Insulation should not interfere with the safety or performance of services and fittings such as heating flues, recessed light fittings, transformers for low voltage lighting, gas appliances and general plumbing and electrical components. This includes providing appropriate clearances. Low voltage lighting transformers should not be covered by insulation and be mounted above the insulation rather than on the ceiling.
Electricians will size electrical cables for the expected electrical load and the heat dissipation qualities of the installations. Bulk insulation that is installed later will affect the heat dissipation performance of the cables. Seek expert advice in this situation to ensure the safety of the insulation installation.
The BCA2011 Guide also notes that the addition of insulation to other building elements may alter the fire properties of those elements. Re-testing or re-appraisal of these elements may be required.