Grounding is required: Metal steel trays (including hot-dip galvanized, stainless steel, and aluminum alloy) must be reliably connected to protective conductors to achieve equipotential bonding and prevent electric leakage and electrification. All metallic cable trays shall be grounded as required in Article 250. An EGC conductor in or on the cable tray. The cable. Cable tray systems have become an essential component in the infrastructure of modern commercial buildings, smart offices, data centers, and various industrial facilities. The main purpose of. A cable tray grounding is best inspected by searching cable tray sections with bonding jumpers (the thick green or copper wires connecting various sections of the tray) and checking them with a device known as a multimeter. For larger ampere ratings, an additional.