When electrical contractors do any work in your home (be it installation, disconnection, reconnection or alteration), you should insist on being given a compliance certificate for any work carried out. These are known under various names - 'Certificate of Electrical Safety', 'Electrical Safety Certificate' and so forth.
It's a legal requirement that contractors provide you with a certificate of electrical safety for any regulated electrical work that's been carried out.
The purpose of this safety certificate is to show that the work has been done by a licensed electrical contractor, and that the work done has been tested to ensure that it's effective, and that it complies with the relevant wiring regulations (AS/NSZ3000:2007)
Each compliance certificate should carry a unique identifying number, and should be produced in triplicate - one copy for yourself, another for your electricity provider, and a third to the responsible government authority in your state or territory.
Testing the installation
There are three types of test that are important as far as certification goes:
Electrical insulation - This test is done with an insulation tester. It proves that there are no paths to earth, and that the insulation is of an adequate standard.
Earth continuity tests - This test will ensure that the safety switch (RCD) will protect your life, and those of others in your home.
Polarisation test - This test ensures that all power points are installed correctly - and safely wired with switches in the active wires.
Are all installations tested?
No, they're not! Unfortunately familiarity breeds contempt - so goes the saying, so tests are often not carried out as they should be. Ask for the tests to be done – in particular on new installations or significant extensions of the house wiring.