Due to their exposure to the open air because of the cable trays, the wires contained within need a very durable outer covering. The regulations dictate that the cables must either be Type TC (also known as Tray Rated) or must be metal-armored (Type MC). Metal raceways, cable trays, cable armor, cable sheath, enclosures, frames, fittings, and other metal noncurrent-carrying parts that are to serve as grounding conductors, with or without the use of supplementary equipment grounding conductors, shall be effectively bonded where necessary to ensure. (i) Metal raceways, cable trays, cable armor, cable sheath, enclosures, frames, fittings, and other metal noncurrent-carrying parts that are to serve as grounding conductors, with or without the use of supplementary equipment grounding conductors, shall be effectively bonded where necessary to. NEC Article 392 explains cable trays, their components, appropriate wiring methods for cable trays, and instances where they are and are not permitted for use. It also focuses on construction and installation practices for cable trays. Article 392. All Wiring Installations. The requirements contained in Article 300 do not apply to the integral part tandards and not the NEC. It is the intent of this Code that the factory-installed internal. Standard Aluminum Ladder • The rungs provide a convenient anchor for tying down cables in vertical runs or where the positions of the cables must be maintained in horizontal runs.