Also, the armor of old style AC or BX (without the aluminum bonding strip) is not recognized as an equipment grounding means, and in reality on longer runs the armor's resistance is not low enough to trip the breaker if a dead short occurs. If your old house has this kind of AC, then I guess you need to feed the circuit with a GFCI breaker, or find the first receptacle and install a GFCI receptacle there, and wire the rest from "load". Don't forget the stick-on markers.
