Why It Matters: High‑voltage and limited energy circuits routed too closely can cause cross‑talk, distortion, or packet errors, especially in dense cable trays or congested ceiling spaces. Best Practice: Use separate trays, conduits, or divider systems to isolate voltage classes. Shielded cable can. This issue of the CableGram presents questions and CTI answers to these questions that have been asked by interested persons and organizations concerning the application of cable tray systems. We believe you will find the answers useful. However, any installation must adhere strictly to the National Electrical Code (NEC) standards. 3 (C) (1):. In industrial settings, electrical and instrumentation (E&I) cable trays or bridge racks play a critical role in organizing and supporting power, control, and signal cables across facilities. An effective layout ensures safety, minimizes interference, reduces maintenance time, and keeps the overall. This guide covers the cable tray types and their appropriate applications, the fill rules for each configuration, ampacity derating requirements, separation of power and signal cables, and the decision criteria for choosing cable tray over conduit. NEC 392 recognizes several cable tray types, each.