I would go so far as to say that it is fine and sometimes needed to suply equipment from multiple sources, 600v motors with 120v control as an example, or anything with mixed AC/DC.
This strikes me as more of an issue of conductor bundeling.
It is necissary to keep all of the conductors (grounded and non) in a circuit bundled to ensure a ballanced current flow, which reduces the inducatnce of the wire run, prevents stray EMF, and prevent conduit heating. That bundle should be continuous to the panel (hense originatng for the same pannel) wher it is consoldated and then continues bundled to the POCO.
I don't know the code section off hand, and bing a Canadian I'm not sure it would help. I know this has ben dicused in other threads.
To sum up all conductors on the same circuit (ie feeding the same load) must run in the same conduit (be it cabtire, romex, EMT etc.)
Hope this helps,
Jon
