Cathy's right.   It's a really old law that they haven't bothered to fix -

Funnily enough, unless you're a licensed electrician, it's illegal to change a lightbulb in Victoria. This doesn't just apply to public buildings, either; it's actually against the law to change the lightbulb in your own home. This one's probably a leftover from the days when having an unlicensed electrician change your lighting was a good way to burn the entire neighbourhood down.

Suffice to say you're unlikely to get charged for doing it today, but even if you do, the penalty's just a $20 fine. Hardly worth worrying about.

Google it