Rack Enclosures

Rack enclosures (rack cabinets, laboratory enclosures) are used to house standard 19 in. rack-mounted components or other standard-sized devices. They are designed to protect personnel from accidental injury and to prevent the ingress of environmental contaminants such as dust and water. Rack enclosures are rectangular or T-shaped, made from a variety of materials, and available in many different sizes, sealing configurations, and mounting styles. Length, width, and height are important dimensions to consider. Inside length, inside width, inside height, and sloped surface length are also important considerations. Length and height are measured vertically while rack enclosures are in the normal operating position. By contrast, width is measured horizontally. Depth equals the distance from the front to the rear of the rack cabinet. Normally, rack height is specified in U where 1U = 1.75 in.

National Electrical Manufacturers Association (NEMA) ratings indicate whether rack 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 Ingress Protection (IP) ratings system from the International Electrotechnical Commission (IEC) describes the degree to which rack 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 rack 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. Specialized products are flame retardant, impact resistant, explosion proof, or shielded from electromagnetic interference (EMI) and radio frequency interference (RFI). Options for rack enclosures include ventilated covers, glass doors, cooling fans, drawers, shelves, and keyboard compartments.

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Part Numbers for Rack Enclosures