The NEC rule requires that the cable cross-sectional areas together may not exceed 50% of the tray area (width x depth = fill). TIA recommends 40%. Cable tray is the preferred wiring method for industrial facilities, data centers, and large commercial buildings where routing dozens or hundreds of cables through individual conduits would be impractical and expensive. NEC Article 392 governs cable tray installations, covering tray types, fill. Performing a correct cable tray ampacity calculation is a critical skill for any licensed electrician, ensuring both safety and compliance with the National Electrical Code (NEC). The process involves determining the maximum current a conductor can carry without exceeding its temperature rating. Size conductors installed in cable tray with NEC 392, NEC 310. 16, tray fill, ampacity adjustment, voltage-drop checks, grounding, and IEC design cross-checks. Here is the summary of the main points found in NEC Article. (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. In this installment of our Code Corner series, Ryan Mayfield focuses on the 2023 National Electrical Code (NEC) changes concerning cable trays, particularly section 690.