During wall construction, the reserved hole shall be about 20mm larger than the length and width of the distribution box. Choose the right box based on environment (indoor/outdoor), load capacity, and durability. Check for proper IP/NEMA ratings and material quality. The body of the boxes shall have sufficient re- enforcement with suitable size of channels keeping a provision for fixin andle conforming to general. The installation requirements and specifications of Distribution box involve many aspects, including site selection, fixing method, wiring specifications and safety protection. The bolt length is generally the sum of the buried depth (75 ~ 150mm), the thickness of the box bottom plate, the thickness of nuts and washers, plus about 5mm "head allowance". For smaller distribution boxes, wood bricks can also be embedded at the installation position (embedded according to the. The best height for installing residential distribution boxes is 1.