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). It also focuses on construction and installation practices for cable trays. Here is the summary of the main points found in NEC Article. Basements present unique challenges for electrical wiring, requiring specific adherence to National Electrical Code (NEC) requirements. The space below grade is susceptible to moisture, necessitating specialized protection to prevent corrosion and ground faults. Cable trays must be installed as a complete system, except mechanically discontinuous segments between cable tray runs, or between cable tray runs and equipment as permitted. A cable tray system is a unit or assembly of units or sections with associated fittings forming a rigid structural system used to securely fasten or support cables, raceways, and boxes [392. Power, low voltage control.