Hello: I have a problem with a drive located in a small production area. It has failed three times due to arcing between two inputs to a control board. These inputs are about 5mm apart and the manufacturer is saying that this could be from material collecting on these terminals or from gases. Now I can understand material conducting between the inputs, but gases seems rather far fetched. The drive is not sealed and it is at regular atmospheric pressure and cooled with a small muffin fan. The drive does not use any high voltage conversion and the input voltage is only 480V. I remember that it usually takes about 3000V/mm for a spark to develop in air, but I can't find any thing in that range in the drive. My question is it possible for an arc to develop spontaneously between to points 5mm apart? And if it is what are some examples of voltage or gases that may be present to facilitate such an event. BTW: Please forgive my ignorance on some of this, I know enough only to get things wrong.