To reduce EMI, unshielded low-voltage circuits should be separated from power circuits by a minimum distance of how many inches?

To reduce EMI, unshielded low-voltage circuits should be separated from power circuits by a minimum distance of how many inches?

• A. 12 in
• B. 24 in
• C. 36 in
• D. 48 in

Answer: (B)

Keeping power and unshielded low-voltage circuits physically apart reduces electromagnetic interference from the power lines. Power conductors create changing magnetic fields that can couple into nearby unshielded cables, causing noise or data errors. The established minimum distance to minimize this coupling is 24 inches (two feet). This distance provides practical separation in typical installations without requiring excessive space. If you can’t maintain that gap, use shielding, metal conduit, or routing in separate paths to still limit EMI. A smaller gap like 12 inches poses a higher risk of interference, while larger gaps (36 or 48 inches) are more conservative than the standard baseline for general practice.

Keeping power and unshielded low-voltage circuits physically apart reduces electromagnetic interference from the power lines. Power conductors create changing magnetic fields that can couple into nearby unshielded cables, causing noise or data errors. The established minimum distance to minimize this coupling is 24 inches (two feet). This distance provides practical separation in typical installations without requiring excessive space. If you can’t maintain that gap, use shielding, metal conduit, or routing in separate paths to still limit EMI. A smaller gap like 12 inches poses a higher risk of interference, while larger gaps (36 or 48 inches) are more conservative than the standard baseline for general practice.