1.1 These requirements cover ground-fault circuit-interrupters intended for use in one of the following
applications:
a) Where the voltage to ground is greater than 150 volts and equipment grounding or double
insulation is required by the National Electrical Code, ANSI/NFPA 70,
b) Where the voltage to ground is 150 volts or less and equipment grounding or doubleinsulation
is provided, but the use of a Class A ground-fault circuit-interrupter is not practical.
1.2 Ground-fault circuit-interrupters addressed by these requirements are divided into three classes,
Class C, D and E, based upon voltage rating and the characteristics of the grounding circuit. Some are
intended for use in circuits where grounding is not provided to the load but double-insulation is provided.
1.3 These ground-fault circuit-interrupters are intended to be applied on circuits as shown in Figure 1.1.
The requirements for Class A ground-fault circuit-interrupters are in the Standard for Ground-Fault
Circuit-Interrupters, UL 943.
UL SUBJECT 943C-2011 history
2012UL SUBJECT 943C-2012 OUTLINE OF INVESTIGATION FOR SPECIAL PURPOSE GROUND-FAULT CIRCUIT-INTERRUPTERS (Issue 2)
2011UL SUBJECT 943C-2011 Outline of investigation for special purpose ground-fault circuit-interrupters