The primary distribution box refers to the main distribution box, typically located in the distribution room. 4kV), power is distributed to a main distribution panel (primary distribution box). Each. In any electrical system, the distribution box is the heart and brain, a critical component that safely manages and distributes power from the main source to various circuits. Whether you're working on a residential building, a commercial facility, or a large industrial plant, understanding the. Electrical distribution boxes are used in commercial and residential buildings and are part of the electrical system, also known as switchboards.