A voltage and/or current sensing device for low-, medium- or high voltage switching devices is disclosed as a constructively enhanced measuring device with high performance for use in switching devices. The sensing device can include a first voltage sensing part, a second voltage sensing part and a current sensing part all arranged in a same common single housing separated, from the switching device, in a way that an output wire from the first voltage sensing part, for sensing voltage at an upper terminal of the switching device, is located close to the current sensing part, the output wire being applied with an insulating cover, and mechanically fixed to the current sensor part, and/or the output wire being implemented in an isolation body, and only located near to the current sensing part.

A fusible switch disconnect device includes a housing adapted to receive at least one fuse therein, and a switchable contact for connecting the fuse to circuitry. A current detecting element, a tripping mechanism, and control circuitry are provided to move the switchable contact to an open position in response to predetermined electrical current conditions in the device.

A circuit breaker protecting an electric low-voltage circuit includes a housing with grid-side and load-side connections and a series circuit of a mechanical isolating contact unit on the grid side and an electronic interruption unit on the load side. The mechanical isolating contact unit has a handle opening and closing contacts. A current sensor unit is disposed in a conductor between the isolating contact unit and the interruption unit, for ascertaining a current level of the low-voltage circuit. A control unit is connected to the current sensor unit, electronic interruption unit, and mechanical isolating contact unit. When current and/or current/time thresholds are exceeded, prevention of a current flow in the low-voltage circuit is initiated. A power supply unit supplying energy to the circuit breaker is connected to conductors of the low-voltage circuit between the isolating contact unit and the interruption unit.