Cable tray supports should generally be spaced 4 to 6 feet (1.2 to 1.8 meters) apart for horizontal runs, depending on tray type, load, and manufacturer specifications.

Standard Guidelines

• Ladder-type cable trays: The National Electrical Code (NEC) recommends that supports be spaced no more than 5 feet (1.5 meters) apart for horizontal runs, with rungs spaced no more than 9 inches apart. Ideally, the run length between supports should be 4 to 6 feet (1.2 to 1.8 meters) to ensure uniform load distribution and prevent sagging .
• Wire mesh or perforated trays: These are typically used for lighter cables, and support spacing can follow similar NEC guidelines, with attention to load and cable weight .
• BS EN 61537 compliance: In the UK and Europe, support spacing should comply with BS EN 61537, which considers cable tray material, height, and load. Calculators are available to determine precise spacing based on these factors .

Factors Affecting Support Spacing

1. Cable weight and type: Heavier power cables require closer support spacing, while lightweight fiber optic or telecommunication cables can have wider spacing .
2. Tray material: Steel trays can span longer distances than aluminum or plastic trays without sagging .
3. Environmental conditions: Outdoor installations or areas subject to vibration may require closer spacing to maintain stability .
4. Vertical runs: Supports for vertical cable tray sections should ensure stability and prevent undue stress on cables, often requiring additional brackets or hangers .

Practical Recommendations

• Always follow the manufacturer's specifications for support spacing.
• Ensure supports are fire-resistant if required by local codes, especially for critical or fire-rated cables .
• For long horizontal runs, consider intermediate supports to prevent sagging and maintain cable integrity.
• Use hanging rods or brackets of adequate diameter (e.g., ≥8 mm) for vertical stability . By adhering to these guidelines, cable trays will maintain structural integrity, prevent cable damage, and comply with safety standards.