Reproduced from Codewords 36, April 2009, Department of Building and Housing
Incorrect installation of thermal insulation over downlights can present a risk of fire in buildings.
The Department of Building and Housing is reminding suppliers, contractors, and building practitioners who are installing, supervising or subcontracting this work about the requirements of the New Zealand Electrical Code of Practice 54 (ECP 54) and the importance of following the downlight manufacturer's installation requirements.
The Department does not recommend using loose-fill insulation in a ceiling cavity that has downlights, unless the downlight manufacturer provides specific instructions for this.
Downlights (especially halogen) can generate considerable heat and when thermal insulation, particularly loose-fill insulation, is installed over existing lights a risk of fire may be introduced.
Insulation must be installed with safe gaps between the insulation and the downlights. Clearances specified by downlight manufacturers must be followed or, if these instructions are not available, the recommended clearances in ECP 54 may be used.
Installing or retrofitting downlights
The installation of downlights is covered by ECP 54, and the work is generally undertaken by electrical practitioners who must certify it if the work involves installing conductors and connecting downlights to them.
Installing downlights in the insulated ceiling of a new or existing house potentially affects compliance of the house with Building Code Clause H1 Energy Efficiency. The gaps in insulation around downlights, while reducing the chance of fire, normally reduce the thermal efficiency of the ceiling.
Where downlights are installed into insulated ceilings, the Department recommends the use of 'closed abutted' (CA)* rated downlights to avoid conflicts with Building Code compliance.
If downlights are not CA rated, then the loss in insulation can be determined using Appendix C of New Zealand Standard NZS 4246:2006 Energy efficiency– Installing insulation in residential buildings.
* Closed abutted (CA) rated downlights: 'Closed' means the opening created by the downlight is less than 5 percent of the area of the hole that is cut into the ceiling (which limits the flow of warm air from the room to the roof space).
'Abutted' means the amount of insulation that needs to be removed for the downlight is only the same size as the hole that is cut into the ceiling (which limits the amount of insulation material that is lost because of the downlight).
→ Buy NZS 4246:2006