When the automobile electrical system adopts single-wire system, one electrode of the battery is connected with the car body, commonly known as "grounding". If the negative pole of the battery is connected to the car body, it is called negative pole grounding; Otherwise, it is called positive grounding. According to the national standard, the electrical system of domestic automobiles adopts negative grounding.

Advantages of negative grounding: less chemical corrosion to frame and body metal and less radio interference.