With the NEC, there's a specific rule: 300. 8 Installation of Conductors with Other Systems. Race‐ ways or cable trays containing electrical conductors shall not contain any pipe, tube, or equal for steam, water, air, gas, drain‐ age, or any service other than electrical. Cable ladder systems and cable tray systems shall be manufactured in accordance with BS EN 61537, channel support. Question 1: Can mechanical utility piping or tubing containing water or compressed air be installed in cable trays with electrical cables? Answer: No. Cable trays are a support system for electrical cables, power, signal, and communication and optical fiber cables. NEC section 300-8 does not permit. Assuming you're talking about hung cable tray (not cable tray on the floor. ) putting wet utilities underneath makes them a lot easier to access and maintain.
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