Extract from AS/NZS 3019:2007
(j) Exposed metal liable to become alive is connected to earth.
4.7.1 Earth continuity tests
(b) The connection between any point on the installation required to be earthed and the switchboard earth bar or terminal is continuous;
(c) The resistance of protective earthing conductors does not exceed the maximum permitted; and
(d) Fixed wired appliances requiring earthing (Class I) are connected to earth.