The thickness of the steel plate meets the requirements of Article 8. 7 of JGJ46-2005: Distribution boxes and switch boxes should be made of cold-rolled steel plates or flame-retardant insulating materials, and the thickness of the steel plate should be 1. Standard for the thickness of distribution boxes under national regulations According to national standards, the wall thickness of the low-voltage distribution box should not be less than 1. A unit that lacks corrosion protection fails within months in humid or chemically aggressive. A distribution box is a low-voltage electrical enclosure that receives incoming power and distributes it safely to multiple outgoing circuits through protective and switching devices such as MCBs, RCDs, RCBOs, fuses, isolators, busbars, neutral bars, earth bars, and surge protective devices. These Distribution Cabinets are to be outdoor type nd to be fabricated out of 2 mm GI sheet steel. The body of the boxes shall have sufficient re- enforcement with suitable size of channels keeping a provision for fixin andle conforming to general. stallation and use of boxes. The box capacity table shown (page A-5) is reproduced in part from the NEC® as a quick reference and. Electrical enclosure sizes are not universal, but most manufacturers follow common size families. This guide explains typical wall-mount and floor-standing dimensions, how to read catalog sizes, and how to choose the right enclosure size for your layout. Do Standard Electrical Enclosure Sizes.