In this post we try and answer when fire rated fittings or fire hoods are required. As with any thing relating to building control it is very important that you consult with your local building controls and fire office from the outset of the project.
Why do we need fire rated light fittings?
Fire rated fittings are specified to maintain the integrity of the fire rating of a buildings typically these are 30, 60 & 90 minutes of protection. Where you have a cut out for a down light this will be seen as a weak point for fire and smoke to access in to other parts of the building from. Fire rated down lights have a seal that expands in the event of heat to stop the passage of smoke as well flames. There is some debate as to how effective some fire hoods are but to mitigate responsibility contractors tend to er on the side of caution and install them any way. There has been some misconception that fire hoods were necessary for 12v halogen lamps due to the heat of the lamp. This is not the case.
Where do I need fire rated lighting?
Part B of the Building Regulations state that any residential dwelling with the top floor height of up to 18m above the ground should have ceilings resistant to fire to up to 60 minutes.
Part B fire safety.
How fire rating lighting works
Fire rated fittings which have been tested and approved by independent test houses such as BRE typically have an in-tumescent material built in which expands and closes the hole when heated. From a lighting design perspective the range of fire rated fittings is limited which is why other methods of maintaining the fire rating are used.
If a down light has not been tested and approved then a fire hood which covers the fitting and provides fire rating is recommended. The main issues with fire hoods is that they are very good at preventing fires escaping which means that they are excellent at trapping the heat which for LED lamps is a disaster as they will over heat and fail. They can also be very difficult to instal as typically you will be required to fit the fire hood in to the hole from below and then fix the fire hood in place.
A firebox is an enclosure which fits around the fitting which is constructed from the same fire proof material as the ceiling. This is seen as the most reliable method as provides a rigid structure and allows the LED to breath as the fire box will be designed around the fitting. This method really only works if you have access from above or below for a new build.
The requirements for residential and commercial lighting vary and fire rated fittings are not needed for all installations, typically the responsibility falls with the installing contractor.
If you do have any questions on fire rated fittings then please get in touch.