I have a multi-wire that is very old and doesn't have a ground. I'd like to change this to using new Romex so that AFCI breakers will work. My question is this... Can I band the red wire in my multiwire cable with green tape and then use that as a ground? Of course, I'd band it with tape on both ends....
The alternative is to either abandon the red wire and use a ground from another source in the next junction box (available) or replace the old 12-3 Romex that doesn't have a ground with a new 12-2 also.
Phrased differently: 1. Replace 12-3 w/o ground with two 12-2 that have grounds 2. Replace 12-3 w/o ground with one 12-2 with ground and reuse old 12-3 w/o ground, using ground from new 12-2 in the next junction box 3. Replace 12-3 w/o ground with one 12-2 with ground and reuse old 12-3 w/o ground, banding with green tape the red wire and using that as the 12-3's ground.