|
C21 only defines the colors that can be used for wires that carry constant polarity. The output of the speed controllers and spikes do not have constant polarity and do not fall under this restriction (which is also stated in the rule)
It is a bit of a pain to explain to the inspectors why a certain speed controller has 2 black wires coming from it, but it is legal.
It seems that I'm just repeating what Nate said, but it seems that not everyone realizes this.
|