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). This is a description of how to select, install, and support these metal or plastic frames, on which electrical wires are installed. However according to IEC 60079-14 in certain location you may use armored cables. Hi, Does IEC. Compared to ordinary power cables, armored cables can resist external impacts, pressure, abrasion, and rodent damage, making them widely used in underground tunnels, cable tray systems, chemical plants, mines, outdoor installations, and data communication networks. Their armor structure can employ. California Code of Regulations, Title 8, Section 2418. These regulations are for the convenience of the user and no representation or warranty is made that the information. en completely installed, without damage either to conductors or structural system use maintain spacing or to keep cables in place when the tray is ect the minimum bend ra-dius for cables as they exit the bottom of the cable tray. They can be rated for outdoor, indoor, for corrosive areas, for hazardous.