Safety verification test of mains polarity with supply isolated

Below is a how to guide on mains polarity safety verification testing with supply isolated. This is additional to, and not a substitute for verification guidelines contained in standard AS/NZS 3017.

  • Testing

This guide is indicative and prepared on the basis that the electrical practitioner will:

  • never enliven mains, unless correct polarity has first been established;
  • be appropriately trained, qualified, authorised and competent to carry out the tests;
  • use a suitable meter and safety equipment, follow all necessary safety procedures; and
  • have a suitable purpose-built polarity tester complete with trailing test lead and earth probe.

Testing safety notes

  • Correct mains polarity should always be confirmed first before carrying out any live test and failure to do so can create an immediate and serious risk of electrocution, shock, or fire.
  • Allways ensure supply is isolated and no voltage is present between earth probe and test points on consumer mains.
  • Always ensure insulation resistance meter is functioning correctly before and after conducting the tests.
  • Ensure all connections are secure and reliable to help achieve true and accurate results.
  • Repeat tests a number of times (if required) to ensure accuracy and consistency of test results.
  • If the supply neutral is not connected and earthed, then the installation is not safe to use.


Note 1 Regardless of the revenue meter being installed or not, the test results should be the same as indicated.

Note 2 Installations wired differently may require access to mains test points at other suitable locations other than indicated.