It involves multiplying the width, depth, and height of an entity to determine its total size or volume. Choosing the correct electrical box dimensions is essential for safe wiring, code compliance, and long-term reliability. This guide explores control panels, electrical boxes, breaker panels, bus bars, junction boxes, and. What is the Meaning of W * D * H? The package won't fit through the doorway! Or perhaps you're an architect envisioning a new building, but miscalculations in measurements lead to space constraints, altering the entire design. It also provides specifications for. stallation and use of boxes.