I'm an electrician that does control wiring as well. Home Depot and most hardware stores sell multi conductor cable in a jacket that can be removed. These can be bought by the foot and come 2 , 4 , 6 , 8 , 10 conductors in a jacket. The most common gauge will be 18 awg but there is also 16 and 22 also. The best part is each wire is a different color. Belden is one brand I use a lot. Good luck.