Under which condition can Class 2 and Class 3 circuits be placed with Class 1 or electric light or power conductors?

Class 2 and Class 3 circuits are designed to operate at lower voltages and carry less power than Class 1 circuits, which are typically associated with higher voltage and power levels, such as electric light or power conductors. The National Electrical Code (NEC) provides guidelines on how different classes of circuits can be installed relative to one another to ensure safety and performance.

When Class 2 and Class 3 circuits need to be placed alongside Class 1 circuits, the requirement is that they must be separated by a barrier. This barrier serves to prevent undesired interactions between the circuits, such as interference, contamination, or other types of electrical problems that could arise due to the different operational parameters of the circuits. The separation ensures that the lower voltage circuits maintain their safety and performance characteristics while being run in proximity to higher voltage conductors.

The option referring to separation by a barrier aligns with the NEC regulations, which aim to safeguard both the integrity of the lower voltage circuits and the safety of the overall installation. Proper separation helps minimize risks such as electrical shock or equipment failure that might occur if the circuits were allowed to interact more freely.