My house has a lot of older armored cable using the armor for ground.
If I'm working in a box and find a three-conductor wire with only black/white in use, and I know where the other end is, should I use the red conductor to improve the ground path of that run and its two boxes (also marking both ends with green tape) or should I leave it alone with the red unused and the armor for ground?
Best Answer
That would be a code violation. You may not re-mark green, green-yellow, or bare to any other color, and you may not re-mark non-ground colors to ground colors.