They are strictly prohibited in hoistways or any location where they could face severe physical damage. Grounding: Metallic trays can serve as equipment grounding conductors (EGC) if they meet NEC requirements. Fill Limits: For power cables, the fill must not exceed 40% of the tray's. Cable tray systems provide a flexible and organized method for supporting various wiring types but are subject to restrictions outlined in NEC Article 392. 12 defines. The primary rulebook used in the safe use of cable trays is NEC Article 392. This is a description of how to select, install, and support these metal or plastic frames, on which electrical wires are installed. When Understanding NEC Article 392, you will encounter several different types of recognized trays. These include ladder trays, ventilated troughs, ventilated channels, and solid bottom tray.
[PDF Version]