Earthing/Grounding Acessories
 
If you don't have a properly earthed mains outlet (for example some European houses or a pre-1960s house in the United States), then you can instead use a grounding rod kit to make a connection directly with the ground outside.
 
The kit consists of a 0.3m (1ft) stainless steel rod with a 12m (40ft) cord.  The rod is pushed into the ground outside, which makes a good electrical connection to the Earth.  The cord is only 2mm in diameter so it can usually be run through the edge of a window frame with the window closed.