31 (C) now aligns with the Code's broader language (like Article 392), allowing these smaller conductors and detailing how to calculate ampacities, the number of conductors permissible in cable trays, how to size cable trays correctly by width, layering. The updated section 690. The Cable Tray ng standards, performance standards, test standards and application in this document have been tested extens ompetent professional en completely installed, without damage either to conductors or. Cable tray types, fill rules for single-conductor and multiconductor cables, ampacity derating, separation requirements, and when to use tray vs conduit. To comply with code requirements and ensure system safety, metallic trays must be electrically continuous, properly bonded at all splice points, and securely connected to. Properly sizing your cable tray is critical for safety and compliance. Our free calculator helps you determine the correct tray size based on NEC and IEC standards. Follow these simple steps: Define Tray Dimensions: Enter the width and depth of your planned cable tray (in mm or inches). It instructs us on how to construct them, where to locate them, and how to stuff them with wires without using too much.