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. While it is technically possible to run power and low-voltage cables in the same tray under strict conditions, segregation or shielding is strongly recommended to ensure safety, compliance, and system reliability. Engineers should prioritize standards like NEC, IEC, and project-specific. Separation of Band I low voltage cables and Band II high voltage cables is mandatory to stop electrical interference. Band I cables can include telecommunication. If you have a 480V circuit in the tray, all cables must be insulated for at least 480V regardless of the actual voltage of the circuit. I assume this is part of an NEC requirement. Do you know where off the top of your head this is talked about in the NEC? I have not been in this. concerning 300/500V cables complying to IEC 60227-4, installed in 3phase system 230/400V, I know that it is acceptable to be installed as per IEC 62440-2008 table 2. (which allows it for up to 320/550V system).
