They are not only suitable for the overhead laying of indoor and outdoor cables in industrial and mining enterprises such as petrochemical, textile machinery, metallurgy and electric power, and radio and television industries, but also can be used for the laying of cables in. They are not only suitable for the overhead laying of indoor and outdoor cables in industrial and mining enterprises such as petrochemical, textile machinery, metallurgy and electric power, and radio and television industries, but also can be used for the laying of cables in. 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. A properly designed and installed cable tray system will provide. Long-span cable trays have a larger support span than ordinary cable trays, with a more sophisticated structural design and greater load-bearing capacity. Because of its closed design, this type of tray should e used in applications where there is minimal risk of heat generation and buildup. This provides the designer and user many benefits. Add, change, modify more easily Longer support spans up to 55' (Chalfant's standard systems to 40'). The mechanical and electrical characteristics, tests, certifications, overall quality management, recommendations mentioned.