The distribution box shall be embedded in the wall. When building the wall, the reserved hole shall be about 20mm larger than the length and width of the distribution box. The reserved depth is the thickness of the distribution box plus the thickness of the. An electrical distribution box, also known as a power distribution box, panelboard, or consumer unit, is the core of an electrical system. It takes the incoming power and safely distributes it to different circuits throughout your building. It is usually equipped with circuit breakers, fuses, terminal connectors, and other components.