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Furthering to try and sort this out...

As the Low Voltage rules would or would not apply under 725.x for Class 2 and Class 3 signal wires or 800.x for Communications (all subject to circuit rating determination)...

It appears an exception would be if "Class 1 wiring methods" were employed under 725.25 and subsequent sections.

The question that would arise is under 725.27 (A) calling for 18 AWG and 16 AWG as "shall be permitted" to be used... and under 725.27(B) calling for "shall be suitable for 600 volts"...

Any ideas where shielded 24 AWG twisted pair conductors rated to 300 volts might fit in with the examples above?

Possibly get your answer in 725.26 B(1) (2) (3)
Mixing of Voltages .Class 1 & Power supply circuits.

if its high voltage no it violates it if low it might pass ill have to check.....

Apparently the crux of the matter is if the Class 2 wires were installed via Class 1 wiring methods, then the conductors can all share the same conduit, boxes, etc. Panel wiring methods come into play also.

The distinction that would apply under Class 1 wiring methods would be the need for 16 or 18 AWG wire and 600 volt insulation.

Therefore I would deduce that 24 AWG CM rated wire with 300 volt insulation would be a "no fly" and the wiring would not meet NEC requirements.

Theres a difference between Class 1,2,3 Circuits .
Not just the way there installed.
Class 1 725.21(A)
Class 2 & 3 725.41
then read 725.26
725.55
2005 NEC

Yooper,

I know, but / and thanks for helping drive the discussion toward NEC subtle details...

Apparently, by driving a Class 2 classification (in this example) based on the power limited supply that feeds it and the Class 2 devices interconnected by the wiring... It is still OK to use Class 1 wiring methods, in other words upgrade the wiring which would then allow the combined conductors in the same raceway (at least, so I'm told.)

Correcting my original post - the Modbus and Lon bus orange wiring in the photo example are 24 AWG with 300 volt rated (CM on the jacket) insulation with soldered twist splices covered by wire nuts.

The way I read it the Class has a big part in the two being able to be put together as well as the wiring methods. Now if you changed the power supply from a class 2 or 3 to a one that might be a different story.
See 725.52 (A) Exception 2 & fPN below
Class 1 rated output of Not more then 30 volts & 1000 volt amps.