When low-voltage and high-voltage cables run in parallel, they should be separated by at least how many inches?

• A. 3 inches
• B. 6 inches
• C. 9 inches
• D. 12 inches

Answer: (B)

When cables run side by side, the magnetic fields from the high-voltage conductors can couple into the low-voltage ones, introducing interference and potential tracking or insulation stress. Keeping a minimum gap reduces inductive coupling and heat transfer, helps keep conductors cooler, and makes it easier to inspect and service them without them touching or rubbing together. Six inches is the commonly used minimum distance in many installations because it provides a practical, safe buffer without requiring excessive space. If six inches can’t be maintained, use barriers or separate conduits/trays to preserve separation and minimize interference.