Conductors of AC or DC circuits rated 1000 volts AC, 1500 volts DC, nominal, or less shall be permitted to occupy the same conduit if ___.

• A. All conductors shall have an insulation rating equal to the maximum circuit voltage applied to any conductor in the conduit
• B. A dividing barrier in the raceway separates the AC and DC circuit conductors
• C. All conductors have a 1500-volt insulation rating
• D. None of these; AC and DC conductors are not permitted in the same raceway

Answer: (A)

The main idea is that when AC and DC conductors share the same conduit, every conductor must be insulated for the highest voltage present in that conduit. In this case, the maximum circuit voltage is 1500 V (DC), so all conductors in the conduit must have insulation rated for 1500 V.

The best choice states that all conductors shall have an insulation rating equal to the maximum circuit voltage applied to any conductor in the conduit. This directly ensures none are underspecified for the highest voltage, which is exactly the requirement for mixing AC and DC in the same raceway.