Step-by-step on-site guide: learn how to plan, mark, support, and install cable trays correctly, from shop drawing approval to final checks. -piece tray istypically used in applications where visual esthetics are important. It is available with a ventilated or solid bottom. The process described here takes a systematic approach to ensuring that cable tray installations meet safety, reliability, and project-specific needs while following to. cable trays are equivalent. When installed and engineered properly, cable.