Under what condition can conductors of AC and DC circuits rated 1,000V or less occupy the same enclosure or raceway?

Conductors of AC and DC circuits rated 1,000 volts or less can occupy the same enclosure or raceway under the condition that all conductors have insulation ratings equal to the maximum voltage being applied. This requirement ensures that the insulation is adequate to prevent breakdown and to maintain safety in the enclosure where the conductors are located. By having insulation rated for the maximum voltage, the risk of electrical faults, such as short circuits or insulation degradation, is minimized.

The other conditions mentioned do not pertain to safety or compliance with the National Electrical Code in the same way. For instance, color coding does not affect the electrical properties or the insulation integrity of the conductors, nor does the material composition directly relate to the risk of voltage breakdown in mixed circuits. While inspections are critical for overall safety, they do not themselves constitute a condition for allowing the mixing of AC and DC conductors in the same raceway or enclosure. Therefore, the requirement for matching insulation ratings is the key factor for safely combining these conductors.