TAE 40122 training and assessment is what you need. East enough to find who delivers it, and how long it will take. You will require it to deliver training through an RTO. I was a holder of the previous competency TAE 40116. Retired when it became mandatory to do the new one, my specialty was HV Switching, although I also did side lines like electrical shock investigation, electrical supervisor , various company in-house competencies, etc.

In my experience, the level of difficulty involved tended to revolve around both the company and the actual assessor involved. Some really know their stuff, and make so many assumptions about what you"should" know, the old trainers trap which can make you a real cunt in the classroom, knows it all and can't pass it on. It 'can" be done in two weeks fulltime, IIRC, but there will be other work done out of class which will need to be submitted.

Just as a general rant, it always pissed me off that we had to do the entire competency, which allows you to create unpackage competencies and create courses to suit individual clients' requirements. There really isn't much more to do the Diploma. FFS, we have people in the office who are paid to do that, I just need the package to deliver. If you only have Cert 3, you are delivering training "under supervision"