When dealing with any mixture of cables, it is crucial to follow the National Electrical Code (NEC) regulations, specifically 392. This guideline provides clarity on how to arrange different types of cables within a cable tray to ensure safety, compliance, and. Cable tray types, fill rules for single-conductor and multiconductor cables, ampacity derating, separation requirements, and when to use tray vs conduit. The key requirements for cable tray installation include: Incorrect installation can lead to overheating, cable damage, or system failure.