I don't know what the Standard is down under, there is CSI, UL, BSI.
But the NFPA wording is:
Equipment Grounding:
The machine and all exposed, non-current-carrying conductive parts, material and equipment, including metal mounting panels that are likely to become energised and are mounted in non-metalic enclosures, shall be effectively grounded.
Anyway, probabally cost about 50˘ to run a bonding wire/strap
Al.