Tagging and checking of all "in-service" electrical plug-in equipment in accordance with AS3760 should now be the norm in all workplaces. If this is not the case in your workplace, as an OHS rep, you should approach your employer and request that this be done as soon as possible. If it is not done, then the employer is breaching his/her duty under Section 21.
If the workplace is a construction site, then the Industry Standard for Electrical Installations on Construction Sites must apply (and also another document which outlines some of the changes to it). WorkSafe has also developed a document answering Frequently Asked Questions on the standard.
Both the Electrical Safety Act, 1998 and the Electrical Safety (Installations) Regulations apply, as well the Occupational Health and Safety Act, 1985. In addition, number of Australian Standards, including AS3760, are referenced in the Industry Standard, and so are mandatory.
For more information, contact your union