Where to fit fire rated downlights

by Steve on May 10, 2009

Are fire hoods or fire rated down lights required in every situation?

Research was commissioned in 1996 to look into the effect on the fire resistance of plasterboard ceilings with conventional rectangular joists having recessed down-lights installed with no boxing or fire hoods. The results were published in the July 1996 edition of Building Control magazine and confirmed that down-lighters, even without being boxed in and with no fire hoods in plasterboard ceilings, have little significant effect on fire resistance ratings up to 30 minutes. It must be inferred from these tests that at least with plasterboard ceilings with conventional rectangular joists, it is not necessary to box in down-lights or to use fire hoods for the purpose of restoring the fire resistance capability of ceilings that are not a fire compartment.

 

It really depends on whether the ceiling forms part of a fire compartment, its construction and if it has been specified by the client/contract. Generally speaking a dwelling is considered to be a single compartment with regards to fire (Part B of the Building Regulations) unless it has an integral garage or has a floor that is above 4.5m from the ground (3-storey).

 

In the case of 3-storey dwellings, fire protection should be fitted to down-lighters between the upper 2 floors unless the first and second floors are served by a protected stairway leading to two fire separated routes on the ground floor or directly to an exit door (no fire separating floors in this situation).

 

Where recessed down-lights are installed in ceilings that are not fire compartments such as the intermediate floor or a 2-storey dwelling the ceiling needs to have a fire rating of 30 minutes.

 

ElectriciansBlog says:

We install hundreds of recessed down lights every year and have come to the conclusion that it is good practice to install fire rated in most situations because:

  • Fire rated fittings form an extra barrier between the ceiling void and the room, thus preventing dust and particles of insulation from settling on the lamp and falling into the room.

  • The fire rated fittings we use (Aurora) also comply with current Building Regulations regarding Resistance to Contaminants & Moisture (Part C), Resistance to the Passage of Sound (Part E), Limitation of Heat Loss (Part L1A).

  • The falling cost of fire rated fittings has made them less than fitting separate hoods.

 

Intumescent Material & Fire Spreading

 

Fire rated downlights should contain intumescent material which expands to 30 times its origional size when exposed to fire.

 

Wiring accessory boxes can also enable the spread of fire through holes and knock-outs, especially where they are mounted back to back in a 30 minute stud wall.

Intumescent gaskets can be installed into the backs of switch and socket boxes.

 

Further information: Best Practice Guide. Electrical installations and their impact on the fire performance of buildings. (Electrical Safety Council)

http://www.esc.org.uk/business-and-community/

 

Insulation

 

Insulation guards are an excellent way of maintaining a suitable air space around the fitting where insulating materials are present.

These are available as flat packs and are easy to installed at the construction stage.

 

 

 

Source information:

 

Electrician’s Guide to the Building Regulations

Download Approved Document P at:

http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADP_2006.pdf

Elecsa website. www.elecsa.co.uk

Aurora Lighting www.aurora.eu.com

Electrical Safety Council http://www.esc.org.uk

 

 

ElectriciansBlog.co.uk

 

{ 3 comments… read them below or add one }

dennis robbins November 6, 2011 at 00:24

OH AND THANK YOU FOR THE ADVICE ON INTUMESCANT MATERIALS SATISFIES
everyones concerns on the matter

dennis robbins November 6, 2011 at 00:21

With regard fitting of down lights I had an instance of fitting down lights in a bathroom
the type that were not encased and had to fit separate hoods to comply with regs
which are expensive so I would recommend fitting down lighters which are fully encased
and will do so if fitting again

Luke October 11, 2010 at 20:19

Fire and Acoustic compliant recessed downlighters have been designed
to meet the stringent legal requirements of the Building Regulations Parts B&E.

The recent addition of Part E to the Building Regulations has presented the House Builder with
the problem of how to maintain acoustic integrity yet allow the installation of downlighters,
which by their very nature, must puncture the ceiling lining, which affords acoustic integrity.

The design provides a sealed barrier between the underside of the ceiling and its associated void area.
This clever design also incorporates intumescent materials which ensure the luminaire can withstand the onslaught of fire in accordance with the requirements of Part B of the Building regulations.

Thus from one simple to install luminaire the both regulations can be complied with, negating the need for separate fire hoods or a segregated ceiling void as requested by The Standard Robust Details.

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