The National Electrical Manufacturers Association (NEMA) has published the 2013 edition of its Electrical Standards and Products Guide, a comprehensive listing of NEMA electrical standards as well as an extensive directory of manufacturers and their products.
 
It is used by military, government, and private buyers who work in lighting, motors and industrial controls, transmission and distribution, transportation, medical imaging, architecture and construction, and other industries that specify and use electrical equipment. 

Click here to download the Guide