If single-conductor cables are randomly distributed in the tray without circuit grouping, the magnetic fields do not cancel and the tray itself can heat up, creating a fire hazard. In the systems fed with single core cables; the cable arrangement and phase sequences should be applied as stated below in single row sequence. To name a few configurations about these; Conclusion In order to meet. Through NEMA and the Cable Tray Institute numerous articles, standards, and other general guidance can be found regarding the proper use and installation of cable tray systems. Cable tray is classified by the NEC (NFPA 70 the National Electrical Code) as a support system and not. Cable tray types, fill rules for single-conductor and multiconductor cables, ampacity derating, separation requirements, and when to use tray vs conduit.