According to national standards, the wall thickness of the low-voltage distribution box should not be less than 1. The Mirage range of practical f outgoing devices. Anything thicker is called a plate. In North America, we measure it in two ways: While Europe and Asia primarily use the metric system, thus millimeters (mm). Generally speaking, the thicker the box, the better its endurance, heat resistance, and safety. If the incoming line is less than 10 square and the number of switch digits is less than 20, the width of the switch is added and the width of the electric box is 20mm on each side, the height is the switch height +.