Should horizontal strips be used for cable tray bends

Horizontal strips are generally not required for standard cable tray bends if proper bend radius and support are maintained, but they can be used to restrain cables in specific applications.

Cable Tray Bend Considerations

Horizontal bends, or elbows, are designed to change the direction of cables while maintaining a smooth path to prevent stretching, pinching, or damage to the cables. Proper installation requires maintaining the minimum bend radius for the cables and supporting the bend at key points, typically at the center of the radius and within 2 feet of each end where the bend connects to straight sections. This ensures cables are not stressed and the system remains safe and reliable.

Role of Horizontal Strips

Horizontal strips, or cable restraining devices, are sometimes used to keep cables in place within the tray, especially in long runs or where vibration, thermal expansion, or heavy cable bundles could cause displacement. They are particularly useful in: Instrumentation and control applications with small or sensitive cablesAreas where visual aesthetics or precise cable alignment is importantSituations where additional protection against sagging or lateral movement is needed However, for standard ladder or ventilated tray bends, the tray itself, along with proper support and alignment, is usually sufficient to maintain cable integrity.

Overuse of horizontal strips can complicate installation and may not be necessary if the bend radius and support spacing are correctly followed.

Best Practices

Use factory bends or properly mitered straight sections to achieve the required angle. Support bends at the center of the radius and near the ends to prevent sagging. Ensure the bend radius meets cable manufacturer specifications to avoid kinking.

Consider horizontal strips only when additional cable restraint is needed due to vibration, long unsupported spans, or sensitive instrumentation cables. Follow industry standards such as BS EN 61537 for tray systems and manufacturer guidelines for installation. In summary, horizontal strips are optional and application-specific.

Properly supported and aligned bends typically do not require additional horizontal strips, but they can be added for extra cable restraint in specialized or high-risk installations.