These are 120v (coil) lighting contactors? If so the signal wires are class 1.
725.26(B)(1) says they can share the same raceway with your power supply conductors. Since these contactors draw fairly low currents (~.5a) 725.28(B)(2) says you only have to look at the power supply conductors for derating and since there are only 3 it is moot.
If your lighting controller provides supplimental O/C protection you can probably go with 16ga or 18 ga signal wires, 725.23. Just be sure they have normal 600v insulation.
