Cable tray weight per unit length can be calculated using tray dimensions, material density, and perforation percentage, typically expressed in kg/m or lbs/ft.

Calculating Cable Tray Weight

For solid or perforated trays, the weight per meter is determined by the metal volume and material density:

1. Developed Sheet Width (Dev): Dev = W + 2H + 2R Where W = tray width, H = side height, R = return flange .
2. Metal Volume per Meter (V): V = Dev × t × 1 × (1 − Open%) Where t = tray thickness, Open% = perforation area fraction (0 for solid trays), .
3. Weight per Meter: Weight (kg/m) = V × Density Common densities: carbon steel ~7,850 kg/m³, stainless steel ~8,000 kg/m³, aluminum ~2,700 kg/m³, FRP ~1,800–2,000 kg/m³ .
4. Conversion to lbs/ft: 1 kg/m ≈ 0.671 lbs/ft. Multiply the kg/m value by 0.671 to convert to lbs/ft.

Ladder Tray Approximation

For ladder trays, the weight is approximated as the sum of:

• Two side rails
• Average rung material per meter, based on rung spacing (typically 200–300 mm), .

Additional Considerations

• Covers: Include cover dimensions if present.
• Joints and Couplers: Add coupler weight per joint.
• Safety Factor: Multiply total weight by a safety factor (commonly 1.1–1.25) for installed allowance .
• Cable Fill: Separate tray self-weight from cable weight to ensure accurate support design .

Example Conversion

If a solid aluminum tray weighs 10 kg/m:

• Convert to lbs/ft: 10 × 0.671 ≈ 6.71 lbs/ft.
• For a 5-meter section: 10 × 5 = 50 kg (≈33.55 lbs). This method allows engineers to plan supports, hangers, and structural load requirements accurately, accounting for both tray self-weight and cable fill .