Hazard alert installing underfloor insulation

Issue 31 – September 2011

Recently a worker risked electrocution while installing insulation under a house. A temporary employee working for a domestic insulation contractor passed out after receiving an electric shock while installing underfloor insulation. The employee was installing a non-conductive insulation product under a house when he accidently stapled through an electrical cable. The Department of Labour is currently investigating the matter.

There have been a number of injuries involving workers and do-it-yourself renovators in New Zealand who have stapled through electrical cables while installing underfloor insulation. In the past 5 years there have been approximately four deaths resulting from installing underfloor insulation in New Zealand. There have also been four deaths in Australia related to the installation of insulation in houses.


Appendix B of NZS 4246:2006 Energy efficiency – Installing insulation in residential buildings provides specific health and safety guidance for the installation of domestic insulation including underfloor insulation.

The Department of Labour advises employers and contractors to eliminate the hazard of electrocution by using non-conductive insulation products as well as non-conductive staples and adhesives. Where elimination is not practicable, isolate the hazard by using physical guards or shields over cables and by using insulated gloves and tools. Minimise the hazard by stapling a pre-determined distance away from any wires or cables – this should only be considered when neither eliminating nor isolating the hazard is practicable.

Note: This material has been prepared by the Department of Labour using the best information available at the time of publication. Information may change over time and it may be necessary for you to obtain an update. This material is also only intended to provide general advice and does not constitute legal advice. You should make your own judgement about action you may need to take to ensure you have complied with your workplace health and safety obligations under the law.

Information supplied by Department of Labour.

Related Standards

  • NZS 4246:2006 Energy efficiency – Installing insulation in residential buildings
  • NZS 4218:2004 Energy efficiency – Small building envelope
  • NZS 4243.1:2007 Energy efficiency – Large buildings – Building thermal envelope
  • NZS 4243.2:2007 Energy efficiency – Large buildings – Lighting
  • NZS 4218:2009 Thermal insulation – Housing and small buildings

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