At approximately 0.5 milliamp of current, what sensation is typically felt?

• A. Tingling sensation
• B. No sensation
• C. Painful shock
• D. Muscle paralysis

Answer: (B)

Understanding how current interacts with the body helps explain this. The nerves in the skin typically start to perceive alternating current around about 1 milliamp at common safety frequencies, so a current of roughly 0.5 milliamp is usually below the perception threshold. In other words, such a small current generally passes without a noticeable sensation. Keep in mind that perception can vary with skin moisture, contact area, and frequency, and that higher currents can still be dangerous even if this tiny amount isn’t felt.