Wall-mounted boxes should be 4. This height makes it easy to reach without bending or stretching. Check and fix the box. With secondary selective service, each distribution transformer must be able to supply the entire load for maximum reliability benefits. Spot Networks are used for customers with the highest reliability requirements. 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 power distribution system at the construction site shall be distributed in different levels. The distribution box shall be set below the main distribution box, and the switch box shall be set below the distribution box, and the. Class I distribution box: the construction power distribution cabinet is used for construction power on the construction site.