Answer: Yes; cables are tied down in cable trays to keep the cables in the cable tray, to maintain spacing between cables, or to segregate or confine certain types of cables to specific locations. The last two items can also be accomplished with a solid fixed barrier. Cable tray is the preferred wiring method for industrial facilities, data centers, and large commercial buildings where routing dozens or hundreds of cables through individual conduits would be impractical and expensive. Code Change Summary: A clarification was made regarding separation of conductors in cable trays when conductors operate at different voltage levels. Answer: The types of cables permitted by the 1996 NEC are indicated in Section 318-3, uses permitted, (a) Wiring Methods. Here is the summary of the main points found in NEC Article. Applicable For: Usually used for multi-conductor power and control cables (4/0 AWG or smaller) in ladder or ventilated trough trays. Principle: Focuses on the physical arrangement and count.
