It’s not just insulation level but be careful with ratings in tests. If the tray is technically PLTC for instance, power conductors in non-limited equipment can’t be mixed in the sane tray without a divider or say innerduct. So if you put motor leads in there, the power limited signaling becomes a Code violation since the test is no longer PLTC.
The usual culprit is Ethernet. Ethernet cable is available in 300 and even 600 V insulation as AWM. It is legal in 508 and 508A panels as those are Listed assemblies and that’s where AWM comes in. But in general use outside a panel, they must be separated. Testing has shown that Ethernet in particularly can be strapped to welding robots, VFD lines, etc., due to massive filtering against low frequency interference and 30 dB SNIR. But since capacitance requirements make #22-24 a requirement, it fails the UL requirement of nothing smaller than #18. This is unlike traditional signal protocols (RS-485 and similar) and analog voltage loops which are much lower frequency and subject to interference without shielded cable. This is for copper Ethernet. ADSS (all dielectric) fiber is if course not a problem running in energized spaces.
A simple solution is to put a divider in the tray but honestly nobody ever maintains it that way over time and cost wise a simple 2-4” instrument tray is just as cheap.
That being said if you eschew Code, lots of industrial plants do this all the time particularly with Ethernet since it is basically immune even with just standard UTP. Inside panels it’s even worse. Few panel builders pay any attention to interference or even proper grounding. Allen Bradley literally wire ties signal conductors with power bundles in their factory built panels with Ethernet, 4-20 mA, VFDs, you name it, with no problems. But be careful to follow grounding rules and shield cable where you need it. This means ground the shield at one end only and the most effective end is at the load. Twisted pair is inherently shielded against electrical but not magnetic fields. Minimize signal loops and avoid ground loops. Basic low interference construction like this works just fine. On analogs be aware that some manufacturers, particularly Allen Bradley, do not have isolated analogs. In that case either short the return sides together to eliminate interference or else use external optical isolators, or buy better cards.
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