Handles three-phase power and typically connects to secondary loads such as motors or machinery. Equipped with larger three-phase circuit breakers. Many feeders leave substation in a concrete ducts and are routed to a nearby pole. At this. 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. From there, it is routed to individual building distribution boxes (secondary distribution boxes), which subsequently supply power to unit-level distribution boxes (tertiary distribution boxes), and finally to household systems. Key Characteristics: Typically acts as the main distribution point for. secondary unit substation is a close-coupled assembly consisting of enclosed primary high voltage equipment, three-phase power transformers, and enclosed secondary low-voltage equipment. The following electrical ratings are typical: As a result of locating power transformers and their close-coupled. These boxes feature bottom entry and exit cables, front-opening doors, and main busbars connected with copper strips for optimal contact. Secondary distribution boxes, also. (1) Power distribution from the primary main distribution board (distribution cabinet) to secondary distribution boards can be branched; that is, one main distribution board may supply power via multiple branch circuits to several secondary distribution boards. (2) Similarly, power distribution.