If unshielded low-voltage circuits are kept close to power conductors, what NEC requirement must be observed?

If unshielded low-voltage circuits are kept close to power conductors, what NEC requirement must be observed?

• A. a shielded raceway is required
• B. no barrier is required if insulation is rated
• C. a continuous, firmly fixed barrier
• D. use fiber optic cables only

Answer: (C)

When unshielded low-voltage conductors run close to power conductors, a physical separation is required to keep the two systems apart and prevent interference, heat transfer, and potential safety issues. The NEC requires a continuous, firmly fixed barrier between the circuits along the entire run. This barrier must be listed and properly installed, ensuring the low-voltage wiring remains isolated from the power conductors within the same enclosure or raceway. Shielding the raceway isn’t the mandated solution for this proximity issue, and simply relying on insulation ratings does not substitute for a separating barrier. Fiber optic cables are another option for isolation, but the NEC requirement in this scenario is the continuous barrier, not a mandate to switch to fiber-only.

When unshielded low-voltage conductors run close to power conductors, a physical separation is required to keep the two systems apart and prevent interference, heat transfer, and potential safety issues. The NEC requires a continuous, firmly fixed barrier between the circuits along the entire run. This barrier must be listed and properly installed, ensuring the low-voltage wiring remains isolated from the power conductors within the same enclosure or raceway.

Shielding the raceway isn’t the mandated solution for this proximity issue, and simply relying on insulation ratings does not substitute for a separating barrier. Fiber optic cables are another option for isolation, but the NEC requirement in this scenario is the continuous barrier, not a mandate to switch to fiber-only.