protected downlights.
Q: Why not specify fire rated downlighters anyway just in case?!
I sympathise with the architect of this project who emails instructed the client to opt for fire rated fittings anyway – just in case. Doing so can do no harm surely – apart from the clients budget maybe? I prefer not to direct for their use when they are not needed – however, we’re happy to accommodate over specifying if that’s preferred?! Some forms of fire rating extend the depth of a fitting behind the plasterboard which can restrict their use.
Q: What types of fire rating are there for downlights so you can specify appropriately?
A flexible cover or ‘firehood’ is placed over the back of the downlight. It has hole
s in it to allow cables to pass into it to power the light and allow the natural heat of the lamp to escape. You would think that a firehood with holes in it would not work but this coverexpands over the back of the fitting when subjected to intense heat, creating a temporary seal.
The most common entry-level downlight approach is a solid metal can be positioned over the back of the downlight. Again, easy to install as they come ready to install. However LED performance can impede in a variety of ways when they are located in ambient running temperatures higher than their specification, i.e. a canned fire rated downlight. When the airflow around an LED lamp is restricted, temperatures rise and the LED will suffer. Its lifespan could be compromised and colour temperatures may shift.
When using dedicated LED downlights, ask the manufacturer how best to achieve the fire rating and keep the running temperatures within acceptable levels. Our common choice of downlight uses an intumescent seal, keeping the back of the fitting open.
A ring of intumescent seal around the back of the fitting, with no hood. This seal expands when subjected to the conditions of fire, keeping the downlight in place and sealing the holes to maintain the integrity of the structure. Nothing additional to fit so installation is easy. Operating temperature of the lamp unit is maintained within ideal parameters.
This is a new one – conjured up by our friends at Integral LED who seem keen to re-engineer things for an LED age. There are alternative versions of the plate method but this is recently launched and exclusively for LED. First look and the fitting looks rather spare of materials. The design simply maintains a barrier to flames below the fitting which has a steel bezel and a special silicate glass to resist heat. The unit is kept in place with a strong spring. Its tested and approved and is less expensive. Its simple cutaway design offers the necessary ventilation for the inter-changeable LED lamps too.
Back to our project – with Grenfell Tower on our screens I understood and appreciated the decision of the client to pay the restock fee and higher cost to exchange them for fire rated downlights – despite us proving they didn’t have to. Naturally, rented properties and their inhabitant’s safety is our first responsibility. Perhaps the real tragedy is that we have to learn from such tragic events in order to make us scrutinise the detail.
For a full and extensive range of fire rated fittings and an appraisal as to where you should deploy them – give us a call, we will be pleased to direct you.
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