Cable tray support quantity can be calculated using a simple formula: Support Quantity = Total Length ÷ Support Spacing + 1 20 ÷ 2 + 1 = 11 supports In a typical project, a 20-meter cable tray with 2-meter spacing requires 11 supports. OBO BETTERMANN has offered prod-ucts and solutions for electrical instal-lation for over 100 years. With our many years of experience, we are one of the leading manufacturers in this field. Establishing partnerships. This publication is intended as a practical guide for the proper and safe* installation of cable ladder systems, cable tray systems, channel support systems and associated supports. The mechanical and electrical characteristics, tests, certifications, overall quality management, recommendations mentioned. If full details of the cabling layout are available then the likely cable load can be calculated using either manufacturer's published information or the tables of Cable Weights and Diameters which are given below. IEC 61537 and IEC 60364 require evaluating tray dimensions based on cable quantity, type, and layout configuration. Below are industry-standard tray and ladder.