Flat steel cable trays are specified by material, dimensions, load rating, and compliance with standards such as ASTM, NEMA, and CSA.

Material and Standards

Flat steel cable trays are typically fabricated from hot-rolled or cold-rolled carbon steel and may be galvanized for corrosion protection. Common standards include:

• ASTM A1011 / A1008: Steel sheet, hot-rolled or cold-rolled, structural quality with high-strength low-alloy options .
• ASTM A653: Zinc-coated (galvanized) steel sheet .
• ASTM B633: Electrodeposited zinc coatings .
• NEMA VE 1: Metallic cable tray systems .
• CSA C22.2: Canadian electrical standards for load and span .

Typical Dimensions

Flat steel cable trays are available in various widths, depths, and rung spacing:

• Rung width: 1 5/8 in (41 mm) welded to side rails for rigidity .
• Maximum open spacing between rungs: 102 mm (4 in) parallel to side rails .
• Tray widths: Commonly 100 mm to 600 mm (4 in to 24 in), depending on cable load.
• Tray depths: Typically 50 mm to 150 mm (2 in to 6 in), selected based on cable volume .

Load Ratings and Deflection

• Safety factor: 1.5× applied to all load ratings .
• Concentrated load: Additional 200 lb (91 kg) can be applied at any point on the tray above published load class .
• Deflection factor: For lighter loads, deflection can be calculated by multiplying the load by the deflection factor; continuous spans reduce deflection by up to 50% .
• NEMA/CSA load classes: C1 to C3, with corresponding span and load tables available in technical catalogs .

Tray Types and Bottom Options

• Solid bottom: Provides maximum cable protection, welded to side rails .
• Ventilated/Perforated: Allows airflow and reduces weight, typically using 75% or less of the plane area for cable support .
• Ladder type: Side rails with rungs for heavy-duty applications.
• Channel type: U-shaped trays for smaller cable runs .

Selection Criteria

1. Environment: Indoor, outdoor, corrosive, or high-temperature conditions determine material and coating.
2. Load and span: Use NEMA/CSA tables to select tray series and size.
3. Cable volume: Determine nominal depth and width based on cable fill.
4. Bottom type: Solid or ventilated depending on cable protection and airflow requirements.
5. Length: Standard sections are 3 m or 6 m (10 ft or 20 ft), with some series not available in longer lengths . This specification ensures that flat steel cable trays meet mechanical strength, safety, and environmental requirements for industrial and commercial installations. For detailed load/span tables and exact dimensions, refer to manufacturer catalogs such as ABB, Eaton, or Legrand .