Distribution box and switch box should not exceed 30 meters. Generally, distribution boxes can be divided into three levels of secondary protection, that is, three levels of distribution boxes: general. Several distribution boxes can be set below the main distribution box; several switch boxes can be set below the distribution box. The main distribution box should be located in an area close to the power supply, and the distribution box should be located in an area where electrical equipment or. These rules exist to prevent electrocution, fire, and equipment damage.