How is the non-ridged smooth-sided parallel wire attached to a chandelier light fixture coded to determine which wire is hot and should be connected to the black?

Answer 1

The ribbed sheathing always denotes the neutral conductor and should be connected to the neutral incoming power conductor (usually white). The non-ribbed sheathing is the hot conductor and should be connected to the hot incoming power conductor (generally black). It will work if wired backward (reverse polarity), but if the appliance is polarized, you should wire it accordingly. For example, a light socket is generally polarized to make the ribbed socket part (which human hands will likely come in contact with) neutral. Wiring with reverse polarity would make this socket hot (not safe).

Answer 2

The side with the 'ridge' is always supposed to be the neutral side. The smooth side is supposed to be 'hot'. Don't bet your life on it, though. Someone may have connected them in reverse at some point in time.