Industrial Power Plant: Requires heavy-duty trays, 2. 5–3 mm thick with widths up to 1000 mm, capable of holding multiple layers of power cables. Although many cable trays share similar nominal widths and depths, dimensions vary significantly by tray type because each design serves a different mechanical and electrical purpose. Ladder, perforated. Cable tray (or cable ladder) systems are a popular alternative to electrical conduit systems, as they have an outstanding record for dependable service, design flexibility and cost savings in commercial and industrial applications. For proper installation, design, and maintenance, adherence to international standards is essential.