Cable Types: Only use conductors rated for open-air environments, such as Tray Rated (Type TC) or Metal-Clad (Type MC) cables. This publication is intended as a practical guide for the proper and safe* installation of cable ladder systems, cable tray systems, channel support systems and associated supports. 5 Requirements for Supporting Cables in Vertical Runs " b) Vertically run cables shall be secured, as required, by support devices installed at intervals in. The National Electrical Code is a set of principles designed to promote public safety and welfare, as well as safeguard public health by regulating the design and operation of electrical facilities and systems. The following are a few points to consider when dealing with cable tray and the National. Cable tray (or cable ladder) systems are a popular alternative to electrical conduit systems, as they have an outstanding record for dependable service, design flexibility and cost savings in commercial and industrial applications.