NEMA and IP enclosures are designed to house electrical components, protect personnel from accidental injury, and prevent the ingress of environmental contaminants such as dust and water. NEMA enclosures are rated by the National Electrical Manufacturers Association (NEMA), a non-profit organization that recommends safety standards for electrical equipment. IP enclosures comply with Ingress Protection (IP) standards from the International Electrotechnical Commission (IEC). There are many types of NEMA and IP enclosures. Examples include electronic and instrument enclosures, operator interface enclosures, console enclosures, consolet enclosures, pushbutton enclosures, personal computer (PC) enclosures, rack enclosures, modular enclosures, and terminal and junction boxes. NEMA and IP enclosures are rectangular or T-shaped and available in many different sizes. Length, width, and height are important dimensions. Inside length, inside width, and inside height are also important considerations. Because some NEMA and IP enclosures can be mounted in several different ways, suppliers recommend viewing product pictures or diagrams to determine which dimensions refer to length and which dimensions refer to width.  

NEMA ratings indicate whether NEMA and IP enclosures are suitable for hazardous or non-hazardous locations and designed for indoor or outdoor use. All NEMA enclosures protect personnel against incidental contact with the enclosed equipment. Types 1, 2, 12, 12K and 13 NEMA enclosures are rated for indoor use in non-hazardous locations. Types 3, 3R, 3S, 4, 4X, 5, 6, and 6P enclosures are rated for both indoor and outdoor use in non-hazardous locations. NFPA 70, a publication of the National Fire Protection Association (NFPA), is the basis of several NEMA ratings for hazardous locations. Type 7 and Type 8 NEMA enclosures are designed for Class I; Division 1; Groups A, B, C or D hazardous locations. Type 7 enclosures are rated for indoor use. Type 8 enclosures are rated for outdoor use. Type 9 NEMA enclosures are designed for indoor use in hazardous locations classified as Class II; Division 1; Groups E, F, or G. Type 10 NEMA enclosures are designed to meet the requirements of the Mine Safety and Health Administration (MSHA). Type 11 NEMA enclosures are designed for immersing the enclosed equipment in oil. 

The IP ratings system describes the degree to which NEMA and IP enclosures provide protection against the ingress of foreign objects and moisture. There are six IP ratings that describe protection against foreign objects. Type 0 enclosures do not provide protection. Type 1 (>50 mm), Type 2 (>12 mm), Type 3 (>2.5 mm), and Type 4 (1 mm) enclosures provide protection against foreign objects of various sizes. Type 5 enclosures provide protection against dust. Type 6 enclosures are dust-tight. There are eight IP ratings for protection against moisture. Type 0 enclosures do not provide protection. Type 1 and Type 2 protect the enclosed equipment against dripping water. Terminal and junction boxes with Type 3 (spraying water), Type 4 (splashing water), Type 5 (water jets), Type 6 (heavy seas), Type 7 (immersion), and Type 8 (submersion) IP ratings are also available.

Selecting NEMA and IP enclosures requires an analysis of construction materials and mounting styles. Most products are made of aluminum, steel, stainless steel, fiberglass, plastic, polycarbonate, acrylonitrile-butadiene-styrene (ABS), or polystyrene. End panels are often made of clear, infrared, solid, or transparent plastic and include cutouts for DB9 or DB25 connectors. Some devices are designed to sit atop desks or mount in freestanding cabinets or open-frame racks. Others are wall-mounted or fit standard DIN rails.