Polyester and Vinyl Ester cable trays are non-metallic, or in a very simple sense, plastic. Fiberglass cable tray loses 10% of its rated strength at temperatures as low as 100°F. For further assistance, contact David Richmond (NEMA Senior Program Manager) at David. The mechanical and electrical characteristics, tests, certifications, overall quality management, recommendations mentioned in this technical guide only apply to our own cable management ranges and cannot under any circumstances be transposed to si osure, overheating or. maintain spacing or to keep cables in place when the tray is ect the minimum bend ra-dius for cables as they exit the bottom of the cable tray. A rung spacing of 6 to 9 inches (150 to 230 mm) is preferable when the cable tray cont d for instrumentation and control applications that require. This article provides a definitive technical checklist for cable tray placement and safety, grounded in ergonomic science and mechanical engineering principles. The primary goal of an ergonomic workstation is to support the body in a "spinal neutral position," reducing the static load on. Steel cable trays, like all metallic structures, undergo dimensional changes when subjected to ambient temperature variations. In this guide, the expansion gaps are explained to be calculated, as well as how to select materials such as aluminum or steel. We aim to ensure your project remains secure and does not breach the NEMA standards, causing it to suffer.