TC-ER-rated cables can be installed in exposed runs outside the cable tray, up to 6 feet between the cable tray and connected equipment, and without conduit—provided that the cable is secured and protected from mechanical damage, per code. Conduit, on the other hand, is a rigid or flexible tube that provides additional mechanical protection and environmental. The decision on whether to use a cable tray or a conduit lies on the scale of the job as well as the amount of heat the wires will generate. Cable trays are more preferable in large buildings or factories since they are not closed and can be readily repaired. In many situations, this is still the standard and the case. However, in many industries. Cable tray types, fill rules for single-conductor and multiconductor cables, ampacity derating, separation requirements, and when to use tray vs conduit. I don't think anyone allows direct burring of cable, or a dangling free run, particularly in an industrial environment. Material cost can appear similar on small runs. The difference emerges at scale.
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