Switchgear is a commonly used name for metal-enclosed distribution apparatus of modular, cubicle-type construction. Despite this commonly used name, there are technical and physical distinctions between various classes of switchgear assemblies. The American National Standards Institute (ANSI) and National Electrical Manufacturers Association (NEMA) have published standards for electrical equipment. These standards are followed by most manufacturers of electrical switchgear. The ANSI lists switchgear assemblies into three main categories, which are further classified into subcategories as shown in Table 7.1.