Is it a general rule that the neutral conductor should not be switched
or used as one leg in a switch loop?
Sorry for all the questions, I am reviewing for an exam and am trying
to figure out the questions I am unsure of.
A neutral is not allowed to be switched. (I think I remember an exception
regarding fuel pumping.) A white wire is not always a neutral. It sounds
like you are referring to what the ignorant among us call "back-feeding the
neutral". The code does not allow the use of a white wire as a "hot" at the
point of connection to a load, so if we're using something like NM-B to make
a path from our supply to a switch and back, we have to use the white wire,
(not a neutral unless it is eventually connected to the neutral buss), to
feed the switch, and the black wire to feed power back to the load.