20/03/2026
The human body’s electrical behavior is dominated by skin resistance and internal tissue impedance, and the image correctly emphasizes how dramatically this changes between dry and wet conditions.
Under dry skin contact, the outer layer of the skin (stratum corneum) acts as a strong insulator. This layer is composed of dead, keratinized cells with very low moisture content, which significantly restricts charge movement. As a result, typical skin resistance can reach ~100 kΩ to 300 kΩ depending on pressure and contact area. Because of this high resistance, even if a voltage is applied, the resulting current remains relatively low (e.g., ~0.5–1 mA range), often below dangerous thresholds. The internal body resistance (muscles, blood, tissues) is much lower (~300–1000 Ω), but under dry conditions, the skin dominates the total impedance.
In contrast, wet skin drastically reduces resistance, often down to ~1 kΩ or even lower. Moisture introduces electrolytes (salts, minerals), which increase ionic conductivity. Additionally, water softens the outer skin layer, reducing its insulating properties and increasing effective contact area. This effectively “bypasses” the high-resistance barrier of dry skin. As a result, the total body resistance becomes dominated by internal resistance rather than skin resistance.
According to Ohm’s Law (I = V/R), when resistance drops sharply, current increases proportionally. For the same applied voltage, reducing resistance from ~300 kΩ to ~1 kΩ can increase current by hundreds of times. That is why the image shows currents rising from sub-milliamp levels to hundreds of milliamps (~220 mA), which is well into the fatal range due to risks like ventricular fibrillation.
The ear-to-ear or hand-to-foot paths are especially dangerous because they pass through the chest and heart. Internally, the body behaves like a combination of resistive and capacitive elements (due to cell membranes), but at power-line frequencies (50/60 Hz), resistive effects dominate for safety analysis.
In summary, the key reason for the drastic difference is:
Dry skin → high resistance barrier (keratin layer)
Wet skin → reduced barrier + ionic conduction
Internal resistance remains relatively constant (~1 kΩ)
This is why electrical safety standards always assume worst-case (wet conditions) when evaluating shock hazards.