The distribution box shall be installed firmly, horizontally and vertically, and the vertical deviation shall not be greater than 3 mm; in case of concealed installation, there shall be no gap around the distribution box, the edge around the panel shall be close to the. The distribution box shall be installed firmly, horizontally and vertically, and the vertical deviation shall not be greater than 3 mm; in case of concealed installation, there shall be no gap around the distribution box, the edge around the panel shall be close to the. Learn how to install a distribution box safely and correctly. Covers wiring, placement, standards, and expert tips for a compliant setup. After the box is placed, the perpendicularity of the box shall be found with ruler board to meet the requirements. It has three categories: residential, commercial and industrial electrical distribution boxes, all of which play important roles in their respective electrical. In order to ensure the beauty of decoration, it is necessary to install the distribution box vertically and horizontally into the wall and keep the 5-6mm gap edge. Distribution box wiring should be neat and regular, so as to avoid finding the corresponding wiring, and each terminal should be. The installation requirements and specifications of Distribution box involve many aspects, including site selection, fixing method, wiring specifications and safety protection.