The NEC requires that cable trays must be supported by members at an interval specified by the cable tray manufacturer, but not more than 5 feet for horizontal runs to support the weight of the cables and other loads. The NEC has a requirement for ladder-type cable trays. Proper installation can significantly reduce electromagnetic interference, prevent fire hazards, and improve overall efficiency. This article provides an in-depth. maintain spacing or to keep cables in place when the tray is ect the minimum bend ra-dius for cables as they exit the bottom of the cable tray. 5 or maybe 2 meters strengthens high-load regions. Clause 522-08-04 Where conductors or cables are not supported. How far apart should I place my mounting brackets? Typically, brackets should be spaced 4 to 5 feet apart for standard cable trays.