Final answer:
Class 2 and Class 3 circuits must not be placed in the same enclosure, raceway, cable, or fitting with Class 1 or electric light/power conductors, unless they are separated by a barrier.
Step-by-step explanation:
In electrical wiring, Class 2 and Class 3 circuits are low-voltage circuits that have specific safety requirements. According to the National Electrical Code (NEC), Class 2 and Class 3 circuits should not be placed in the same enclosure, raceway, cable, or fitting with conductors of Class 1 (high-voltage) or electric light or power conductors, unless they are separated by a barrier.
This is to ensure that the low-voltage circuits are kept separate from high-voltage circuits for safety reasons.