A ground fault puts the person in series with body resistance R_b, floor resistance R_f and footwear R_s: I = V / (R_b + R_f + R_s + R_earth). A residual-current device (RCD/GFCI) compares live and neutral current and trips when the imbalance exceeds its rating, typically within 40 ms at the rated current and within 300 ms between half and full rating.

Physiological bands follow IEC 60479-1 in simplified form: about 0.5 mA perception, 10 mA let-go limit, 30 mA breathing difficulty, 75 mA and above fibrillation risk (duration dependent). Real body resistance varies from about 500 ohm (wet skin) to 100 kohm (dry). This is an educational model, not a substitute for electrical regulations; always have installations checked by a qualified electrician.