A GFCI is designed to protect a person from electrocution when contact between a live part of the protected circuit and ground causes current to flow through a person's body. A GFCI will disconnect the circuit when a current equal to or higher than the calibration point (4 mA to 6 mA) flows from the protected circuit to ground. It will not eliminate the shock sensation since normal perception level is approximately 0.5 mA. It will not protect from electrocution on line-to-line contact since the nature of line-to-line loads cannot be distinguished.
