Do vertical cable trays not require supports

Yes, vertical cable trays require supports at specified intervals to ensure safety and maintain cable integrity.

Support Requirements for Vertical Cable Trays

Vertical cable trays are not self-supporting over unlimited heights. Even though some steel trays may be self-standing for short sections (e.g., up to 20 feet for 6-inch deep, 14-gauge galvanized steel trays), supports are still required at intervals to secure the cables and prevent sagging or displacement. Cables in vertical runs must also be fastened at intermediate points to remain fully within the tray.

Standards and GuidelinesNEC Article 392 defines cable trays as support structures rather than raceways and emphasizes that trays must be installed in open, accessible areas with proper support to prevent mechanical stress on conductors.

IEE

E Std 525-1992 recommends supporting cables in vertical runs according to conductor type and manufacturer specifications, including armored, shielded, or coaxial cables. Manufacturer recommendations often provide maximum unsupported heights and intervals for vertical tray sections, which should be followed to ensure structural integrity and compliance.

Practical Considerations

Intermediate supports: Vertical trays should have support devices installed at intervals sufficient to keep all cables secured within the tray. Cable fastening: Cables should be tied to the tray's transverse members to prevent movement and maintain spacing, which also aids in heat dissipation. Material and depth: The tray material, depth, and gauge affect self-supporting capability; deeper or heavier trays may require more frequent supports.

Outdoor or long runs: For extended vertical runs, expansion splice plates or additional supports may be necessary to accommodate thermal expansion and prevent mechanical stress.

Key Takeaway

Vertical cable trays always require supports, even if the tray can stand on its own for short distances. Properly spaced supports, cable fastening, and adherence to NEC, IEEE, and manufacturer guidelines are essential for safety, compliance, and long-term reliability of the cable system.