Typical home wiring in years past is all 12/2 romex (black, white, bare copper/ground) rather than 12/3 romex (black, red, neutral, bare copper/ground). In a standard 240v box, the wires would be ckt.1 -Black, ckt. 3 - Red, ckt. 5 - black, ckt. 5 - Red, etc. Same theing with ckt. 2, 4, 6, 8, etc.. 12/2 is cheaper so a lot of romex jockeys will use standard 12/2 and tape the neutral as needed.
