The invention relates to a circuit (1) for detecting a switching state of an electrical switching contact (2) in a current supply path (5) for at least one electrical load (3). The monitoring circuit (1) has a monitoring unit (8) and a transformer (9). The transformer has a primary winding (10) connected to the monitoring unit (8) and a secondary winding (11) connected to the electrical switching contact (2). The secondary winding (11) forms a monitoring current circuit (6) together with the electrical switching contact (2) electrically connected to the secondary winding. The monitoring unit (8) is designed to apply electrical power to the primary winding (10) and to determine the switching state of the electrical switching contact (2) in dependence on a measured value (UA) proportional to the current (IA) flowing through the primary winding (10).