I think I know the answere but. I was working on a new machine and the hand held controls were sitting on a table we were welding on and there was some arcing between ontrolls and table. The controls moved an arm and are not on the same circuit as the welder. I checked and nothing was wrong with any of the switches in the box and thought that the ground wire connected to box was an earth ground and the ground on table from the grounding clamp was some sort of floating ground isolated in the welding circuit. Is this correct? Or am I clueless?