22 (A) (1) (a) through 392. 22 (A) (1) (c) outlines the rules for placing multiple conductor cables within a cable tray. In industrial settings, electrical and instrumentation (E&I) cable trays or bridge racks play a critical role in organizing and supporting power, control, and signal cables across facilities. 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. When dealing with any mixture of cables, it is crucial to follow the National Electrical Code (NEC) regulations, specifically 392. ANY MIXTURE. 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. Prevent cable damage during installation and maintenance due to overcrowding. Cable trays give cables a clear path. We use different types of trays for different jobs: Ladder.