When the distribution box is installed on the wall, it should be fixed with split bolt (expansion bolt). The bolt length is generally the sum of the embedded depth (75-150 mm), the thickness of the box bottom plate, the thickness of the nut and washer, plus the "head. Choose the right box based on environment (indoor/outdoor), load capacity, and durability. Check for proper IP/NEMA ratings and material quality. Avoid installing in a humid and corrosive environment to prevent equipment damage. The bolt material, characteristics, size, tooth type, and mechanical. An electrical distribution box, also known as a power distribution box, panelboard, or consumer unit, is the core of an electrical system.