With a cable duct, you have to remove the cover to get inside. It's not ideal if you need to access cables often. 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. Each system has unique characteristics that make it more suitable for specific applications. It indicates the direction in which the wires will follow from one side of a building to the other. From. Choosing between open cable tray and enclosed wireway/duct affects heat dissipation, ampacity derating, code compliance, and long-term maintenance.