Ground fault circuit interrupter (GFCI) devices, systems, and methods

A ground fault circuit interrupter (GFCI) circuit breaker, comprising:

• a current transformer (CT) comprising:
• a single core;
• a ground fault (GF) sense winding wound around the single core;
• and
• a test winding wound around the single core;
• a line wire passing through the single core;
• a neutral wire passing through the single core;
• a GF detection module operatively connected to the GF sense winding to receive signals from the GF sense winding and configured to determine whether a line-to-ground fault exists;
• a test signal stimulus operatively connected to the test winding to supply a test signal to the test winding when activated such that the test signal is coupled onto the GF sense winding via the CT and detected by the GF detection module which receives the signal from the GF sense winding to determine if the CT and GF signal chain is operating correctly;
• a grounded neutral (GN) detection module operatively connected to at least one winding and configured to receive signals from the at least one winding to determine whether a neutral-to-ground fault exists, wherein the CT includes a GN sense winding, wherein the at least one winding of the CT that is operatively connected to the GN detection module is the GN sense winding.

A ground fault circuit interrupter (GFCI), comprising:

• a current transformer (CT) comprising:
• a single core;
• a first winding wound around the single core;
• and
• a second winding wound around the single core;
• a ground fault (GF) detection module operatively connected to the first winding to receive signals from the first winding and configured to determine whether a line-to-ground fault exists;
• a GN stimulus operatively connected to the second winding to provide a GN stimulus signal to the second winding;
• and
• a grounded neutral (GN) detection module operatively connected to the second winding and configured to receive signals from the second winding to determine whether a neutral-to-ground fault exists.