The primary distribution box refers to the main distribution box, typically located in the distribution room. From the transformer's low-voltage side (0. 4kV), power is distributed to a main distribution panel (primary distribution box). They also include metering systems, ensuring. The outgoing line from the low-voltage end of the transformer is 0. 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. Class I distribution box: the construction power distribution cabinet is used for construction power on the construction site. It helps organize, protect, and control electrical connections in residential, commercial, and industrial electrical systems.