One of the worst mistakes you can make on an EPC project is to run low-voltage instrumentation cables and high-voltage power cables in the same tray. Since cable tray is not defined as a raceway, would NEC 300. 3 (C) (1) still apply to cables in the tray system? 392. 3 (C) (1) is more strict requiring the. Cable tray types, fill rules for single-conductor and multiconductor cables, ampacity derating, separation requirements, and when to use tray vs conduit. Cable tray is the preferred wiring method for industrial facilities, data centers, and large commercial buildings where routing dozens or. What are the NEC rules for mixing different voltage cables in the same cable tray? At times it becomes necessary, or even desirable, to route medium- or high-voltage cables (greater than 600V) in the same cable tray with cables rated 600V or less. Unlike power cables, instrumentation cables generally transmit. Answer: The 1996 NEC in sections 318-6 (i) and (j) indicates that there shall be sufficient space maintained around cable trays to allow adequate access for installing and maintaining the cables and that cable trays shall be exposed and accessible. An effective layout ensures safety, minimizes interference, reduces maintenance time, and keeps the overall.