If the locking plugs/recectpacles require 10/3 in the setup,
then use the required cable for the job. Save the 10/4 for another job.

Jury rigging electrical work is not a good thing. Weird stuff can and
does happen so no need to offer a path for stupid stuff to occur.

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"What you hear in a great jazz band is the sound of democracy. “The jazz band works best when participation is shaped by intelligent communication.”
Harmony happens whenever different parts get to form a whole by means of congruity, concord, symetry, consistency, conformity, correspondence, agreement, accord, unity, consonance…….