When it comes to managing and protecting cables in various environments, both cable trays and cable ducts serve as essential components. However, they are not interchangeable. Each system has unique characteristics that make it more suitable for specific applications. Understanding the differences. Channel tray — Small (4" or 6" wide) for small quantities of cables or instrument tubing. Cable duct (wireway, or cable trunk) is an enclosed sheet-metal or PVC raceway with a hinged or removable cover. NEC Article 376 covers metal wireways. Their open design facilitates heat dissipation, preventing overheating of cables and reducing the. If you're working on an electrical project, you've likely asked yourself this: Should I use a cable duct or a cable tray? It's a common question. Large Buildings: Use of large building wires in the main wires that run between the basement and the roof.