The National Electrical Code (NEC) lays out specific guidelines regarding which cables are permitted for use in these trays, ensuring safety and compliance with industry standards. It is the first joint effort of NEMA and CSA International to put in one place standards for metal trays per both NEMA and CSA methods. NEMA's Cable Tray Institute is comprised of engineers from 12 cable tray manufacturers who meet to collectively set guidelines and recommendations for. NEMA, short for National Electrical Manufacturers Association, is the leading trade association for electrical equipment manufacturers in the United States. The Cable Tray ng standards, performance standards, test standards and application in this document have been tested extens ompetent professional en completely installed, without damage either to conductors or.