Hi bill, in my 25+ years as a commercial electrician i have seen many lost hours caused by guys pulling the wrong color wire into a breaker panel.to comply with nec code the low voltage colors are black,red,blue and the high voltage colors are brown,orange,yellow.the 42 numbers are the circuit breakers.odd on left,even on right.lets say i have to pull circuit #27 low voltage.the proper color is red.the colors are redundant top to bottom.punch circuit number into calculator and find proper color.also calculator could tell how many neutrals to pull when pulling multicircuit branch wireing.thanks bob