Secondary distribution boxes, also known as sub-distribution boxes, generally serve specific power supply areas. These boxes have inner and outer doors, powder-coated exteriors, and are designed for safety and aesthetic appeal, with rainproof tops for outdoor work. A feeder usually begins with a feeder breaker at the distribution substation. Many feeders leave substation in a concrete ducts and are routed to a nearby pole. From the transformer's low-voltage side (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.