Abstract: A ground fault circuit interrupter has a residual current transformer (7) which is connected via evaluation and tripping electronics (6) to a open circuit shunt release (3), the open circuit shunt release (3) via a breaker mechanism (5) actuating the main contacts (10) in the leads (L1, L2, L3) to be monitored, the line voltage supply of the evaluation and/or tripping electronics (6) and/or the open circuit shunt release (3) being connected electrically separably to a least two leads (L1, L2, L3, N) via auxiliary contact apparatus (8). In this way the line voltage supply for the evaluation and/or the tripping electronics (6) and the open circuit shunt release (3) can be interrupted independently of the line-side or load-side terminal with respect to the main contacts (10) and is still ensured when one or two leads (L1, L2, L3, N) are interrupted.