Cable tray supports are typically spaced between 1.5 to 3 meters, depending on tray type, load, and installation conditions.

Typical Support Spacing

The number of supports per meter depends on the support spacing, which is influenced by the tray type, material, and the weight of the cables. Common guidelines include:

• Standard indoor steel trays: supports every 2 meters is typical, resulting in 0.5 supports per meter (1 support per 2 meters) .
• Ladder trays or heavy-duty trays: may require closer spacing, around 1 to 1.5 meters, giving 0.67 to 1 support per meter .
• Long-span trays: specially reinforced trays can span up to 6 meters between supports, reducing the number of supports to 0.17 per meter .

Calculation Formula

To calculate the total number of supports for a given tray length:

Support Quantity = (Total Length ÷ Support Spacing) + 1 .

For example, a 20-meter tray with 2-meter spacing requires: 20 ÷ 2 + 1 = 11 supports .

Factors Affecting Support Spacing

1. Load and Cable Weight: Heavier cables require closer support spacing to prevent sagging .
2. Tray Material and Strength: Aluminum or fiberglass trays may need shorter spans than steel trays .
3. Installation Environment: Vibration, wind, or temperature fluctuations may necessitate closer spacing .
4. Regulatory Compliance: NEC Article 392 recommends typical spans of 2–3 meters for standard trays, with long-span trays allowed up to 6 meters .

Practical Recommendation

For most indoor installations with standard steel ladder or perforated trays, placing supports every 2 meters is a safe and commonly used practice, equating to approximately 0.5 supports per meter. Adjust spacing based on load, tray type, and environmental conditions to ensure structural integrity and compliance with electrical codes.