Most inline SMPS power supplies come with a floating output i.e. the 0V connection is NOT connected to EARTH. If not connected to a suitable ground (earth) point then you may experience static discharge when you contact any metal part in your system. The addition of a solid 'ground' will eliminate this.
Please note that the addition of such a grounding mechanism may introduce a 'ground loop' which may need to be treated.
Currently we can only provide special mains plugs for the Australian market (and countries using the same mains plugs). Users in other countries will need to provide their own EARTH connection