Third level distribution box: refers to the final junction box of each electrical appliance, which can be movable and fixed. 4kV to the distribution cabinet (primary distribution cabinet), then the outgoing line is led to the distribution box (secondary distribution box) in each building, and finally the outgoing line is led to the distribution cabinet. The primary distribution box refers to the main distribution box, typically located in the distribution room. These boxes feature bottom entry and exit cables, front-opening doors, and main busbars connected with copper strips for optimal contact. Today, electrical systems are essential for homes and industries.