The electrical enclosure is essentially a metallic box with a lid. To mount components in the box, a back panel on standoffs is added to create the finished enclosure. The application and environment dictate the variations on this base concept.
Starting with the enclosure itself, certain applications may call for a different material of construction. Environments where exposure to caustic or corrosive chemicals or extreme weather is expected, making the box out of fiberglass or polycarbonate ABS is a better option. In normal, dry conditions, a mild steel enclosure is suitable and for wet environments a stainless steel enclosure is best. The National Electrical Manufacturer Association (NEMA), came up with a rating system to describe these applications and environments and some of the main types are described as follows: Read the full article here.