Interference that could be inducted from on system to another and may interfere with a communication or control circuits and should be considered. One also must assure that the insulation rating of the conductors are rated for being installed next to one another. Placing a conductor with 250v insulation rating next to a conductor carrying 480v is not acceptable.
Identifying the conductors may be something that also should be considered. As an example in the MCCs that I have sold power wire was black, the common control circuit was red, separate source AC that entered and exited was yellow, and where there was DC blue wire was used.
