I don't think people know the difference between 10-2 and 10-3, there is some obvious confusion about the subject... hence the 3-wire and 4-wire dryer/receptacle comments being made...
The picture below is 10-2 NM, notice that if this was used for a dryer, you would be forced to use the bare copper wire for the neutral, this is the code violation, the neutral conductor MUST be insulated... Hence the use for 10-3 which would contain a blk,red,white, and bare copper conductor...
Here are some examples of the 1996 code change dealing with 3-wire and 4-wire receptacles...
Three Wire Hook-up, Notice the Grounded (neutral) is also bonded to the frame of the dryer, so the neutral was also the ground.
Four Wire Hook-up, Notice the Grounded (neutral) and Grounding (ground) conductors are isolated...

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