Make sure you also connect the ground rod to the back of the plasma cutter earth ground connection. If it is EMI, it is coming from the plasma cutter. By connecting the housing to earth ground you are creating a Faraday cage.
Make sure you also connect the ground rod to the back of the plasma cutter earth ground connection. If it is EMI, it is coming from the plasma cutter. By connecting the housing to earth ground you are creating a Faraday cage.