Selecting shielded or unshielded tray cable depends on the application and installation requirements. Shielded cables are necessary in environments with high electromagnetic interference (EMI) to prevent equipment damage. Let's dive into how shielding works, which trays offer the best protection, and how to improve EMI shielding. When common mode current is generated through a copper conductor, EMI is created naturally by the copper's electrical. Solid bottom trays are frequently specified for: Why? In some cases, metallic solid trays can also provide incidental electromagnetic shielding, though they should not be considered a substitute for proper cable shielding.