This might come across as an off topic question but then again it might keep someone from getting their ride caught on fire. Here is my question.....When using a mig welder on a vehicle, are you supposed to remove/disconnect the ground cable on the battery? If this is not done will it cause a fire? Here is what happened to me: I took my car hauler/parts chaser -- 1995 Dodge Ram 3500 Dually truck to a muffler shop to get a hanger welded on the tail pipe to keep it from hanging. The guy put it on a lift and began welding the hanger on the frame. He was using Lincoln Mig welder and he placed the ground clamp on the frame. He seemed to be having a hard time and kept moving the ground clamp around to different spots. Soon after another dude came and messed with the settings on the welder, the first dude resumed welding and after a couple of minutes, the horn on the truck started to go off then smoke started coming out from under the hood. The fuse box that is under the hood by the battery caught on fire. After all the excitement and one empty fire extinguisher later, I brought my truck home. Several people have told me that the fact that the dude did not disconnect the battery is what caused the fuse box to start on fire.