Spring knot is used to connect cable tray or trunking to channel. Approved and correct fittings are used. Installed containments are free of damages. Whether you're building a commercial setup or upgrading an industrial plant, proper cable tray installation ensures neat wiring, safe access, and easy maintenance. This guide breaks down the process step by step. en completely installed, without damage either to conductors or structural system use 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. The following pages address the 2014 National Electrical Code® requirements for cable tray systems as well as design solutions from practical experience.