As someone who is an electrical engineer in Australia, it doesn't mean jack in terms of electrical safety law (in QLD anyway). The only real protected class is those with an electrical work license, and if you try to do some of the training, no one will even listen (yes, I tried
) unless you are signed up to be an electrician apprentice for 4 years. If you are a chartered engineer (I don't think it actually says anything about "electrical") then you can sign off on big government projects.
But I have talked with the state government about this, and my very basic understanding is that as long as you don't touch fixed wiring, anyone can do anything as long as it is "part of your profession" in an "OH&S certified workplace". So people with no degree or anything can build electronics that plugs into the mains, so long as these are in place. This makes sense, because no business could afford to pay electricians' rates to do basic pcb assembly. I never fully went down this path, because the law around this area is both very clear and extremely confusing at the same time (I don't really know how else to explain it!) so I decided it wasn't worth it.
In terms of certification for your device: you should be able to dodge a lot by buying pre-certified components. For example, power supplies are fairly easy to get that already come with C-Tick (that's us), UL from the US, CE from Europe and TUV from Germany. Just be careful as some cheap chinese outfits are known to forge these numbers.
of course: IANAL, don't quote me, YMMV, etc
I hope this unconfused you more.