scope:

This NEMA white paper is applicable to products conforming to Class A GFCI levels established from scientific data and research presented by Dr. Charles Dalziel, which shows how 6 mA is the established limit that defines the let-go threshold value to prevent electrocution.

Products intended primarily to protect human beings from harmful effects of electric shock by sensing ground fault(s) and/or leakage current(s) on grounded and/or ungrounded systems rated 1000 volts AC or DC and below, and interrupting the electric circuit to the load when a fault current to ground and/or leakage current(s) exceeds some predetermined value that is less than that required to operate the overcurrent protective device of the supply circuit. Class A GFCIs provide effective protection against electrocution when the current-to-ground exceeds 6 mA on supply circuits, single- or three-phase AC, not exceeding 150 volts-to-ground.

The interrupting mechanism of this equipment may be separate from the sensing device or integral with the sensing device. Ground fault circuit interrupters may be combined with other signaling or limiting products.

Excluded from the Scope of this white paper are products primarily intended to provide ground fault protection of equipment (GFPE) against damaging line-to-ground fault current levels less than protection by supply-circuit overcurrent devices. It is important to note that these GFPE products are not designed for personnel protection. GFCI and GFPE are defined in accordance with the NEC^®.